Sudden Sensorineural Hearing Loss: Intratympanic steroids as a treatment
The loss of hearing of at least 30 dB over at least 3 contiguous frequencies occurring within 3 days or less is known as Sudden Sensorineural Hearing Loss (SSHL). In more than 90% of patients, the true cause of the hearing loss is not discovered, constituting an idiopathic disease. The estimated incidence of such disease is 5 to 20 cases per 100,000 annually . The rate of spontaneous recovery is approximately between 32% and 70%. The lack of consensus in the management of SSHL is due to difficulty in finding the true etiology of the deafness. Numerous treatments have been described: steroids, antiviral drugs, osmotic diuretics, anticoagulants, vasodilators, hyperbaric oxygen, carbogen; most therapies showed some benefits in restoring hearing notwithstanding the lack of robustness of the data.
The most widely employed drugs in the management of SSHL are steroids that are administered as a single agent or associated with other drugs. Although the treatment is started within a reasonable time after onset of the hearing loss, the result is not always achieved and about 30%–40% of patients have no benefits after systemic treatment.
Intratympanic injection is administerd in supine position with the head rotated to 45° to the unaffected side. Under microscope a myringotomy is done in the anterior–inferior quadrant of the tympanic membrane in order to allow the exit of the air in the middle ear during drug injection. A solution of Dexamethasone 4 mg/ml is then injected through the posterior–inferior quadrant filling completely the middle ear. The patient is maintained in the same position of the head for 20 min and is instructed to avoid swallowing, speaking and movements of the head. The intratympanic injection is repeated five times every two days. An audiogram is done weekly during the treatment.
A response to the treatment is considered if a change is recorded in PTA.