A 44-year-old woman presented with typical vestibular symptoms of superior semicircular canal dehiscence syndrome (SSCDS). In addition, the patient experienced a rapidly progressive mixed hearing loss in the affected ear prior to surgical intervention that was unresponsive to oral steroid administration. Following middle fossa craniotomy with repair of the dehiscence, the patient's mixed hearing loss resolved to normal levels with no air-bone gap. In this report, we discuss the possible etiology of this rapidly progressive hearing loss and its implications on the differential diagnosis of patients with new onset mixed hearing losses. We also contrast the index case of progressive mixed loss with the more frequent conductive hearing loss seen in SSCDS.