Unruptured cerebral aneurysms are commonly undiagnosed and untreated because often they do not cause any symptoms. However, unruptured cerebral aneurysms may be diagnosed and located if they have become enlarged and begun to cause neurologic deficits due to compression of adjacent neural structures. In addition, unruptured cerebral aneurysms may be found accidentally while performing cerebral tests for other conditions such as cerebral trauma or brain tumor. The goal of treatment of an unruptured cerebral aneurysm is to prevent rupture of the aneurysm and to control symptoms if they are present. Surgery is the primary treatment for unruptured cerebral aneurysms. The most common surgical treatment of an unruptured saccular cerebral aneurysm is the total elimination of the aneurysm sac with complete preservation of the surrounding normal blood vessels. First, the aneurysm neck is clipped with a stainless steel, non ferro-magnetic clip in order to shut off blood flow to the aneurysm while maintaining the blood flow and integrity of the surrounding blood vessels. After the aneurysm has been clipped it is then punctured and deflated. During the process of clipping, puncturing, and deflating the aneurysm, the surrounding normal blood vessels may be transiently occluded for several minutes. This process softens the aneurysm and reduces the chance of intraoperative hemorrhage from the aneurysm.

Surgical treatment of an unruptured cerebral aneurysm may not be feasible due to the location of the aneurysm, the size of the aneurysm, or the medical condition of the patient. There are a limited number of non-surgical methods used to treat unruptured cerebral aneurysms, including the following.

• Restricting patient activity, which often includes complete bed rest
• Treating symptoms of the aneurysm such as headaches, nausea, or neck pain
• Prescribing preventive use of antiseizure medications

Ruptured cerebral aneurysms are much more serious than unruptured cerebral aneurysms and require immediate emergency treatment. Initial treatment of a ruptured cerebral aneurysm includes reducing intracranial pressure. Surgical clipping of the aneurysm, which is quite similar to surgical clipping of an unruptured cerebral aneurysm, is usually performed within the first 3 days after rupture of the aneurysm.

As with an unruptured cerebral aneurysm, surgical treatment of a ruptured cerebral aneurysm may not be feasible due to the location of the aneurysm, the size of the aneurysm, or the medical condition of the patient. Nonsurgical treatments of ruptured cerebral aneurysms include the following.

• Guglielmi detachable coil (GDC) emoblization was introduced in 1991 and is an endovascular technique which involves the use of a very soft, flexible microcoiled platinum wire with intrinsic helical memory. First, the coil is attached to a delivery mandrel by a special soldered joint which can be detached by electrolysis once the coil is in or near the cerebral aneurysm. A microcatheter system is used to deliver a number of coils into the lumen of the cerebral aneurysm. The aneurysm is filled with coils and resulting thrombus in order to prevent blood flow into the aneurysm and hence to prevent bleeding from the ruptured aneurysm. Animal studies have shown that this technique leads to organization of the thrombus in the aneurysm. Upon further healing a membrane forms across the neck of the aneurysm and thus completely excludes the aneurysm from the vascular blood flow.
• Balloon embolization is an endovascular technique which involves placing a detachable balloon at the site of the ruptured aneurysm in order to occlude the blood vessel. Balloon placement within the ruptured aneurysm has been associated with significant morbidity and has been replaced by balloon trapping in which balloons are placed intravascularly above and below the aneurysm. In theory this technique leads to complete occlusion of blood flow to the aneurysm. However, complete occlusion is not always achieved, which allows some degree of intracranial bleeding to continue.
• Drug therapy
• Bed rest

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