Paradoxical autonomic response to procyclidine in the neuroleptic malignant syndrome.
BACKGROUND
Neuroleptic Malignant Syndrome (NMS) is an adverse reaction to dopamine receptor antagonists, characterised by hyperpyrexia, extrapyramidal rigidity and impaired autonomic function. It might result from central dopamine receptor blockade that causes severe muscle contraction.


METHODS
Case Study.


RESULTS
High dose intravenous therapy with the anticholinergic drug, procyclidine hydrochloride, temporarily diminished the muscle rigidity and reversed most of the autonomic features in a patient with NMS occurring after a single intramuscular dose of the dopamine antagonist metoclopramide. Paradoxically, however, the heart rate decreased and bowel movements increased with this atropine-like drug.


CONCLUSIONS
Since the degree of tachypnoea, tachycardia, and bowel hypotonia closely paralleled the severity of the muscle rigidity, it is suggested that these autonomic features of NMS result from sustained muscle contraction rather than a direct effect of neuroleptic drugs on the central nervous system.
Balzan
M V
MV
Department of Medicine, Saint Luke's Hospital, Guardamangia, Malta.
D001341:Autonomic Nervous System / Q000187:drug effects*; D006547:Hernia; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D009127:Muscle Rigidity / Q000188:drug therapy; D009459:Neuroleptic Malignant Syndrome / Q000188:drug therapy*; D011352:Procyclidine / Q000627:therapeutic use*
D011352:Procyclidine