[Gerstmann-Sträussler-Scheinker syndrome in a Sicilian patient. Neuropathological aspects].

A case of Gerstmann-Sträussler-Scheinker syndrome observed in a 54 year-old woman is reported. The disease lasted over 4 years and was mainly characterized by ataxia and progressive dementia. The patient belongs to a Sicilian family and some of her relatives have been (or still are) affected by similar clinical syndromes. The neuropathological investigation disclosed an impressive number of PAS-positive amyloid deposits (plaques) in the cortex of the cerebrum and in particular of the cerebellum, in the basal ganglia and thalami as well. These plaques were of different size and morphology: multicentric and Kuru-like, cotton-wool and Alzheimer-like, compact and punctate. In some of them, remnants of dystrophic neurites were detected with ubiquitin-reaction and with the metallic method of Gallyas. No reactions were observed with tau-protein, GFAP and Campbell's method. The immunohistochemical investigations for prion-protein, kindly performed by Prof. Kretzschmar (Goettingen) confirmed that the plaques did not contain beta-protein A4, but reacted positively with anti-prion-protein. These results confirmed the diagnosis of GSS syndrome. The importance on an exact neuropathological investigation employing immunohistochemical reactions and metallic methods in every case of progressive degenerative encephalopathy with PAS-positive (amyloid) deposits (dementia of Alzheimer type, suspected Prion-encephalopathies, etc.) is emphasized. Potential infectivity of the tissue in prion-encephalopathies is deactivated soaking the blocks for histology in formic acid (95-100%) for one hour, followed by formalin for at least three days. Moreover the pretreatment with formic acid does enhance the positivity of PAS-reaction.