抄録
A 56-year-old woman who was diagnosed with schizophrenia at 30 years old presented with acute exacerbation of psychiatric
symptoms. She was treated with increasing doses of antipsychotics owing to suspicion of worsening schizophrenia. Thereafter,
she rapidly developed pyrexia, marked sweating, tremors, myotonia/postural abnormalities, stupor with akinesia, and decreased
blood pressure, suggesting neuroleptic malignant syndrome (NMS) caused by the increased dose of antipsychotics. As a
differential diagnosis, we considered malignant catatonia caused by schizophrenia. In addition, because the patient showed
atypical symptoms and an atypical course of schizophrenia, we considered malignant catatonia caused by an organic disease
and performed an antibody test of her cerebrospinal fluid. Modified electroconvulsive therapy was performed to treat the NMS,
and the patient’s psychiatric and somatic symptoms improved. During treatment, she exhibited positivity for anti-N-methyl-D-aspartate (NMDA) receptor antibodies. However, she did not meet the consensus criteria for anti-NMDA receptor encephalitis.
Thus, as a final diagnosis, we considered NMS of atypical schizophrenia with anti-NMDA receptor antibody positivity. Anti-NMDA receptor encephalitis can be misdiagnosed as schizophrenia because of similar psychiatric symptoms. This case
emphasizes the importance of testing for anti-NMDA receptor antibodies in patients with an atypical course of schizophrenia.
