[A case of severe involvement of the motor neuron system accompanied with cerebellar ataxia]

Here we report a sporadic case of severe involvement of the motor neuron system accompanied with cerebellar ataxia. A 55-year-old Japanese woman was admitted to our hospital because of unstable gait and clumsiness of hands. Since she had prominent ataxia, she was initially diagnosed as late onset cortical cerebellar atrophy (LCCA). However, mild muscular weakness and atrophy were pointed out. Weakness in extremities progressed slowly and she became unable to walk in two years. On the second admission, in addition to cerebellar ataxia, she had moderate to severe muscular weakness and atrophy with fasciculation in extremities. Although she had no sensory impairment, micturitional disturbance nor orthostatic hypotension, she had impaired skin sweating response. MRI imaging revealed moderate cerebellar and brain stem atrophy. Neurophysiological examination revealed upper and lower motor neuron damage. Beta-D-N acetylglucosaminidase activity was normal and SCA1, DRPLA and Machado-Joseph disease were excluded by DNA studies. Combination of motor neuron disease and cerebellar degeneration has been very rare. Only two cases similar to our case were reported before. Our patient had anti GM1-ganglioside antibody in her serum, suggesting that motor neuron disease and cerebellar degeneration may occur with the same pathophysiological mechanism.