Patients and aneurysm characteristics
We performed microsurgical clipping in 420 patients with ruptured intracranial aneurysms, of which, 150 (35.7%) had ruptured AComA aneurysms. The patients were predominantly male (83 men and 67 women) and with a mean age of 51.33 years (standard deviation, 11.49 years). Hypertension was the most common comorbidity (45 patients; 30.0%), followed by diabetes mellitus (13; 8.7%). Most of our patients (107 patients; 71.3%) presented with sudden headaches, and most patients had excellent admission neurological status with a Hunt and Hess grade of 1 or 2 (97 patients; 64.7%) and a WFNS grade of 1 or 2 (109 patients; 72.6%). Patient characteristics are summarized in Table 1.
Radiographic findings included isolated thin or thick aneurysmatic SAH (modified Fisher scale score, 1 and 3) in 68 (45.3%) patients. In the remaining patients (82 patients; 54.7%), some degree of intraventricular hemorrhage was evident. Intracerebral hemorrhage mainly within the gyrus rectus was found in 47 (31.3%) patients (Table 2).
Digital subtraction angiography was performed for 146 patients, and the remaining 4 patients were evaluated using computed tomography angiography for preoperative planning. Angiography revealed that the AComA aneurysms primarily originated from the left A1–A2 junction (95 patients; 63.3%) and less often from the right A1–A2 junction (47 patients; 31.3%), and true AComA aneurysms were found only in 8 (5.3%) patients. The mean width of the aneurysm neck was 2.96 ± 1.16 mm, the mean dome width was 5.47 ± 2.54 mm, and the mean dome-to-neck ratio was 2.00 ± 0.98. The aneurysm dome was projected in the anterior direction in 70 (46.7%) patients, in the superior direction in 54 (36.0%), in the inferior direction in 21 (14.0%), and in the posterior direction in 5 (3.3%). Twelve (8.0%) patients had multiple other aneurysms, none of which showed any evidence of rupture during radiographic examination (Table 2).
Variations in the structure of the ACA were detected in 85 (56.7%) patients. A1 segment hypoplasia was the most common normal variation (81 patients, 54.0%). In these patients, A1 segment hypoplasia was more common on the right side, and most of the aneurysms originated from the side without hypoplasia. Other variations were fenestrated AComA (5 patients; 3.3%) and triplicated A2 segment (2 patients; 1.3%) (Table 2).
Surgery and complications
At our institution, the operation was performed as soon as possible after onset of symptoms of aneurysmatic SAH. Most of the patients (101; 67.3%) underwent surgery within 72 hours after onset. Delay was associated with delay in referral and with hemodynamic instability. Twenty-one (14%) patients exhibited preoperative neurological deterioration, which was suspected to result from aneurysmal rebleeding.
The mean operative time was 339 ± 68 mins, and the mean estimated blood loss was 632 ± 314 mL. Intraoperative aneurysmal rupture was observed in 22 (14.7%) patients. Surgical obliteration of the aneurysmal neck was recorded as completed obliteration (146 patients; 97.3%), and incomplete obliteration was achieved with muscle wrapping (1 patient; 0.7%). Data on obliteration was unavailable for 3 (2%) patients (Table 3).
Postoperative complications were divided into operation-related and systemic events. Postoperative cerebral infarction was seen in 55 (36.7%) patients, neurological deterioration in 38 (25.3%), and symptomatic vasospasm in 33 (22.0%). Eight (5.3%) patients developed seizures after surgery, but these could be controlled with a single antiepileptic drug. Postoperative infection was found in 38 (25.3%) patients, which manifested as pneumonia in 17 (11.3%) patients. Venous thromboembolism was found in 3 (2%) patients.
Neurological outcomes
Seven (4.7%) patients died during hospitalization. The other patients were monitored at the outpatient clinic during the rehabilitation period. At postoperative 6 months, 9 (6%) patients were lost to follow-up, 108 (71.9%) patients achieved favorable outcomes with mRS scores of 0–2, and a total of 12 (8.0%) patients had died (Table 4).
Risk factors for unfavorable outcomes at 6 months
Thirty-three patients (22%) had an unfavorable outcome at postoperative 6 months. Univariate analysis showed that age ≥60 years, the presence of hypertension, alteration of consciousness during aneurysmatic SAH onset, poor Hunt and Hess and WFNS grades (3–5) on admission, dome-to-neck ratio <2, A1 segment hypoplasia, preoperative intraventricular hemorrhage (IVH), postoperative cerebral infarction, and infectious complications were associated with unfavorable outcomes.
Moreover, multivariate logistic regression analysis revealed that the prognostic factors significantly associated with unfavorable outcomes were preoperative IVH (odds ratio, 19.7; 95% confidence interval, 5.1–75.8; P < 0.001), A1 segment hypoplasia (odds ratio, 8.9; 95% confidence interval, 2.8–28.0; P < 0.001), and postoperative cerebral infarction (odds ratio, 3.2; 95% confidence interval, 1.2–8.9; P = 0.025; Table 5).