Indications
Absolute
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Subarachnoid hemorrhage with intraparenchymal hemorrhage requiring emergent evacuation
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Subarachnoid hemorrhage with anterior communicating artery (Acomm) aneurysm not repairable by endovascular coiling
Strong
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Large aneurysm (≥10 mm)
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Unruptured aneurysm (≥7 mm) in a patient 50 years old or younger
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Aneurysm with intraluminal thrombus
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Anterior projecting aneurysm
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Hunt and Hess grade I, II, or III in a patient 50 years old or younger
Contraindications
Strong
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Aneurysm with significant calcification or atheroma
Relative
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Hunt and Hess grade IV or V with aneurysm repairable by endovascular coiling
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Subarachnoid hemorrhage with aneurysm repairable by coiling in a patient older than 60 years
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Unruptured aneurysm less than 7 mm in a patient older than 70 years
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Posterior-projecting aneurysm
Planning and positioning
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It is generally preferred that the aneurysm be approached from the patient’s nondominant side. Contraindications to this approach are the following:
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The patient possesses a dominant-sided intraparenchymal hemorrhage requiring evacuation.
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Early access to a dominant A1 branch would be difficult.
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It is planned to clip multiple aneurysms during the same operation (e.g., left middle cerebral artery and anterior cerebral artery).
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Placement of an external ventricular drain or lumbar drain during the preoperative period for cerebrospinal fluid drainage is frequently advantageous.
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A radiolucent head holder should be used in case intraoperative angiography is performed.
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Proper head positioning helps to minimize brain retraction.
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Antibiotic prophylaxis should be administered before skin incision.
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Mannitol given at the time of skin incision helps with brain relaxation.
Figure 21-1:
Preoperative imaging is essential in helping to define a patient’s anatomy and may consist of a combination of modalities, including computed tomography (CT) scan, magnetic resonance imaging and magnetic resonance angiography, CT angiography, and four-vessel cerebral angiography. Examples of noncontrast head CT scan ( A ), cerebral angiography ( B ), and digital subtraction three-dimensional reconstruction ( C ) are shown. CT scan shows a common finding associated with ruptured Acomm aneurysms with intraparenchymal hemorrhage into the left gyrus rectus. Angiogram and three-dimensional reconstruction show a lobulated Acomm aneurysm being filled from right A1 segment with hypoplastic left A1.
Figure 21-2:
Pterional craniotomy is the standard approach for aneurysms arising from the Acomm complex. The patient’s head is placed in a three-pin radiolucent head holder with the head rotated 30 to 60 degrees contralateral to the craniotomy site. The degree of rotation depends on the patient’s anatomy. The goal is to provide a vertical corridor through which the Acomm complex may be accessed.
Procedure
