Marom Bikson
All right, Tom, I got a lot of questions for you. So, let's see how many we can get through. you know, one of my questions really relates to, I guess, what was your thesis work, which was dorsal column stimulation for pain. And the reason this is interesting to me is, you know, you often have sort of major developments in some area and, you know, it's hard to point to one thing that changed the course of history.
..in that there were many labs, many contributing over a long period of time. But, you know, this particular paper, Electrical Inhibition of Pain by Stimulation of the Dorsal Columns, preliminary clinical report, which was, know, Shealy, you and Reswick in 1967. My sense is that that paper launched spinal cord stimulation as a therapy, which is now a multi-billion dollar business... which has impacted, I don't know, hundreds of thousands of people, right? So I want to hear this, I just want to hear the whole story of how that paper happened, like, you know, and so, yeah, maybe you can start there.
Thomas Mortimer
Marom, I would say serendipity is a good word to use there. Serendipity actually is a word that plays many, has played a role in so many elements of my professional life, actually my life, but certainly in the, in how my life rolled out in the world of electrical stimulation. So, I'm going to back up. from that, if I may. I wanted, my plan here is to kind of introduce to you how those three people, Reswick, Shealy and Mortimer came together.
So, I arrive at Case Institute of Technology in January of 1964, having graduated from Texas Tech with an electrical engineering degree.
I show up and I, well, there was, was a serendipity there that I ended up in Jim Reswick's lab. I had made an application to case to biomedical engineering graduate school. I'd heard that bioengineering was something that was there. And my letter was picked up by Bob Plonsey in the bioengineering side. And he saw that
I had expressed an interest in restoring function to spinal cord injured patients, which for me was driven by a very close friend having been in an automobile accident and rendered quadriplegic. So that's a driving force for me. I arrived in Jim Reswick's lab. Jim Reswick had started probably in their very early 60s a project to restore function for high level spinal cord injured patients using an exoskeletal structure that was pneumatically powered and that the subject put their arm in and then there was a pre-recorded set of programs to move the person's arm around so they could brush their teeth, shave, comb their hair, eat, know, things like that that were on a desk in front of them.
And that project was just coming to completion when I arrived in 1964 as a graduate student entering the master's program.
So, I take also my start taking graduate courses and I get a course into a course, physiology and biophysics or something like that by Bob Plonsey and Dave Fleming putting this course together. And most of our notes were on things called mimeograph, which were blue, was blue type things on white paper, very old way of reproducing.
This is well before Xerox came along. Or about the time actually Xerox was coming along. It was about the same time. So anyway, I take this course and I learned there about golgi tendon organs and muscle spindles.
Part one, now another piece of the puzzle that sits in here is that Loise Vodovnik arrives within days of when I show up at case, him from Yugoslavia as a postdoc, I guess. And he comes with the idea of, he's…electrically activating paralyzed muscles as a way of restoring function. And so he sees Jim Reswick's device, he can replace the pneumatic motors in his mind's eye with electrically stimulated muscles. The exoskeletal structure is the skeletal structure of the patient. The system that they had built was using closed loop control.
And so, they needed position information on this exoskeletal structure to control it. So Mortimer sees this thing called goji tendon organs and muscle spindles as, hey, if we go this other route and any new thing, maybe we could replace all of these electromechanical transducers on the outside of this device with recording from spindles and tendon organs, because they record force and they record muscle length. So Mortimer says, convinces Reswick, who knows nothing about this kind of stuff, that this is a project I'd like to do as a master's thesis.
Marom Bikson
Reswick was not an electrical stimulator.
Thomas Mortimer
No, nothing but he was a mechanical engineer out of MIT. And he came to CASE as I think a full professor. And his mentor was John Rohns, who was the provost at CASE Institute of Technology. So, Jim was a mechanical engineer. From my perspective, I always viewed him as an engineer's engineers. I loved his solution by idea to problems. They were so simple off. I just, really relished in just hanging around and see what he did. And there it was, and the climate he provided for us was remarkable in there. I mean, the fact that he didn't know anything about Rote tendon organs recording these things and let me go into it and try it. I didn't know zero, I knew zero about this. So, because I was interested, I needed somebody at Case to work with. And so, the only person that Jim seemed to know about was Joe Foley who was head of neurology at that time. So, he introduces me to Joe Foley.
And I go meet with Joe Foley and tell him this story that I want to do for a master's thesis. I'm going to record from nerves and I'm going to use these signals for length and force and length transduction.
So, Foley says, no, I wasn't thinking at all about stimulation then. You know, this was just, this was information that would be available in a paralyzed, in my mind, in a paralyzed limb. So, I was going to tap into it and use it for whoever you, or whatever way. But Dovnik here sitting here beside me as a postdoc pushing this idea of electrical stimulation of paralyzed muscle.
Thomas Mortimer
That's not me. Although he had influenced Bill Crocheter, who was one of my classmates and a very good friend to actually work, began working on this problem of electrically activating paralyzed muscles using closed loop control, but not from spindles and tendon organs that wasn't available.
So, you in your mind and your knowledge should be thinking that was really a way out of line idea for Mortimer to be thinking about these kinds of things. Maybe there is a track, but that guy sure didn't know much about recording from the nervous system. Well, that's true. So, I go over and meet with Foley. Foley says, I don't have anything here in the department of neurology, but in the...
Thomas Mortimer
neurosurgical department, there's a guy named Norman Shealy who is working with cats and maybe he could help you in this. Maybe they have the setup so you could, you I don't know, the setup is there. Maybe he'll help you, maybe he won't, I don't know, but I'll introduce you to him. So, I get introduced to Norman Shealy. Where's, let me back up just a little bit. So
Before I meet Norman Shealy and I meet Joe Foley, Joe Foley says, I have a former resident at Mass General, Joe Vander Mulen, and another guy, I can't remember his name, who do cat experiments over there. And they've done these kinds of recordings that you're interested in. I think I could arrange for you to meet with them.
So, Tom Mortimer gets in an airplane, probably the second airplane he's ever been on in his life. Maybe that was the first. Fly to Boston, meet Joe VanderMeulen and this other guy in their lab. And they set up an experiment to show me how to record from muscle, spindles, and golgi tendon organs. They actually run the experiment. So, I come in there, they anesthetize the cat, they shave the hair.
They expose the nerve down in the top of the teal fossa of the cat's hind leg. And they do a, and they cut, make an incision along the spine, do a laminectomy, open the dura and expose the dorsal roots in there. So, I get to see this once, okay, how it's done. And so it's like, well, this is interesting. And I did kind of like it.
It did fascinate me. So, I come back and then Foley introduces me to Shealy and I tell Shealy about this experiment that I saw Vander Mulen run. And Shealy has a good technician that that understands all this. And he starts and he said, sure, I'll help you get started in here. So, I'm over there.
And Reswick knows nobody in here except Foley, doesn't know Shealy at all. I'm over there working on this stuff. And I start recording from, I figured I find out how to record, how to identify them, to measure conduction velocities. It was an interesting experience. And you know what I'm talking about, if you do it for the first time, it's intriguing when you do this kind of thing.
So, I had a lot of, it was kind of fun. And so I started setting out to build a way to do chronic recordings of this, because this is what I would have to do as a chronic recording. And I would have to be able to put this electric, the cuff on a nerve that contained both efferent and afferent information moving. And I need to be able to identify what, which one was which on there.
So, I set up to.
Marom Bikson
Then there's there already are cuffs so this would been a wire at this point.
Thomas Mortimer
No, these were cuffs. Cuffs I built. All this stuff I built. You couldn't buy, at least I didn't know where to buy anything. So, it was just whatever I dreamed up. And I think probably a lot of these was a piece of silicone rubber tubing that had stuck a wire in it somehow and made a recording electrode out of it. So anyway, I got this. This turned out to be tremendously hard to be able to get a
Marom Bikson
I see.
Thomas Mortimer
I had a way of identifying the direction it was going and if it was something I wanted and there was, repeating it and then you look at statistically, it keeps showing up. So, you know what it is. I'd set up timing stuff. So, in a way, it kind of worked and I really hated it when, because I'd set this, I created an artificial nerve that created all these action potentials going to different velocities and in different directions. And then I put my algorithm to how to determine which of these action potentials belong to which. And it's pretty good, worked pretty well. But boy, when you stick that electrode in an animal, everything starts to fall apart pretty quickly. So.
Marom Bikson
such as what, the nerve was getting damaged.
