Characterizing Hearing Outcomes Following Treatment of Epidermoid and Meningioma Tumors of the CPA

Objectives: The most common tumors of the cerebellopontine angle (CPA) other than vestibular schwannoma include meningiomas and epidermoid cysts. While these lesions and efforts to address them can impact hearing, there is limited data regarding posttreatment hearing preservation. In this study, we characterize treatment and hearing outcomes for CPA meningiomas and epidermoids, and identify preoperative factors associated with hearing loss for surgically treated lesions.

Methods: We identified all adult patients with primary or recurrent CPA meningiomas and epidermoids who were treated with microsurgery or Gamma Knife Radiosurgery (GKRS) at our center between 2012 and 2022. We selected patients whose lesions involved the vestibulocochlear nerve, as evidenced by: subjective hearing loss on affected side, objective hearing loss on pre-treatment audiogram, or nerve involvement on MRI. Patient demographics, tumor characteristics, radiographic appearance and audiometry were evaluated. A poor hearing outcome was defined as pure tone average (PTA) >50 dB and speech discrimination scores (SDS) <69% on post-treatment audiogram. Patients who were treated via hearing-preserving surgery were further analyzed using Multivariable Cox proportional hazards regression models to identify factors predictive of postoperative hearing loss.

Results: We identified 83 patients with CPA meningiomas and 23 patients with CPA epidermoids that involved the vestibulocochlear nerve. The mean pre-treatment PTA and median SDS for epidermoid tumors were 17 ± 11 dB and 100% (85–100%). All epidermoids were treated with microsurgery, most commonly through retrosigmoid approach (21, 91%). The mean pre-treatment PTA and median SDS for meningiomas were 33 ± 28 dB and 92% (0–100%). Meningiomas were treated with microsurgery (46, 55%) or GKRS (37, 45%). GKRS-treated meningiomas were smaller in volume than surgically-treated meningiomas (3.1 vs. 12.5 cm3, p < 0.0001). Most surgically-treated meningiomas involved the internal auditory canal (IAC) (34, 74%): 25 had partial IAC-involvement, 8 had full IAC-involvement, and 1 expanded the IAC. Similarly, most GKRS-treated meningiomas were IAC-involving (24, 65%): 17 partial and 7 full. A retrosigmoid approach was used to resect most meningiomas (40, 87%). Ten epidermoid patients had post-op audiograms: 9 had hearing preserved (90%). Eleven patients with GKRS-treated meningiomas had posttreatment audiograms: 10 had pretreatment hearing preserved (91%). Thirty-three patients with surgically treated meningiomas had post-op audiograms: 25 had pretreatment hearing preserved (76%); all 8 patients who lost hearing post-operatively had IAC-involving tumors. Controlling for age, tumor size, recurrence status, and pre-operative SDS, circumferential vestibulocochlear nerve involvement by tumor was found to be associated with postoperative hearing loss on multivariable analysis of surgically-treated meningiomas (HR:10.3, 95% CI:1.5-81, p = 0.02). Because of excellent hearing outcomes following epidermoid resection, no predictors of post-operative hearing loss for epidermoids were identified. Apart from hearing loss, the most common complication of microsurgery was sixth nerve palsy for meningiomas (7/46, 15%) and CSF leak for epidermoids (6, 26%).

Conclusions: When appropriate treatment is selected, most patients with meningiomas and epidermoids of the CPA will have their pretreatment hearing preserved, even when the vestibulocochlear nerve is involved. The relationship of CPA meningiomas to the nerve on pre-operative imaging should also be considered, as circumferential involvement may portend poor hearing outcomes in surgical patients.

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Artikel online veröffentlicht:
05. Februar 2024