Abstracts

Rationale: Anti-N-methyl-d-aspartate (NMDA) receptor encephalitis is an autoimmune encephalitis commonly found in patients with antibodies against NR1 or NR2 subunits of the NMDA receptor. Methods: Case Study Results: Three-year-old black male presented with left sided arm and leg jerking lasting 2 minutes with postictal weakness and no loss of consciousness. Electroencephalography (EEG) was normal. Brain magnetic resonance imaging (MRI) with and without contrast and computed tomography (CT) without contrast were benign. Patient had returned to baseline and was discharged without antiepileptic drugs. Four days later, patient presented unresponsive initially with right sided jerking that progressed to a generalized tonic clonic, eye deviation to the right, and urinary incontinence. The seizure lasted 20 minutes and he was given lorazepam and levetiracetam. He was discharged home the next day on oral levetiracetam 100mg/mL solution, 2 mL twice a day and to follow-up with neurology for outpatient EEG. Three days following discharge he presented with a headache, fever (100.5 Fahrenheit), and left knee pain. Labs were normal other than an elevated erythrocyte sedimentation rate of 29 mm/hr. Repeat brain MRI without contrast and EEG were normal. A continuous EEG revealed seizure during sleep of the right parasagittal and right temporal regions lasting about 4 minutes. He received fosphenytoin 20 mg/kg. Periodically throughout the night patient spiked fevers, unrelated to seizure, reaching a maximum of 102.1F. Hours later the patient had a prolonged subclinical seizure lasting 40 minutes that progressed to left sided facial twitching. It was decided to admit the patient to the intensive care unit (ICU) for treatment of status epilepticus. Serum and cerebrospinal fluid (CSF) were negative for infectious markers. Clinically he became more encephalopathic, lethargic, and difficult to arouse. Repeat brain MRI revealed bilateral areas of restricted diffusion most extensively in the left frontal and temporal lobes but also involving the left parietal and occipital lobes and the right frontal lobe, overall consistent with encephalitis. Patient started becoming increasingly agitated; he would bicycle kick his legs, thrash his arms, was non-verbal, and would scream. Patient was started on empiric ceftriaxone and vancomycin for 10 days. Although labs were negative, MRI was suspicious for herpes simplex virus (HSV) encephalitis and there were no other sources of infection at that time. Infectious disease recommended treating empirically with acyclovir for HSV encephalitis. With new MRI findings and continued clinical decline on antibiotics, autoimmune etiologies including paraneoplastic and NMDA receptor antibodies were tested and intravenous immunoglobulin for 5 days was completed. Patient began to recover with IVIG treatment. NMDA Antibody titers were 1:40 in the serum and 1:10 in CSF. Acyclovir was discontinued and patient was started on rituximab 375 mg/m2 weekly for 4 doses, with continued clinical improvement.  Conclusions: Presentations of encephalitis can vary making it difficult for clinicians to appropriately diagnose. Clinical suspicion of NMDA receptor encephalitis should be considered with patients presenting with rapidly worsening focal seizures with febrile illness. Confirmation of the clinical diagnosis of anti-NMDA receptor encephalitis can be made with a positive serum or CSF sample screening for antibodies to the NMDA receptor subunit. Funding: No funding