Thomas Mortimer
I mean, just stuff. It didn't work very well. It just was like, man, yeah, the work amount of work I had to do to even demonstrate that it was, I could do it much less see it was feasible was almost overwhelming. Well, I would say probably overwhelming was pretty good point because they did finish my master's degree.
And I was pretty disillusioned with myself as a candidate to be a guy in research in biomedical engineers hearing working with animals. This was nothing like I had experienced in an electrical engineering lab. A lot of frustrations, a lot of very nice long nights and running experiments, a lot of
when animals die before I finish. It was endless frustration. And then the net result really wasn't that exciting, my thesis. So I ended up with my master's pretty disillusioned about whether I would ever be a biomedical engineer or not. I could come up with a decent research idea in there.
Marom Bikson
I would say that the thing you were struggling with is exactly what biomedical engineering is about in a sense. mean, it's not that you're exactly you were working through the essential hard issues already, but yeah, they're frustrating.
Thomas Mortimer
But you know, didn't have a, there was no mentor around to say, yeah, I've been here. I've done this. Yeah, you're, doing fine. Keep going. I didn't, that was not there. It was either, it was just what I could see for myself. Okay. Now I'm going to back up again, slightly. So while I'm working in, Shealy's laboratory, Shealy and I kind of become
sort of friends there. I, with my new case graduate students, had learned to play squash. These guys had taught me squash. And so I was playing squash and Shealy decided he wanted to play squash. And so, you know, it was turnabout fair try, you know, let me use all the stuff. And by no means was I a good squash player. And I said, you know, I'll play, I'll show you what I know.
So we began playing squash. Now this is in the time, Marrone, that there was Case Institute of Technology and Western Reserve University. Shealy was in the School of Medicine at Western Reserve. I'm at Case Institute of Technology as Jim Reswick's graduate student. And so I start playing squash with Shealy and Shealy can't play till the end of the day. So like five or 530, we go have a squash game. So we play at Case sometimes and I'm living in what was called the Graduate House. The Graduate House is now called Tudor Arms. It used to be way a long time ago called Tudor Arms. The Graduate House at my time was a university circle facility where professional and graduate students at Case and Western Reserve
were housed. It was really by any standard, it was really up class housing. The cost of housing there, Marrone, was $125 a month for room and board. My stipend was 135. So I needed to get lower rent. I need to get a lower, something that costs less.
Marom Bikson
Okay.
Thomas Mortimer
And I take on a lot of jobs to get some money to go on dates or do something in there. $10 doesn't last very long. It was lasted longer than you would think today. anyway, so Shealy and I are walking back. He rode his bicycle down often from his home up an edge up in Euclid Heights. We're walking along and chatting there after the squash game. I don't know why I'm walking in that direction other than going back to Case to class or to study. And I start telling Sheila about I'm gonna need a place to stay. You know, I'm looking for a place to stay. So Sheila proposes, and this is now I'm finished my master's. So now I'm at the summer of 1965. And Sheila says,
You know, I have some work I need to do in the third floor of our house. If you would be interested in, you know, painting and plastering and doing some of that work there, you know, you could stay for free. So I said, well, you know, I don't know, let me see what I'm getting into. So I over and looked at their house. I said, yeah, I think I could do this. So, you know, this was, we were talking about a summer.
I was going to do all this in the summer and then I would have to find somewhere else to live in the fall.
The deal they made with me was, and we'll give you room and board for nothing. I ate breakfast there. His wife prepared a lunch for me and him and kind of like sent us off to work with these brown bag lunches, outstanding food. And they were really in the gourmet cooking too, both of them. So I ate with them every meal in there.
And, you know, sort of was a member of their family. They had two small children at the time and eventually became the godfather for one of them, the middle one, who became the youngest one who became the middle one later. And so all of this to say, you know, is how they unfolded me into their family.
Thomas Mortimer
This and the two of them, Norman and Shardy, his wife, Mary Charlotte, were pretty sophisticated people. They had been, he had done a postdoc in, what's the guy's name that was in Australia? Sir, you'd probably, anyway, big neurophysiologist name in Canberra. He had his lab in Canberra. I'm blocking on that name right now.
His name was Sir something or other. And anyway, so they had spent that I mean, these are such worldly people to this boy coming out of North Texas, that it was it was just I was a very different piece of work for them. So I'm now learning gourmet cooking there. So eventually, then it goes on she said they I finished this job time fall comes.
Thomas Mortimer
They say, you know, if you want to stay on, just stay on. You know, we can stay here. So, boy, I still wasn't paying anything. So, know, I had my whole stipend to live on. so the deal they worked out with me was that, and Norman, Shardy would make all the meals except Sunday evening. And one Sunday was Norman's, next Sunday was mine. We alternated there. And they had
They took Gourmet Magazine. So, I would pick a menu out of there and she would do the shopping and I would prepare the from Gourmet Magazine. So, I was learning a lot there about other things in there. So anyway, this kind of goes on. I'm living there and actually when...
Marom Bikson
Are you now in the PhD program?
Thomas Mortimer
Yes, but floundering, not going anywhere, because I'm still very disillusioned about where I'm going to go in this whole PhD thing. I'm just taking graduate courses, you know, to move on in there. So, let me see…there's, have all, they have silverware and crystalware that we eat with these gourmet meals. And when they go out of town, they say, if you want to have a party for your class, your graduate school classmates, come here and do this. So I'm using, a graduate, I'm a graduate student entertaining other graduate students with sterling silver and crystal, man, you know, high end stuff doing gourmet cooking in their stuff. You know, that was, that was what was going on.
So, I think at this point, Reswick starts to get a little bit upset with me. I'm not making any progress. I'm not going anywhere. And so he and I guess Sheely have a conversation that I'm not aware of.
But I knew Shealy was still interested in pain and working on pain. Most of that was what he was doing in his lab. And I was doing some experiments with him.
So, Reswick talks Shealy into having a meeting at Shealy's house up in Cleveland Heights between Shealy, Reswick and Mortimer. We're in the living room of Shealy's home and Reswick is starting to lay the law down on Mortimer.
Marom Bikson
This is not a good meeting for you.
Thomas Mortimer
This is not a good meeting for me. I'm feeling the squeeze.
Marom Bikson
Okay.
Thomas Mortimer
Okay, and so this is about 1966. Shealy comes up, Shealy has now read the Science Magazine publication by Melzack and Wall.
Marom Bikson
for gate-control.
Thomas Mortimer
Gate Theory. And while Shealy was in residency in Boston, he actually knew Pat Wall. And they were still conversing, probably talking about some of this stuff. Shealy spoke of Pat Wall like he was a friend in there. So Shealy sees this and he comes and he has the idea, we're going to do, I think we can treat pain by electrically activating the large diameter fibers that come into the spinal cord. And so that's his idea.
Marom Bikson
But why, because you can stimulate peripherally as well. mean, why go there? not stimulate peripherally? mean, the tens or even, you know, at the nerve at the arm. Why? I mean, now we know it works, but at the time.
Thomas Mortimer
Well, in Shealy's mind, he saw that some of his patients were cancer patients and the pain was distributed over large areas of the body. And his reasoning was that if I got into the dorsal columns, now I can work into an area that has many large diameter sensory fibers available here that I wouldn't have in any other place in the body.
So that's his idea to electrically stimulate fibers in the dorsal columns. You know, and if then if you work backwards, you see it's the antedromic pulse that comes in and bifurcates and goes into the substantia gelatinosa, was what we were after.
Marom Bikson
He was aware of that. He wasn't just thinking of stimulating up. He was aware that you're going to have the collaterals going in.
Thomas Mortimer
At first, I'm not sure I could say for sure that was what he was. Probably he did. I finally saw that once I understood how the gate theory worked, I saw that that's how it had to happen, would have to happen. It would have to be this anodromic invasion coming back down in through where the bifurcation came and go in the large diameter fibers provide that input to the substantial gelatinous cells.
Marom Bikson
Because if it can harp on that, because if it wasn't for that, it would have been the wrong place to stimulate. It would have been too far up unless you're doing gate. Okay.
Thomas Mortimer
Correct.
Correct. mind you, there's another element that I think is actually in hindsight spectacular. That article came out in 1965. Reswick and Shealy are beating on Baldwin Mortimer in Shealy's living room to build this thing. Shealy, Reswick has the money.
Reswick has the belief that Mortimer and Shealy will actually pull this off. And it's money he has assigned to him that he's spending on, you know, this guy out of North Texas and this other wild guy neurosurgeon. Shealy and Reswick hit it off actually really well. They are very, very similar in, you know, in their sort of
Marom Bikson
Okay.
