The Audiological Impact of Posterior Fossa Tumors: Influence of Size and Anatomical Location

Purpose: To assess the impact of tumor size and anatomical location on pure-tone audiometry (PTA) and auditory brainstem response (ABR) results in patients with posterior fossa tumors. Materials and Methods: A prospective cross-sectional study was carried out at Mustansiriyah University’s College of Medicine, Baghdad, Iraq, in collaboration with Ghazi Al-Hariri Hospital between November 2024 and May 2025. Comprehensive audiological tests, including otoscopic examination, tympanometry, PTA, and ABR testing, were performed on 18 patients with magnetic resonance imaging-confirmed posterior fossa tumors. Tumors were categorized based on their size and location within the posterior fossa. Results: Tumor location significantly influenced ipsilateral PTA thresholds and audiogram configurations, with cerebellopontine angle (CPA)-extended tumors exhibiting the worst thresholds. These lesions also demonstrated the most severe ABR anomalies, which frequently led to absent waveforms as a result of brainstem compression. Tumors ≥2 cm were associated with significantly elevated low-frequency thresholds in the ipsilateral ears and delayed contralateral wave V latencies ( P < 0.05). There was no significant relationship between tumor size and audiogram pattern. Conclusion: Tumor location within the posterior fossa, especially CPA extended tumors, affects audiological results more strongly than tumor size alone. The most severe ABR abnormalities and hearing loss are linked to CPA-extended tumors. Larger tumors (≥2 cm) predominantly affect low-frequency hearing and contralateral ABR wave V latency. These results highlight the value of integrating bilateral ABR evaluations with PTA in the diagnosis and prognostic assessment of posterior fossa tumors.