Electronystagmography

Electronystagmography

A patient undergoing electronystagmography testing.

Electronystagmography (ENG) is a diagnostic test used to record involuntary movements of the eye, known as nystagmus. This test is primarily used to assess the function of the vestibular system and the auditory system, which are integral to maintaining balance and spatial orientation.

Purpose

The primary purpose of electronystagmography is to evaluate patients with symptoms of vertigo, dizziness, and balance disorders. It helps in diagnosing conditions such as Meniere's disease, vestibular neuritis, and labyrinthitis. ENG is also used to assess the function of the cranial nerves, particularly the vestibulocochlear nerve (Cranial Nerve VIII).

Procedure

During the ENG test, electrodes are placed around the eyes to detect electrical activity associated with eye movements. The patient is asked to perform various tasks, such as following a moving object with their eyes or focusing on a stationary target. The test may also involve stimulating the inner ear with warm or cold water or air, a process known as caloric testing.

Caloric Testing

Caloric testing is a component of ENG that involves irrigating the ear canal with warm or cold water or air. This stimulation causes a temperature change in the endolymph of the semicircular canals, leading to nystagmus. The direction and speed of the nystagmus are recorded and analyzed to assess the function of the vestibular system.

Interpretation

The results of electronystagmography are interpreted by analyzing the patterns of nystagmus. Abnormal results may indicate a dysfunction in the vestibular system or central nervous system. The test can help differentiate between peripheral and central causes of vertigo.

Advantages and Limitations

ENG is a non-invasive and relatively simple test that provides valuable information about the vestibular and auditory systems. However, it has limitations, such as the inability to detect all types of vestibular disorders. Additionally, certain conditions, such as eye muscle disorders, can affect the accuracy of the test.

Related pages

• Nystagmus
• Vestibular system
• Balance disorder
• Meniere's disease
• Vestibular neuritis