Case Presentation: A 13-year-old previously healthy female with recent psychosocial stressors was admitted with progressive expressive aphasia and right upper extremity sensorimotor changes. Symptoms began six weeks prior to admission with recurrent right arm tingling sensations that progressed to right-sided upper and lower extremity twitching. During the period between onset of symptoms and admission, she had a seizure-like episode and became progressively less verbal.Her neurologic exam was significant for expressive aphasia and hyperkinetic right-hand movement impacting her handwriting. Continuous EEG revealed focal slowing over the left hemisphere with abundant focal epileptiform discharges, which correlated with her speech difficulty and right-sided symptoms. MRI brain with contrast was unremarkable.Anti-epileptic therapy was initiated with lacosamide, which led to improvement in speech fluency. Lumbar puncture was performed, and CSF studies revealed mild pleocytosis (17 nucleated cells) with otherwise normal indices. Due to high clinical suspicion for autoimmune encephalitis, treatment with high-dose IV steroids and IVIG was initiated, resulting in further improvement in speech and handwriting. Abdominal and pelvic MRI did not reveal an underlying ovarian teratoma. She was discharged on a prolonged steroid taper and monthly IVIG infusions. CSF autoimmune panel confirmed the presence of anti-NMDA receptor antibodies. On subsequent outpatient visits, her speech and overall neurologic status have reportedly returned to baseline.
Discussion: Anti-NMDA receptor encephalitis is a rare neuropsychiatric disorder with diverse presentations that can mimic more common psychiatric or neurologic conditions, delaying diagnosis and appropriate treatment. Clinical presentation varies by age; children present more commonly with aphasia, seizures, abnormal movements, insomnia, and irritability. Early diagnosis and the decision to initiate empiric treatment is challenging and requires a high degree of clinical acumen as diagnostic testing is not particularly helpful. EEG findings can be variable, and it has been reported that up to one-third of cases may have normal EEG, MRI, and CSF studies. Ovarian teratomas are frequently associated with anti-NMDA receptor encephalitis in adolescent females, though underlying neoplastic processes are less commonly identified in children. Initial imaging may miss small or occult tumors, necessitating repeat imaging to reduce rates of relapse. Without treatment, symptoms may become life threatening with progression to altered consciousness, autonomic instability, and hypoventilation. However, empiric treatment is not benign as high-dose steroids and IVIG both carry risk to the patient and significant cost. With a history of familial loss and recent school stressors, this patient’s early symptoms were initially thought to be psychosomatic. However, key aspects of her presentation fit the Graus criteria for autoimmune encephalitis, including the subacute time course, expressive aphasia, EEG findings, and focal sensorimotor symptoms.
Conclusions: Autoimmune encephalitis is an important diagnosis to consider in clusters of symptoms including speech dysfunction and behavioral changes, even with normal initial diagnostic work-up. Hospitalists are often the first to evaluate these complex cases and must maintain a high index of suspicion, and early empiric treatment is essential to prevent disease progression.