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Introduction ⬇

Electronystagmography (ENG) is a series of tests that measure the changes in the electrical field within the eye. ENG aids in the differential diagnosis of lesions in the brainstem and cerebellum and can confirm the causes of unilateral hearing loss of unknown origin, vertigo, or ringing in the ears. Evaluation of the vestibular system and the muscles controlling eye movement is based on measurements of the nystagmus cycle. In health, the vestibular system maintains visual fixation during head movements by means of nystagmus, the involuntary back-and-forth eye movement caused by initiation of the vestibular-ocular reflex.

Procedure ⬆ ⬇

  1. The test is usually done in a darkened room with the patient sitting or lying down.

  2. Remove any earwax before testing.

  3. Tape five electrodes at designated positions around the eye.

  4. During the study, ask the patient to follow a light about 6-10 feet away, stare at a fixed light, follow a light as it moves like a pendulum, follow a light as it moves back and forth out of their visual field (without moving the head), and change head position or sit up quickly.

  5. Toward the end of the test, gently blow air into each external ear canal, starting on the affected side. Instill cold water and then warm water into the ears during the test to record eye movement in response to various stimuli.

  6. Follow guidelines in Chapter 1 for safe, effective, informed intratest care.

Procedural Alert

Water irrigation of the ear canal should not be done when there is a perforated eardrum. Instead, a finger cot may be inserted into the ear canal to protect the middle ear

Clinical Implications ⬆ ⬇

Prolonged nystagmus and postural instability following a head turn is abnormal and may be caused by lesions of the vestibular or ocular system, as in the following conditions:

  1. Cerebellar disease

  2. Brainstem lesion

  3. Peripheral lesion occurring in older persons; head trauma; middle ear disorders

  4. Congenital disorders

  5. Ménière's disease

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain test purpose and procedure. No pain or known risks are associated with the test. The procedures to stimulate involuntary rapid eye movements (REMs) are uncomfortable.

  2. Have the patient remove makeup.

  3. Have the patient abstain from all caffeinated and alcoholic beverages for at least 48 hours. Heavy meals should be avoided before testing.

  4. In most cases, medications such as tranquilizers, stimulants, or antivertigo agents should be withheld for 5 days before the test. If in doubt, consult the healthcare provider who ordered the test.

  5. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Clinical Alert

The test is contraindicated in persons who have pacemakers

Posttest Patient Care

  1. Allow the patient to rest as necessary.

  2. Provide treatment for nausea, vertigo, and weakness as needed and ordered. Check with the healthcare provider who ordered the test.

  3. Review test results; report and record findings. Modify the nursing care plan as needed.

  4. Monitor the patient for brain disease, which may manifest as loss of balance, or middle ear disease, which may cause spasmodic eye movement, vertigo, or hearing loss.

  5. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Interfering Factors ⬆ ⬇

  1. Test results are altered by the inability of the patient to cooperate, poor eyesight, blinking of the eyes, or poorly applied electrodes.

  2. The patient's anxiety or medications such as central nervous system depressants, stimulants, or antivertigo agents can cause false-positive test results.

Reference Values ⬆

Normal