We describe two boys whose distinct and remarkable clinical pictures suggested the possibility of anti-
N-methyl-d-aspartate receptor antibody
encephalitis. Both patients responded to
immunotherapy, but neither manifested that antibody. Patient 1 exhibited florid
encephalopathy with psychotic manifestations including inappropriate affect, intermittent
delirium,
visual hallucinations, severe
anorexia, agitation, paranoid ideation, and abnormal electroencephalogram results. He responded to
intravenous immunoglobulin, with steady improvement over 3 months to almost complete remission for 1 year, followed by a relapse that again responded, more quickly, to
intravenous immunoglobulin. A second relapse occurred 1 month later, and again responded to
intravenous immunoglobulin. Patient 2 exhibited progressive, severely debilitating
limb dystonia that worsened over 1.5 years, with milder psychiatric symptoms including mood instability, aggressiveness, impulsivity, and depression. When he developed
thymic hyperplasia 1.5 years into his illness, he underwent a
thymectomy, and improved significantly on a regimen of
plasmapheresis and
intravenous immunoglobulin. Patients presenting with symptoms suggestive of
autoimmune encephalitis, but without
antibodies, may still respond to
immunotherapy.