Small needles are inserted into the muscle and mild electrical shocks are given to stimulate the nerve. Discomfort may be associated with this test. Evoked potentials record the brain's electrical response to visual, auditory and sensory stimuli. This test is useful in evaluating and diagnosing symptoms of dizziness, numbness and tingling, as well as some visual disorders. Discomfort may be associated with this test.
Sleep studies involve tests that diagnose specific causes of sleep problems.
To perform the tests, it is often necessary for a patient to spend the night in a sleep laboratory. Brain wave activity, heart rate, electrical activity of the heart, breathing and oxygen in the blood are all measured during the sleep test. The test is painless. In this test the lower back is numbed with local anesthesia, and a thin needle is placed into the space that contains the spinal fluid. The amount of spinal fluid needed to diagnose the specific problem is removed and the needle is withdrawn.