intracranial aneurysm, localized dilation of any of the cerebral arteries. Characteristics of the condition include sudden severe headache, stiff neck, photophobia, nausea, vomiting, and sometimes loss of consciousness. Rupture of an intracranial aneurysm produces a mortality rate approaching 50%, and survivors face a high risk of recurrence. Some forms of intracranial aneurysm may be treated surgically. Kinds include berry aneurysm, fusiform aneurysm, mycotic aneurysm.
