Sudden Deafness

Idiopathic sudden sensorineural hearing loss (ISSHL) or “sudden deafness” (SD) is a sudden or rapidly progressive hypoacusis in which no known cause of sensorineural hearing loss can be identified. The hearing loss is due to pure damage of the cochlea; and four main theories are proposed to explain this disturbance: vascular, viral, round window rupture and auto-immune disorders. Although these hypotheses are controversial, the most likely cause involves impaired oxygen delivery to the organ of Corti. Cochlear activity is dependent on energy supply which is itself directed by the oxygen metabolism; and it has been well demonstrated that perilymphatic oxygen tension decreases significantly in patients with SD. According to these pathophysiological data, various therapeutic agents (steroids, vasodilators, hemodilution, among others) supposed to enhance rheology and oxidative metabolism have been proposed. In the same way, and due to its general and specific effects, hyperbaric oxygen therapy (HBO) is able to increase perilymphatic oxygen pressure, by restoring the oxidative metabolism in the stria vascularis and by protecting neurosensory cells. All these drugs and techniques have been tried singly or in combination for many years. Despite the results of retrospective and prospective studies, their therapeutic efficacy is difficult to establish due partly to the high rate of spontaneous recovery. Conventional therapies and HBO are extensively discussed in this chapter, together with evidence from the literature