Go-2 Spinal Stimulator Helps Return Leg Function: Interview With Jan Öhrström, Chairman Of The Board

GTX Medical, a medtech company with offices in The Netherlands and Switzerland, has announced that it received Breakthrough Device Designation for the Go-2 system, an implant that provides targeted epidural spinal stimulation therapy for patients with spinal cord injuries. The device aims to allow such patients to regain leg motor function and neurological control.

At present, patients with lower limb paralysis caused by traumatic spinal cord injuries have limited options in terms of regaining substantial functional recovery. The Go-2 systems aims to change this for patients with a sufficient number of remaining spinal nerve fibers. The device imparts electrical pulses to remaining nerve fibers that mimic motor impulses that occur during walking.



These impulses are synchronized with movements the patient makes in real-time and in effect, the device trains the brain to use the remaining nerve fibers to assist with walking. When used over time the device enables neural re-wiring which can result in long-term improvements in patient mobility.

GTX has also developed a non-invasive wearable system called LIFT for patients with upper limb paralysis after spinal cord injury. The LIFT device received FDA Breakthrough Device Designation in 2017.

Medgadget had the opportunity to talk to Jan Öhrström, Chairman of the Board at GTX Medical about this technology.

Conn Hastings, Medgadget: Please give us an overview of the current therapeutic options for people with spinal cord injuries and paralysis.



Jan Öhrström, GTX Medical: The initial therapeutic options after a spinal cord injury are focused on limiting the damage caused by a traumatic event as much as possible by stabilizing the individual, applying neuroprotective therapies, performing surgeries and considering the use of ventilation (more information can be found on the website of the Reeve Foundation). Rehabilitation following a traumatic spinal cord injury cannot start before the acute care phase is completed.

Most therapeutic options are focused on physical rehabilitation and occupational therapy with the aim to recover as much as possible and learning how to live with the condition. Functional goals are set during the rehabilitation program by a multi-disciplinary team of rehab physicians, physical therapists, occupational therapists, psychologists and social workers. Standard rehabilitation usually lasts between 3 and 12 months, depending on the type of injury and the reimbursement of rehabilitation in different geographies. Besides conventional rehabilitation exercises, a number of modern rehabilitation aids are available such as Functional Electrical Stimulation (FES), exoskeletons and gait training with body weight support systems, robotic treadmills, sometimes combined with virtual reality, etc. Once the rehabilitation ends, patients are encouraged to continue exercising to maintain the progress they have gained.

Medgadget: Is there a significant unmet therapeutic need for this patient population?

Jan Öhrström: The standard of care for people who suffer a spinal cord injury is rehabilitation. Initial recovery leading to the maximal extent recovery in the first months with conventional rehabilitation is sometimes enhanced with automated rehab tools. However, neither medical therapies, nor conventional devices like exoskeletons promotes much recovery for wheelchair-bound people. Hence, the message sent by healthcare providers is more about learning to live your life in your new condition rather than focusing on hope of recovery.

For decades, researchers have been searching for curative solutions. Stem cells may be an attractive option one day, but this is still far away from clinical applicability. Neurostimulation is the single breakthrough promoting functional recovery and bringing hope to patients living with spinal cord injury.

Medgadget: How do you anticipate that the Go-2 system will help to address these unmet needs?

Jan Öhrström: In incomplete spinal cord injuries, dormant fibers are still available in the spinal cord. By using targeted epidural spinal cord stimulation (TESS), these intact circuits located below the lesion can be reactivated. The electrical stimulation immediately enables voluntary control of paralyzed muscles during walking.

GTX specifically targets individuals who have sufficient remaining spinal nerve fibers and therefore have the best chance of walking again. Our unique approach with stimulation of the spinal cord focuses on training the brain to use the remaining nerves in the spinal cord to activate individual leg muscles. This method promotes the permanent and previously unimaginable recovery of leg control, leading to a patient’s physical, social and emotional rehabilitation.

While we intend for our therapy to work closely with rehabilitation, our goal is different: we intend for each patient to regain as much function as possible from our therapy, including walking without human assistance. We want them to retain and build on hope, since we offer a truly life-changing solution.

Medgadget: What types of benefits do you anticipate that the system might produce in terms of increased movement and power for patients with paralysis?

