Electroneurodiagnostic Tests

Electroneurodiagnostics is the study and recording of electrical activity in the brain and nervous system. These tests are harmless, painless, and performed by technologists who record the diagnostic information. The results are then interpreted by a specially-trained physician.

Our physicians perform electroneurodiagnostic testing at Women and Children’s Hospital – the state’s only freestanding children’s hospital with pediatric physicians in more than 30 specialties. The hospital’s EEG lab uses the latest technology for accurate, timely results.

Some electroneurodiagnostic tests commonly performed include:

Electroencephalogram (EEG)
An EEG measures and records the electrical activity of your brain. Special sensors (electrodes) are attached to your head and hooked by wires to a computer. The computer records your brain’s electrical activity on the screen or on paper as wavy lines. Certain conditions, such as seizures, can be seen by the changes in the normal pattern of the brain’s electrical activity.

An EEG may be done to:
     • Diagnose epilepsy and see what type of seizures are occurring. (An EEG is the most useful and important test in confirming a diagnosis of epilepsy.)
     • Check for problems with loss of consciousness or dementia.
     • Help find out a person’s chance of recovery after a change in consciousness.
     • Find out if a person who is in a coma is brain-dead.
     • Study sleep disorders, such as narcolepsy.
     • Watch brain activity while a person is receiving general anesthesia during brain surgery.
     • Find out if a person has a physical problem (in the brain, spinal cord and/or nervous system) or mental health problem.

Similar to EEG monitoring in the hospital setting, ambulatory EEG monitoring can be done at home, allowing patients to continue with their daily activities while recordings are made. The test records patterns of electrical changes, both normal and abnormal, from the millions of nerve cells in the brain. Its ability to record continuously for up to 72 hours increases the chance of recording an ictal (physiologic) event, such as a seizure stroke or headache, or interictal epileptiform discharges (spikes in epileptic syndromes).

Ambulatory EEG testing is done to:
     • Diagnose epilepsy and determine what type of seizures are occurring. EEG is the most useful and important test in confirming a diagnosis of epilepsy.
     • Distinguish fainting spells from seizures.
     • Quantify the number of abnormal discharges or seizures in patients with epilepsy.
     • Evaluate periods of unconsciousness or memory loss. 
     • Monitor the effectiveness of medications. 
     • Study events that occur sporadically.

Prolonged 24/48 Hour Video EEG
Long-term monitoring is the simultaneous recording of EEG and videotaped behavior over extended periods of time. It is useful in diagnosing patients with intermittent of infrequent disturbances.

Evoked Potential (EP)
An EP test measures the time it takes for nerves to respond to stimulation. The size of the response is also measured. Nerves from different areas of the body may be tested. Types of responses are:
     • Visual evoked response or potential (VER or VEP): when the eyes are stimulated by looking at a test pattern.
     • Auditory brain stem evoked response or potential (ABER or ABEP): when hearing is stimulated by listening to a test tone.
     • Somatosensory evoked response or potential (SSER or SSEP): when the nerves of the arms and legs are stimulated by an electrical pulse.

Each type of response is recorded from brain waves using electrodes taped to the head. The visual evoked response (VER) is the most commonly used evoked potential test in the diagnosis of multiple sclerosis (MS). EP is also helpful in identifying different neurological problems, including spinal cord injuries, acoustic neuroma and optic neuritis.

Pediatric Polysonogram
A PSG is a recording during sleep that uses EEG, end tidal C02, and other physiologic measures to evaluate sleep disorders. Patients usually spend one or two nights in the lab being monitored. A technologist records the information for interpretation by a specially-trained physician. The test is used to help evaluate patients who experience excessive sleepiness during the day or who have trouble falling asleep or staying asleep at night. Common sleep disorders include obstructive sleep apnea, infantile sleep apnea, insomnia, parasomnias, RLS, nocturnal seizures and narcolepsy.