Misdiagnosis of Schizophrenia for a Patient With Epilepsy

To the Editor: In diagnosing schizophrenia, exclusion criteria may be just as important as diagnostic criteria. In the case presented here, faculty and residents at a major university misdiagnosed a patient as having schizophrenia, and over a ten-year period deprived the patient of treatment for a seizure disorder.

A 46-year-old African-American woman was hospitalized in a university-affiliated facility in a major metropolitan area. She complained of depressive symptoms and reported unpleasant visual and auditory hallucinations that urged her to commit suicide. She exhibited poverty of thought and speech, agitation, and sickliness. Her affect was one of pained concern. She mentioned that a seizure disorder had been diagnosed when she was a child, but she could not explain why phenytoin was discontinued ten years before.

The patient had been seen for ten years at the university outpatient clinic, where her record indicated that she was thought to have schizophrenia or schizoaffective disorder. She was given high-potency neuroleptics but no anticonvulsant. Over the ten-year period, she consistently reported hallucinations. During the year before she was hospitalized, the hallucinations briefly disappeared when she started taking olanzapine at a dosage of 20 mg a day. However, she stopped taking olanzapine and did not keep subsequent appointments at the outpatient clinic.

An electroencephalogram (EEG) carried out during her hospitalization showed frequent epileptiform discharges "compatible with complex partial epilepsy of the left anterior temporal area." When she was given phenytoin in the hospital, all observable signs of illness disappeared in one day, as did her hallucinations and depressive symptoms. She demanded to be allowed to return home "because there is nobody to take care of my kids."

When she resumed her visits to the outpatient clinic, clinicians reapplied the diagnosis of schizophrenia. We later determined that the outpatient clinicians made no notes in her record about the seizure disorder, the results of the EEG, or her response to anticonvulsant medication. Her unpleasant hallucinations reappeared. Olanzapine was restarted and the hallucinations stopped, but the patient gained 30 pounds in one month and discontinued it. Risperidone was started, but the patient did not return to the clinic for follow-up.

This patient's chronic psychosis, which was alleviated by phenytoin, was attributable to a seizure disorder and not to schizophrenia or schizoaffective disorder. The case suggests that olanzapine can suppress psychopathology related to an untreated seizure disorder. Her good response to olanzapine provided false confirmation of the diagnosis of schizophrenia.

This case illustrates the importance of diagnosing schizophrenia only after ruling out the effects of medical conditions on psychopathology. A subtle but important diagnostic skill is to rule out the effects of psychotropic drugs on psychopathology. Unfortunately, a patient's response to new antipsychotic drugs may reinforce diagnostic errors, as happened in this case with olanzapine. The interests of our patients and our profession might be better served if DSM first stated the exclusion criteria in its description of schizophrenia, which would reflect their primacy.

Dr. Swartz is now affiliated with the department of psychiatry at Southern Illinois University School of Medicine in Springfield.