Background
Surgery for subarachnoid hemorrhage (SAH) is used to prevent the extravasation of blood into the subarachnoid space between the pial and arachnoid membranes, which has a detrimental effect on both local and global brain function and leads to high morbidity and mortality. Other than trauma, the most common cause of SAH is an intracranial aneurysm; therefore, the procedures discussed will focus primarily on treating aneurysms.
An estimated 15-30% of patients with aneurysmal SAH (aSAH) die before reaching the hospital, and approximately 25% of patients die within 24 hours, with or without medical attention. Mortality at the end of 1 week approaches 40%. Half of all patients die in the first 6 months, and only half of the patients who make it to the hospital return to their previous level of functioning.
SAH accounts for half of all spontaneous atraumatic intracranial hemorrhages (usually as the result of aneurysmal or arteriovenous malformation [AVM] leakage or rupture), with the other half consisting of bleeding that occurs within the brain parenchyma. Intracranial arterial dissection, though rare overall, may give rise to SAH as a complication.
Ancient Greek, Egyptian, and Arabic literature all have references to intracranial aneurysms, but the first successful treatment was reported in the early 19th century. However, such positive outcomes did not become routine until the advent of modern neurosurgical techniques.
Walter Dandy performed the first successful clipping of an aneurysm in 1937, using a vascular clip designed by Harvey Cushing.
In the following years, advancements in microneurosurgical techniques, including the operating microscope, microsurgical instruments, better anesthesia, and improved management of SAH complications, led to significant improvements in surgical outcomes.
Endovascular therapy for the treatment of intracranial aneurysms was pioneered in the mid-1970s by Serbinenko at the Moscow Institute of Neurosurgery. This initial approach, which attempted to achieve parent vessel occlusion using latex balloons, was moderately successful in a limited subset of cases. However, it never gained widespread applicability. Other balloon devices, including detachable silicon and latex balloons, were subsequently developed in the United States, Europe, and Japan. The success of balloon embolization has been tempered by the associated complications of deflation and aneurysmal rupture.
In 1990, Guglielmi et al at the UCLA (University of California, Los Angeles) Medical Center developed the Guglielmi detachable coil (GDC), a radiopaque platinum coil that is delivered through a microcatheter into an aneurysm, which then is detached by electrolysis. The GDC system is approved by the US Food and Drug Administration for treatment of aneurysms that have the potential for high surgical morbidity and mortality. In Europe, GDCs have been used as a first-line intervention in lieu of surgical treatment for patients without contraindications for endovascular therapy. Endovascular coiling has become first-line treatment for aneurysms at most US centers.
Controversy remains regarding the question of which aneurysms are appropriate for surgical or endovascular treatment; rigorous studies coupled with additional clinical experience will help with the formation of guidelines. Some aneurysms may require a combined approach.
Although detachable coil therapy is, to date, the most promising development in the realm of endovascular methodologies for SAH, it is almost certain that approaches will be developed that are even safer and more efficacious in occluding aneurysms. The future of SAH management most likely will revolve around the continuing development and refinement of minimally invasive endovascular techniques.
See also Subarachnoid Hemorrhage, Emergent Management of Subarachnoid Hemorrhage, Arteriovenous Malformation, Cerebral Aneurysms, and Cerebral Vasospasm After Subarachnoid Hemorrhage.