Thomas Mortimer
willingness to look at different things or different approaches, might say. ⁓ has in this has the idea, Reswick's willing to pay for it and you're sitting in the middle.
Thomas Mortimer
This Mortimer, you build this thing for Shealy. That was my instruction. And I say, OK, but I don't want to do any animal experiments. Shealy says, ⁓ I'll take care of that. Don't worry like that. Well, actually turned out that wasn't true. I had to do a lot of animal experiments. And that's where I a lot of work on cat brains. So, I learned to do I could work in a lot of different places on a cat.
You know, with the skill set I was acquiring over all those years, even though I was kind of kicking and screaming, I don't want to do this, I was picking up a lot of technique about animal surgery. I could do my own anesthesia. I mean, these are all things that later on, all of my students could do too. They could do their own animal anesthesiology, their own surgery, all their own animal experiments. That was part of the training that they had in my lab…because I felt like it was important. So anyway.
Marom Bikson
Why can't I mean I know I've heard you speak about you know this was a time where people would stimulate themselves, you know, things progressed very differently right so in this case. What did you actually have to build that wasn't already on the shelf and why do you.
Thomas Mortimer
Nothing was on the shelf. Nothing. Absolutely nothing.
I had to build a stimulator, had to build the electrodes, I had to build the leads, everything had, there was nothing, there was one single item in that whole thing that was pulled off the shelf, Marom. I needed, I was using RF transmission for the signal. And I needed an antenna that looked like it would be appropriate to be in the, in a clinical environment. And I couldn't make anything so slick looking.
As an antenna and I found one at Medtronic and so that talked them into giving me this antenna or I could buy I don't remember how we got them but anyway I got that man antenna the rest of it I built everything that the case the driver everything.
Marom Bikson
Initial system, wasn't, I just thought it was a wire. I didn't think there was anything but a wire coming out of the person into something.
Thomas Mortimer
gotcha. You're right. I wasn't moving quite as fast as Shealy wanted me to move with the implantable simulator.
Marom Bikson
the idea was first make you were assigned to make an implantable first.
Thomas Mortimer
Right, but I wasn't moving as fast because I was having, I couldn't get this built fast enough.
Marom Bikson
Yeah, usually that's like a project for a company, you know, not a grad student, but okay. Okay.
Thomas Mortimer
Yeah, you're right.
But you know, it's also kind of important, I think, in hindsight to think this article came out in 1965. And by 1967, we had two patients implanted.
was incredible, but it didn't seem incredible. But it was, you in hindsight, this is the, that was incredible. So, the first patient, we didn't have the implantable thing. And I had this idea of, I could run hypodermic needles through the skin into a receptacle that was below the skin. So, I built that thing. And the electrode that we would put in that first patient would be the same electrode system that I would put on the spinal cord of the implantable system.
But so that part of it was now back up again, the electrode that I put on the spinal cord.
So, I had to come up with a material. I need, so I decided looking around, everybody uses platinum. I'll use platinum too. I didn't know where to buy platinum.
So, I think, well, you know, who uses platinum around Cleveland? Jewelers use platinum around Cleveland. So I go to this really high end, very fancy jewelry store down in downtown Cleveland. And only the old timers in Cleveland know this person. I can't come up with this name right now. So, I'm asking these guys, I'm telling this guy behind the counter selling diamonds and all this stuff.
I need some platinum. So, he said, okay, I'm going to give you a name. And I almost said his name again. Ray Linsky.
Go talk to Ray Linsky and he's, this jewelry store was some downtown, somewhere downtown and Ray Linsky's place where he did custom jewelry was on say six or seventh floor of the Rose building at ninth and Euclid. And the only time Ray Linsky worked was at night. So, I had to go see Ray Linsky at night. I go into a dark building, go up to the sixth floor and meet with Ray Linsky.
in there. Knock on his door. He shows up with a .45 in his hand and know peeks through the door. He's got diamonds and all kinds of know gems in this place. So that's why he's got that gun. He knows I'm coming but anyway so we meet and I tell him what I want and I buy a piece of platinum of him that is a chunk
If you ever looked in my doctoral thesis, you'd see this is not a little piece of film that I'm using in there. This is a large block of platinum that I had. And I made two electrodes out of this thing. You know, I'm actually made four, two for the first implant and two for the second implant. So, I've got a lot of platinum. never saw the end of this stuff. I don't know where it went. No, because I had always prepared them for when we did surgery, but
They just appeared from my hands after that. So, I meet, Ray helps me do this. A side story, within months or something, I meet this woman and I get excited about her and then decide to get engaged. And then I need some, a wedding ring. Her grandmother gives me some gold to melt down and I go to Ray Linsky and he shows me how to build a wedding ring.
Marom Bikson
They're going to make her a platinum ring out of those.
Thomas Mortimer
I didn't have that stuff. anyway, I built those and I used hypodermic needles into a receptacle that was implanted under the skin for the first guy. Now the receiver was made out of glass or the implanted device because I needed something that was non-conductive because I had those same access points in that
receiver. So, I could measure the voltage going actually into the spinal cord or the current measured into the spinal cord or amount of charge that was being injected. Backing up again, I had to do a bunch of animal experiments and we used the blood brain barrier of cat to figure out whether we were damaging using the blood brain barrier as a
good indicator for impending damage to the nervous system. That was Shealy's idea. So those experiments, conducted those, came up with an expression, mathematical expression to fit a bunch of variable data, totally unsatisfying for me. But anyway, it was a number I could get. And we built that number into the stimulator so that a person at the hospital who didn't really know anything about this stuff could never exceed these boundaries.
Marom Bikson
bi-phase stimulation back then, or not?
Thomas Mortimer
Yes, I had been totally indoctrinated with John Lilly's idea of balance charged biphasic pulses, totally indoctrinated with it. And so everything I was doing was balance charged biphasic pulses. So anyway, we got that.
Where are we? ⁓ so Shealy now takes a job in La Crosse, Wisconsin at the Gunderson Clinic before we implant anything here. So we're now about 1967 somewhere, probably Western Reserve and Case are federated in this timeframe.
Thomas Mortimer
Shealy moves to La Crosse, Wisconsin, and that's where we do the implants. So I made everything there a case and we did all the...
Marom Bikson
I see.
Thomas Mortimer
Pretty much took it there, sterilized it there and implanted it there. And then in both cases, I stayed there after the surgery gathering data to say whether this worked or not to support the idea that this was working.
Marom Bikson
And this was epidural or this was into the spinal, this was into the spine.
Thomas Mortimer
It was a subdural. All of the electrodes I made had made to be put in the dura. So they were sutured with the dura around them with the platinum interface directly on the PS surface.
Marom Bikson
Okay. Okay. All right. And it worked. It's a straight it worked and it worked well and it worked fast. that is.
Thomas Mortimer
I gathered all the data I needed and yes, it worked. And the woman who was the second one, the first guy, he didn't live, but maybe 24, 48 hours longer. And he reported that every pain was gone, including the incision pain in his back, which was incredible in my mind.
And the second patient, which had received the implantable device, she had that device for at least four more years and used it. The curious thing about that, Marrone, when Christmas would roll around, she was of Norwegian descent. Christmas was a big holiday in her family.
Thomas Mortimer
She lived alone and amazingly the device quit working. So she would have to be admitted to the hospital again. When Christmas was over, the device would start working again. And this repeated, I think for several years.
Marom Bikson
Interesting.
Thomas Mortimer
So there, know, and if you look at the gate control theory, Melzack and Wall had this central control box sitting there. Remember in there, if you remember the gate theory, there was a central control coming down from the top working at the spinal level.
So that may have been that.
Marom Bikson
You didn't think, oh, interesting. Did you know how important this was when you first patient person telling you that? Okay.
Thomas Mortimer
No, this is serendipity. The fact that I mean that the three guys, Shealy, Reswick and Mortimer, this experiment would not have been done without those three guys. That would not have happened. Reswick, where he fits in, most people don't even remember him, know anything about him. Shealy.
She really promoted this thing heavily to Medtronic and to the neurosurgical community. So that a physician promoting this was and has turned out in my mind to be one of the most important elements for the likes of me who develop neuroprosthetic devices. I can't put these in humans. I can't promote these to my community.
these guys promoted to the likes of the community who became North American Neuromodulation Society.
