Vagal nerve stimulator for stroke rehab nabs FDA nod

Regulatory NewsRegulatory News | 27 August 2021 |  By 

The first-ever vagal nerve stimulation system for chronic ischemic stroke rehabilitation has received approval through the US Food and Drug Administration’s (FDA’s) most stringent pathway.
The vagal nerve stimulation (VNS) system will be marketed by MicroTransponder as the Vivistim Paired VNS System. The device enters the market through FDA’s premarket approval pathway after receiving breakthrough device designation.
"People who have lost mobility in their hands and arms due to ischemic stroke are often limited in their treatment options for regaining motor function," said Christopher M. Loftus, acting director of the Office of Neurological and Physical Medicine Devices in FDA's Center for Devices and Radiological Health. "Today's approval of the Vivistim Paired VNS System offers the first stroke rehabilitation option using vagus nerve stimulation. Used alongside rehabilitative exercise, this device may offer benefit to those who have lost function in their upper limbs due to ischemic stroke," added Loftus in the press announcement of the approval.
The device is available by prescription for use both in the clinic and at home. It consists of a subcutaneously implanted pulse generator that sits under the skin of the patient’s chest; an implanted lead wire carries a mild electrical signal to the vagal nerve that runs along the left side of the neck.
The device’s other components include software for clinician use that comes preloaded onto a laptop, together with a wireless transmitter that sends signals to the implanted pulse generator. The software allows a clinician to control the amplitude, frequency and pulse width of the vagal nerve stimulation; it also tracks historic data about the patient’s Vivistim therapy.
Patients, after training, can use the system at home after passing a magnet over the site where their pulse generator is implanted, which begins a 30-minute session of stimulation for home rehabilitation exercises.
The principle that lies behind the Vivistim system’s effectiveness in stroke rehabilitation is that the afferent vagal nerve signal generated by the pulsed stimulation triggers neuromodulator release in the brain. “The release of transmitters increases the relevance of the physical therapy. The resulting brain reorganization and strengthening of the neural connections contributes to the enhanced motor function,” explains MicroTransponder in a webpage about its stroke technology.
FDA’s approval of the device was based on a multi-site study of 108 chronic ischemic stroke patients in the US and the UK who were divided 1:1 into a treatment and a sham intervention group. Patients had experienced stroke at least 9 months, and up to 10 years, before study enrollment. “To maximize masking of treatment allocation, all participants were implanted with the vagus nerve stimulation device,” explained the University of Glasgow’s Jesse Dawson and coauthors in an article in The Lancet detailing the pivotal clinical trial.
Study participants assigned to the sham intervention received a sub-therapeutic level of electrical stimulation; both groups were assigned 300 to 400 physical therapy exercises to perform for 90 minutes a day, at least three times a week, for a period of 6 weeks.
At the 6-week mark, patients who received the Vivistem intervention experienced, on average, more than twice the improvement in a stroke-specific measure of upper extremity impairment. Looking at the data another way, almost half (47.2%) of patients in the treatment group saw a clinically significant improvement in their upper extremity impairment scores, compared with not quite a quarter (23.6%) of those who received the sham intervention.
Adverse events were common in both study arms; no severe events were deemed associated with the study device, and the number of events overall were similar between groups. However, one control group participant did experience vocal cord palsy after device implantation, which resolved 5 weeks after surgery.
Breakthrough device designation by the FDA is reserved for devices “intended to treat or diagnose a life-threatening or irreversibly debilitating disease or condition,” and must either be a breakthrough device, or have no approved or cleared alternatives (or offer “significant advantages” over any approved or cleared alternatives). Alternatively, breakthrough device designation may be granted if “the availability of the device is in the best interest of patients,” according to FDA’s announcement of the Vivistim approval.


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