Conversion disorder revisited: severe parasomnia discovered.

In light of recently described and reviewed disorders of movement and behaviour during sleep, the long standing diagnosis of conversion disorder in a forty-nine year old Vietnam veteran was reappraised. Polysomnographic studies showed that the nocturnal component of his "pseudoseizures" was due to physical disorder, a severe mixed parasomnia comprising the recently described REM behaviour disorder and a non-REM parasomnia. His sleep architecture was also deranged, featuring reduced REM latency and increased REM density. An association between these abnormalities and psychological trauma is recognised in the literature. Treatment with clonazepam has abolished the nocturnal behavioural disturbance. His daytime pseudoseizures occur less frequently and his general well being is improved. The case is a reminder that physical disorder may underlie and act as prototype to the psychologically-driven symptom. Before attributing behavioural disturbance at night to psychological causes alone, polysomnographic studies should be done to exclude a treatable parasomnia.