Lower limb areflexia without central and peripheral conduction abnormalities is highly suggestive of Gerstmann-Sträussler-Scheinker disease Pro102Leu.

Gerstmann-Sträussler-Scheinker disease Pro102Leu (GSS102) is a rare autosomal dominant inherited prion disease due to a substitution of proline for leucine at codon 102 in the Prion Protein gene, and characterized by early walking difficulties and much later occurring dementia. We report clinical, electrophysiological and neuroradiological features of seven novel Italian cases of GSS102. The findings in our series support the thesis that early signs of GSS102 (including areflexia, ataxia, lower limb weakness, and painful dysesthesias) are likely due to a caudal myelopathic process, and suggest that GSS102 should be included among the causes of ataxia with areflexia. Moreover, our observations show that in patients with GSS102, as opposed to Friedreich's ataxia and other forms of ataxia with areflexia, nerve conduction studies and somato-sensory evoked potentials are normal, despite the presence of lower limb areflexia. Hence, in subjects with walking difficulties, the presence of lower limb areflexia without central and peripheral conduction abnormalities is highly suggestive or possibly pathognomonic of GSS102, and can easily guide the clinicians to make the diagnosis of this rare neurodegenerative disease.