This study will determine whether an electric shock to the forearm can improve hand function
in patients with chronic stroke and, if so, whether the improvement is related to brain
reorganization. Some studies indicate that electromyography-triggered neuromuscular
electrical stimulation (EMG-triggered NMES) on the forearm improves wrist motor function in
patients with chronic stroke. The shock is delivered to the wrist extensor muscle of the
forearm, causing greater hand movement than the patient can make on his or her own. The
study will determine if the electric shock is more effective given after the patient
initiates the hand movement (EMG-triggered NMES) than at times unrelated to patient effort
Stroke patients with muscle weakness on one side of the body may be eligible for this study.
The stroke must have occurred at least 12 months before the patient enters the study.
Candidates will have a medical history and physical and neurological examinations.
Participants will be divided randomly into two groups: EMG-triggered NMES, and NMES alone.
For EMG-triggered NMES, two electrodes from the NMES machine and two EMG electrodes are
placed on the wrist extensor muscle of the forearm. The patient relaxes the hand, then
contracts the wrist extensor muscle to produce movement. This movement triggers the NMES to
deliver enough electrical stimulation to produce maximum wrist extension. For NMES alone,
only the two NMES electrodes are placed on the forearm. The patient relaxes the hand and
stimulation is applied at an intensity to produce full wrist extension without any patient
At the first clinic visit, baseline hand function is measured with the following tests:
- Wrist extension - wrist extension is measured with a digital instrument called an
- Pinch power - grip strength between thumb and index finger is measured with a digital
- Jebsen-Taylor hand function - function is evaluated through activities such as moving a
can and lifting a pin
- H reflex - (Note: I could not find a description of this test or its purpose in the
consent or the protocol)
In addition, transcranial magnetic stimulation (TMS) is done to examine brain activity. For
this test, an insulated wire coil is placed on the patient's scalp. A brief electrical
current passes through the coil, creating a magnetic pulse that travels through the scalp
and skull and causes small electrical currents in the outer part of the brain. The
stimulation may cause muscle, hand or arm twitching, or may affect movement or reflexes.
During the stimulation, electrical activity of muscles are recorded with a computer or other
recording device, using electrodes attached to the skin with tape.
Participants will be instructed in how to use the NMES machine at the first visit. They will
be required to practice with the machine at home 30 minutes twice a day every day for 4
weeks, for a total of about 56 sessions. Follow-up evaluations of hand function will be done
one day after the first NMES or EGM-triggered NMES task, then after 2 weeks and after 4
weeks of performing the exercise. These evaluations include the tests described above for
baseline measurements, plus TMS.
The purpose of this study is to investigate the effect of a newly developed electrical
technique, electromyography (EMG) triggered neuromuscular electrical stimulation NMES) known
as EMG-Stim., on brain reorganization. Clinically EMG-Stim. is thought to improve a chronic
hemiparetic hand [1-3], but its underlying mechanism is poorly understood. We plan to
determine: (1) if EMG-Stim. on a chronic hemiparetic hand as a result of stroke enhances
improved hand motor function; and (2) whether any clinical improvement is related to brain
Subjects with residual arm function who have had a single cortical monohemispheric stroke
(documented by CT or MRI) at least 12 months before, with normal visual acuity (with or
Subjects with more than one stroke.
Subjects with proprioceptive deficits.
Subjects with cerebellar lesion.
Subjects unable to extend metacarpophalangeal (MP) joints at least 10 degrees.
Subjects unable to extend the wrist 10 degrees.
Subjects with cognitive impairment which might interfere with the understanding of
instructions for motor testing (defined as equivalent to a mini-mental state exam score of
20 or less).
Subjects with severe depression, poor motivational capacity, or severe language
Subjects with severe uncontrolled medical problems (e.g. cardiovascular disease, active
joint deformity of arthritic origin, uncontrolled epilepsy).
Subjects with heart pacemakers.
Subjects with contractures in the hand.