Tardive dyskinesia presenting as a psychosis.

Tardive dyskinesia (TD), a movement disorder secondary to neuroleptic medication, is frequently found in psychiatric patients. The authors review reasons why some patients with TD go undetected. In addition, they report on another clinical situation which led to TD going undiagnosed: two cases which developed TD, then incorporated their movement disorder into a delusional system. Their clinicians focused exclusively on their psychosis, missing the underlying neurological disorder. How commonly this occurs in clinical practice is unknown.