[An autopsied case of progressive supranuclear palsy, initially diagnosed as spinocerebellar degeneration with severe olivopontocerebellar involvement].

A Japanese female patient presented with dysarthria and gait disturbance with ataxia at the age of 63. She was initially diagnosed with spinocerebellar degeneration because a head CT showed atrophy of the cerebellum and brainstem, and dilatation of the fourth ventricle. Symptoms including abnormal behavior, dementia, vertical gaze palsy, dysphagia, retrocollis, axial rigidity, grasp reflex and positive Babinski's sign were gradually observed. Tegmental atrophy of the brainstem and dilatation of the third ventricle were apparent on images. The diagnosis was modified to progressive supranuclear palsy (PSP), 6 years after the onset of symptoms. Gastrostomy and tracheotomy were performed 7 and 8 years after onset, respectively, and the patient died one year later. At autopsy the brain weighed 1,030g and showed atrophy of the frontal lobe and cerebellum. The brainstem was also atrophic, particularly in the tegmentum and pontine base. Neurofibrillary tangles, mainly globose-type, were widespread in the subcortical structure, particularly in the globus pallidus, subthalamic nucleus, nucleus of the oculomotor nerve, substantia nigra, locus ceruleus, pontine nucleus, and the inferior olivary nucleus. Numerous glial fibrillary tangles and argyrophilic threads were also observed particularly in the frontal lobe, basal ganglia, brainstem and cerebellar white matter. The cerebellar dentate nucleus showed neuron loss with grumose degeneration and the Purkinje neuron layer showed neuron loss and Bergmann's gliosis with torpedoes. Tau positive inclusions in the Purkinje neurons, Bergmann glias and dentate nucleus neurons were observed. Pathological findings were consistent with the diagnosis of PSP but the olivopontocerebellar involvement and the quantity of Gallyas-positive/tau-positive structures were generally more severe than in typical PSP cases. According to these clinicopathologic findings and a review of the literature, we speculate on the existence of a PSP subtype with severe olivopontocerebellar involvement that tends to be clinically misdiagnosed as spinocerebellar degeneration.