Case Report: Focal Myoclonus with a Striatal Lesion as a Presentation of Subacute Sclerosing Panencephalitis.

Adult-onset subacute sclerosing panencephalitis (SSPE) is rare, and focal myoclonus as a presenting feature poses a diagnostic dilemma. We report an adult SSPE patient with unusual clinical and radiological features. A 20-year-old girl had jerky neck movement 9 months earlier, which progressed to left hemimyoclonus in 2 months and generalized frequent myoclonus and fall at 4 months. By 6 months, she was bedbound. On examination, her Mini-Mental State Examination score was 10, and patchy retinitis was observed around the macula. Magnetic resonance imaging revealed corpus striatal involvement and electroencephalography showed periodic discharges. Measles cerebrospinal fluid/serum immunoglobulin G index was 3.3 (normal < 1.3), confirming the diagnosis of SSPE. SSPE should also be considered in adults having focal myoclonus with corpus striatal lesion. EEG is helpful in the diagnosis.