Chapter 39 Subarachnoid hemorrhage

Abstract

Subarachnoid hemorrhage (SAH) is defined as bleeding into the subarachnoid space of the brain. The most common etiology of SAH is trauma, and Other etiologies includes aneurysmal SAH, perimesencephalic hemorrhage, vertebral artery dissection, and arteriovenous malformations (AVMs) to name a few. This chapter focuses on aneurysmal SAH that accounts for approximately 85% of all causes of non-traumatic SAH, and reviews perimesencephalic SAH and SAH from vertebral artery dissection and traumatic SAH. Intracranial aneurysms are uncommon vascular lesions that can cause significant morbidity and mortality if they rupture. Intracranial aneurysms can be defined by their morphology. The majority are saccular in nature although fusiform aneurysms occur. Saccular aneurysms are usually acquired and are believed to result from prolonged hemodynamic stress and subsequent arterial degeneration, particularly at branch points. Hypertension, cigarette smoking, oral contraceptives, alcohol consumption, pregnancy, and cocaine use are all risk factors for aneurysm formation and probably increase the risk of rupture. The four main complications following rupture of an intracranial aneurysm are cerebral vasospasm, aneurismal re-hemorrhage, hydrocephalus, and seizures. The chapter discusses the genetics of intracranial aneurysm formation, diagnostic approach to aneurysmal SAH, pathology of SAH, treatment of ruptured cerebral aneurysms, and other causes of SAH.