Case Presentation: Pontine Astrocytoma Masquerading as a Peripheral Hearing Disorder

A 34-year-old female presented with a 3-month history of progressive vertigo and unilateral hearing loss. Initial otologic evaluation suggested sensorineural hearing loss, raising suspicion for acoustic pathology. Auditory Brainstem Response (ABR) testing showed prolonged interpeak latencies, inconsistent with typical cochlear loss. This finding prompted advanced imaging.

Imaging Findings

Brain MRI with and without contrast revealed a diffusely infiltrating mass centered in the pons, expanding the brainstem. The lesion was hypointense on T1-weighted images and hyperintense on T2/FLAIR sequences, consistent with a low-grade glioma. Notably, no enhancing neuromas or extra-axial masses were identified along the vestibulocochlear nerve. The diagnosis was a pontine astrocytoma, a type of glioma arising from glial cells.

Clinical Correlation

Although pontine gliomas rarely present with isolated acoustic symptoms, tumor infiltration of the cochlear nuclei and vestibular pathways within the pons can mimic sensorineural hearing loss and vertigo. Unlike vestibular neuromas (schwannomas) which typically show abnormal ABR with retrocochlear patterns, here the MRI clarified the central origin. Careful interpretation of ABR and imaging is essential to differentiate intrinsic brainstem tumors from more common peripheral lesions.

Management and Prognosis

Given the eloquent location, surgical resection was not feasible. The patient underwent stereotactic biopsy confirming WHO Grade II astrocytoma. Treatment included fractionated radiotherapy and temozolomide chemotherapy. Vertigo and hearing symptoms improved modestly with corticosteroids and vestibular rehabilitation. Long-term prognosis remains guarded due to the infiltrative nature of pontine gliomas.

Key Takeaways

Pontine astrocytoma can present with acoustic and vestibular symptoms mimicking neuromas.
MRI is the gold standard to differentiate intrinsic brainstem tumors from extra-axial lesions.
Abnormal ABR with delayed interpeak latencies should raise suspicion for central pathology even when sensorineural hearing loss is present.
Vertigo and hearing deficits in pontine gliomas arise from nuclear or tract involvement, not peripheral nerve compression.

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see also: gamma_knife_bleed | gamma_knife_hearing_loss | neuroma_of_5th_nerve