Tardive dystonia and diffuse idiopathic skeletal hyperostosis.

Tardive dystonia is a late side effect of long term neuroleptic treatment. A Chinese woman with tardive dystonia in the form of retrocollis for ten years showed radiological evidence of diffuse idiopathic skeletal hyperostosis (DISH) in the cervical spine. This association has not been previously reported in the literature. It is postulated that the retrocollis led to an abnormal stress of the cervical spine where excessive bone formation occurred. Hence tardive dystonia may act as a risk factor for DISH in patients who have an ossifying diathesis.