Ｓｕｐｅｒｉｏｒ ｏｂｌｉｑｕｅ ｍｙｏｋｙｍｉａ症例

Abstract

A patient with superior oblique myokymia, a term introduced by Hoyt and Keane in 1970, is described. The lesion responsible for superior oblique myokymia is discussed on the basis of the results of Neurootological examinations and Magnetic Resonance Imaging (MRI).A 55-year old woman consulted Gife University Hospital on November 28, 1985, complaining of abnormal eye movements.Neurootological findings : Her left eye showed abnormal movements characterized by rapid (8-9 Hz), small amplitude, intorsional and vertical motility. These eye movements were seen best when she looked down and to the left. The diagnosis was superior oblique myokymia. Optokinetic nystagmus and visual suppression of caloric nystagmus were within normal limits.Neuroradiological findings : MRI showed a lesion, suspected of being an arterio-venous malformation, which extended from the right cerebellar peduncle to the flocculus.Ishikawa (1983) reported that the lesion responsible for superior oblique myokymia was the contralateral flocculus. MRI findings in our case supported his speculation. But the results of optokinetic nystagmus and visual suppression tests suggested that the function of the flocculus was not impaired. We speculate that the lesion did not affect the function of the flocculus or that it affected the part of the flocculus which was not related to optokinetic nystagmus and visual suppression of caloric nystagmus.