Thomas Mortimer
It's the Shealys, it's not the Mortimers, it's not the Reswicks who make a difference there. And so that was, that was, yeah, it was to me, just as I look on, I didn't follow this up. I never did do anything in pain after this. Never. I couldn't get away from it fast enough. is that? I didn't want any more to do with this stuff. know, pain, how do you quantify pain?
I was trying to building advice to fix something that I couldn't measure. That's not very satisfying for the likes of me. I wanted hard numbers, I wanted to see things work and so on and so forth. This just didn't fit my need at that moment. So, I guess probably in fairness, or just it looks like the story stops there for me. It certainly did from the standpoint of working on pain suppression. I never did anything more in that field.
I go, I take a postdoc in Sweden at the end of my doctoral thesis. So I finish in say June of 68 and I go to Sweden for a postdoc and I get there in September, August, I guess of 68. And leave there in September of 69 to come back to Case to become a faculty where I had a faculty appointment waiting for me.
Now what happened in Sweden was another serendipitous turning point for me. You see a guy totally disillusioned with doing animal experiments. You see a guy totally disillusioned with electrical stimulation stuff in there.
But there was this same guy knew Vadovnik really well and knew Krošetýr really well. And sitting side by side to them when we were drinking beer and having parties, I knew the problems they were running into with that work. It was fatigue of an electrically activated muscle was so fast that it probably wouldn't be practical to have such a device. So I go to Sweden working in a lab that was looking at EMG. And they're doing contract work for the shipyard. And the shipyard is interested in Sweden and the rapid fatigue of their workers. So this group is Chalmers is taking the, they're doing EE stuff. They take an EMG and then they run a 4A analysis of the thing and look at the spectrum.
Thomas Mortimer
Okay. And so, when they run the spectrum on there, before fatigue, they see a spectrum. And then as the muscle fatigues, they see the energy shift to the lower frequencies. So they think there's, this is a sign that we're going to use for shipyard workers to help understand the fatigue these guys are having. And so,
Thomas Mortimer
They assigned me this job of coding 48 transform. Discovered I hated coding. This is not for me. they kind of put people in the world generally put up with me. It's amazing. So, these guys kind of just let me go to work. And there's an incredibly good library there in Gothenburg where I was at. So, I spend a lot of time in the library.
And this is at the same time, the whole idea of fiber types was discovered. And there was a group in Stockholm that had actually been on the forefront of this. one of the guys that I worked with in there, one of the guys I worked for, knew these guys in Stockholm and arranged for me to go talk with them in there. And about this fiber typing,
And as soon as I saw that, said, I know exactly why the dough making crochet tier ran into this problem. They were stimulating large diameter fibers because they had the lower threshold and those go to fast twitch glycolytic fibers, which nobody knew about until these guys were describing them.
So, I knew why Winovnik had, at least I perceived in my most arrogant self, I guess, I know why these guys had a problem. And I think I know how to fix it. Because, know, if we train, you know, we do exercises, I can increase my stamina. I can run further. I can do things. So maybe electrically induced exercise would be the ticket here. That would be how to fix this problem.
Marom Bikson
Okay. So just saying to use the stimulation almost as for training.
Thomas Mortimer
The process in of it. exactly. So I come back from Sweden and, you know, with this idea in the back of my head, I think I know a fix, but I didn't know where I was going to use it.
I get back from Sweden, show up in Reswick's office. Now I've got an appointment as an assistant professor of biomedical engineering. And I'm sitting there talking to Reswick, I think three or four days after I got back from Sweden. And he tells me, Tom, I'm leaving in January to go to Rancho Los Amigos. Rancho Los Amigos was our competitor for the whole number of years I was working for Shealy, for Reswick. He was going, and that group had done a similar arm assist device, but using electric motors rather than pneumatic motors. And Shealy and Reswick had been mesmerized with the Dovenick's idea of electrical stimulation. And I thought, ⁓ my God, you know, how am I, I can't compete with this guy. You know, he's going to take all my knowledge. He's going to take everything.
This was totally, you know, really kind of deflating. I'd come back to be work under this guy to kind of get my feet on the ground. And, you know, he was going to show me the ropes. I'd never written a grant in my life. And I was, you know, quite naive. Well, he goes on to say, by the way, Tom, you know, your money is going to run out in April of next year. And you have to get that grant if you want to get money renewed on that, you're going to have to turn in a grant by the end of this month. Okay. And I knew in the back of my head, where I was writing that grant was the same place that res week had written grants. And that that place was very skeptical of anybody doing any animal experiments. They only wanted to see human work. Biomedical engineers working on humans.
Marom Bikson
Okay.
Thomas Mortimer
All I had was animal experiments to do. So we wrote a grant. One of them was to show that electrically induced stimulation, I could do fiber conversion. can convert them from fast-switch glycolytic to oxidative fibers with fatigue resistance. And then employ that within human studies. And then Craig O was gonna come up with a, he was working his master's degree or finished…going to do his PhD now on stimulating goji tendon organs to suppress spasticity. And we had some other thing in there in this grant to deal with the shoulder control of a wheelchair.
Thomas Mortimer
They funded that thing to a tune of about $100,000. It's enough money to support Peckham and Crago, one technician, know, maybe something else and piece of my salary.
Thomas Mortimer
There's no way that what I wrote impressed anybody to fund that thing - that particular organization. I'm quite sure that Reswick pressured the folks in the social rehabilitation services with whom he was very well connected to at least support this grant for three years to ease my guilt in leaving him.
And they did! You know, Peckham did, was very successful in showing that this fiber conversion worked. And with that, we started to have some, you know, we had credentials with NIH people, because they understood animal experiments. You know, and if these guys were doing animal experiments rather than surface electrodes on human paralyzed patients, we had a kind of credence that the other guys didn't have. And so we went inside the body. Everything we did was inside, we never use surface electrodes. And we were always putting inner muscular electrodes in and well…you saw the history of that the other day. Yeah, where we got started with that. And I mean, being able to run wires through the skin, we could do things in humans and animals that otherwise would never have been able to be done.
Thomas Mortimer
And that's serendipity. We didn't know that that would work. We didn't know why it did work, but we eventually figured out. Open helix gets encapsulated and doesn't piston. And then as it moves around, it's well tolerated.
Marom Bikson
So, I when you're talking about luck, I'm thinking like going back to these experiments you did with pain. It could have not worked, right? You could have had the wrong frequency. You could have put the electrode too high or too low. Do you think there was a, I mean…or maybe you tried a lot of things that, know, in real time until you, did you fiddle? I mean, what, how much luck was there in?
Right. It could have been, it could have been a hundred reasons why it doesn't work even now, right. When they program people, some people don't respond to spinal cord stimulation or some people only respond to a particular way form, but you, if it hadn't worked on that first or second patient, you might've just given up on the whole project, right?
Thomas Mortimer
I'm not sure where I'd be. I may be back to fixing cars in a garage. I don't know where. mean, that… that all had to work. The location of the electrode was specifically planned, designed to be in the area in the in the. Dermatome in the area where the patient perceived the pain, that was very specific choice.
Marom Bikson
dermatome will overlap.
…And they felt the paresthesia. felt the table.
Thomas Mortimer
I, and, you know, and I mapped all of this is and reported this in my doctoral thesis. You know, how it has a function of amplitude. I never used it. I've never used anything in my life except rectangular pulses. That's what I use. don't see any real.
Marom Bikson
…And still use,
Thomas Mortimer
There's no other reason to use anything else. At least I haven't learned why one should, what advantage something else might do, at least from basic understanding of how you create a propagated action potential.
Marom Bikson
I heard Cameron McIntyre was giving a talk and he was talking about pulse widths and he basically made a joke. said, look, I spent a decade trying to find better pulse widths. And the short answer is the square waves work just fine.
[Correction: Bikson meant to say pulse shape]
Thomas Mortimer
No, it's the narrowest pulse you can use works best. You'll always use a lower charge. It takes less charge on a narrow pulse than it does a wider pulse. So use the narrow. If you use the narrowest possible pulse you can use, meaning you run your stimulator at full amplitude, you automatically optimize charge injection by using pulse width modulation.
Marom Bikson
So, a lot of, yeah. So, it's really about how much current you feel comfortable pump, you know, the total amount of current you feel comfortable putting on.
Thomas Mortimer
For me, it's not that it's the limits or what's the IPG? What can it do? I drive the IPG as far as high as it'll go. Those things aren't capable of generating too much.
Marom Bikson
Okay, you're not worried about getting into some electrochemical regime that is.
Thomas Mortimer
I always worried about electrochemistry. Always. my big worry was in the, if you look in the toolkit, there's a whole section on electrochemistry.
