Eustachian Tube Dysfunction following Resection of Trigeminal Schwannomas

Introduction: Trigeminal schwannomas are benign nerve sheath tumors. Advances in surgical technique and approach have improved surgical morbidity; however, trigeminal deficits are expectedly commonplace given the nature of the tumor. Hearing loss as a postoperative deficit and its evaluation are not universally reported. Discussion differentiating neural and conductive hearing loss and their potential causes is also scarce. There are few reports of eustachian tube (ET) dysfunction as a postoperative sequela, but these cases were from direct tumor extension through the foramen ovale resulting in direct obstruction of the ET orifice in the nasopharynx. There are no reports of ET dysfunction as a result of damage to the motor root of the trigeminal nerve. The goal of this work is to describe the cases of two patients who underwent resection of a trigeminal schwannoma who went on to develop ET dysfunction. We will also relate the anatomy and physiology of the ET to the pathophysiology of its dysfunction in the setting of trigeminal schwannoma resection.

Case Series: This series follows two cases of unilateral trigeminal schwannomas that presented to our institution. Neither had evidence of extracranial extension nor evidence of preoperative ET dysfunction and both eventually underwent surgical resection. Both patients developed postoperative ET dysfunction and have been managed conservatively with observation thus far. Follow-up ranged from 1 to 7years.

Conclusion: Trigeminal schwannomas are rare tumors that typically require surgical resection. Hearing loss is a potential postsurgical deficit and warrants evaluation by an otolaryngologist and consideration should be given for a preoperative audiogram. Eustachian tube dysfunction as a result of trigeminal motor branch sacrifice should be included in the differential diagnosis of postoperative hearing loss in this patient subset.