Unruptured Acomm Aneurysm
Sepideh Amin-Hanjani, MD, FAANS, FAHA, Professor of Neurological Surgery, University of Illinois Chicago, Chicago, Illinois
This case demonstrates craniotomy and clipping of a superior projecting unruptured Acomm artery aneurysm.
The video demonstrates the craniotomy technique, in addition to the microsurgical technique. It is a classic case of utilizing a fenestrated clipping strategy for these aneurysms.
This is a 40-year-old woman with an unruptured Acomm artery aneurysm. Her examination was normal, and she was previously healthy. She underwent a left-sided modified orbitozygomatic craniotomy for microsurgical clipping.
The modified orbitozygomatic approach incorporates a small frontal craniotomy with removal of the anterolateral orbital roof in a single piece. The temporalis muscle is minimally disrupted in order to avoid complications such as postoperative jaw pain or difficulty with chewing. The incision as shown here is a traditional one behind the hairline and results in an excellent cosmetic result. Alternatively, an eyebrow incision can be used and has been well described for treatment of Acomm artery aneurysms.
The modified OZ approach allows for improved visualization of the Acomm complex and less brain retraction. The left side was chosen as it allows for immediate proximal control of the anterior cerebral artery supplying the aneurysm; as seen on preoperative imaging, the right ACA is hypoplastic. A right-sided approach could also be used in this case to avoid dominant frontal lobe retraction; however, the lack of immediate proximal control is a drawback to this approach.
The patient is placed in the supine position with the head rotated approximately 30 degrees. Extension of the head allows for maximal frontal lobe relaxation.
The incision as shown here is a traditional one behind the hairline and results in an excellent cosmetic result. Alternatively, an eyebrow incision can be used and has been well described for treatment of Acomm artery aneurysms.
Following reflection of the scalp and temporalis, the craniotomy shown here incorporates a one-piece method for the modified OZ. The medial borders of the orbital cut are the supraorbital notch. The key-hole is used to access both the dura and the orbital contents. A two-piece method can also be used.
The microsurgical clipping strategy shows is typical for the treatment of superior projecting acomm aneurysms; fenestrated clips allow for maintenance of ipsilateral A2 patency and aneurysm neck occlusion. Additional clips can be stacked if necessary. The contralateral A2 must be well visualized as well. We use ICG videoangiography routinely; we have found that it has essentially supplanted intraoperative angiography at our institution.
The patient was observed in the PACU and then sent to the step-down unit after surgery. We do not utilize the ICU in uncomplicated aneurysm surgery in the unruptured patient. She went home on POD #2 and was back at work in 4 weeks without restrictions.
Alternatives to the chosen treatment method include the following: Observation - The aneurysm measured 6 mm in diameter. Although ISUIA indicated that aneurysms smaller than 7 mm in size in the anterior circulation had a very low rupture rate, the study included very few Acomm artery aneurysms (1). The Acomm artery region is considered a high-risk region for aneurysm rupture, and even small aneurysms commonly present in this location with subarachnoid hemorrhage (2). In a patient with nearly 40 years of life expectancy, treatment is the option of choice so long as it is relatively low risk and efficacious.
Endovascular Coiling - This aneurysm was relatively wide-necked and multilobulated. Though not unreasonable, in patients younger than age 50, there is evidence that surgical morbidity is very low while there is no evidence that rates of ischemic perioprocedural stroke are lower with endovascular treatment (3, 4). This data, combined with the durability of microsurgical clipping, make this treatment the one of choice for this patient (though it must be done in experienced centers with high surgical volumes and low complication rates).
Pterional Approach -
The pterional approach is the traditional route of approach used for most anterior circulation aneurysms. It is not unreasonable to use in this case; when performed, care should be taken to drill off the orbital roof extradurally to maximize visualization and minimize brain retraction. Additionally, exposure of the temporal lobe is unnecessary and the craniotomy should be minimized.
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