EEG is performed by a technologist, and involves pasting electrodes to the surface of the head that will record the brain waves at rest and during certain activities. Initially patients close their eyes, but during the test the technologist may routinely ask them to open and close their eyes, hyperventilate, and/or watch a flashing light to see how the brain responds (for example, watching a flashing light can induce seizures in susceptible people). At the conclusion of the test, the technologist removes the electrodes and cleans any remaining paste. There are no restrictions following an EEG. A neurologist specially trained in reading EEGs will interpret the test and send a report of the findings to the referring physician.
EMG and NCV testing are used in the evaluation of carpal tunnel syndrome, peripheral neuropathy (that may, for example, be part of diabetes), and radiculopathy (pinched nerves in the spine), as well as other nerve-related problems. A physician performs an EMG by inserting sterile pins with a microscopic electrode on the tip into certain muscles of the patient’s limbs or back. The test can be helpful in evaluating the causes of numbness, tingling, pain, weakness, fatigue and muscle cramping. The NCV test is performed by placing several electrodes on the appropriate limb and applying a mild electric stimulus to the site. This measures the speed of the electrical impulses and provides general information about the health of the nerves being tested and may identify the location of suspected pinched nerves. After the test, the physician will usually briefly explain the findings. The patient may experience a mild discomfort in certain areas of their limbs, but this generally returns to normal within 30 minutes. There are no restrictions or limitations following EMG or NCV testing.