末梢性頭位性めまい症の病態と病巣

Abstract

Using infrared CCD camera and electronystagmography, we analyzed positional nystagmus in 33 patients with peripheral positional vertigo.1) Patients were classified into three categories: (a) lateral type: horizontal nystagmus occurs in lateral position; (b) sagittal type: rotatory nystagmus occurs in head-hanging position (so-called benign paroxysmal positional vertigo); and (c) mixed type.2) Vertigo and nystagmus began with a few seconds latency after the head was tilted, briefly increased to a maximum, and then gradually decreased.3) In all types, the number of female patients was greater than that of male patients.4) In the lateral type, the mean period from the onset to the disappearance of vertigo was about 3 weeks. However, in those with the sagittal type or mixed type it was much longer.5) The intensity of positional nystagmus was influenced by the direction of gravity in all types.The free-floating particles theory seems to be able to explain the latency of the nystagmus, the gradual decrease in its intensity, and recurrence of the vertigo. Lateral type lesions are thought to be in the lateral semicircular canal, and sagittal type lesions perhaps in the posterior semicircular canal; mixed type lesios are thought to be in both.