Fig. 4

A Forest plot of odds ratio (OR) for chronic extradural hematoma being post-traumatic versus spontaneous. CI = Confidence Interval. Cohort studies that reported chronic extradural hematoma secondary to traumatic brain injury as well as those without trauma. B Funnel plot as a graphical visualization of rank correlation and regression test for publication bias assessment. No significant funnel plot asymmetry with high p value (p = 0.8458 and p = 0.9596, respectively). The small size of included studies can explain the scattered distribution