Sentinel headache (SH) is a kind of secondary headache that is characterized as sudden, intense, and persistent, preceding spontaneous subarachnoid hemorrhage (SAH) by days or weeks. It can occur in 15-60% of patients with spontaneous SAH and its pathophysiology has not been fully elucidated. The current consensus is that structural changes in the aneurysm wall or minor bleeding could be the factors responsible for the pain 1) 2) 3) 4) 5) 6) 7) 8).

1)
Anderson C, Anderson N, Bonita R, Dunbabin D., Hankey G., Jamrozik K., et al. Epidemiology of aneurysmal subarachnoid hemorrhage in Australia and New Zealand: Incidence and case fatality from the Australasian Cooperative Research on Subarachnoid Hemorrhage Study (ACROSS) Stroke. 2000;31:1843–50.
2)
Asano AG, Silva WF, Valença MM. Cefaléia sentinela: Sinal de alerta da hemorragia subaracnoide. Migrâeas Cefaléias. 2008;11:78–83.
3)
Inagawa T. What are the actual incidence and mortality rates of subarachnoid hemorrhage? Surg Neurol. 1997;47:47–52.
4)
Linn FH, Rinkel GJ, Algra A, van Gijn J. Incidence of subarachnoid hemorrhage: Role of region, year, and rate of computed tomography: A meta-analysis. Stroke. 1996;27:625–9.
5)
Polmear A. Sentinel headaches in aneurysmal subarachnoid haemorrhage: What is the true incidence? A systematic review. Cephalalgia. 2003;23:935–41.
6)
Schwedt TJ, Matharu MS, Dodick DW. Thunderclap headache. Lancet Neurol. 2006;5:621–31.
7)
Suarez JI, Tarr RW, Selman WR. Aneurysmal subarachnoid hemorrhage. N Engl J Med. 2006;354:387–96.
8)
Van Gijn J, Rinkel GJ. Subarachnoid haemorrhage: Diagnosis, causes and management. Brain. 2001;124:249–78.