Background: Access to advanced histomolecular diagnostic testing for central nervous system(CNS) tumors is limited in low and middle-income countries (LMICs), hindering adequate characterization and failure to reach a WHO CNS 2021 diagnosis. LMICs also lack access to targeted therapies, and even conventional chemotherapy and radiation therapies vary between LMICs and high-income countries. Consequently, whether histomolecular subclassification is clinically beneficial and if it provides prognostic information in an LMIC setting is not clear. Here, we address this question by presenting the first systematic prospective study of CNS glioma patients from Pakistan, examining differences in overall survival (OS) by histomolecular subtype. Methods: A total of 194 patients with CNS tumors were enrolled at a single tertiary-care centerin Karachi, Pakistan. Routine histochemical processing, immunohistochemistry, and molecular testing using fluorescence in situ hybridization analysis, limited targeted-panel next-generation sequencing, and polymerase chain reaction were performed to test for isocitrate dehydrogenase (IDH) 1 and 2, P53, ATRX, Ki-67, 1p/19q co-deletion, and MGMT promoter methylation. Results: The results revealed that IDH status was a significant independent prognostic factor,regardless of age (p=0.016), with a 1-year survival rate of 76% and median OS of 16.15 months in IDH-wildtype high-grade gliomas. Conversely, the 1-year survival rate was 95% for IDH-mutant gliomas. Significant survival differences were observed for ATRX status (retained vs. loss) in IDH-mutant gliomas (p=0.046), P53 mutations in IDH-wildtype high-grade gliomas (p=0.05), and 1p/19q co-deletion in grade 3 gliomas (log-rank p=0.023). Conclusion We provide empirical evidence supporting a role for histo-morphological and limitedmolecular testing in neuro-oncology practice in LMICs.

Background: Cerebellopontine angle (CPA) tumors present surgical challenges due to their proxim-ity to the facial nerve. Despite preservation efforts, facial nerve paresis is a major issue. This study aims to identify key factors affecting facial nerve preservation during microsurgical resection of large CPA tumors in a low- and middle-income countries (LMIC) setting. Methods: This retrospective cross-sectional study, conducted at Aga Khan University, includedpatients who underwent microsurgical resection of large (>3 cm) CPA tumors with House-Brackmann (HB) grades 1–4. Postoperative facial nerve function was assessed using the HB grading system. Data was extracted from medical records and analyzed using SPSS 22. Results: This study analyzed 95 patients (M:F=1:1.16, mean age 44.24±13.71 years) withCPA tumors who underwent microsurgical resection. Common presenting complaints included a complete hearing loss (57.9%), headache (52.6%), and abnormal gait (40%). Preoperative facial nerve function was normal (HB grade I) in 75%, with 19%, 7%, and 2% having HB grades II, III, and IV, respectively. Schwannoma (69.5%), meningioma (16.8%), and epidermoid cyst (10.5%) were the most common diagnoses. Postoperative preservation of facial nerve function was achieved in 73.7% of patients. At six months, HB grades I and II were observed in 64% and 11.5%, respectively, while none had complete facial nerve palsy. On univariate analysis, larger tumor size and higher HB grade correlated with worse facial nerve outcomes (p=0.02). Complications were more frequent in patients with worsened outcomes (72% vs. 38.6%, p=0.004). However, in multivariate analysis, only preoperative HB grade was identified as a predictor. Conclusion Facial nerve preservation during CPA tumor resection is influenced by intrinsic tumorcharacteristics, surgical complexity, and patient-specific factors. Detailed preoperative counseling is crucial to set realistic expectations.