Merck Manual

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Evaluation of Ear Disorders


David M. Kaylie

, MS, MD, Duke University Medical Center

Last review/revision Dec 2022
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Patients with nystagmus Nystagmus Nystagmus is a rhythmic movement of the eyes that can have various causes. Vestibular disorders can result in nystagmus because the vestibular system and the oculomotor nuclei are interconnected... read more or altered vestibular function may benefit from computerized videonystagmography (VNG) or electronystagmography (ENG), which quantifies spontaneous, gaze, or positional nystagmus that might not be visually detectable. In ENG, eye movements are recorded by electrodes placed around the eye, while in VNG they are recorded by infrared goggles. In both cases, data are analyzed by computer and interpreted by an audiologist. Computerized VNG or ENG caloric testing quantifies the strength of response of the vestibular system to cool and warm irrigations in each ear, enabling the physician to discriminate unilateral weakness. Different components of the vestibular system can be tested by varying head and body position or by presenting visual stimuli.

Posturography uses computerized test equipment to quantitatively assess the patient's control of posture and balance. The patient stands on a platform containing force and motion transducers that detect the presence and amount of body sway while the patient attempts to stand upright. The testing can be done under various conditions, including with the platform stationary or moving, flat or tilted, and with the patient's eyes open or closed, which can help isolate the contribution of the vestibular system to balance.

Primary imaging tests include CT of the temporal bone with or without radiopaque dye and gadolinium-enhanced MRI of the brain, the latter with attention paid to the internal auditory canals to rule out a vestibular schwannoma Vestibular Schwannoma A vestibular schwannoma, also called an acoustic neuroma, is a Schwann cell–derived tumor of the 8th cranial nerve. Symptoms include unilateral hearing loss. Diagnosis is based on audiology... read more . These tests may be indicated in cases of trauma to the ear, head, or both; chronic infection; hearing loss; vertigo; facial paralysis; and otalgia of obscure origin.

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NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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