Marom Bikson
So then why not no concern about higher and higher currents? Higher and higher currents means more and more voltage. At some point you could trip something that you don't wanna have.
Thomas Mortimer
Everything works on charge that you inject into the electrode. The faster you inject it, that's the current in there. But you're just putting charge on there. And you build a charge on and you charge this electrode, you charge the double layer always, right in parallel with the reactions that go on. So, you just have to pay attention to the amount of charge you're putting on there.
Now it turns out that it deviates from electrochemical thinking. And when you look at the Shannon plot, there is an area dependence there. And what is reported in Coombsa papers, she worked in the lab during my days of retirement.
we learned that we saw there was a good correlation between K equal 175 and when you start to dissolve platinum. So, platinum dissolution accelerates when you cross K equal 175 in many different surface area electrodes. So, it seems to be, in my mind, there's a message there.
Platinum is a very reactive material and it's used in cancer treatment, cross-links DNA, but that's not going to be a player role here because these are not dividing cells. But platinum somehow may be involved with astrocytes or however some metabolites, but there are issues with when neurologic issues associated with treating cancer with platinum products.
Marom Bikson
Platinum is reactive. mean, in the stimulation you use platinum because it's not reactive, right?
Thomas Mortimer
Well, when you say not reactive….generally when I started this I thought platinum didn't corrode but a lot of us along the line discovered actually platinum does corrode I know exactly where it does start to corrode in there and I know how to avoid the corrosion in there . And so, if platinum were in fact the cause of damage, the fix is easy.
Thomas Mortimer
Just imbalance the charge. Don't let the potential go into the region where platinum dissolution occurs. That's how we fix that problem in stainless steel. And it works in platinum too. that's the, know, in stainless steel, was just electro corrosion we're concerned with, not damage. And because the corrosion products in stainless steel primarily are iron, and that's okay. There's not a problem with iron in the body…big problem, at least we don't know of it.
But platinum, you know, it's a catalyst. And it does things that I don't really fully understand, but it may it could interfere with the metabolic processes in cells. And so, the test that needs to be carried out now is the McCreary
Thomas Mortimer
Not the McCreary test. I didn't like his way of doing it. It's Agnew. McCreary sacrificed those cats the minute he finished the stimulation. Agnew waited five or six days to see what the tissue was doing in there. And in my conversations with Mark Cohen, a pathologist at Case, he looked at the data that...
McCreary and all had published. He said he could see same data published by other people and that was not, those cells were not dying, they were not dying. They were changed, but they were not dying.
Marom Bikson
So those were conservative limits in a sense.
Thomas Mortimer
Well, yeah, it's, know, you and I know by now, if only one lab runs these data, there can very well be a bias there that they can't see that they're using, particularly when they're looking at histochemistry, histology. They just don't see the same thing. They don't interpret the same way. And all of the data on tissue damage came out of Huntington Medical Research Institute.
Nobody else did their data. Nobody else, as far as I can tell, scrutinized. No neurophysiologist or pathologist actually really took a hard look at their data. And as I said, later data showed, as Mark Cohen pointed out to me, very similar, but these cells weren't dying.
Marom Bikson
I want to ask you a big question really about, well, I mean, the specific question would be looking at Case’s success, right?...Especially, I mean, I know neural engineering, right? So, it's spectacular success in neural engineering, year after year, decades after decades. In some cases, you know, these were people who were there and were clearly, you know, they were mentored by someone else. So maybe mentorship is playing a role, but in other cases, these are people coming from the outside.
And yet when they arrive, they're thriving, right? And they're building a programs also in collaboration. what's your, know what, mean, obviously you have more insight than anybody. So, what was the formula that made Case so successful and continues to sort of drive innovation at Case, again, in neural engineering, which is what I'm most familiar with.
Thomas Mortimer
When, well. I think the people that drove this thing were... Sort of free to explore their ideas.
I think it was an environment that was, certainly that I grew up in Reswick's place where I had incredible latitude. Every one of us did.
My lab was not like Reswick's lab at all. I had a lot - I was exercised a lot more control over what projects my students did. Reswick exercised almost nothing. I mean, witness what I did. This guy knew nothing about this stuff. Look what I got away with. I mean, it was, and he had money to, he had to do that. I never had that kind of money. I had some money that I could be a little – use as discretionary money and do different things. But almost all of it was grants that I had a specific job to get done in that grant. I didn't, I never felt like I had the latitude.
One, I had one student. Who I guess kind of started to work that way. Zi-Ping Fang.
I don't remember, Zi-Ping came, well Zi-Ping and I met when I went to China in 1981. We didn't actually meet, but his advisor and I met and I actually had a long kind of a relationship with his advisor. And anyway, and this guy wanted us, this advisor wanted to send a student there and his first choice was a woman. And for some reason or another she didn't come and then Zi-Ping came instead. And Zi-Ping in my mind is a phenomenal student.
I had been working for a number of years on the idea of creating unidirectionally propagating action potentials.
Thomas Mortimer
And we were always looking at this as making, collision blocking a pudendal nerve so we could make a bladder assist device.
And so a number of graduate students or several graduate students had become involved in that. Chris VandenHoner was the first. He was a really, he was incredible guy. Then Jim Sweeney, you probably knew Jim Sweeney, Ira Unger, you may not have known, he just did his masters there. I'm trying to, you know, who else came along there? But Zi-Ping came along and looked at that.
And he said, you know, we ought to be able to invert the recruitment order using this because the large fibers will block first for the small. And I said, you know, that's a pretty good idea. Let's try it. So Zi-Ping you know, said, do it. So what do do? Showed Zi-Ping how to do a laminectomy on a cat, how to record from dorsal roots, bam, you know, he worked through it. And, you know, and then ventral roots too, because a lot of his, because we were looking at the motor recruitment order and sure enough, it worked. And then Narendra Bhadra took that idea on and said, okay, now we know how to drive the bladder without driving the sphincter. And now we can make a bladder assist device.
And so that project sadly did not have the benefit of a Norman Shealy, who could recruit the patient to work on that and show that that work and then take it into his community. The respiratory assist device that we'd worked on since 1981 that went into Christopher Reeve in summer 2000 something. We'd worked on that for 20 years and lucked out there. And then the surgeon that put that in took this to his community. And that's why that project, it's Synapse Biomedical. They made 2000 patients now have that in them over 2000 because the physician took it. I couldn't do that.
Marom Bikson
And that's also what happened all the way back with spinal cord stimulation that it was, Shealy sort of became an advocate and he promoted it and he was a physician. People listen or.
Thomas Mortimer
Absolutely. You got. Yeah.
Well, and he had a voice that people would listen to.
Marom Bikson
But if he hadn't, the spinal cord stimulation for pain would have died on the vine or it would have had to be rediscovered 50 years later.
Thomas Mortimer
So, you’ve brought up TENS. I'm not aware of, I know Shealy was aware of TENS specifically because...
This is the problem with aging. My memory fails me at the worst times.
Marom Bikson
I think our memory fails us all the time. I think when you're old, blame it on aging, but actually everyone's memory is failing all the time.
Thomas Mortimer
This guy, well, there's a guy that promoted TENS from MGH where, and Shealy knew him. And I think Shealy had trained with him, Bill Sweet. Bill Sweet. Yeah. And Bill Sweet knew Pat. These are guys, Sweet, Shealy, Pat, Wall, all knew each other in Boston.
And I mean, when Shealy and I ran across each other, he hadn't been more than a couple of years from his residency training in Boston and there. And I knew, he was aware that Sweet was working on TENS using surface stimulation in the peripheral nerve as a way to suppress pain.
Marom Bikson
…in the late 60s.
Thomas Mortimer
Well, okay, I mean you almost have to say late 60s if it happened, because the gate theory didn't come out till 65. Okay, you know, I mean…
Marom Bikson
Was tens around before gate theory and then after gate theory?
[Note: Electrical stimulation for pain did exist before Gate Control theory. But modern electrotherapy for pain developed from Gate Control theory.]
Thomas Mortimer
No, not to my knowledge. I don't believe TENS existed in that idea. I think TENS came out of Melzack-Wall theory and I think Shealy may have thought about it. It's so obvious once you look at that, at the gate theory. It's a pretty obvious change - but it's kind of like restricting to it a particular a very small part of the body, not as a general thing like Shealy’s idea of going into the dorsal columns where I have a massive area of large fibers that could project in the substantial gelatinosa over a large range. That was, I think, unique to Shealy.