Jan Öhrström: Great improvements on the Functional Independence Measure scale have been observed for patients in the feasibility study, even though they had been paralyzed up to 14 years earlier (unpublished data). These improvements might be considered a miracle by those who understand the severity of this condition. The Functional Independence Measure (FIM – scale of 91 motor points) is a clinical test evaluating the amount of assistance required by a person with a disability to perform basic life activities, ranging from complete dependence to full independence. For example, a gain of 20 motor points readily translates to a €0.5M cost reduction per patient over the lifetime (Miller et al. 2016). On average, for each person with spinal cord injury, a €2M overall healthcare associated cost over a 25-year life span is due to decreased independence (bathing, toilet, to and from the bed, mobility inside and outside the house) and organ functions (bladder and bowel control).



Medgadget: How does Targeted Epidural Spinal Stimulation work?

Jan Öhrström: To implement TESS therapy, surgeons implant an electrode array to deliver electrical stimulation in the region controlling motor function. The array delivers precisely timed pulses to specific parts of the spinal cord. These pulses mimic the timing and location of the motor commands from the brain that drive walking. When the right foot is put down, for example, mild stimulation is provided to start raising the left leg in anticipation of taking the next step. When he/she feels the stimulation, the patient will be able to activate the leg muscles and make a step in a natural fashion. The patient always remains in control and will not have the feeling his body became some sort of robot.

It has been shown in early trials that this approach successfully trains the brain both to use the remaining healthy nerves spared by the injury as well as to actually grow new, functional nerve connections. Combined with rehabilitation, TESS therapy leads to recovery of neural pathways controlling movement, even without stimulation. Prof. Courtine published a demonstration of restoring locomotion after paralysis in Nature in 2018.

Over time, TESS promotes an anatomical reorganization of the spinal cord and residual neural pathways spared by the injury. The rewiring restores voluntary control over the legs, even when the stimulation is switched off. This approach enables long-term continuous training at home. This complements the patients’ rehabilitation sessions and helps them to both achieve independence while also improving their condition.

Medgadget: Please tell us about the latest FDA Breakthrough Device Designation and what this will mean for the Go-2 in terms of testing and the pathway to approval.

Jan Öhrström: The FDA Breakthrough Devices Program was established to help patients receive timely access to breakthrough technologies that provide a more effective treatment option compared to the current standard of care for life-threatening, or irreversibly debilitating diseases or conditions.

This Breakthrough Device Designation is an important regulatory milestone, accelerating the regulatory pathway to market approval. It underscores the transformative potential of the Go-2 system and the unmet medical need it addresses.

The designation provides GTX the opportunity to frequently interact with FDA regulatory experts, thereby gaining valuable advice during the premarket review phase, and to receiving a prioritized review of GTX’ submissions.

Medgadget: Please give us an overview of the noninvasive wearable LIFT system that is currently in development.

Jan Öhrström: LIFT is a transcutaneous and wearable stimulation therapy intended to improve hand- and arm function, independence and quality of life in people with tetraplegia after a spinal cord injury. GTX is carrying out further product development in advance of a pivotal Up-LIFT clinical trial in the USA.



Improvement in neuromuscular function is directly linked with an improvement in quality of life. Regaining the ability to hold a spoon or a cup results in increased independence and improved motor skills may allow individuals with a spinal cord injury to operate, for example, a computer.

GTX is developing the transcutaneous LIFT device for non-invasive electrical spinal cord stimulation (NESS) therapy to enable restoration of motor control and function in the upper limbs after spinal cord injury.

The LIFT stimulator delivers non-invasive and painless electrical pulses through a patented waveform to restore the communication between the brain and the spared neural networks below the injury.

Wearable gel electrodes are attached to the skin on the back of the patient’s neck (cervical spine) and controlled via a hand-held stimulator programmed with a tablet. The LIFT device has adjustable settings for current, frequency, waveform and duration of stimulation.

The scientific basis for development of the LIFT system is predicated upon research studies performed on animal and human subjects with spinal cord injury demonstrating residual (spared) sensory and motor pathways are critical in mediating the voluntary movements that are possible when NESS therapy is paired with task-based training by the individual.

The LIFT System is intended to be used at a rehabilitation therapy clinic, in the hospital and at home.

A pivotal study in the USA is planned for Q4 2020, to support an application for market clearance to the FDA in the USA by 2022.

Here’s a video explaining how TESS works:

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