Electromyography (EMG) and Nerve Conduction Studies
Nerves control the muscles in the body using electrical impulses. Whenever a muscle contracts (tenses up) in response to a signal from the brain, it also produces an electrical discharge of its own. Electromyography (EMG) measures the electrical discharge made by the muscle. Nerve conduction studies (nerve conduction velocity or NCV) measure how well individual nerves can transmit electrical signals.
Measuring the electrical activity in muscles and nerves can help detect the presence, location, and extent of diseases that can damage muscle tissue (such as muscular dystrophy) or nerves (such as amyotrophic lateral sclerosis). In the case of nerve injury, the actual site of nerve damage can often be located. EMG and nerve conduction studies are often done together to provide more complete information.
Office-based / Routine EEG
Electroencephalography (EEG) records the electrical activity of the brain. Sensors (electrodes) are attached to your head and connected by wires to a computer. The computer records your brain’s electrical activity on paper as wavy lines. Certain brain abnormalities can be detected by observing changes in the normal pattern of the brain’s electrical activity. The routine in-office EEG provides a 20- to 40-minute sample of brain electrical activity.
Ambulatory Electroencephalogram (EEG)
In some patients, such as those with epilepsy, an office-based EEG may appear normal. To aid in the diagnosis of epilepsy, we typically perform an ambulatory EEG with 24 to 48 hours of video recording for continual monitoring. Monitoring patients while they are both awake and asleep can help identify seizures, determine the type and frequency of seizures, and evaluate the effectiveness of epilepsy medications.
Evoked Potential Tests (BAER/VER)
Evoked potential tests measure electrical activity in certain areas of the brain in response to stimulation of certain groups of nerves. These tests are often used to assist in the diagnosis of multiple sclerosis (MS) because they can indicate problems along the pathways of certain nerves that are too subtle to be noticed or found during a doctor’s exam. Problems along the nerve pathways are a direct result of the disease. The demyelization causes the nerve impulses to be slowed, garbled, or halted altogether.
Electronystagmography (ENG) (Vestibular Testing)
Electronystagmography (ENG) is done to help determine whether damage to the structures or nerves in the inner ear or brain is causing dizziness or vertigo. ENG involves a series of tests that evaluate how well the eyes, inner ears, and brain help a person maintain balance and a sense of position (such as being able to distinguish standing up from lying down).
Electronystagmography measures certain involuntary eye movements called nystagmus. These eye movements occur normally when the head is moved. However, spontaneous or prolonged nystagmus may be associated with certain conditions that affect the nerves or structures of the inner ear or brain.
Transcranial Doppler and Carotid Doppler
A transcranial Doppler ultrasound sends sound waves through the skull (cranium) to measure the speed of blood flow to your brain. When an artery or vein that carries blood to your brain is narrowed, blocked, or damaged, your brain may not get enough blood and oxygen, which can lead to an embolism, hemmorhage, or other cerebrovascular disease. Similarly, a carotid Doppler ultrasound checks blood flow in the vessels at the base of the neck (carotid arteries) that supply blood to the brain. It is performed to evaluate the risk of stroke.