Thalamic gliomas: A systematic review and meta-analysis

Thalamic gliomas are rare tumors with unique anatomical and histopathological characteristics which make them challenging to identify and manage. The aim of the present meta-analysis is to consolidate the evidence for clinical outcomes, tumor grade, laterality, operation type, and complications of thalamic gliomas.

We conducted a Preferred Reporting Items for Systematic Reviews and Meta-analyses - conformant systematic review and meta-analysis. 327 patients were included in 15 studies. Statistical analysis included heterogeneity testing for tumor grades, laterality, and outcome of operations using pooled proportions. Dichotomous outcomes were analyzed using odds ratios (ORs) and random-effects models. Complications and adjuvant treatments were also examined.

The statistical analysis showed a significant association between tumor grade and clinical outcome, with clinical improvement occurring in 83% of low-grade versus 46% of high-grade thalamic gliomas (odds ratio = 0.366; P = 0.006). Laterality had no significant impact on outcomes (improvement: right-sided 42%, left-sided 41%). Subtotal resection showed higher improvement (54%) than gross total resection (32%), though differences were not statistically significant. Pediatric patients had slightly better improvement (54%) and lower mortality (11%) compared to adults (49% improvement and 15.8% mortality). The most common complication was hemiplegia (35.4%). The transventricular approach was most used (36.4%).

Tumor grade remains the strongest prognostic factor in thalamic glioma surgery. While laterality and extent of resection appear less predictive, tailored surgical approaches supported by advanced imaging and intraoperative monitoring can optimize outcomes. Further research incorporating molecular subtypes is warranted to refine surgical strategies and prognosis.