What EEG findings are characteristic of anti-NMDAR encephalopathy?

Updated: Oct 09, 2019
  • Author: Eli S Neiman, DO, FACN; Chief Editor: Selim R Benbadis, MD  more...
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Anti– N -methyl-d-aspartate receptor (NMDAR) encephalitis is a neuroimmune syndrome in patients with autoantibodies recognizing extracellular epitopes of NMDAR, and the autoantibodies attenuate NMDAR function through the internalization of NMDAR.” [84]

This autoimmune encephalitis is characterized by headache, confusion, memory deficits, psychiatric disturbance, including psychosis, dyskinesias, coma, autonomic instability, and seizures. [84, 85, 86] Anti-NMDAR encephalopathy is often due to ovarian teratomas in young women, with children less likely to have the above tumors. [84] Many patients need ICU admission and close monitoring because of autonomic instability, coma, and seizures. [84, 86] Extreme care must be taken when evaluating the abnormal movements often seen in anti-NMDAR encephalitis. In one study, false impressions of status epilepticus rather than encephalopathy were reported in 6% of the cases reviewed. [86]

Anti-NMDAR encephalitis can sometimes be reversed with immunotherapy, including steroid treatment, intravenous immunotherapy, and surgery (removal of the teratoma). When able, physical, occupational, speech, cognitive, and behavioral therapies are often required. Recovery can be slow, with cognitive and motor deficits sometimes significant. [84]

EEG patterns seen in this autoimmune encephalopathy can include focal or hemispheric slowing and often diffuse background slowing. [87] With more prolonged hospitalization, a unique “delta brush”–type pattern has been observed in up to 30% of adults with anti-NMDAR encephalitis in one study of 23 patients. [88] This pattern can be continuous or become rhythmic and is often quite refractory to anticonvulsant therapy. Focal nonconvulsive or convulsive status epilepticus can be seen as well, requiring video or continuous EEG monitoring for closer surveillance. [85, 86]

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