[Study of the blink reflex in spinocerebellar degeneration]

Blink reflex (BR) was composed of R1 and R2. R1 is considered to indicate the brainstem function. The purpose of this study was to evaluate the brainstem function of spinocerebellar degeneration (SCD) by the R1 latency (R1). BR was evoked by the percutaneous stimulation of supraorbital nerve. And R1 was measured by the action potential of orbucularis oculi muscle. Direct response was recorded by the percutaneous stimulation of facial nerve to determine the terminal latency of facial nerve (D). By these methods R1, D, R1/D and difference between at right and left side of these data (delta R1, delta D, delta R1/D) were measured in 21 normal subjects (57.7 +/- 10.1 ys.) and 28 cases of SCD (56.6 +/- 8.2 ys.), including 12 cases of sporadic type olivopontocerebellar atrophy (SOPCA), 4 of Menzel type olivopontocerebellar atrophy (MOPCA), 6 of late cortical cerebellar atrophy (LCCA) and 6 of Holmes type cortical cerebellar atrophy (HCCA). There was no difference between all types of SCD and normal subject at D, but significant difference of R1 and R1/d was observed between at MOPCA and normal subject. Concerning the difference between right and left side delta R1 and delta R1/D showed the significant difference with MOCA and SOPCA, but delta D showed no difference. Elongation of R1 and R1/D without the delay of facial nerve and the significant difference of R1 and R1/d between at right and left side suggested the synaptic transmission disorder form trigeminal nerve to facial nerve at brainstem of MOCA.