Dizziness and Vertigo
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Approach to the patient
The term dizziness is used by pts to describe a variety of sensations or gait unsteadiness. With a careful history, distinguishing between faintness (presyncope; Chap. 50) and vertigo (a sense of movement of the body or the environment, most often a feeling of spinning) is usually possible.
When the meaning of dizziness is uncertain, provocative tests to reproduce the symptoms may be helpful. Valsalva maneuver, hyperventilation, or postural changes leading to orthostasis may reproduce faintness. Rapid rotation in a swivel chair is a simple provocative test to reproduce vertigo.
Benign positional vertigo is identified by the Dix-Hallpike maneuver to elicit vertigo and the characteristic nystagmus; the pt begins in a sitting position with head turned 45°; holding the back of the head, examiner gently lowers pt to supine position with head extended backward 20° and observes for nystagmus; after 30 s the pt is raised to sitting position and after 1 min rest the maneuver is repeated on other side.
If a central cause for the vertigo is suspected (e.g., no signs of peripheral vertigo, no hearing loss, no ear sensations, or the presence of other neurologic abnormalities indicating central nervous system [CNS] disease), then prompt evaluation for central pathology is required. The initial test is usually an MRI scan of the posterior fossa. Distinguishing between central and peripheral etiologies can be accomplished with vestibular function tests, including videonystagmography and simple bedside examinations including the head impulse test (rapid, small amplitude head rotations while pt instructed to fixate on the examiner’s face; if peripheral, a catch-up saccade is seen at the end of the rotation) and dynamic visual acuity (measure acuity at rest and with head rotated back and forth by examiner; a drop in acuity of more than one line on a near card or Snellen chart indicates vestibular dysfunction).