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Pittsburgh – In a pilot study, an epidural implant with electrodes that stimulate the spinal cord at the level of the cervical spine improved the function of the partially paralyzed hand of two patients undergoing rehabilitation treatment following a stroke. The effect was following the publication in Nature Medicine (2023; DOI: 10.1038/s41591-022-02202-6) still detectable even following the planned removal of the electrodes.
Most strokes occur in the brain, the spinal cord is usually unaffected. Paresis and paralysis occur because the motor neurons no longer receive specific instructions from the damaged brain regions or these are reduced to the point where they only lead to weak muscle movements.
One of the goals of rehabilitation treatment is to improve residual mobility. Over time, it is often possible to recruit other undamaged brain regions for motor tasks. In many patients, however, the paresis partially resolves over time.
A team led by Marco Capogrosso from the University of Pittsburgh would like to support the rehabilitation treatment by stimulating the spinal cord. In one operation, 2 band-shaped implants are placed above the dura mater directly on the spinal cord in the area of vertebrae C3 to Th1. They are equipped with electrodes that stimulate the sensory nerves.
Such epidural spinal cord stimulators have been used for the treatment of various pain syndromes for a number of years now also in Germany. In the case of motor disorders, its effectiveness has not yet been proven.
The aim of the treatment is to strengthen the activity of the motor nerves via the reflexes at the level of the spinal cord. The signals coming from the brain should be supported.
Treatment appears to have worked well in the first two patients in an ongoing study (as far as can be judged without a comparison group). A patient had suffered a hemorrhagic stroke 10 years earlier at the age of 23 following the rupture of a brain aneurysm. The second 47-year-old patient suffered an ischemic stroke years ago.
Epidural spinal cord stimulation was used as part of a rehabilitation treatment. The devices were switched on for 4 hours on 5 days a week.
The two patients were asked to perform certain exercises following activating the devices. At first glance, they seem to have succeeded quite well. According to Capogrosso, grip strength improved by 40% in one patient and as much as 108% in the other. The speed of movements increased by 30% to 40%.
Patients were able to perform some everyday movements that they were previously unable to do. This ranged from moving a hollow metal cylinder or grasping for common household items like a soup can to picking a lock.
Interestingly, the effect persisted even following the removal of the epidural electrodes, which was scheduled at 4 weeks in the study. The temporary implantation might therefore be suitable to support rehabilitation treatment, although the effectiveness would have to be checked in further randomized studies before approval. The treatment appears to have few side effects. One patient reported only a slight “vibrating” sensation in her arms.
The study was funded by the Brain Initiative sponsored by the US National Institutes of Health. The researchers have already founded a start-up company, “Reach Neuro”, with which they want to carry out further clinical studies. © rme/aerzteblatt.de
