Rete Middle Cerebral Artery Aneurysm: A Case Report and Systematic Review

Background  Middle cerebral artery (MCA) anomalies are a rare finding and may be associated with vascular changes, such as intracranial aneurysms. Among them, the rete MCA aneurysm is very rare, with only 22 cases reported to date. Case Description  A 50-year-old woman presented with subarachnoid, intraventricular, and intracerebral hemorrhage secondary to a ruptured aneurysm of rete MCA from an anomalous collateral artery of the anterior cerebral artery, treated successfully by microsurgical clipping. She presented a good recovery after a 2-year follow-up. Conclusion  A systematic review of rete MCA aneurysms is presented, comparing aneurysms originating from twig-like MCA, with 16 reports, and twig-like networks of an anomalous collateral artery, with 6 reports including ours. Several factors influence the treatment decision-making, though microsurgical clipping is the main procedure. A wider use of coiling is requested for a better comparison of the treatment approaches.

Rete middle cerebral artery anomalies: a unifying name, case series, and literature review

OBJECTIVE

Rete middle cerebral artery (MCA) is extremely rare and has not been frequently discussed. Rete MCA is a weblike anomaly of the MCA that does not coalesce and forms a prominent, large single branch from the plexiform vessels in the fetal stage. The purpose of this study was to further elucidate the clinical and radiological characteristics of patients with rete MCA.

METHODS

A total of 2262 cerebral digital subtraction angiography procedures were performed on 1937 patients at the authors' institution from February 2013 to May 2017. Data analysis included age, sex, clinical symptoms, underlying diseases, coexisting cerebral arterial anomalies, and operative methods and findings.

RESULTS

Rete MCAs were found in 13 patients, and the incidence of this anomaly was 0.67% (13 of 1937) in this study. Of the 13 patients, 3 had hemorrhagic strokes, 6 had ischemic strokes, and 4 had no symptoms. Eight patients underwent conservative treatment, and 5 patients underwent surgical treatment. Rete MCA is considered a congenital disease of the cerebral vasculature with the possibility of an acquired abnormality, such as an aneurysm, caused by hemodynamic stress. Although an epidemiological survey of rete MCA was not conducted, it is assumed that rete MCA has a high prevalence in Asia. Ischemic and hemorrhagic stroke events are fairly common in rete MCA.

CONCLUSIONS

Clinicians should understand the radiological and clinical features of patients with rete MCA to avoid misdiagnosis and unnecessary treatment. This anomaly should be differentiated from other vascular diseases and patients presenting incidentally should be carefully monitored because of their vulnerability to both hemorrhagic and ischemic strokes.