Brain-computer interfaces in SCI

We caught up with Dr Chet Moritz, a Professor of Electrical and Computer Engineering at the University of Washington to learn about his background and find out what brain-computer interfaces are and how they work, as well as making electrical stimulation devices accessible to those living with spinal cord injury.

Did you always want to be a scientist, what did you want to do if not?

My first career interest was to be a forensic scientist (this was way before CSI Miami or similar shows!), but I took a detour and wanted to be a physical therapist where I could help patients directly.

During the prerequisites for physical therapist training I worked on animal studies and got the research bug.

How did you progress into your current position?

After undergraduate study doing research on large flying insects, I did a PhD at Berkeley studying locomotion biomechanics (how the legs walk and run over surfaces that might change stiffness or height). This required a lot of focus on understanding how the spinal cord controls these processes.

I then did a post-doctoral fellowship studying the dexterous movements of the hand muscles and how the spinal cord was controlling individual nerves and muscle fibres of the hand.

My second post-doc at University of Washington was looking at brain-computer interface technology and the activity of brain neurons (nerve cells) to stimulate muscles that might have been paralysed.

I am now a professor at the University of Washington, where I’m focused on hand function, walking, and how stimulating the spinal cord can help restore movement.

Can you tell us simply about your area of research?

We focus on several areas, one of which are brain computer interfaces for spinal cord injury. Brain computer interfaces are more appropriate for people with more complete SCIs – with very little or no sparing of connections between the brain and the lower spinal cord.

However even if there is a complete separation between the brain and the spinal cord, we demonstrated that we could record activity from neurons in the brain that were related to planning to move the hand in monkeys.

The monkeys would learn to play a video game with their hand while we recorded the neuron activity, then we would temporarily paralyse the hand using an anaesthetic and continue to record from the neurons in the brain. The monkey would learn how to play the game by just controlling activity of these neurons.

We were the first group to use this neuron activity to stimulate the paralysed muscles. We would route that signal from the brain around the injury through a simple brain-computer interface and stimulate the nerves and muscles in the forearm to continue playing the game even though the wrist was paralysed.

How will this help someone with a spinal cord injury?

This work has gone forward into at least two clinical trials (trials in people) and the approach seems to have worked fairly well.

We were less enthusiastic about the muscle stimulation itself – we noticed a lot of fatigue in the muscles when using Functional Electrical Stimulation (FES), so we shifted our focus to the spinal cord.

We demonstrated that you could stimulate the spinal cord below the injury with tiny wires that penetrated the spinal cord (intra-spinal stimulation). We have since moved on to spinal surface (epidural stimulation) and most recently skin surface (transcutaneous stimulation). We and others have demonstrated these types of spinal stimulation in rodents, monkeys and people with SCI can improve hand and arm function even many years after injury.

Simply stimulating the spinal cord alone – either directly or through the skin – does result in improvements in hand function, walking function, bladder and bowel function and blood pressure. Most excitingly, these improvements last for months to years beyond the time of stimulation, as long as can be measured in research studies.

Does this treatment work for both complete and incomplete injury?

Interestingly, the vast majority (roughly 90%) of people with SCI have some ability to turn on their muscles below the level of injury even if it is so weak that no movement occurs. My colleagues have done studies where they have recorded the electrical activity in leg muscles of people with SCI and every single person has had some electrical activity when they’ve tried to move.

There are two applications of spinal stimulation:

One is ‘direct stimulation’, where the stimulator produces a specific movement outside the control of the individual. This might be the best approach for those with no movement at all.

The other is ‘enabling stimulation’, where we aren’t trying to cause a movement but to enable the movement that the person wants to perform. The stimulator then functions like the training wheels on a bicycle, supporting the individual in starting that movement. Over time, with practise, the person can often make many movements they couldn’t before without requiring stimulation at all.

What is the current state of play in terms of research progress?

I’m consulting for a company called Onward and we’re working together on a transcutaneous (applied to the skin) spinal stimulation device, for which we’ve seen recovery in hand function, walking function, bladder and bowel function, heart rate and blood pressure.

This would only require applying simple adhesive electrodes to the back of the neck for an hour a day, three days a week in combination with physical therapy and would initially be available in physiotherapy clinics.

Next would be an epidural stimulator, applied over the spinal cord itself, for things like blood pressure control which would replace the need for drugs and their side effects.

What obstacles are currently slowing the progress of research?

It’s currently the commercial, financial, approval-type obstacles. We’ve recently completed a multi-site clinical trial on hand function using transcutaneous stimulation. We are waiting for the FDA to evaluate the data from this study showing that it is both safe and effective. Once approved, it could be sold to physical therapy clinics, and after that the next step is possibly making it available directly to the public.

Things are moving really quickly, which is exciting, but there are still those hurdles of cost and access in the clinic. Nonetheless, this is so much closer than other treatment approaches like stem cell therapies or biologics which are further away commercially.

Electrical stimulation has been around for a long time – what has changed?

Electrical stimulators have been around for treating back pain for decades and have been implanted in hundreds of thousands of people. However, more recently several SCI researchers teams have begun using them off label to try and help people with SCI stand and step. They’ve figured out the correct level to stimulate, different electrode locations, different patterns, etc.

In the meantime we’ve been working on stimulating the spinal cord from the surface of the skin. This is a method of stimulation which uses a very high frequency waveform to block the sensation in the skin and pass five times more energy to access the spinal cord. Pairing that stimulation with physical therapy is the sweet spot and where we have been seeing recovery of hand and arm function.

We have people who have gone back to playing electric guitar, oil painting, very complex movements as a result of stimulation training and these effects are permanent, even without the stimulator.

We’ve also had additional beneficial effects on functions that we weren’t even targeting. For instance, within weeks of doing hand exercises, individuals would find low blood pressure issues went away. Others were able to sweat below their injury again, recovered some sensation, or had less chronic pain.

We’ve also seen improved bladder and bowel function in about 30% of our participants. Some stopped requiring the need for a catheter to void their bladder and eliminated frequent UTIs, another had their bowel program time cut in half. These things are more life changing for the majority of people with SCI than making walking movements. We aren’t sure why these benefits are happening, but they also seem to be permanent when they occur.

Do we know when any meaningful therapies may be available?

Hold out for a year or two – you will soon see treatments on the market. First the transcutaneous and hopefully shortly after the epidural stimulators.

Any specific plans for this year?

We’re very excited to share the results of this transcutaneous stimulation trial improving hand function. We’re also continuing to work on other challenges, such as bladder function, blood pressure control, and walking.

We are very passionate about spinal cord injury, but in order to create medical products that can survive on the market, we are also starting to work with other populations that could benefit from these treatments, like children with cerebral palsy. To keep these treatments on the market, often you need a device that is going to sell to millions of people, including people with other neurological injuries and conditions. The future looks very bright for improving spinal cord injury function in parallel with these other conditions.