Classified as a hearing loss of at least 30bB occurring within 3 days over at least 3 frequencies. Usually presenting as sudden unilateral hearing loss, tinnitus, aural fullness and vertigo. There are an estimated 5-20 cases per 100,000 annually. The cochlea and it’s structures require a high oxygen supply. Pt’s with ISSHL have show to have decreased oxygen tensions to these structures.

HBOT has shown to increase diffusion of oxygen to the damaged areas. Patients with ISSHL have the greatest benefit when treated with in 14 days of symptom onset.