This study will investigate problems with muscle weakness and control using
electromyography-a test of nerve-muscle cell communication. Advanced techniques called
single fiber electromyography and macro-electromyography, which evaluate individual muscle
fibers, will be used. Besides aiding in diagnosis, these tests provide information about
disease progression that may be useful in guiding therapy.
Adult patients with suspected neurological disorders of muscle control and weakness may be
eligible for this study. Normal volunteers may also participate. For the electromyography
procedure, a special needle is inserted into a muscle. The patient will slightly tense the
muscle and maintain the tension while electrical signals from the muscle fibers are being
recorded. The electrical signals are played through a loudspeaker, providing feedback to
help the patient tense the muscle the appropriate amount. The test, which is usually done
for only one muscle, takes 1 to 2 hours. If needed, short breaks can be taken.
If the patient cannot maintain tension in the muscle for the entire test period, a nerve
will be stimulated to activate the muscle. A thin needle is inserted near the nerve, and a
series of small electrical shocks are given to activate a nerve fiber. The electromyography
needle is inserted into the muscle to measure the response, as described above.
A neurologist receiving specialized training in clinical neurophysiology will do the
electromyography procedure under the direct supervision of an experienced neurologist.
This is a training protocol to enable fellows in clinical neurophysiology to learn and
perform technically advanced electrodiagnostic studies, such as single fiber EMG and macro
EMG, on patients with neuromuscular diseases.
Adult patients with weakness or motor dysfunction: 8/year.
Normal volunteers, adults: 2/year.
Anticoagulation or uncorrected bleeding disorder.
Children are not optimal subjects for fellows undergoing training in these techniques and
will be excluded.