Morphology and variations of middle cerebral artery: systematic review and meta-analysis.

To review morphometry, morphology, branching patterns and anomalies of middle cerebral artery (MCA). The databases of PubMed, Google Scholar and Scopus were searched with different keywords. The review comprised of 45 studies. Meta-analysis was done for dimensions of MCA, shapes, patterns and MCA anomalies. Newcastle-Ottawa Scale was used for assessment of literature. Statistical analysis was done using R software using meta package. Thirteen research were combined to determine the proportion of MCA length and pooled proportion was 16.53 cm (15.33 to 17.72 cm); I²=98%; P-value<0.01. Nine studies were combined to determine proportion of MCA diameter and pooled proportion was 2.85 cm (2.52 to 3.17 cm); I²=100%; P-value<0.05. M1 segment mean length is more on left side as compared to right side. Mean length in males (16.57±1.40 cm) is more than females (15.9±1.32 cm). Mean diameter of M1 segment is similar on both sides. Mean diameter in males (3.20±0.09 cm) is higher than females (3.14±0.18 cm). Different branching patterns observed were single trunk, early bifurcation, bifurcation, trifurcation, quadrifurcation and multiple trunks. The most typical MCA branching pattern is bifurcation. The shapes of MCA like straight shaped, U shaped, C shaped, inverted U shaped and S-shaped of M1 segment have been described. Straight MCA is the most common shape. The MCA measurements and branching pattern will assist surgeons in limiting errors in the treatment of cerebral aneurysms and infarcts and providing the best possible result for the patients. An understanding of MCA shape will aid surgeons and physicians in effective endovascular recanalization.