Evaluation of Ear Disorders

Patients with abnormal hearing on history or physical examination or with tinnitus or vertigo undergo an audiogram.

Patients with nystagmus 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. Patients with peripheral vestibular disorders can suppress nystagmus by focusing on an object (also known as visual fixation); thus, without specialized testing equipment, nystagmus can sometimes be challenging to observe (1). In VNG, eye movements are recorded by infrared goggles. In ENG, eye movements are recorded by electrodes placed around the eye. 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 determine whether peripheral vestibular weakness is unilateral or bilateral and whether a patient's symptoms are a result of vestibular dysfunction or from other causes of dizziness or vertigo that do not affect the peripheral vestibular system (eg, lightheadedness due to hypotension, vestibular migraine, persistent postural perceptual dizziness). Different components of the vestibular system (eg, semicircular canals, utricle, saccule, inferior and superior vestibular nerve) can be tested by varying head and body position,by presenting visual stimuli, or measuring reflexive muscle responses to loud sounds.

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.

Rotary chair testing is a another technique for measuring the performance of the vestibular system. In rotary chair testing, the patient is seated in a chair and video goggles track the patient's eye movements during rotation at pre-set angular velocities and accelerations. This testing, which relies on assessment of the vestibulo-ocular reflex (VOR), is useful for revealing unilateral vestibular weakness (eg, partial loss of afferent vestibular input), the degree to which this weakness is compensated, and in some cases, in differentiating peripheral from central causes of dizziness or vertigo (2).

Primary imaging tests include computed tomography (CT) of the temporal bone with or without radiopaque dye and gadolinium-enhanced magnetic resonance imaging (MRI) of the brain. With enhanced MRI of the brain, attention is paid to the internal auditory canals and cerebellopontine angle to exclude a vestibular schwannoma (most common tumor at this location) or a meningioma (second most common tumor at this location). Imaging may be indicated in the following conditions:

• Trauma to the ear, head, or both

• Chronic infection

• Hearing loss

• Tinnitus (constant or pulsatile)

• Vertigo

• Facial paralysis

• Otalgia of obscure origin