Sporadically occurring neurologic disease

Spastic paraplegia as the primary neurologic syndrome occurs as a manifestly inherited disorder (hereditary spastic paraplegia [HSP]1) and in subjects with no known family history (apparently sporadic spastic paraplegia [ASSP]). Other than the family history, there are no clinical parameters that reliably distinguish “hereditary” from “apparently sporadic” spastic paraplegia. Typically, ASSP is a transitional diagnosis applied for a number of years until 1) a pathogenic mutation in an HSP gene is identified or a family history emerges, and the diagnosis is then changed to HSP; 2) the disorder progresses to involve upper extremities, speech, and swallowing, and the diagnosis is then changed to primary lateral sclerosis; 3) another etiology is identified (e.g., amyotrophic lateral sclerosis). Nonetheless, for many subjects, despite adequate family size and structure and reliable family history, the disorder remains “apparently sporadic” and serial examinations over many years document insidiously progressive neurologic deficits largely confined to corticospinal tracts affecting the lower extremities, often associated with urinary urgency, and sometimes associated with mild decrease in distal lower extremity vibratory sensation. This is …