No abstract

There is evidence in favour of an association between episodic cluster headache and REM sleep whereas no such relation to chronic cluster headache has been reported. Particular features in the microstructure of sleep and arousal mechanisms could play a role in the pathogenesis of cluster headache. Reports indicate that cluster headache and obstructive sleep apnoea are associated. Single cases show improvement upon treatment of sleep apnoea, but the causal relationship remains in question.

T orsade de pointes is a rare but potentially fatal arrhythmia; more than 40 cases have been reported in the literature. However, current evidence concerning this complication is very limited. A systematic review and meta-analysis were conducted of all published case reports of perioperative torsade de pointes. A systematic search was made of MEDLINE for cases of perioperative torsade de pointes that included patients of all age groups and those that happened in the immediate perioperative period to the third postoperative day. Patient and case characteristics as well as QT interval data were extracted. Forty-six cases of perioperative torsade de pointes were identified, 29 of which occurred in women (67%), and 2 were fatal. Craniotomies and cardiac surgery accounted for 40% of all cases. Preceding events were hypokalemia (12/46, 26%; 99% confidence interval [CI], 9%Y43%) and bradycardia (7/46, 15%; 99% CI, 2%-28%). Drugs were a factor in approximately one third of the events (14/46, 30%; 99% CI, 13%Y48%). The mean corrected QT (QTc) at baseline was 457 T 67 milliseconds (minimum, 320 milliseconds; maximum, 647 milliseconds; data were available in 27 of 46 patients). At the time the event occurred, the mean QTc increased to 575 T 77 milliseconds (minimum, 413 milliseconds; maximum, 766 milliseconds; data available in 33 of 46 patients). On average, QTc increased by + 118 milliseconds (99% CI, 70Y166 milliseconds) between baseline and after the torsade de pointes event. Every patient, except 2, had a substantially prolonged QTc interval at the time of the event. This systematic review identified several common risk factors for perioperative torsade de pointes. Because of the nearly uniform presence of a substantial QTc interval prolongation at the time of a torsade de pointes episode, increased watchfulness for prolongation of a perioperative QTc interval may be indicated.