中心性脳橋融髄症の１症例

Abstract

A 42-year-old male complained of tremor of the hands and titubation. Neurological and neurotological examinations revealed 1) tremor of the hands, 2) truncal ataxia, 3) mild cerebellar ataxia of the extremities, 4) mild limitation of eye movement to the right, 5) geotropic positional nystagmus, 6) down-beat positioning nystagmus, 7) impairment of horizontal eye movements including smooth pursuit, optokinetic nystagmus (OKN) and vestibulo-ocular reflex (VOR) and 8) absence of stapedial reflex. Among the negative findings, 9) there were no signs of damage of the paramedian pontine reticular formation of the left side, medial longitudinal fasciculus or the abducens nerve, 10) vertical ocular movements were not impaired, 11) pure tone audiometry and auditory brainstem response were normal and 12) the facial muscles were not palsied. T2-weighted images of NMR-CT in the coronary plane revealed a horseshoe-shaped high-signal region extending bilaterally in the central area of the pons. A diagnosis of central pontine myelinolysis (CPM) was made from the clinical course and the NMR-CT findings, but the serum electrolytes were not abnormal. An alcoholic history and malnutrition might have contributed to the development of C PM in this patient. The finding that OKN and VOR were impaired only in the horizontal direction and not in the vertical direction indicates that the vertical eye movement system connecting with the vestibular nucleus (VN) is independent of the horizontal system connecting with the VN.