外側半規管型頭位性めまい症の分類 Classification of Horizontal Canal Positional Vertigo
Peripheral positional vertigo is classified into the posterior semicircular canal type and the horizontal semicircular canal type. In the posterior canal type, rotatory nystagmus occurs on the Dix-Hallpike maneuver. The horizontal canal type demonstrates direction-changing horizontal nystagmus in a supine position with head turn. We classified horizontal canal positional vertigo into 3 types. Eighty-eight patients aged between 22 and 85 years (average age, 56.9 years; 65 women and 23 men) were studied. Each had direction-changing horizontal positional nystagmus, without evidence of neurologic disease. Nystagmus patterns were classified into three types: 1) apogeotropic type (nystagmus is always persistent, namely nystagmus lasts more than one minute), 2) persistent geotropic type (nystagmus lasts more than one minute), 3) transient geotropic type (nystagmus decays and stops within 30 seconds). Apogeotropic nystagmus was detected in 31 patients with 30 patients exhibiting the persistent geotropic type, and 27 patients the transient geotropic type. The apogeotropic type is explained by heavy debris cupulolithiasis of the horizontal semicircular canal. The pathophysiology of persistent geotropic type is considered a result of light debris cupulolithiasis of the horizontal semicircular canal. Transient geotropic type is explained by canalolithiasis of the horizontal canal.
耳鼻咽喉科臨床 101(7), 509-514, 2008-07-01
The Society of Practical Otolaryngology