Case Presentation: 17 year-old-male with a history of anti-NMDAr encephalitis three years prior presented with two days of confusion, agitation and insomnia. Associated symptoms included anorexia, blunted affect, slow movements and, though awake, refusal to respond or engage with others. Family also reported apparent hallucinations and associated aggression including biting. Neurologic examination with non-verbal patient, intermittent ability to attend and follow commands, hypertonic extremities, 3+ patellar reflexes and ankle clonus bilaterally. MRI Brain was normal and CSF analysis confirmed anti-NMDAr antibodies. EEG showed diffuse slowing. Paraneoplastic work-up was negative. Prior presentation in Mexico was associated with seizure and protracted impairment which resolved after treatment with steroids and IVIG. Initial management with pulse-dose steroids and IVIG resulted in minimal improvement, thus the patient was treated with Rituximab. Patient received monthly infusions and after three months returned to baseline.
Discussion: Anti-NMDAR encephalitis is a well-described syndrome of autoimmune encephalitis and one of the most common etiologies of non-infectious encephalitis in children. Though possible, anti-NMDAR encephalitis is less likely to be paraneoplastic in children and males. Presentation classically includes neuropsychiatric symptoms such as agitation, psychosis, behavior and personality changes as well as memory loss, chorea and hyperkinetic movements, and coma. Studies may be normal other than CSF anti-NMDAr antibodies, though may reveal CSF lymphocytic pleocytosis and elevated protein and various MRI abnormalities. Up to 25% of patients may experience a relapse of symptoms, often months or years after initial presentation as in our case. Relapse may be more likely to occur in patients who do not receive immunotherapy at first presentation and relapsed symptoms may differ from prior and classical presentation.
Conclusions: Early diagnosis and initiation of immunotherapy leads to decreased levels of anti-NMDAr antibodies. This aids in reducing the risk of relapse, as relapses have been reported in 12-25% of patients. Risks for relapse include lack of immunotherapy and relapses have been described as occurring up to 15 years later. Our case is unique as relapse is less often described in the pediatric patient. Early treatment, milder disease, and malignancy resection (when applicable) come with a more favorable prognosis. It is unclear time to treatment during his initial presentation and there was no associated malignancy; however our patient had more severe disease and did not receive any immunomodulatory therapy. Additionally, relapse can occur after months or years with significant recovery in between, just like our patient who had returned to baseline.The question remains whether or not he will have an another relapse after receiving immunomodulatory therapy; there is limited data available regarding relapses but there have been several cases of 3-4 relapses described, all associated with partial clinical symptoms of typical anti-NMDAr and less severe presentations.