ear, nose, and throat disorders
Evaluation of Ear Disorders
Testing
Patients with abnormal hearing on history or physical examination or with tinnitus or vertigo undergo an Testing . 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. 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 . 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. 