Cerebellopontine angle ependymoma presenting as isolated hearing loss in an elderly patient: A case report and literature review

Background:

Ependymoma is an uncommon tumor accounting for approximately 1.9% of all adult central nervous system tumors. Ependymomas at the cerebellopontine angle (CPA) are even more rare and only previously described in isolated case reports. Typically, acoustic neuromas and meningiomas represent the bulk of adult CPA tumors. Diagnosis can be challenging, as ependymomas have clinical findings and imaging characteristics that overlap with more common tumor histologies at the CPA.

Case Description:

We present the case of a 70-year-old male patient with progressive, isolated left-sided hearing loss found to have a World Health Organization (WHO) Grade II CPA ependymoma, representing one of the oldest recorded patients presenting with this primarily pediatric malignancy in this unique location. The patient presentation with isolated hearing loss was particularly unusual. When associated with neurologic deficits, CPA ependymomas more characteristically result in facial nerve impairment with fully preserved hearing, while vestibular schwannomas tend to present with isolated hearing loss. The standard of care for pediatric ependymomas is maximal safe resection with adjuvant radiotherapy, but treatment paradigms in adult CPA ependymoma are not well defined particularly for WHO Grade II disease. After resection, he received adjuvant radiation to decrease the risk of local recurrence. Twenty-nine months after resection, the patient remains free of treatment-related toxicity or disease recurrence.

Conclusion:

We review this patient’s clinical course in the context of the literature to highlight the challenges associated with timely diagnosis of this rare tumor and the controversial role of adjuvant therapy in preventing local recurrence in these patients.

Microsurgical techniques for achieving gross total resection of ependymomas of the fourth ventricle

Ependymomas arising from the ventricular surface present a major challenge to achieving a complete operative extirpation when located in the fourth ventricle given the presence of significant adherence to the floor of the same. Overzealous dissection and removal of a tumor from this zone may precipitate potentially catastrophic neurological deficits attributable to cranial nucleopathies and cranial neuropathies. Consequently, the classic neurosurgical teaching has advised attempted gross total resection, leaving adherent residual in the floor of the fourth ventricle, in order to prevent the development of major cranial nucleopathies and cranial neuropathies. Following surgical tumoral extirpation, residual tumor is adjuvantly stereotactically irradiated. Authors have consequently developed novel neurophysiologically guided microsurgical techniques designed to remove adherent tumor from the fourth ventricular floor. These strategies have successfully and consistently facilitated gross total resection and improved clinical outcomes in patients harboring ependymomas of the fourth ventricle. We discuss and evaluate the innovation in microsurgical strategies developed to achieve complete operative extirpation of tumoral adherence to the floor of the fourth ventricle.