Complete Hearing Recovery after Retrosigmoid Resection of Jugular Foramen Schwannoma with Concurrent Ipsilateral Vestibular Schwannoma

Introduction: Cerebellopontine angle (CPA) tumors can present with hearing loss, which influences whether a hearing preservation vs hearing ablative surgical approach is chosen. Hearing ablative approaches may be selected in cases of severe preoperative hearing loss secondary to CPA tumors, especially when this allows a more favorable surgical corridor. We discuss a unique case of complete hearing recovery after retrosigmoid resection of a jugular foramen schwannoma (JFS) in a patient who also had a concurrent ipsilateral small intracanalicular vestibular schwannoma (VS).

Case: A 46-year-old woman presented with left ear fullness, tinnitus, and imbalance for nine months. She had no lower cranial nerve (LCN) dysfunction on clinical exam and flexible laryngoscopy. Audiometry showed significantly reduced pure tone thresholds and 4% word recognition in the affected ear, consistent with class D hearing. Weber lateralized to the contralateral ear. Preoperative VNG showed absent caloric response on the left ([Fig. 1]). MRI demonstrated a left 3.3-cm JFS and separate left 1 cm intracanalicular VS ([Fig. 2A, B]). The jugular foramen tumor was noted to cause brainstem compression as well as midline shift. A retrosigmoid approach was selected, with the goal of removing the jugular foramen tumor. Access to the superior pole of the tumor required inferior drilling of the internal auditory canal. Both tumors were clearly separate. A radical subtotal resection of the JFS was achieved, relieving the stretch on the vestibulo-cochlear nerve and brainstem compression. A small rind of tumor was left behind which was tethered to the LCNs. The small intracanalicular VS was not manipulated ([Fig. 2C, D]). Pathology confirmed the diagnosis as schwannoma with NF2 mutation in the tumor, but normal NF2 germline. The patient reported significant post-operative hearing improvement on post-operative day one and Weber tuning fork exam lateralized to the operated ear. Post-op audiometry at 6 weeks showed normal audiometric thresholds with 100% discrimination ([Fig. 3]). Subtle left caloric response was noted on post-op VNG and post-op VHIT demonstrated ongoing unilateral vestibulopathy ([Fig. 4]). Central oculomotor findings improved.

Fig. 1 Preoperative caloric testing.

Fig. 2 (A and B) Preoperative MRI with JF tumor (*) and separate JF (*) and IAC tumors (arrow). (C and D) Postoperative MRI with residual JF tumor (*) and residual JF tumor (*) with non-manipulated IAC tumors (arrow).

Fig. 3 Postoperative audiometry.

Fig. 4 Postoperative caloric testing and vHIT.

Discussion: This is the first documented case of concurrent unilateral JFS and VS with complete hearing recovery after JFS resection. While the underlying mechanism of rapid reversible hearing loss has yet to be fully understood, we theorize that the preoperative hearing loss was due to stretching of the junction between the vestibulocochlear nerve and its entry point to the brainstem. As there is no current consensus for optimal management of JFSs, this case supports the use of a hearing-preservation approach in similar cases regardless of preoperative hearing status. These findings corroborate previous reports of reversal of hearing impairment following resection of non-VS CPA tumors, including but not limited to JFSs, with hearing-preservation approaches.