Atypical Presentation of Anti-NMDAR encephalitis in a Male Patient – an Unfortunate Mimic

Abstract

Background Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a neuroinflammatory disorder with a predilection for females. Males present differently, with seizures rather than the better-recognized constellation of psychiatric and behavioral symptoms dominating the initial stages of the disease, providing a potential substrate for delayed recognition and treatment. Case Presentation An 18-year-old man presented with fever and “seizures. When examined, he was febrile but alert and coherent. His neurologic, respiratory, cardiovascular, and abdominal examinations were unremarkable. Diagnosed with infective meningoencephalitis, he was started on intravenous ceftriaxone and acyclovir concurrently with anti-epileptic medications. However, he deteriorated into refractory status epilepticus. Electroencephalograms showed left temporo-parietal seizures. Cerebrospinal fluid analysis revealed inflammatory features, but the virologic assays and bacterial cultures returned negative. Magnetic resonance imaging scans performed in the first and second week from symptom-onset demonstrated the interval development of widespread sulcal T2 hyperintensity, with florid and diffuse leptomeningeal enhancement. Anti-NMDAR antibodies were subsequently detected in his cerebrospinal fluid by indirect immunofluorescence. Diagnosed with anti-NMDAR encephalitis, he received plasmapheresis, methylprednisolone and immunoglobulin infusions. Conclusion Anti-NMDAR encephalitis should be considered in patients, especially males, who are treated for suspected infectious meningoencephalitis, but continue to deteriorate, even in the absence of prominent psychiatric or behavioral symptoms, considering how the initial symptoms differ between the genders. The interval development of diffuse and florid leptomeningeal enhancement on sequential magnetic resonance imaging scans of our patient has not been described in prior reports, and may be reflective of the underlying inflammatory processes.