Progressive supranuclear palsy: Neuropathology of patients with a short disease duration due to unexpected death

Progressive supranuclear palsy (PSP) presents with a wide variety of signs/symptoms, making early initial diagnosis difficult. We investigated the clinical and neuropathological features of five patients with autopsy-proven PSP of short duration, ranging from 11 to 41 months (average, 26.2 months) due to unexpected death, focusing particularly on the distribution and severity of neuronal loss as well as neuronal and glial tau pathology in the affected brain. Clinical features were studied retrospectively through careful review of the medical records, and neuropathological examinations were carried out, along with tau immunohistochemistry using a monoclonal antibody AT8. These patients were diagnosed as having probable PSP (n = 4) and suggestive PSP (n = 1), respectively. In all cases, neuronal loss was evident in the substantia nigra, subthalamic nucleus, globus pallidus, and locus ceruleus. AT8-identified tau lesions, that is, pretangles/neurofibrillary tangles (PTs/NFTs), tufted astrocytes (TAs), and coiled bodies/neuropil threads (CBs/NTs), were distributed widely in the brain regions, especially in patients with longer disease duration. All cases showed variation in the regional tau burden among PTs/NFTs, TAs, and CBs/NTs. There was also a tendency for tau deposition to be more predominant in neuronal cells in the brainstem and cerebellum and in glial cells in the cerebral cortex and subcortical gray matter. These findings suggest that in PSP, the initial signs/symptoms are associated with degeneration and subsequent death of neurons with pathological tau deposition, and that the tau deposition in neuronal cells is independent of that in glial cells.