Introduction: A significant proportion of patients with vestibular schwannomas greater than 3 cm have serviceable hearing preoperatively. Postoperative hearing preservation rates reported in the literature for these patients with large tumors are relatively low ranging from 0-33%. The clinical and radiographic factors predicting hearing preservation in smaller vestibular schwannomas are well described; however, the impact of these factors in larger tumors are less known. We investigated clinical and radiographic factors predicting hearing preservation in large vestibular schwannomas.
Methods: The clinical and radiographic data of 85 patients who underwent retrosigmoid craniotomies for unilateral vestibular schwannomas larger than 3 cm were retrospectively reviewed. Preoperative and postoperative audiograms, preoperative symptoms, preoperative MRI features and postoperative facial weakness were analyzed. Preoperative imaging features included tumor size, internal auditory canal length and width, degree of internal auditory canal filling, cystic or solid appearance, the presence of a CSF cleft surrounding the tumor, fourth ventricular width, cerebellar edema, brainstem edema and hydrocephalus.
Results: Hearing was preserved in 41% of patients. The presence of hypertension and diabetes increased the likelihood of preoperative hearing loss. Preoperative tinnitus was associated with a lower likelihood of hearing preservation. No radiographic factors were found to be predictive of hearing preservation; however, larger tumor size, smaller fourth ventricular width and the presence of a CSF cleft surrounding the tumor were predictive of postoperative facial weakness.
Conclusions: Systemic comorbidities may influence hearing loss preoperatively in patients with large vestibular schwannomas. Tinnitus may be an indicator of hearing reserve and potential for hearing preservation. Preoperative radiographic features were not found to predict hearing preservation despite some features being associated with postoperative facial weakness.
Patient Care: We found that systemic comorbidities influence preoperative hearing loss in large vestibular schwannomas. Some patients with smaller vestibular schwannomas that are minimally symptomatic or asymptomatic are observed with serial imaging. Counseling on the impact of hypertension and diabetes and optimization of these chronic comorbidities may lower the likelihood of developing hearing loss during the preoperative observation period.
We also found an association between tinnitus and hearing preservation rates. Tinnitus may be an early marker of impending hearing loss.
Learning Objectives: 1. By the end of this session, participants should recognize that hearing preservation in larger vestibular schwannomas is possible.
2. Describe the clinical and radiographic factors associated with hearing preservation rates in large vestibular schwannomas.