Exploring Hemispheric Vulnerability in Crossed Cerebellar Diaschisis: A Systematic Review and Meta-Analysis.

BACKGROUND

The cerebellum is increasingly recognized as a hub for motor, cognitive, and affective functions. Crossed cerebellar diaschisis (CCD) refers to decreased cerebellar activity or metabolism contralateral to a supratentorial lesion and is associated with functional deficits. The distribution of hemispheric involvement may reflect lesion lateralization and is of interest for future research into its potential clinical relevance.

METHODS

A systematic search in PubMed and EBSCO using "(cerebellar diaschisis) AND ((hemisphere) OR (lateralization))" following PRISMA guidelines was performed. Original studies including patients with CCD assessed via neuroimaging were included. A random-effects proportion meta-analysis was performed to estimate the pooled proportion of left-sided cerebellar CCD, with left-sided as the reference category in a binary classification of hemispheric CCD laterality. Study-specific proportions were calculated as the number of left-sided cases divided by total CCD cases. A logit transformation (PLOGIT) with inverse-variance weighting was applied. Between-study heterogeneity was assessed using Cochran's Q, I2, and τ2 (Paule-Mandel); publication bias was evaluated via funnel plot and Egger's regression test.

RESULTS

Seventeen studies comprising a total of 328 patients were included in the meta-analysis. The pooled proportion of left-sided CCD was 0.45 (95% CI: 0.39-0.51). Statistical heterogeneity was low, although moderate heterogeneity could not be excluded due to imprecision (Q(16) = 15.99, p = 0.45; I2 = 0.0%, 95% CI: 0.0%-51.1%). In total, 142 of 328 CCD cases were left-sided. No statistically significant funnel plot asymmetry was detected using Egger's regression test (t(15) = -2.05, p = 0.059), although the small sample size limited statistical power.

CONCLUSIONS

The present meta-analysis found no evidence for preferential distribution of CCD between cerebellar hemispheres. Moderate study variability was present. CCD remains an intriguing research area, but most available studies are small and heterogeneous. Further well-powered investigations are needed to clarify potential hemispheric patterns and their clinical relevance.