An EEG records electrical activity of the brain. Highly sensitive monitoring equipment records the activity of neurons through electrodes placed at measured intervals on the scalp. EEGs help physicians to diagnose a variety of neurological conditions from common headaches and dizziness to seizure disorders, strokes and degenerative brain disease. It also may be used to look for organic causes of disabilities in children and psychiatric disorders.
EMGs measure the electrical activity of muscles at rest and while contracting. Nerve conduction studies measure the ability of nerves to send electrical signals. Nerve and muscle disorders cause muscles to react improperly to electrical signals. This test helps diagnose diseases that damage nerves, muscle tissue or neuromuscular junctions or the cause of weakness, paralysis and muscle twitching. Examples include carpal tunnel syndrome, peripheral neuropathies, herniated discs, muscle disease, Cerebral Palsy and conditions like Amyotrophic Lateral Sclerosis (ALS) and Guillian-Barre.