Clinical Trial Tests Epidural Stimulation for Low Blood Pressure After Spinal Cord Injury
A multicenter clinical trial including researchers from the University of Miami of Medicine is testing whether an implanted epidural stimulation system can help people with spinal cord injury maintain blood pressure while sitting or standing.
Key Takeaways
- The Empower BP study is testing whether epidural electrical stimulation can help people with spinal cord injury manage orthostatic hypotension.
- The implanted system targets spinal circuits involved in blood pressure regulation and can be activated when participants change positions or experience low blood pressure symptoms.
- The randomized, double-blind clinical trial is ongoing, and results are not yet available.
Of all the debilitating ways a spinal cord injury can affect a person’s life, severe hypotension adds a significant insult to the injury.
A temporary drop in blood pressure can leave you dizzy or lightheaded when you stand up quickly.
“Imagine feeling that way all the time, to the point where it’s really challenging to keep your blood pressure at a level where you feel alert and engaged in your environment,” said Leslie Morse, D.O., chair of the Department of Physical Medicine and Rehabilitation at the University of Miami Miller School of Medicine.
Dr. Morse is principal investigator for the Miller School site on a multicenter clinical trial that could help people with spinal cord injury control their low blood pressure. James Guest, M.D., Ph.D., professor of neurological surgery at the Miller School and member of The Miami Project to Cure Paralysis, helped to design the study and worked closely with the FDA to finalize the treatment protocol.
The ONWARD Empower BP study is the first of its kind to implant an epidural electrical stimulation device to treat orthostatic hypotension, a condition caused by an inability to regulate blood pressure.
“Past studies have only included small, highly selected groups of subjects. The Empower study is the first study that could lead to an approved epidural stimulation treatment that could have a transformational effect on people with spinal cord injury on a larger scale,” said Dr. Guest.
Since August, Joacir Graciolli, M.D., Ph.D., a UHealth—University of Miami neurosurgeon and member of The Miami Project to Cure Paralysis, has surgically implanted the epidural stimulation systems in four study participants, with additional patients undergoing screening and enrollment.
Dr. Morse expects to enroll 12 people in Miami total out of the study’s expected 80 participants.
“Our environment, infrastructure, ability to collaborate, and to recruit and retain participants in a study says a lot about how industry partners look to us as a leader,” said Dr. Morse.
How Common is Hypotension in People with SCI?
Normally, the body constantly redistributes blood as you stand up, sit or lie down through reflex feedback. This autonomic reflex is often disrupted in those with a spinal cord injury, which can reduce blood flow to the brain when sitting or standing. The condition is called orthostatic hypotension.
Around 85% of people with a spinal cord injury suffer from orthostatic hypotension, ranging from mild to severe. Some people manage with medication or a leg or abdominal binder. Others have more extreme symptoms, limiting their ability to stay awake, eat and function.
Hypotension causes less blood to reach the brain, which can have an impact on the following:
- Cognition
- Awareness
- Vision
- Energy levels
- Ability to sit up straight
- Ability to stay awake and even conscious
- Increased risk of stroke
“Being able to reverse that, and provide somebody with a daily shift in how engaged they are in their environment is hugely impactful long-term,” said Dr. Morse.
Frequently Asked Questions
What is orthostatic hypotension?
Orthostatic hypotension is low blood pressure that can occur when a person sits or stands. After spinal cord injury, disruption of the body’s autonomic reflexes can make it difficult to maintain blood flow to the brain when changing positions.
How might epidural stimulation help regulate blood pressure?
The implanted system delivers electrical stimulation to a region of the lower thoracic spinal cord involved in blood pressure regulation. Researchers are testing whether activating these spinal circuits can help trigger the body’s natural blood pressure response, including vasoconstriction, or the narrowing of blood vessels.
Is epidural stimulation an approved treatment for low blood pressure after spinal cord injury?
No. The Empower BP study is evaluating epidural stimulation for orthostatic hypotension in a randomized clinical trial. The trial is still underway, and results are not yet available.
How Epidural Stimulation may Help Regulate Blood Pressure
Epidural spinal cord stimulators are FDA-approved for chronic pain. Neurosurgeons at UHealth regularly implant them in people who can benefit from the device.
As early as 2011, a study indicated that people with severe spinal cord injuries could have some voluntary movement when epidural stimulation was applied to them. Dr. Guest collaborated with researchers at the University of Louisville at the time, and said, “It opened up a whole new understanding of what it means to have a complete spinal cord injury.”
Unlike past epidural stimulator studies, the Empower study is among the first large-scale randomized “pivotal” clinical trials of epidural stimulation designed to evaluate potential therapeutic effects for people with SCI.
Participants in the study first undergo surgical implantation to have a small pulse generator connected to a lead placed near their spinal cord. They can then use a smartwatch to activate programmed spinal cord stimulation when they change positions or experience low blood pressure symptoms.
The stimulation targets a region of the lower thoracic spinal cord involved in blood pressure regulation. By activating these spinal circuits, the electrical stimulation can help trigger the body’s natural blood pressure response, including vasoconstriction (the narrowing of blood vessels that increases vascular resistance and helps maintain blood pressure).
How the Study Works
Dr. Guest, the medical monitor for the multi-site study, which includes 13 other locations, says the study uses a 2-to-1 randomization design. A third of the people are randomized to receive a sham therapy for the first three months. After that first endpoint, they are compared with those randomized to active treatment. After that point, everyone crosses over to receive active therapy for up to two years to further evaluate safety.
“Even if a person is initially randomized to sham therapy, they still get their chance to test the device effectiveness,” said Dr. Guest.
One of the advantages to starting with blood pressure for testing epidural stimulation on spinal cord injury is that improvement doesn’t require lengthy, systematic rehabilitation.
“If you previously couldn’t get out of bed or put your chair up vertically, and now you start doing that after using the stimulation, these are restorative physiological effects that don’t require going to the rehab center,” said Dr. Guest.
It’s too early for results to emerge from the clinical trial, but Dr. Morse said the device would significantly improve people’s quality of life if it’s successful.
“I’m really excited to see how this might be implemented clinically in the next few years and become a standard of care for people who are really suffering from low blood pressure,” she said.
Dr. Guest is hopeful the study may be a gateway to future studies on other ways an epidural stimulator might benefit people with spinal cord injury, such as reducing high fluctuations in blood pressure from autonomic dysreflexia, reducing neuropathic pain, improving bladder and bowel function, postural and trunk control, reducing spasticity, improving upper extremity strength and facilitating ambulation.
“I hope that this will succeed and be the first approved epidural stimulation therapy, so then it could become a platform for other research,” said Dr. Guest.
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Tags: Department of Neurological Surgery, Department of Physical Medicine and Rehabilitation, Dr. James Guest, Dr. Leslie Morse, epidural, neurological surgery, The Miami Project to Cure Paralysis, transcutaneous spinal cord stimulation