Chorea has been described as an initial sign of relapse in children with herpes simplex virus encephalitis. We describe the detection of anti-basal ganglia antibodies (ABGA) in plasma and cerebrospinal fluid (CSF) of a 2.3-year-old girl with severe chorea 3 weeks after acute herpes simplex virus (HSV) encephalitis. Although common neuroleptic and antidopaminergic drugs were ineffective, plasmapheresis combined with immunosuppression was followed by rapid and complete neurological recovery. These findings suggest a post-infectious, immune-mediated mechanism in this case of chorea after HSV encephalitis.

HSV encephalitis accounts for 10–20% of all viral encephalitis in the US.¹ Occasionally, chorea has been described as an initial sign of relapse with often poor prognosis. At least three pathogenic mechanisms are possible: occurence of late-onset symptoms of the initial viral infection, recurrence of viral replication (owing to incomplete treatment of the initial HSV encephalitis or by selection of clones of aciclovir-resistant virus), or induction of a deleterious immunoinflammatory reaction.² Autoimmune-mediated brain disorders are well known after group A β haemolytic streptococcal infections: for example, Sydenham’s chorea or paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS). Here, we report on a case of severe chorea with positive ABGA 3 weeks after acute HSV encephalitis.

At 2.3 years, a previously healthy girl experienced acute HSV encephalitis with positive type 1 HSV polymerase chain reaction (PCR) in CSF and was treated with aciclovir, 30 mg/kg/day, for 15 days with rapid recovery. …