Prevalence of persistent falcine sinus: a systematic review, meta-analysis and meta-regression of 5,457 subjects

The persistent falcine sinus (PFS) is a rare anatomical variant connecting straight sinus, or its tributaries, to the superior sagittal sinus and may be critically important during posterior interhemispheric transfalcine approach. We aimed to systematically evaluate the current literature, identify the gaps, and quantitatively assess the global pooled prevalence of PFS. PubMed/Medline and EMBASE databases have been searched by two authors. A quality check and risk of bias were assessed both qualitatively with Anatomical Quality Assessment (AQUA) tool, and quantitatively evaluating Luis Furuya-Kanamori (LFK) index of Doi plot asymmetry. A PRISMA-compliant systematic review and random-effects meta-analysis was conducted. Of 127 de-duplicated records, a total of five articles met the eligibility criteria including 5,457 participants with a combined sample-size weighted mean age of 22.8 years. Four studies utilized magnetic resonance imaging for PFS detection whereas one used computed tomography angiogram. The global pooled prevalence of PFS was estimated at 2.5% (95% CI 0.7-5.4%, I2 = 94.6, Cochran's Q = 73.4, p < 0.05). Meta-regression was conducted to explore the sources of heterogeneity. Moreover, four studies reported a rate of associated congenital anomalies, which was calculated to be 22.9% (95% CI 0-76.1%, I2 = 95.9, Cochran's Q = 73.5, p < 0.05), higher in older and lower in the most recent series. 3.1 mm sinus caliber may be the cutoff point distinguishing between truly persistent (smaller) versus de novo recanalized (larger) falcine sinus with the area under curve of 0.929. PFS is a variant of intracranial venous channel with the pooled prevalence of 2.5% that may coexist with congenital anomalies. The low-to-moderate certainty of evidence and substantial heterogeneity warrant cautious interpretation of the calculated epidemiological pooled estimates.