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Electromyography and Nerve Condition Study |
Basic Information
EMG/NCV study is the basic diagnostic test used to diagnose
nerve and muscle disease. The test is generally performed
in a doctor's office, without sedation. There are two components
to the test. First, nerve conduction studies are performed.
This involves applying a brief electric shock to the nerve
and then measuring the nerve responses. The second part of
the test involves a needle examination of several muscles,
to look for abnormal muscle or nerve activity. The test is
generally considered modestly uncomfortable but not significantly
painful. Most studies take from 30 minutes to an hour to complete.
Neurologists are expert at performance and interpretation
of nerve conduction studies. These studies may be performed
for the initial diagnosis of conditions such as carpal tunnel
syndrome and generalized neuropathy. They may also be used
to compliment other studies such as MRI of the spine or brain.
Neurologists will often work with neurosurgeons, physiatrists,
and other doctors to help evaluate and interpret these studies.
An abnormal EMG/NCV study may lead to other diagnostic tests
such as laboratory work, spinal fluid examination, MRI to
evaluate the central nervous system, and possible nerve/muscle
biopsy.
EMG/NCV is used to diagnose the following conditions:
- Generalized neuropathy or peripheral neuropathy.
- Nerve entrapment such as carpal tunnel syndrome, ulnar
nerve entrapment at the elbow, and other such entrapments.
- Autoimmune neuropathies such as Guyon-Barré syndrome.
- Pinched nerves in the spine (spinal radiculopathy), caused
by herniated disc disease.
- Various neuromuscular conditions such as ALS and myasthenia
gravis.
- Muscle diseases such as polymyositis and steroid-induced
myopathy.
- Autonomic dysfunction as seen in diabetes and other conditions.
Other test information:
- Nerve biopsy may be recommended, which allows doctors
to directly review nerve anat-omy and determine the cause
of pathology.
- Muscle biopsy has the same use, and often the two are
done together
- Nerve entrapments, like carpal tunnel syndrome, are important
to diagnose because the respond readily to simple decompressive
surgery.
Web site: American
Association of Electrodiagnostic Medicine |
