【文献Abstract】くも膜下出血の「前兆頭痛」はどれくらいの頻度である？

〈要点〉

・動脈瘤性くも膜下出血の前兆頭痛の病歴は10-43%
・発生率は対象者の5%（0～約40%まで変化する可能性）

〈雑感〉

今回、あるスタッフが頭痛を訴え過呼吸に。2週間前から頭痛がありそれが強くなったとのことだが、救急搬送で精査をお願いするとクモ膜下出血の診断だった。ともすれば片頭痛が強くなっただけで経過観察する可能性もあったのかなと思い、肝を冷やす。
文献によると、10～40％で2～8週間前に前兆頭痛があるとのことだが、頭痛の全例に頭部CTを行うわけにもいかず…かといって死亡率も25～50％とも言われており、本当に診断が難しい。。

〈文献〉

Cephalalgia. 2003 Dec;23(10):935-41. doi: 10.1046/j.1468-2982.2003.00596.x.
Sentinel headaches in aneurysmal subarachnoid haemorrhage: what is the true incidence? A systematic review
A Polmear 
Abstract
The aim of this systematic review was to determine the incidence of sentinel headache reported by patients with aneurysmal subarachnoid haemorrhage, and whether they are likely to be due to recall bias or to misdiagnosis of a previous haemorrhage. Nine studies of good quality, which reported the number of patients with aneurysmal subarachnoid haemorrhage with a history of sentinel headache, gave rates of 10% to 43%. Two case-control studies, in which the frequency of a history of sentinel headache in patients with aneurysmal subarachnoid haemorrhage was compared with that in controls with non-aneurysmal subarachnoid haemorrhage or with stroke, gave an incidence of 5% (95% confidence interval 0.5, 16) in controls, suggesting that only a small number of apparent sentinel headaches are due to recall bias. Sentinel headaches appear to be a real entity. Their true incidence may vary from near zero to about 40% according to the rate of misdiagnosis in the community under consideration.