Marom Bikson
I see. Yeah, for some reason, I had this notion that tens must have been around for a very long period of time. And then people said, well, let's try to go into the spinal cord, which is much more ambitious. But it seems like once gate theory came along, the engineers came in real quick to try to make technology that would leverage it.
Thomas Mortimer
I would say…. I do know the guy that Sweet would have gone to. ….Avery, Roger Avery. So Roger Avery was, but Roger Avery built a lot of the number of devices for stimulation. And I think Bill Sweet turned to Roger Avery for this, as did Blaine Nashhole later down at Duke, turned to Roger Avery for some of the electrical devices that he wanted for bladder stimulation. So, Avery Electronics, I played a role in there. Roger was, Roger built those things in a way, Roger did what I did, but he was much better at it.
I mean, he had a company that, you know, you look at what he produced and you look at what I produced is like, God, it's pretty crude stuff that Mortimer was building, but hell, it worked. And, where Roger Avery's looked really nice and, you know, worked too. So it was Roger, but it was, it's always… it's been most of the time it's the physician, you know, again, well, let's say…
Thomas Mortimer
I'm promoting an idea that the physician plays an absolutely important role. I was dissuaded from letting a physician have the controlling element of what I was doing. I didn't like to have to wait for them to do the experiment with the animal. So that's why I learned it. I didn't want to have them called away because they had to do something, weren't available. So that's why I learned. I had learned how to do animal experiments. And now when I had my own lab and my own students, I could teach them.
We did not need a physician there. Dave Peterson, Ryan Schmidt, Harish Iyer, were all able to do endoscopic surgery because Tom Stellaro had taught David Peterson, David Peterson taught Ryan Schmidt, Ryan Schmidt taught Harish Iyer how to do endoscopic surgery on dogs.
Thomas Mortimer
And Nancy Karras did the anesthesia. You we didn't need a physician there - until we really had the device we had to implant. In the bladder, I didn't have the right guy. In the diaphragm, now this is 20 year project and we find Ray Onders just by accident and serendipity. And Ray gets as a young guy, new…and loves this idea and show him how to do it in a dog. And he's already a good surgeon. So he learned how to use these tools ⁓ that Arisha and I had developed to make this work. And bam, he went to work with it. he can...
All of these diaphragm patient systems are implanted as outpatient procedures now.
Marom Bikson
You talk a lot about sort of the serendipity in this process, but when someone like you has had a track, I mean, I don't know how many times can you win the lottery, right? it's not just, I mean, maybe opportunity knocks, right? But you still have to be able to open the door, right? So, when you talk, it's serendipity, but it's also the ability then to take advantage of an opportunity when it's presented.
Thomas Mortimer
I guess I think I see where you're going.
I kind of back, go backwards onto looking at the origin of the word, where it came from, “serendipity”. As I read the history of that word, it was invented, say 15 something, 1570 something, by a guy named Horace Walpole.
And Horace Walpole is writing to a friend and he's trying to describe this phenomena that we call, you know, serendipity, but there was not that that word didn't exist and he coined it and he drew and the name and the word was drawn from a Arabic poem about three princes living on the Island of Salon or Sri Lanka now. And I think the Sanskrit name of the word for island is ‘sarin’. So, sarin is a Sanskrit word for island. And the poem was about these three princes who would get on their horse in the morning and ride about their island.
without looking for anything but discovering fantastic things. Always, know, but they had their eyes open, you know, what was going to be there? You know, they weren't looking for it, but it was like, something's waiting for me out there. I just have to find it.
So that's the way I see serendipity playing out. I always, Marom, always, came to view the Case Western Reserve campus as my island. All I had to do is come to work in the morning and walk around the campus.
Marom Bikson
You have to have your eyes open is the point. See what's before you to take advantage of that opportunity.
Thomas Mortimer
Right.
And I sort of have a knack for, you know, when I walk in, if I walked into your office, I walked into your lab, you and I might be chatting, but I would look around and see what kind of equipment this guy has. Is he having anything I can use? You know, what's going on in this guy's world? So, I'm curious about, maybe it's the curiosity, because I do think I am curious that I find these things, but it's definitely serendipity.
I don't know how much… were you at the award ceremony at NANS? Did you hear my…
Marom Bikson
I heard about your speech. I wanted to ask you about that. Ask you about that. But wait, before we go there, hold on, before we go there. So really when you're talking about serendipity, it's not you're walking down the street and someone hands you a hundred bucks. It's having your eyes opened to opportunities. And it seems to have a lot to do with creativity, I guess, and being able to...see possibilities? …what would you, what is the role of creativity you think in your success and in success in engineering?
Thomas Mortimer
I'm not sure I can answer that question directly, but I have an answer.
As an engineer, I think I'm basically looking for problems to solve.
The act of solving a problem is something that is very satisfying to me.
And so. looking for problems to solve - I'm always on, I think of myself always on the hunt for a problem to solve.
Marom Bikson
Yeah.
Thomas Mortimer
So. Creativity?
In a sense, would be nice to think of myself as being creative. I'm not sure I'd want to label myself as that.
Marom Bikson
I mean, if creativity is how we solve problems…
Thomas Mortimer
Maybe I'm trying to model my behavior as an engineer after my mentor, Jim Reswick, who I’d love to watch him come up with solutions to problems. They were always so simple. They weren't convoluted. They were just good solutions to problems. He thought in the mechanical world, and I can easily trans...
You know, visualize things in a mechanical world. That's easy for me. So, watching him work was such a pleasure.
Marom Bikson
I mean, I think that's something I heard you mentioned before. You talked about the simplicity of the solutions, like winding a cable or something like that, right? Is that something you see as a common theme that these breakthroughs come through simple solutions to problems?
Thomas Mortimer
I think you may know of my-self sizing cup electrode.
Marom Bikson
Yeah.
Thomas Mortimer
I think that that qualifies in the same range as I viewed Jim Reswick's solutions. For a long time, say, know, two or three years, I wanted a cuff electrode that would be in close contact with the nerve, but not squeeze it too much. And so, I knew I needed, I wanted a spiral cuff.
And I, but I didn't know how to make it. And I played with all kinds of ideas trying to make it. And then one day I was driving to Case on Cedar [Ave]. And I happened to think about what is it about a tube that makes it hold this round structure?
And if I open it, you know, it goes back. What is it? And then I realized this, it had a, the material on the interior was stretched relative to the exterior, was tighter. That's why this thing curled. And if I took a, if then it morphed into: Okay, if I put two pieces of silicon rubber sheeting together, stretched one and laminated it to the other, this thing would curl.
Thomas Mortimer
And, you know, I remember this event that was so powerful when it started to unload. I had to pull the car over to the side of the road and just let it flow. This is how to do it. This is how I can make this thing. So, I recruit. Hmm. God, I just, I can't come up with his name. He came from Notre Dame. He did his master’s with me. He worked over in the, at Metro. If I keep going, I'll come up with his name.
Anyway, he did this as his master's thesis and he's the first author on the patent. But it was that to me was okay, I can be in the same ranks as you Jim Reswick because this was a simple solution to building these things. This was really simple. All I had to do is laminate it, that one inside layer, stretch it and laminate it to an outside layer and just curl up like a wind shade - window shade.
Marom Bikson
It's a wonderful feeling. mean, it's a wonderful feeling to have the idea. It's a wonderful feeling when it works as well, right? guess. But you sort of almost knew that it was going to work when you had the idea. was sort of like, this is it. You already
Thomas Mortimer
As soon as I saw that a piece of tubing, the inside, it was in tension as soon as you opened it and then it would close back. As soon as I saw that, I just created a structure that stretched, going to be in tension on the inside and would fold it up. So yeah, I knew it would work.
Marom Bikson
When you have a simple solution, I mean, again, it's simple, but obviously nothing is simple in implementation. It's much more practical.
Thomas Mortimer
Greg Naples. Greg Naples. Greg Naples is the student. I was going to call you at three in the morning when I got it.
Marom Bikson
So, when you go to a simple solution, it's easier to build it, right? You don't need a decade of work and a billion dollars, right? It's a sort of simple solutions also lend themselves to productization, right? To translation, right? Well, there are other ideas that are, they're more fantastic, right? They're more ambitious. They require doing things that best case scenario, right - Are going to be a decade and a billion dollars.
So is that also maybe a theme for your success, maybe a theme for Case’s success that they were able to come up with simple solutions and able to build them quickly and then quickly get it to animal, quickly get it to first in man and not get as opposed to projects that we know that are equally great - But you know, this is like a career just to get it to an animal.
