Microsurgical strategies for small unruptured dorsal internal carotid artery aneurysms.

[OBJECTIVE] This study aimed to develop microsurgical strategies based on the anatomical relationship between dorsal internal carotid artery (ICA) aneurysms, the falciform ligament (FL), and the anterior clinoid process (ACP).

[METHODS] Between 2017 and 2022, 25 patients with unruptured dorsal ICA aneurysms (less than 4 mm in diameter) underwent microsurgical direct clipping. These cases involved the left ICA (n=17) and the right ICA (n=8), with a mean aneurysm size of 3.3 mm (range, 2.5 to 4 mm). We used computed tomography angiography (CTA) and digital subtraction angiography to elucidate the anatomical relationship between dorsal ICA aneurysms and other structures. All procedures involved an ipsilateral pterional approach with securement of the ipsilateral cervical ICA for proximal control.

[RESULTS] Among the 25 dorsal ICA aneurysms, 8 (32%) were clipped without the FL being incised. Another 5 (20%) were clipped solely after the FL was cut. For the remaining 12 cases, the aneurysms were successfully clipped following FL incision and partial ACP removal. Patients exhibited favorable postoperative recoveries with good outcomes, and postoperative CTA revealed complete aneurysm clipping without any residual remnants. Conclusions: We were able to perform clipping without removing the ACP in 13 patients (52%), and in 8 of these (32%), the clipping was carried out directly without cutting the FL. Microsurgery, coupled with proximal control of the cervical ICA, can serve as a viable alternative for patients with small dorsal ICA aneurysms, especially when endovascular treatment options are limited, and 3D CTA confirms a clear anatomical relationship with the ACP.