Allocortical neurofibrillary changes in progressive supranuclear palsy.

Silver techniques for intraneuronal cytoskeleton abnormalities (neurofibrillary tangles and neuropil threads) and extracellular A4-amyloid deposits were used to examine lesions of the cerebral cortex in six cases of progressive supranuclear palsy (three were mentally unimpaired and three showed moderate degrees of dementia). Deposits of A4-amyloid protein occurred in small numbers or were absent. Neurofibrillary tangles and neuropil threads were present in all cases and were largely confined to the allocortex. A characteristic pattern of changes was found in the entorhinal cortex. The three mentally unimpaired individuals had mild cortical changes virtually confined to the transentorhinal region while all of the demented patients showed severe destruction of the superficial cellular layer in both the transentorhinal and entorhinal region. This pattern of allocortical destruction closely resembles that seen in clinically incipient Alzheimer's disease or in mentally impaired cases of Parkinson's disease. The entorhinal region receives dense input from isocortical association areas and projects via the perforant path to the hippocampal formation. The cells of origin of major portions of the perforant path are located within the superficial entorhinal cellular layer. Destruction of this layer partially or totally disconnects the hippocampus from the isocortex. The specific pattern of entorhinal destruction is considered to contribute to cognitive impairment and personality changes, frequently seen in patients with progressive supranuclear palsy.