Saccular aneurysm at the anterior communicating artery complex associated with an accessory middle cerebral artery : report of two cases and review of the literature

Anatomical Variations and Anomalies of the Middle Cerebral Artery

OBJECTIVE

Intracranial arteries have a high rate of variation, but a clear schematic overview is lacking. In this pictorial review we classify and depict all the variations and anomalies within the middle cerebral artery (MCA).

METHODS

PubMed was searched with the MeSH-term "Middle Cerebral Artery." Articles were selected based on their description of variants within the MCA. Cross-referencing was used to broaden the range of articles. The anatomical variants were then schematically drawn using the anteroposterior and lateral view during angiography of the internal carotid artery.

RESULTS

A total of 29 unique medical illustrations were made, depicting variation in number of vessels; variation in vessel origin; and variation in morphology.

CONCLUSIONS

The MCA provides vital blood supply to the frontal, parietal, temporal, and central brain structures. An overview of these variations is important to diagnose and treat patients with MCA-related pathology correctly and safely. They can aid in distinguishing pathology from normal anatomical variance; aid neurosurgeons during aneurysmal clipping or arteriovenous malformation resections; and aid interventional radiologists during thrombectomy or coiling. This article provides a summary regarding current knowledge of anatomical variations within the MCA, their prevalence and clinical relevance. A total of 29 unique illustrations were made, depicting currently known variants. We encourage all who diagnose, treat, and study the MCA to use this overview for a uniform and better understanding of its anatomy.

Anatomical Variations and Anomalies of the Anterior Communicating Artery Complex

BACKGROUND

Intracranial arteries have a high rate of variation, but a clear schematic overview is lacking. In this pictorial review we classify and depict all variations and anomalies within the anterior communicating artery complex.

METHODS

PubMed was searched with the terms "Anterior Communicating Artery" AND "Variations" OR "Anomalies." Articles were selected based on their description of variants. Cross-referencing was used to broaden the range of variations. Surgical view during pterional craniotomy and transsylvian approach was used as a baseline for schematic drawings of the variations.

RESULTS

A total of 42 variants were identified, schematically drawn and classified into A1-A2 segment, anterior communicating artery, and the recurrent artery of Heubner.

CONCLUSIONS

The anterior communicating artery complex consists of the anterior cerebral artery, anterior communicating artery and the recurrent artery of Heubner. An overview of these variations may be helpful in distinguishing pathology from anatomical variations, assist neurosurgeons during clipping of cerebral aneurysms, and support interventional radiologists during endovascular treatments. This article summarizes the current knowledge of anatomical variations within the anterior communicating artery complex, their prevalence and clinical relevance. A total of 42 variants were identified and schematically depicted. We encourage all who diagnose, treat, and study the anterior communicating artery complex to use this overview for a uniform and better understanding of its anatomy.

The Clinical Characteristics and Treatment Considerations for Intracranial Aneurysms Associated With Middle Cerebral Artery Anomalies: A Systematic Review

Background: As a result of their low incidence, most of the studies on intracranial aneurysms associated with middle cerebral artery (MCA) anomalies were presented as case reports or small case series. No systematic review on this specific entity has been conducted.

Methods: A PubMed search of the published studies was performed on April 6th, 2019 for patients who had intracranial aneurysms associated with MCA anomalies. The languages included in this study were English, Chinese, and Japanese.

Results: Finally, 58 articles reporting of 67 patients including 1 case in our center were included. The identified patients (37 females, 55.2%) aged from 4 to 81 (49.85 ± 15.22) years old. 50 (50/67, 74.6%) patients presented with hemorrhagic stroke either from the MCA anomalies associated aneurysms or other sources. 63 aneurysms (63/67, 94.0%) were saccular, 3 (4.5%) were dissecting or fusiform, and 1 (1.5%) was pseudoaneurysm. 32 (32/65, 49.2%) patients had other concurrent cerebrovascular anomalies. 56 (83.6%) patients underwent open surgeries, 8 (11.9%) patients underwent endovascular treatment, and 3 (4.5%) patients were conservatively managed. 56 (56/61, 91.8%) patients achieved a good recovery.

