The PubMed search identified 113 records. Fifty-nine records were excluded based on titles and abstracts screening. After assessing the full text of the remaining 54 articles, 5 were further excluded. A manual searching of the reference lists of the remaining 49 articles was performed, which yielded 9 additional articles. Finally, 58 articles reporting of 67 patients including 1 case in our center were included for the analysis. Searching strategy is presented in Figure 2.
The identified patients (37 females, 55.2%) aged from 4 to 81 (49.85 ± 15.22) years old. Fifty (50/67, 74.6%) patients presented with hemorrhagic stroke either from the MCA anomalies associated aneurysms or other sources. The MCA anomalies associated aneurysms were located at the left side in 32 (32/66, 48.5%) patients. Sixty-three aneurysms (63/67, 94.0%) were saccular, 3 (4.5%) were dissecting or fusiform, and 1 (1.5%) was pseudoaneurysm. Thirty-two (32/65, 49.2%) patients had other concurrent cerebrovascular anomalies in addition to MCA anomalies associated aneurysms. Fifty-six (83.6%) patients underwent open surgeries, 8 (11.9%) patients underwent endovascular treatment, and 3 (4.5%) patients were conservatively managed. Ten (10/62, 16.1%) patients experienced procedure-related complications. Fifty-six (56/61, 91.8%) patients achieved a good recovery.
Accessory MCA aneurysm
Nineteen studies reporting of 20 patients including 1 case in our center were identified (Table 1) [4-22]. The patients aged from 4 to 73 (48.65 ± 16.70) years old, with a male to female ratio of 1:1. Eighteen (18/20, 90%) patients presented with intracranial bleeding from ac-MCA associated aneurysms or other sources. The sizes of aneurysms were below and above 10 mm in 18 (90%) and 2 (10%) patients, respectively. Seventeen (85%) aneurysms were saccular, 2 (10%) were dissecting, 1 (5%) was pseudoaneurysm. The left to right ratio of aneurysm allocation was 1:1. The locations of ac-MCAs were A1, A1-A2 junction, and A2 in 16 (16/19, 84.2%), 2 (2/19, 10.5%), and 1 (1/19, 5.3%) patient, respectively. Of the 20 aneurysms, 14 (70%) were located at the origin of ac-MCA, 6 (30%) were on the trunk. Nine (9/18, 50%) patients had other concurrent cerebrovascular anomalies. With respect to the treatment, 14 (70%) patients underwent microsurgical clipping of the aneurysms, 4 (20%) (3 coiling, 1 glue embolization) underwent endovascular treatment, 1 (5%) underwent resection of the pseudoaneurysm and distal ac-MCA, and 1 (5%) underwent aneurysm wrapping. Procedure-related complications occurred in 1 (1/19, 5.3%) patient. Eighteen (18/20, 90%) patients experienced good recovery.
Duplicate MCA aneurysm
Twenty-seven studies reporting of 34 patients were finally included (Table 2) [3, 7, 23-47]. The patients aged from 20 to 76 (50.79 ± 13.72) years old, with a male to female ratio of 0.62:1 (13:21). Twenty (20/34, 58.8%) patients presented with intracranial bleeding from d-MCA aneurysms or other sources. The sizes of aneurysms were below and above 10 mm in 33 and 1 patients, respectively. All of the aneurysms were saccular except a fusiform one. The left to right ratio of aneurysm allocation was 1.2:1 (18:15). Of the 34 aneurysms, 32 (94.1%) were located at the origin of d-MCA, 2 were on the trunk. Nine (9/18, 50%) patients had other concurrent cerebrovascular anomalies. Of the 34 patients, 18 (52.9%) have concurrent cerebrovascular anomalies. Twenty-seven (79.4%) patients underwent microsurgical clipping of the aneurysms, 3 (8.8%) patients underwent endovascular coiling, 1 (2.9%) underwent trapping of the aneurysm and simultaneous superficial temporal artery-d-MCA anastomosis, and 3 (8.8%) patients were conservatively followed up. Procedure-related complications occurred in 7 (22.6%) patients. Twenty-six (89.7%, 26/29) patients experienced good recovery.
MCA fenestration aneurysm
Twelve studies reporting of 12 patients were identified, aging from 14 to 81 (49.3 ± 13.1) years old (Table 3) [2, 48-58]. The male to female ratio was 1:1. All of the patients were admitted for intracranial bleeding. All of the aneurysms were smaller than 10 mm except for 1 the size of which could not be determined. All of the aneurysms were saccular. Nine (9/12, 75%) of the aneurysms were located at the right side. All of the fenestrations were located on M1 segment of the MCAs. The aneurysms were located proximal to, in, and distal to the fenestration in 5 (41.7%), 4 (33.3%), and 3 (25%) patients, respectively. Concurrent cerebrovascular anomalies were identified in 5 (41.7%) patients. With respect to the treatment, 10 patients underwent surgical clipping, 1 underwent aneurysm wrapping, and 1 underwent coiling. Two (2/11, 18.2%) patients experienced procedure-related complications. All of the patients experienced good recovery except for 1 patient the outcome of whom was not provided.
Duplicate MCA origin aneurysm
d-MCA origin aneurysm was only identified in a 49-year man incidentally, who was admitted for vertigo . No other cerebrovascular anomaly was reported. The saccular unruptured d-MCA origin aneurysm was microsurgically clipped. The postoperative course was uneventful and no neurological deficit was reported.
A 59-year old man was admitted for sudden onset of headache 2 days before. He was a smoker and denied history of any chronic diseases. He was alert on admission. Physical examination was unremarkable except for neck rigidity. Head computed tomography (CT) revealed subarachnoid hemorrhage of modified Fisher grade 2 (Figure 3 A-B). Further CT angiography showed the A1 segments of the bilateral ACAs gave rise to their respective ac-MCAs (Figure 3 C). A saccular aneurysm was noted at the origin of the left ac-MCA (Figure 3 C-D). No other cerebrovascular anomaly was identified. After discussion between the neurosurgical and neuro-interventional members and sufficient negotiation with the patient’s legal relatives, endovascular coiling of the aneurysm was planned.
Preprocedural digital subtraction angiography also confirmed the findings on CT angiography (Figure 4 A-B). An Echelon-10 (Medtronic, Irvine, CA) microcatheter was advanced into the left ACA directed by a 0.010-in guidewire. The tip of the microcatheter was introduced into the aneurysm. The aneurysm was satisfactorily coiled using 3 detachable coils with preservation of the distal ACA and ac-MCA (Figure 4 C-D). He experienced an uneventful postprocedural recovery and was discharged the next day without neurological deficit. Follow-up CT angiography 1 year later revealed no recurrence of the aneurysm.