Thomas Mortimer
Well, I certainly appreciate that a lot of people worked, looked at what we were doing is this is a career of animal experiments that would never go on forever. And if you looked at, you know, the diaphragm pacing thing, that's 20 year project, several million dollars in by the VA to do that. So, we got something that we were comfortable enough to work - Okay, this will work in a human. We can make this work. It's ready.
Marom Bikson
Okay. 20 years until the first…
Thomas Mortimer
The time we started working on it on that project, it started with an infant. that's in that, if you go back and review the toolkit if you want, I did do a little aside on Dave Fleming, introduced, you know, he had a patient that needed this and we tried it on this neonatal patient and it didn't work. But we knew why it didn't work. And because it didn't work, we knew - because what we thought it was the reason it didn't work - we knew it would work on an adult. And so, we then started going, how do we build this electrode system to do this? That's what we need is an electrode system. So, the electrode system was an intramuscular electrode that a pediatric, a pediatric general surgeon, I guess, put into this infant, but he went into a thoracotomy so he could see where the phrenic nerve entered the diaphragm. We wanted to go in endoscopically because that was going to be far less invasive. So, we go into the abdomen and do this, but we had to find the place and we had to get the electrode in the right place. And so, all of those years, there were three PhD thesis that finally came up with the right tool to do this.
Marom Bikson
Hmm. But okay, but so the difference between in the case of spinal cord that was you in a year, right, versus this other project still you but now 20 years and several PhDs. What, what, what, what, what, was one so fast and one was so relatively slow.
Thomas Mortimer
Really lucky.
I mean, you know, if you want to put an electrode on the dorsal columns, there was no new technology required to do that. You just had to build the electrodes to go there. Shealy knew how to put these things in. He could probably do it blindly. You know, do the laminectomy to get in there and put it in. He was trained to do this.
Now, there weren't any tools for the diaphragm because first you had to find the site. And if you look at the diaphragm, here the diaphragm is, here's the abdomen here. You had to go in here to get an electrode to go in parallel with the muscle fibers of the diaphragm. That means this has to come down. So, you need a tool. You can't come in here and poke it in here because the diaphragm is only about three or four millimeters thick. You'll go right through it with an electrode that say has 10 millimeters in length, an intermuscular electrode. So, you can't do that. We had to develop a tool. And once we developed the tool, which was where we tried one thing with David and we knew it would work, but it wasn't cool and it wasn't easy enough for the surgeon to do. Then we developed another electrode with Brian.
And that assembly, the surgeon loved it because it was stapled in. It was so easy to put in. The problem is that the, you looked on the inside of it next to the muscle, the mechanical irritation of the electrode was just building up connective tissue and eventually this thing would fail. So that's why we nixed that one. Went back to the inner muscular electrode. We had to develop a tool to put it in now. And that's where Harish came in with building that tool. I like to think of, you know, all of the people that worked in there…
Marom Bikson
Yeah. But the one thing I want to go back to this point, the fact that you could get the spinal cord in one year is one thing you're saying is that you were lucky that the anatomy was such that you could build a simple device that that she really with what he knew in the time could insert without damaging the tissue. And in fact, you said this one patient had it in for years. First go and you have something that lasts for a year.
It was a, it was fortuitous just the way the spinal cord was built that you could go that fast.
Thomas Mortimer
I guess you could frame it that way. would have said gate control theory laid it all out what to do. That was the nice thing about gate control theory that it told you what to do.
Marom Bikson
But you mentioned with the diaphragm, there's other applications where you really have to develop 20 years to develop the tool to just get the electrode where it needs to be. In this case, it took you however many months…
Thomas Mortimer
Well, this was all pre FDA stuff. As far as I know, well, I know there was no FDA regulations to get that those dorsal column stimulators in. And, you know, I was never there when Shealy spoke to the two candidates, I don't know what he told them. You know, I just I would just and I don't know whether Shealy had to tell anybody … looked at Gunderson Clinic, what he was doing, for getting the approval. And my understanding anyway is that if they did, it was kind of a blank check. Yeah, I'll go ahead and do it. Nobody stood in anybody's way. I mean, FDA involvement came maybe a decade after this…yeah, the clearing, you know, the regulations of a hospital, well, of getting any of this stuff with animals, we didn't have to do anything like that. I remember early on when I was writing grants, I never added into the budget animals. They were so cheap.
Marom Bikson
The 1970’s
Thomas Mortimer
It wasn't a big deal. mean, you know, we'd get one from the pound and, you know, 10 bucks or maybe not even that. I don't know. You know, the animals were... That wasn't an issue. You didn't have to get approval from anybody to do anything. you know, was without having to get approval, things moved one hell of a lot faster. And I think...
Marom Bikson
Right.
Thomas Mortimer
Probably, well, that's the only explanation I could say why we were able to do it then. When I say it now, and I said it as we said early on, two years, impossible now, impossible. Diaphragm pacing, there's a lot of years of work in there getting it through the FDA. I just didn't have to do any of that. I didn't have to spend any, find any money to hire people to do that. Didn't have to put up the time. You know, Shealy took care of all this stuff and it wasn't an issue.
Marom Bikson
But still, there's an aspect of spinal cord stimulation that it happens to be a convenient place to stick an electrode. I wonder also that's why it's so successful today that these procedures are routine for that reason. And that explains maybe part of its commercial and clinical success that it just happens to be a, there's a pocket - it's like a long space that just waiting for you to slide in an electrode.
Thomas Mortimer
Yeah, if you want to, you know, the anesthesiologist had done epineurial work way before I was ever going anywhere. I mean, you know, my wife had that with our child, you know, instead of sticking a tube and putting some fluid in there, just put an electrode in there. They know how to do this and it's easy. And that's why so much of it is epidural now, because you can, you've got an anesthesiologist who's interested in doing this, it's money for them. They know how to do it.
If you want to put an electrode in the subdural space, you cannot use an anesthesiologist. You must use a neurosurgeon - in there. And suddenly the whole, you know, the time the patient stays in the hospital is now much different in that kind of a procedure than if they do this insert this thing. It's all done epidural stuff, outpatient procedures.
Thomas Mortimer
And, you know, I think localizing the electrode to the right position is a bigger challenge. And certainly we didn't have that issue with this electrode that was sutured right into the dura. That thing was stable and didn't move around.
Marom Bikson
Right, now they can migrate….
Thomas Mortimer
And now, you know, the ones in the epidural space can migrate.
Marom Bikson
All right, I got a couple more questions. One has to do with when's a sort of a sciencey one. I know you're not working in pain now, but now there is work on dorsal root ganglion stimulation, right? Going all the way back there. So I wanted to ask you about that. mean, that was not a, that's not something that it's maybe a harder procedure, right? But that's not something that you know that you and Shealy started wanted to try.
And the other thing I wanted to ask you about is this emergence of sub-paresthesia neuromodulation, right? So, stimulating at 10 kilohertz or even at intensities below paresthesia, right? And whether that suggests that maybe it's not, maybe you can do it without gate control. Maybe it wasn't gate control ever? We just were wrong about it. Or maybe it is gate control, but you don't have to necessarily feel the paresthesia? I guess, yeah, what are your thoughts on those two things?
Thomas Mortimer
No, I think we had the idea that the electrode was going into an area that served a particular dermatome. So, the sensation there, paresthesia was a logical phenomenon to occur. If you buy into gate theory, which I did at that time, I saw that we needed to drive an input into the substantial gelatinosa that represented a large fiber component.
I like that it fits very well with my view of what neuro-prostheses are - or what the whole area is about controlled and targeted release of neurotransmitters. In that case, the transmitter I'm after is Enkephalin. I want to release in Enkephalin on cells in the substantial gelatinosa. So that's the target and that's the...transmitter that I want to release, which fits very nicely in the world that I like to live in. I’m more comfortable there.
You know, when I'm talking about paresthesia there, paresthesia not - personally, I've, there's nothing that happens in the nervous system that doesn't involve a release of a neurotransmitter. It doesn't, I don't -I don't talk about anything else. I'm not interested in talking to you. It becomes magic at that point. And that's not something that I'm scientifically built to process. We eat comfortably. yeah, think gate theory, I love it because I can understand it. It makes sense. whether it's curious, I don't remember.
Thomas Mortimer
of all of this, I'm not sure if how many experiments were actually set out. There surely have been people working in this field to verify what or to complement what Wall and Melzack did. I just not aware of it. mean, they all got involved. Everybody in my world I saw you get involved with the money, not looking at the basic science.
