A 56-year-old woman presented with a 1-year history of nonprogressive gait disturbance. On examination she had marked parkinsonian features limited to the right side. Her symptoms started after a flulike illness that lasted 2 months and had manifested with sore throat, fever, severe fatigue, and sleepiness. Findings from her workup revealed a high titer of anti–Epstein-Barr virus IgG antibodies and a left substantia nigra lesion on her magnetic resonance imaging scan (Figure). The cerebrospinal fluid content was unremarkable. Findings from antistreptolysin O titer, West Nile serology, and cerebrospinal fluid oligoclonal bands testing were negative. The lesion seen on magnetic resonance imaging correlates with the clinical symptoms and likely represents a subtle postencephalitic scarring of the substantia nigra. Unlike previously published images,1 this finding is subtle and it may be missed if not looked for.
Hallevi H, Oh IJ, Valdez SR, Kidder BG, Schiess MC. Postencephalitic HemiparkinsonismClinical Imaging Correlation. Arch Neurol. 2008;65(6):837. doi:10.1001/archneur.65.6.837