The test is considered positive if it provokes the characteristic torsional and vertical nystagmus. This causes a large rotation of the posterior semicircular canal within its own plane, moving the loose otolith and reproducing the symptoms. The examiner then drops the patient back to the supine position, with the head hanging down off the stretcher 10°–30°. The patient should be asked to hold onto the examiner’s arm for stability. This aligns the posterior semicircular canal in the vertical plane. 12 The examiner holds the seated patient’s head 45° to the left or right. The most common form of BPPV, caused by an otolith in the posterior semicircular canal, is diagnosed by finding torsional nystagmus on the Dix-Hallpike test. In most cases BPPV is idiopathic, although 10% follow a bout of vestibular neuritis and 20% follow an episode of head trauma. Patients are well until a head movement, usually vertical, precipitates the paroxysm of symptoms. The paroxysms of intense symptoms lasting less than a minute are defining, as is positional provocation. 10 Patients present with brief episodes of intense vertigo, precipitated by a change in position. Central mimics of BPPV have been described, but they tend to be caused by tumors rather than strokes, and are recognized by association with other abnormalities. Finally, we will propose indications for neuroimaging.īenign paroxysmal positional vertigo is a distinct condition not typically confused with cerebellar infarction. 5 Then we will review the physical diagnosis of cerebellar infarction. This review will first address differentiation of cerebellar infarction from the four most common vertigo syndromes: benign paroxysmal positional vertigo (BPPV), Meniere’s disease, migrainous vertigo, and vestibular neuritis. 4 In contrast, important physical signs are present in the majority of patients with cerebellar infarction. Resorting to computed tomography (CT) is insufficient because it is only 26% sensitive for acute stroke. Physical diagnosis is the most important diagnostic modality for cerebellar infarction. Patients with missed cerebellar infarction in general are at higher risk for complications, with a mortality rate possibly as high as 40%. 1, 2 Because the symptoms of cerebellar infarction overlap substantially with benign conditions it is commonly overlooked, with a misdiagnosis rate estimated at 35% 2. While most patients who present to emergency departments (ED) with isolated vertigo have benign disorders, approximately 0.7–3% have cerebellar infarction.
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