Sudden Hearing Loss

If the hearing loss happens suddenly or develops over a period of up to three days, it is called sudden hearing loss.

Sudden hearing loss may have various causes. The first aetiologic factor that must be excluded is a benign tumour of the auditory nerve, called acoustic neuroma. This is why a CT-scan or MRI is usually ordered for the case assessment.

Perilabyrinthine fistula is another cause of sudden hearing loss, usually suspected from the history. This happens in cases of high pressure gradient between the inner ear and the middle ear cavity, as in diving. If the diver forces equalization by blowing with mouth and nose closed (forced Valsalva), and the eustachian tube is blocked, as in an upper respiratory tract infection, the pressure gradient can cause rupture of inner ear membranes and leakage of inner ear fluid in the middle ear cavity.

Unfortunately, in the vast majority of cases, the cause of sudden hearing loss is unknown. We believe that two major etiologic categories play the most important role: The vascular and the immunologic causes. Vascular causes include contraction and occlusion of the minute feeding vessels of the inner ear, while immunologic causes refer to immunological reactions within an infection, usually viral.

Sudden Hearing Loss is considered an otological emergency. The sooner the treatment starts, the higher the chance for recovery of hearing. There is no general consensus on its management. Several therapeutic regimens have been proposed, including:

• Medical treatment by mouth on an outpatient basis.
• Admission to Hospital and intravenous medical treatment, based on steroids and vasoactive drugs.
• Hyperbaric Oxygen (with or without medical treatment)
• Intratympanic steroid injection, typically performed in one to four sessions).

No option seems to offer a better prognosis over the rest. The final decision on the treatment depends upon the evaluation of the clinical and audiological data and the preference of the individual patient. At present, we tend to favour the intratympanic injection, as it is easy, quick, painless, and is performed on an outpatient basis, not disturbing professional or other activities of the patient. Repeated audiolograms during the course of treatment, will show the patient’s response and guide to further management.