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Objective:
Current clinical practice guidelines of the American Academy of Otolaryngology-Head and Neck Surgery recommend MRI or auditory brainstem response testing in patients who present with sudden sensorineural hearing loss (SSNHL) to exclude a retrocochlear pathology.[1] This recommendation was based on smaller studies reporting the incidence of a retrocochlear lesion as a cause for SSNHL ranging from 4.4 - 13.75%. The purpose of our study was to assess the incidence of relevant retrocochlear pathology in our database of patients undergoing MRI for SSNHL, the largest to be reported, and determine if there are specific patient factors that would yield a higher positive incidence.

Materials and Methods:
Using the institutional Research Patient Data Registry (RPDR), we identified patients with SSNHL who obtained MRI between August 2015 and November 2022. A retrospective chart review to categorize MRI findings into relevant positive findings and incidental findings, and further examined whether these patients required intervention or observation.

Results:
During the study period, 863 patients with SSNHL underwent MRI of the brain. Of these, 31 (3.5%) patients had a relevant tumor, 9 (1%) patients with a relevant tumor proceeded to intervention, 7 patients proceeded to surgery; 6 with vestibular schwannomas (mean largest dimension: 17.2 mm) and 1 patient with a meningioma (mean largest dimension: 28 mm). Three of the 7 surgical patients elected for surgery based on patient preference, and 4 had surgery recommended. Two patients underwent radiation for meningiomas (mean largest dimension: 40mm). When excluding the patients who underwent elective surgery, 6 patients had tumors requiring intervention (0.6% of patients imaged with SSNHL). Twenty-two patients underwent observation, most receiving MRI in follow-up visits, on average 1.7 MRI/patient. Suspected findings of labyrinthitis were found in 7 patients (0.8%). No significant difference in pure tone average audiometry was detected between patients with relevant findings and those without relevant findings (<em>p</em> = 0.056). Incidental actionable findings were found in 9 patients (2 vascular lesions, both observed), 6 findings observed (5 contralateral or trigeminal schwannomas, 1 presumed low-grade glioma), 1 deemed noncontributory with suspected superior semicircular canal dehiscence (symptoms not matching findings).

Conclusion:
Although current clinical practice in regards to treatment of SSNHL recommend the use of MRI to exclude retrocochlear pathology, our large database suggests that the incidence of positive findings is lower than previously reported. Furthermore, only 0.6% of patients had a finding requiring intervention. Clinical practice guidelines require further refinement with large data-driven studies.