Primary lateral sclerosis: a distinct clinical entity in patients with chronic spastic paraparesis.

The development of neurologic deficits confined to the corticospinal tracts has been referred as Primary Lateral Sclerosis (PLS). Through the years, this diagnosis has remained uncertain. In this study we describe seven patients with chronic involvement of the pyramidal system. Two of these patients had serologic evidence of human T-lymphotrophic virus type I infection, one patient had multiple sclerosis and in four patients the clinical diagnosis of PLS was made. The clinical characteristics and diagnostic studies of these patients are presented. A review of the literature with emphasis in the differential diagnosis and a proposed workup for patients with chronic spastic paraparesis are made. This study provides supporting evidence in favor of the clinical entity of PLS.