Refractory "status dyskineticus" in a child with post-herpes simplex virus 1 N-methyl-D-aspartate receptor encephalitis: a case report.

Background: Herpes simplex virus 1 (HSV-1) encephalitis may result in relapsing neurological symptoms secondary to immune-mediated processes, including anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Refractory status dyskineticus (RSD), a severe subset of status dystonicus, is characterized by a hyperkinetic movement disorder phenotype alongside dystonic features. This critical condition presents substantial challenges in neurocritical care. The present case highlights the importance of prompt intervention and immunotherapy escalation in managing severe movement disorders due to pediatric autoimmune encephalitis.

Case Presentation: A previously healthy 2-year-old boy was admitted with HSV-1 encephalitis, confirmed by brain MRI and cerebrospinal fluid (CSF) analysis. When initially treated with acyclovir, the patient achieved partial recovery but later developed encephalopathy, vomiting, behavioral regression, and severe dyskinetic movements. Upon transfer to our center, NMDAR antibodies were detected in the CSF, with no evidence of HSV reactivation. Despite first-line immunotherapy with intravenous steroids and immunoglobulins, his condition deteriorated, progressing to status dyskineticus (SD), with dystonia, hyperthermia, and hypercapnia, requiring intensive care management and mechanical ventilation. A treatment escalation regimen including both immunotherapy with rituximab, rapamycin, bortezomib, and multiple symptomatic therapies resulted in gradual improvement and resolution of the movement disorder.

Conclusions: This case underscores the crucial role of neurocritical care in managing refractory movement disorders associated with autoimmune encephalitis. Early recognition and immunotherapy escalation are essential to improve outcomes in children with complex, life-threatening neurological conditions. A comprehensive, multidisciplinary approach in the neurocritical care setting is key to achieving recovery and minimizing long-term neurological damage.