What is the pathophysiologic cause of a headache from subarachnoid hemorrhage?
The pain caused by aneurysmal rupture may be related to stretching of the blood vessel wall. Another theory is that there is a temporary rise in intracranial pressure to equal the mean arterial pressure in order to abate the bleeding from the aneurysm. Other potential etiologies are likely to exist, however, as patients with nonaneurysmal rupture also have severe headaches. Possible causes include increased local inflammation and irritation of the surrounding blood vessel, vasospasm, and mechanical stimulation of trigeminovascular afferents or meningeal irritation and inflammation. It is possible that all of the above are causes of the headache following subarachnoid hemorrhage, but at different points along the course of the disease.