A Low Threshold Needed To Diagnose and Treat NMDA Receptor Antibody Associated Limbic Encephalitis (P02.228)

Abstract

Objective: To analyze the clinical features and course of recent cases of N-Methyl D-Aspartate receptor antibody (NMDAR Ab) positive limbic encephalitis (NMDA-LE) to formulate decision pathways that could expedite diagnosis and treatment. Background NMDA-LE is a recently described entity, with evolving associated clinical symptomology. Successful treatment may be associated with early intervention, though algorithms remain non-standardized. EEG findings in patients with NMDA-LE have been described only to a limited extent. Design/Methods: Retrospective case series of four patients diagnosed with NMDA-LE at the North Shore LIJ Medical Center between 6/2010-10/2011. Results: Patients were female, ages 13-27 years, and all were initially evaluated by psychiatry for behavioral abnormalities. Onset was within 1-2 weeks prior to admission, and only one had prior psychiatric history. Three of four were on antipsychotic medications and had dyskinetic movements upon initial neurological consultation. Complex partial seizures were suspected in all four and clinically observed seizures were seen in two patients. EEG was unrevealing for typical epileptiform discharges in 3/4. Frequent temporal lobe seizures were observed in one patient. A unique pattern of persistent rhythmic monomorphic asynchronous delta, varying slowly between 2-4Hz and in lateralization without evolution was observed in two others, with intermittent clinical clonus in one. NMDAR Abs were requested between 5-9 days after neurological evaluation. NMDAR Abs were determined positive by CSF in all, with results available 22-39 days after admission. All were treated with immunomodulatory therapy as soon the diagnosis was suspected 7-24 days following admission. Ovarian teratomas were identified in 2/4. Conclusions: Young females with new onset bizarre psychotic behavior, altered mentation, dykinesias, and suspected seizures should undergo testing for NMDAR Abs without delay, although results are often late in return. Seizure treatment is based on clinical findings, however may be complicated by dyskinesias and odd behaviors. A unique rhythmic EEG pattern may be pathognomonic. Disclosure: Dr. Peguero has nothing to disclose. Dr. Patel has nothing to disclose. Dr. Hwang has received personal compensation in an editorial capacity for Continuum. Dr. Sarren has nothing to disclose. Dr. Koenig has nothing to disclose. Dr. Harden has received personal compensation for activities with UCB Pharma, Pfizer, and GlaxoSmithKline as a speaker. Dr. Harden has received research support from Forest Pharmaceuticals.