[1][4] In subarachnoid hemorrhage, there may be syncope (transient loss of consciousness), seizures, meningism (neck pain and stiffness), visual symptoms, and vomiting.
The pain usually precedes other problems that are caused by impaired blood flow through the artery into the brain; these may include visual symptoms, weakness of part of the body, and other abnormalities depending on the vessel affected.
[1][2] If both investigations are normal, the specific description of the headache and the presence of other abnormalities may prompt further tests, usually involving magnetic resonance imaging (MRI).
It is not usually necessary to proceed to cerebral angiography, a more precise but invasive investigation of the brain's blood vessels, if MRA and MRV are normal.
[3] The importance of severe headaches in the diagnosis of subarachnoid hemorrhage has been known since the 1920s, when London neurologist Charles Symonds described the clinical syndrome.