Orthostatic Hyperkinetic Disorders in Subacute Sclerosing Panencephalitis - A Novel Observation.

BACKGROUND: Subacute sclerosing panencephalitis (SSPE) is a progressive, often fatal inflammatory encephalitis caused by persistent measles virus infection of the central nervous system. The neurological manifestations of SSPE are well characterised, encompassing cognitive decline, periodic myoclonic jerks, and often relentless progression. CASE REPORT: We report a case of a 14-year-old male with SSPE who developed bilateral lower limb shaking and knee buckling, with associated loss of quadriceps tone on standing. These features resulted in recurrent falls and necessitated supported ambulation. DISCUSSION: To our knowledge, this combination of orthostatic limb shaking and loss of tone in the context of SSPE has not been previously described in the literature. This case expands the recognised phenotypic spectrum of SSPE.