In some instances, your specialist may recommend that you undergo an injection of gentamicin into the middle ear instead of a steroid. Gentamicin is an antibiotic which is known to have mildly toxic effects on both the balance and hearing parts of the ear, although its toxic effects on the vestibular system are very much more potent than on the hearing. Despite this, there is an increased chance of a hearing loss occurring with intratympanic gentamicin injections. For this reason, they are usually reserved for patients with a pre-existing severe hearing loss at the time the vertigo is diagnosed.
Clinically, the success rate of Intratympanic steroid therapy in patients with SHL is variable in the literature and the available studies are limited to retrospective and non-controlled prospective ones. In those studies steroids were used in various concentrations, regimens and delivery methods and their effectiveness have not been established due to the lack of randomized controlled trials. There have been some studies in the literature that discussed the effectiveness of Intratympanic steroid therapy as a salvage mode of therapy in patients who failed to respond to oral steroids (Herr & Marzo 2005, Slattery et al 2005).
The injections are performed with the patient lying down and using the office microscope. The ear is first cleaned of wax. A small area of the eardrum is numbed with a drop of medication. A small needle and syringe are then used and the needle is passed through the eardrum at the site that is numbed so that the tip is in the ear, near the round window. This is a membrane where drugs are absorbed in to the cochlea. The fluid is injected in to the middle ear and the patient stays lying down for 20-30 minutes during which he does not swallow or sniff. The drug sits against the round window and is absorbed in to the inner ear. The patient then sits up slowly and leaves the office. Patients should not drive for a few hours after this procedure. Water is kept out of the ear until it is confirmed that the tiny hole has healed.