Conclusions: The pathophysiological genesis of intracranial aneurysms associated with MCA anomalies is still obscure. The inflicted patients tend to have other concurrent cerebrovascular anomalies, which denotes that congenital defect in cerebrovascular development might play a role in this process. Most of the affected patients could experience a good recovery after treatment.

Relationship between the morphology of A-1 segment of anterior cerebral artery and anterior communicating artery aneurysms

BACKGROUND

The anterior communicating artery (ACoA) is one of the most frequent sites for cerebral aneurysm. The peculiar directions of projection of aneurysms offer great challenges to clinical treatment.

OBJETIVES

To establish the relationship between morphology of A-1 segment of anterior cerebral artery (ACA) and aneurismal projection.

METHODS

Randomly selected digital subtraction angiography data of 264 anterior communicating artery aneurysms (ACoAA) cases and 296 cases of other cerebral vascular diseases in the same period were retrospectively analyzed.

RESULTS

Among 264 ACoAA patients, the morphology of A-1 segment showed type 1a in 158 sides, type 1b in 11, type 2a in 35, type 1 2b in 87, type 3 in 171 and absence in 66. The morphology of A-1 segment in 296 patients with other cerebral vascular diseases displayed type 1a in 195 sides, type 1b in 20, type 2a in 47, type 2b in 74, type 3 in 217 and absence in 39. The non-visualization of A-1 segment in the group of ACoAA occurred more than in the control group (χ(2)=11.482, p=0.001). The classifications of ACoAAs in 264 patients were confirmed as anterior-superior type in 121 cases, anterior-inferior type in 105, complicated type in 16, posterior-inferior type in 12 and posterior-superior type in 10. The correlation between morphology of A-1 segment of ACA and classifications of ACoAA was significant (p=0.000; C=0.619, p=0.000). The direction of ACoAA was downward when the A-1 segment of ACA was Type 1a or Type 2a, and was upward when it was Type 1a or Type 2a and was upward or downward or complicated when it was Type 3.

CONCLUSION

The relationship between morphology of A-1 segment of ACA and classification of ACoAA is clarified in the present study, which is helpful to surgical treatment.

Aneurysm of a duplicate middle cerebral artery

BACKGROUND

Anatomic middle cerebral artery (MCA) anomalies are rare, but each of the described variants (eg, duplicate, fenestrated, accessory) can be of clinical significance.

CASE DESCRIPTION

A 34-year-old man with a history of left hemispheric stroke was found to have an aberrant, early-arising duplicate left M1 segment of the MCA with an associated asymptomatic fusiform aneurysm. The patient was treated with a superficial temporal artery (STA) to distal MCA bypass followed by surgical trapping of the aneurysm.

RESULTS

Intraoperative and follow-up angiography performed postoperatively at 3 months showed complete isolation of the aneurysm from the circulation and patency of the bypass graft. The postoperative course was uneventful with the exception of a craniotomy flap infection, which was effectively managed with intravenous antibiotics, flap removal, and subsequent use of a fabricated replacement.

CONCLUSIONS

This rare case is presented and used as a framework for a brief discussion of the literature regarding both variant MCA anatomy and treatment considerations for these anomalies when associated with an aneurysm.

Ruptured anterior cerebral artery aneurysm at the origin of the accessory middle cerebral artery

A 36-year-old female patient was admitted to our hospital with a rare case of aneurysm at the origin of the accessory middle cerebral artery (MCA) manifesting as severe headache and vomiting. Neurological examination did not detect any abnormalities or consciousness disturbance. Computed tomography demonstrated diffuse subarachnoid hemorrhage. Magnetic resonance angiography showed an aneurysm in the horizontal portion of the left anterior cerebral artery (A(1)). Digital subtraction angiography and three-dimensional digital subtraction angiography demonstrated a saccular aneurysm originating at the junction of the left A(1) and accessory MCA. Another accessory MCA originated at the proximal portion of the left A(2) without an aneurysm. Two accessory MCAs were found on the left. Neck clipping was performed via a left pterional approach. One month after admission, she was discharged without neurological deficits.