Sudden sensorineural hearing loss (SSHL) is a relatively rare cause of sensorineural hearing loss of at least 30 dB at three contiguous frequencies for three days. A common associated complaint in 90% of patients is tinnitus, usually unilateral. Patients may also experience a feeling of fullness or ear blockage or vertigo.
SSHL has many causes, but idiopathic SSHL still predominates. Numerous etiologies have been proposed with approximately the same number of treatments. SSHL is believed to be related to hypoxia of the inner ear because the cochlea requires a high supply of O2. Hyperbaric oxygen increases the partial pressure of oxygen (pO2) in the inner ear.