The
U.S. Food and Drug Administration today approved the MicroTransponder
Vivistim Paired VNS System (Vivistim System), a first-of-its-kind,
drug-free rehabilitation system intended to treat moderate to severe
upper extremity motor deficits associated with chronic ischemic
stroke—a stroke caused by a blockage of blood flow to the brain with
long-lasting symptoms—using vagus nerve stimulation (VNS).
“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, M.D., acting director of the FDA’s Center
for Devices and Radiological Health’s Office of Neurological and
Physical Medicine Devices. “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.”
A
stroke occurs when blood flow to part of the brain is interrupted,
causing brain cells to die from a lack of oxygen and nutrients
contained in the blood. There are different types of stroke, but the
most common type is ischemic stroke, meaning the blood vessels to the
brain become clogged, which blocks blood flow from reaching the brain.
Depending on how long the brain is deprived of blood and where in the
brain the stroke occurs, stroke can lead to brain damage, temporary or
permanent disabilities, and in some cases, death. Disabilities
resulting from stroke may include, but are not limited to, total or
partial paralysis or difficulty with muscle movement.
The
Vivistim System is intended to be used, along with post-stroke
rehabilitation therapy, in patients who have had ischemic stroke, to
electrically stimulate the vagus nerve—a nerve that runs from the brain
down to the abdomen—to reduce deficiencies in upper limb and extremity
motor function and to improve patients’ ability to move their arms and
hands. To use the Vivistim System, an implantable pulse generator (IPG)—which
generates a mild electrical pulse—is implanted just under the skin in
the chest of the patient. Attached to the IPG is a lead wire that is
implanted under the skin and leads up to electrodes that are placed on
the left side of the neck where the vagus nerve is.
Accompanying
the implantable components are clinician software preloaded onto a
laptop and a wireless transmitter to be used only by a health care
provider. The software allows a health care provider managing a
patient’s rehabilitation to input the appropriate settings on the IPG,
including amplitude, frequency, and pulse width for the stimulation,
and also records stimulation history, movements performed, and
information about the IPG. The wireless transmitter communicates
adjustments to the IPG settings made using the software.
The
Vivistim System, a prescription device, may be used in both clinical
and at-home settings to provide VNS. If it is to be used during home
rehabilitation exercises, the software and the wireless transmitter are
not used by the patient. However, the patient is supplied with a magnet
that can be passed over the IPG implant site to activate the IPG to
begin a 30-minute stimulation session during rehabilitative exercise.
When directed by a physician and with appropriate programming to the
IPG, patients are trained on how to use the Vivistim System at home, as
well as its safety features, to avoid any unwanted electrical
stimulation.
The
FDA evaluated the safety and effectiveness of the Vivistim System in a
clinical study of 108 patients at 19 clinical sites in the U.S. and the
U.K. who received the Vivistim System. Patients were split into a study
group (53 patients) and a control group (55 patients), whereby both
groups were asked to complete 300-400 physical therapy exercises for 90
minutes a day, three times a week for six weeks. The control group
received only a very low level of VNS for the first five exercises of
the 300-400-movement series and had no stimulation whatsoever for the
rest of each session. The treatment group received the appropriate
amount of VNS throughout all 90-minute rehabilitation sessions. Both
groups received physical therapy sessions that were equivalent in
quantity and quality. Following the initial six-week study, all
patients received follow-up assessments at 1, 30, and 90 days following
the study.
Effectiveness
for the Vivistim System was measured using the Upper Extremity
Fugl-Meyer Assessment (FMA-UE), a stroke specific measure of motor
impairment. Progress was measured as an increase in motor function from
baseline after six weeks of therapy. Patients in the treatment group
had an average score increase of 5 points, whereas patients in the
control group had an average score increase of 2.4 points.
Additionally, 47.2% of those in the treatment group saw an improvement
of 6 or more points in the FMA-UE score 90 days post-therapy as
compared with 23.6% in the control group.
Adverse
events included but were not limited to dysphonia (difficulty
speaking), bruising, falling, general hoarseness, general pain,
hoarseness after surgery, low mood, muscle pain, fracture, headache,
rash, dizziness, throat irritation, urinary tract infection and
fatigue.
The
Vivistim System is not approved for use outside of its intended use to
stimulate the vagus nerve during chronic ischemic stroke rehabilitation
therapy for moderate to severe loss of upper extremity function. It
should not be used in patients with vagotomy, which is surgical removal
of part of the vagus nerve.
Patients
should discuss with their providers any prior medical history of: other
concurrent forms of brain stimulation; current diathermy treatment,
which uses electrical current stimulation to produce “deep heating”
beneath the skin in subcutaneous tissues, deep muscles and joints;
depression or suicidality; schizophrenia, schizoaffective disorder, or
delusional disorders; rapid cycling bipolar disorder; previous brain
surgery or central nervous system injury; progressive neurological
diseases other than stroke; cardiac abnormalities, including arrhythmia;
dysautonomias, or medical conditions caused by problems with the
autonomic nervous system; respiratory diseases or disorders, including
dyspnea and asthma; ulcers; vasovagal syncope; and pre-existing
hoarseness.
The
Vivistim System was granted Breakthrough Device designation.
To qualify for such designation, a device must be intended to treat or
diagnose a life-threatening or irreversibly debilitating disease or
condition and meet one of the following criteria: the device must
represent a breakthrough technology; there must be no approved or
cleared alternatives; the device must offer significant advantages over
existing approved or cleared alternatives; or the availability of the
device is in the best interest of patients.
The
FDA reviewed the MicroTransponder Vivistim Paired VNS System under
the Premarket Approval (PMA)
pathway. PMA is the most stringent type of device marketing
application required by the FDA and is based on a determination by the
FDA that the PMA application contains sufficient valid scientific
evidence to provide reasonable assurance that the device is safe and
effective for its intended use.
The
MicroTransponder Vivistim Paired VNS System is manufactured by
MicroTransponder Inc.
Additional
Resources: |