NCV
To perform nerve conduction studies, the physician tapes small metal
electrodes on the skin and applies a brief electric stimulus to one portion
of a nerve. Nerve stimulation will cause a tingling sensation. The physician
can then evaluate the electric response of the nerve or muscle to which the
nerve is attached and determine if the nerve impulse is a) conducted
normally, b) at a slow speed or c) not transmitted at all, suggesting damage
to the nerve.
Evoked Potentials
Electrodiagnosis may also include a number of other tests, such as evoked
potentials. These studies use different stimuli, such as auditory clicks, a
changing visual pattern such as a checkerboard, or small electric stimuli
applied to specific nerves. The recordings are made over the surface of the
head and the spine to evaluate whether the sensory impulses are conducting
normally through the nerves, spinal cord or brain.
Special Precautions
The patient does not need to do anything special to prepare for this test,
except to keep the skin free of any lotions or emollients on the day of the
examination. Be sure to inform the physician, however, if you are taking
blood-thinning medication such as Coumadin, have hemophilia or a cardiac
pacemaker. Patients with myasthenia gravis should ask their physician
whether or not to take anticholinesterase medications on the day of the
test.
Patient Questions
This document is not a substitute for an informed discussion between a
patient and his or her physician about the examination. If you have
questions, they will be answered at the time of your examination.