Prevalence of Cerebellar Cognitive Affective Syndrome in Patients with Cerebellar Disorders: A Systematic Review and Meta-Analysis.

Cerebellar cognitive affective syndrome (CCAS) is increasingly recognized across cerebellar disorders, but its prevalence remains uncertain because study populations and assessment methods vary. We systematically evaluated CCAS prevalence across cerebellar disorders and synthesized estimates according to assessment method. MEDLINE, Embase, Scopus, CINAHL, and two trial registries were searched from inception to November 5, 2025, without language restrictions. Two reviewers independently selected studies, extracted data, and assessed risk of bias using the Joanna Briggs Institute checklist. Studies using conventional neuropsychological assessments were included in the review but excluded from the meta-analysis because of their small number and methodological heterogeneity and were summarized descriptively. CCAS-Scale studies were pooled using random-effects models. Fifteen studies in 17 publications (712 participants) were included; five were at high risk of bias. Two conventional neuropsychological studies reported CCAS prevalence of 22.2% and 55.6%. Among 13 CCAS-Scale studies, pooled definite CCAS prevalence was 67% (95% CI, 53%-79%; I² = 91.0%; τ² = 0.21). In 11 studies reporting all four categories, proportions were 7% for no CCAS, 18% for possible, 15% for probable, and 62% for definite CCAS. Sensitivity analyses yielded estimates of 65%-69%, with persistent heterogeneity. Egger's test suggested small-study effects (p = 0.009). Definite CCAS was frequently identified using the CCAS-Scale, but considerable heterogeneity limits application of the pooled estimate to individual patients or clinical populations. The CCAS-Scale should be interpreted as a screening tool, with comprehensive neuropsychological assessment considered when clinically indicated. Standardized criteria and within-participant validation are needed.