[The diagnosis and follow-up evaluation of acute cerebellar ataxia supported by a cerebellar stimulation study].

A 70-year-old woman who has been suffering from diabetes mellitus since 67 years of age rapidly developed severe truncal ataxia. Neurological examination showed severe truncal ataxia, incoordination and decreased deep sensations in the bilateral lower extremities. A CSF study revealed a moderately elevated total protein (125 mg/dl) without any elevation of the cell count. A nerve conduction study supported the diagnosis of polyneuropathy. Lumbar MRI revealed spinal canal stenosis at the L3/L4-L5/S1 intervertebral levels due to disk herniations and ossification of the yellow ligaments. We examined cerebellar stimulation in order to determine whether the ataxia was due to dysfunction of the cerebellum or peripheral nervous system. Conditioning electrical stimulation over the cerebellum did not change the size of motor potentials evoked by magnetic cortical stimulation in the right first dorsal interosseous muscle. Her clinical course was good, and the limb and truncal ataxia became very mild about 4 months after the onset, although there was little change in the decreased deep sensations. The cerebellar stimulation in the second study was normal. We diagnosed her as having acute cerebellar ataxia and thought that the decreased deep sensations were due to diabetic polyneuropathy and lumbosacral radiculopathies. A cerebellar stimulation study was useful for the diagnosis and follow-up evaluation of acute cerebellar ataxia in this patient.