What's new in primary lateral sclerosis?

Primary lateral sclerosis as a nosological entity distinct from amyotrophic lateral sclerosis has been the subject of controversy since it was first d escribed in the nineteenth century. Primary lateral sclerosis has been defi ned as a rare, non-hereditary disease characterized by highly progressive s pinobulbar spasticity, related to the exclusive loss of precentral pyramida l neurons, with secondary pyramidal tract degeneration and preservation of anterior horn motor neurons. We carried out a study in nine patients with a diagnosis of primary lateral sclerosis. Our clinical, electrophysiological and pathological investigations provide evidence that the disease has a he terogeneous clinical presentation and that degeneration is not restricted t o the central motor system but also affects the lower motor neuron. In view of this similarity with amyotrophic lateral sclerosis, primary lateral scl erosis may represent a slowly progressive syndrome closely related to motor neuron disease and amyotrophic lateral sclerosis.