And so I don't know where that really is. And I hightailed it out of there as soon as I got my doctorate. Because now muscle, I could make a measurement there. I could see that.
Marom Bikson
Is science catching up? I mean, when I was getting my PhD, no one worked on spinal cord stimulation, right? An ANCL, not no one, not Warren, not Durand. I think it was considered like a dull - like it was solved. It was gate controlled. There's nothing to do with technology. There was nothing to do with mechanism. And I was talking to, you know, Scott Lempka, think. Yeah. So, he might've been the first - He was maybe among the first PhDs to focus on spinal cord stimulation, period. It was interesting that when I was getting all my training at ANCL, we didn't really talk about spinal cord stimulation. Despite it being the largest market for neuromodulation, it was kind of like, and now I think it's almost like, I don't know, there's a massive interest in new science and old science around it.
Thomas Mortimer
Yeah.
Marom Bikson
All right, the last question. So your speech at NANS, right? Which unfortunately I missed, but I heard about it because someone later on was like, oh boy.
Could you talk about what you chose to speak about then?
Thomas Mortimer
Sure. actually, what I'd like to go back to was the president.
Patrick…president of NANS at the time, the introduction that he gave...was - I'm not sure the best words to describe it.
There were two elements to it, Marom. One is the fact that Shealy Mortimer and Reswick had done that experiment. And the idea, okay, if you're willing to accept this was the first kind of experiment like this, it might qualify as the birthing of the area of neuromodulation.
But that's just a point. It's serendipitous that that happened. Everything about it is serendipitous. Lucky. You know, guy - Shealy is the guy that really is credited there.
Shealy couldn't have done it without Mortimer or Reswick. I couldn't have done it without them. These guys just did an experiment.
But when he mentioned the award, he mentioned that, and then he mentioned a series of names of people who had trained in my lab... and the audience knew them way better than me - the audience knew who they were, even though they maybe not didn't know who I was. And to me, that was okay. That's what I did. That's what I can be proud of. You know, the people who trained in the lab.
They've done some amazing things.
Marom Bikson
Including me. That's right.
Thomas Mortimer
So that to me was the total surprise that I kind of started to realize. It was the people who I worked with who made the difference in the world.
And okay, that's worth credit - know, there was luck in that that those guys wanted to be there, but there was a series of them who really have done some fantastic things. You know, I did only one thing in the area, dorsal column stimulation, pain. I never worked there again. So that's kind of a little milestone, a little point, but look at what he told, what he said afterward. That's the important part of maybe deserving to have a lifetime achievement award. Doing that first experiment doesn't constitute a lifetime achievement award - It's just a milestone.
You know, important one, you want to label it. Yeah, it was. It was the first. A lot of people set off, but. I just was there. Did it. Reasonably good engineer working on this thing, floundering, trying to find his way through it, building stuff that nobody ever built like it again.
Marom Bikson
But it, yes, but it was also, I think there's a connection between that effort and the sort of training machine that Case was because that effort sets a model for looking at mechanism, right? For engineering the appropriate hardware with the appropriate level of sophistication, not too much, not too little. Engineers collaborating with clinicians, moving through, right? Preclinical to clinical….rigorous documentation. So, you could argue that paper in ‘67 is like a star, right? That all these other people training and working a Case, they could use that, right? It's like, well, this is a beautiful example. And then of course, never mind the impact it's had, right - On how to get hundreds of thousands of people, right? So there is a, I wonder if that…you know, whether you did explicitly or implicitly, you sort of set up a model. And that's why I trying to ask you before, why was Case so, it is so successful?
Thomas Mortimer
I like to think that, well, when we first started in this work of trying now to realize the Dolnick's and Reswick's dream, that the competition were all using surface electrodes and they weren't really looking at the basic physiology.
We went inside the body and we were very focused on the basic physiology. We were heavily engaged in animal experiments. None of the other groups that we were competing with were doing animal experiments. They were all working on patients. And the people who came out, I like to think that as crazy as it was that I learned to do animal experiments and thought I'd made a huge mistake, was serendipitously a huge asset I brought. I knew how to do animal experiments. I'll go back and, I forgot to tell you, the Swedish experiment, experience.
Marom Bikson
Yeah.
Thomas Mortimer
So, they were working on the spectrum shift, as I mentioned when I got there. I read about this and I started thinking, you know, maybe it's the fast-switched glycolytic fibers that are dropping out because of fatigue. And maybe that's why this is, because they're recording EMG when they do this. And that's because I'd seen that.
And that was an idea that this may be where fiber type fits in there. So, none of this crowd in Sweden had done any animal experiments. They didn't do that. So, I'm there with now some guys who were working on kidney transplants at the time - Because that was the new thing to go in. They were trying to figure out how to get a kidney to stay alive when you implanted it - and they had a big program there in Sweden. And one of our friends that was there at the same time, American, was working there. And so, I asked him one day, I said, do you know of a lab that I could go into? Because I'd like to run this experiment because I could run this experiment on the soleus muscle and the lateral gastroc because I've got two good fiber types that are representative in cat there. So, I could run this experiment and do this because I knew how to do that. And so, he fishes around and he comes up with this guy named Björn Folkow. Björn Folkow is a really was an internationally known specialist in muscle blood flow. He was also sat on the Nobel Prize committee who made the award.
So, he was a big deal there. And so, I mentioned to him and I went over and this was now getting into the summer when I was getting ready to come back to Cleveland in this summer. And so, I go talk to Björn Folkow - and the nicest guy. And he said, you know, that's an interesting idea you've got. I've got a, can do all of that and that all that can be done in my lab. and have a good technician there and she doesn't have anything to do this summer. Take her.
So, I, with her help and she, and now I'm working on how to manipulate the blood flow in this, in the, in these two muscles. And so, she knows how to do all of this and I'm recording the EMG. So, we clamp the blood flow to these two muscles and I'm watching the action potential go. And I see something that is not what I expected with the two muscles. But what I see is the conduction velocity slowing in both muscles.
If the conduction velocity of the action potential slows, where does the energy go? From high to low frequencies. And then that was the answer. It's because the muscles are ischemic. And when you clamp them, this blood flow start, the conduction velocity starts to slow. So, are you running out of oxygen or is it blood flow? So, my friend who's doing this kidney transplant stuff has all kinds of stuff at his armatarium, you know, about kinds of stuff to flush through the organ. So, he gives me one that's without oxygen and not going to supply anything, but you know, it's just perfusing the muscle. I perfuse the muscle with this stuff. The conduction velocity doesn't slow down. You know, we're removing lactic acid is what we're doing.
And that's what caused the spectrum shift. So, here's Tom Mortimer, a guy that thinks there's no thing in the future for him as animal experiments, solves a problem with an animal experiment. And Tom Mortimer says, well, maybe there's a place for me in the world, an engineer that knows how to do animal experiments.
Thomas Mortimer
So, I think that's what I feel like, you know, I brought to the lab. I don't know that they do that, that it goes that way that much now. And we don't use cats either. You know, everything's gone to smaller and smaller, you know, rodents and things like that.
Marom Bikson
Yeah, but at this point, what you innovated at the time, I think now is like par for the course. It's indoctrinated or whatever it is. Of course, you're going to work with animal models, plus obviously computation and translation. That is, it's certainly kicked in at Case. It's certainly kicked in to everyone who got trained at Case. Everyone's using some level an appropriate animal model to answer their question.
Thomas Mortimer
They're moving away from it, I feel.
Marom Bikson
So, what are they doing? Just more modeling or?
Thomas Mortimer
More modeling, AI is playing a bigger role in the kind of research people are doing, particularly looking at how to control an assistive device using brain signals. These guys don't know how to do any of the experiments. They know how to process data. They need a…there's no, how do you? I don't know, maybe Don Taylor puts electrodes in monkeys. I don't know exactly what she does, but there are very few engineers out there, you know, working with animal experiments directly anymore. There's more processing and, you know, playing with parameters like in DBS. A lot of people are working in there, but there…
There are not lot of people, I think the effort to try to understand the mechanism DBS has been really hard to get at and frustrating. And I don't think you're gonna draw students into something where the work is just too frustrating. You don't feel like you're getting anywhere, particularly when you're trained. You end up like a guy like me, I didn't wanna even, I'd given up going into biomedical engineering - until I had that positive experience in Sweden. I needed that to keep going.
Marom Bikson
Yeah.
All right, Tom, this was very good. really actually I really enjoyed it. I appreciate it.
