A3 Aneurysm

The unilateral interhemispheric approach is a well-known operative technique for distal anterior cerebral artery aneurysms (DACA). However, this approach presents several risks, such as postoperative venous infarction due to occasional sacrifice of the parasagittal bridging vein or postoperative frontal lobe damage due to retraction force. To overcome these risks, Cho et al., used a bifrontal craniotomy with a straight dural incision and cutting of the superior sagittal sinus (SSS). This method helps to overcome the shortcomings of the prior unilateral approach.

They retrospectively reviewed 61 aneurysm patients (42 unruptured- and 19 ruptured- A2 aneurysm and A3 aneurysm) who received clipping surgery through bifrontal interhemispheric approach between March 2007 and December 2017. This included 35 A2 aneurysms and 27 A3 aneurysms, and the mean size of the aneurysms was 5.45 mm. The modified bifrontal interhemispheric approach involved three steps: bifrontal craniotomy of the centrobasal portion of the frontal bone, ligation and division of the anterior one third of the superior sagittal sinus, and approaching the aneurysm via the interhemispheric space. All patients underwent computed tomography (CT) scans on the third and seventh postoperative days for the evaluation of brain retraction damage or venous infarction.

Of patients with ruptured aneurysms, 79% had a favorable outcome (Glasgow Outcome Scale 4 or 5) 6 months after primary subarachnoid hemorrhage and all patients with unruptured aneurysms had favorable outcomes. The surgical outcome was strongly related to the preoperative neurologic grade of Hunt and Hess (H-H). Three patients had poor outcomes due to their poor H-H grade on admission (Grade III: 2, IV: 1). In follow up CT scans, venous infarction did not occur in any of our 61 patients.

The modified bifrontal interhemispheric approach might be a safe and effective method for treating A2,3 aneurysm with relatively good clinical outcome and no surgery-related complications 1).

Traditional craniotomies for treatment of the aneurysms at the A3 segment of anterior cerebral artery (A3As), such as frontal approach and interhemispheric approach, require pre-hairline incision and relatively long incision, extensive bone flap, inevitable supraorbital nerve injury, opening frontal sinus, and increased operative time. Here we reported anterior interhemispheric keyhole approach with minimally invasive advantages for treatment of A3As.

MATERIAL AND METHODS: Thirteen A3As and one A1 aneurysm in thirteen patients were confirmed by computed tomographic angiography (CTA) and/or digital subtraction angiography (DSA). All patients underwent anterior interhemispheric keyhole approach with a hairline incision across the midline and a bone flap 3-4 cm in diameter, combined with external ventricular drainage, neuronavigation, intraoperative neurophysiological monitoring (IONM), and transcranial Doppler (TCD). Clinical characteristics and therapeutic results of the patients were analyzed, and the postoperative functional capacities of those patients were evaluated using Glasgow Outcome Scale (GOS) six months later.

RESULTS: All aneurysms were successfully obliterated via the anterior interhemispheric keyhole approach combined with external ventricular drainage. Mean duration of surgery (from skin incision to wound closure) was 100 minutes with a range of 70 to 135 minutes. No severe interhemispheric keyhole approach related complications, postoperative infections, secondary intracranial haemorrhage, severe cerebral vasospasm, and aneurysmal neck remnants were detected. Median hospital stay after surgery was 9.0 days (range 8 to 11 days). And the postoperative functional capacities evaluated by GOS were normal six months later 2).

Cho YH, Yang IC, Kim YS, Kim TS, Joo SP. Bifrontal Interhemispheric Approach Involving Cutting the Superior Sagittal Sinus for Distal Anterior Cerebral Artery Aneurysms. World Neurosurg. 2019 Apr 10. pii: S1878-8750(19)31033-2. doi: 10.1016/j.wneu.2019.04.041. [Epub ahead of print] PubMed PMID: 30980976.
Zheng SF, Yao PS, Yu LH, Kang DZ. Surgical Technique for Aneurysms at the A3 Segment of Anterior Cerebral Artery Via Anterior Interhemispheric Keyhole Approach. Turk Neurosurg. 2017;27(1):22-30. doi: 10.5137/1019-5149.JTN.14271-15.1. PubMed PMID: 27593742.
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