Unruptured intracranial aneurysms: an assessment of the annual risk of rupture based on epidemiological and clinical data

Br J Neurosurg. 1988;2(3):369-77. doi: 10.3109/02688698809001008.


From autopsy and neuroradiological studies a maximum prevalence of unruptured intracranial aneurysms (UA) of 0.5% in the general population is revealed. Studies concerning the incidence of aneurysmal subarachnoid haemorrhage (SAH) revealed 10 cases per 100,000 inhabitants per year. From these epidemiological parameters a minimum annual risk of 2% of rupture of an UA is calculated. It is in accordance with clinical studies, which also demonstrated an annual risk of UA rupture of at least 2%. No critical size of the UA predisposing to rupture has been found. Operation on diagnosed UA is recommended because of the serious prognosis after aneurysmal SAH (morbidity 20%-25% and mortality 50%-60%) and because the morbidity (4%) and the mortality (0%) after operative treatment of UA are very low.

Publication types

  • Review

MeSH terms

  • Humans
  • Intracranial Aneurysm / complications*
  • Intracranial Aneurysm / epidemiology
  • Intracranial Aneurysm / surgery
  • Risk Factors
  • Rupture, Spontaneous / epidemiology
  • Subarachnoid Hemorrhage / epidemiology