Technical and logistical details of ITS service
As detailed in figure 1, our department reviews patients within 72 hours of onset for an audiogram and assessment. If deemed to have SSNHL, they are given oral prednisolone. Two weeks later, audiometry is repeated within an emergency clinic. If hearing thresholds have not improved by an average of 30dB relative to the unaffected ear, patients are offered ITS therapy. This constitutes three ITS injections, of between 0.4-0.8mls of 40mg/ml Methylprednisolone, injected into the middle ear through a phenol anaesthetised tympanic membrane segment, with patients placed in a recumbent position facing away from the affected side, and asked to not swallow for 30 minutes. Injections are undertaken in a specialty doctor run minor ops clinic, which runs half-daily each week, allowing up to 4 injections per session. Each injection is given a week apart. After six weeks, a final PTA is performed to qualitatively assess changes in hearing. An MRI is performed to exclude retrocochlear pathology.5