The Effectiveness of Hyperbaric Oxygen Therapy in Severe Idiopathic Sudden Sensorineural Hearing Loss

[...]this treatment initially accelerates recovery in patients with a hearing loss below 80 dB. [...]the appropriate indication for HBOT benefits in patients with severe or profound ISSNHL should be reviewed. Hyperbaric oxygen therapy, idiopathic sudden sensorineural hearing loss, steroid, intratympanic injection INTRODUCTION Idiopathic sudden sensorineural hearing loss (ISSNHL) is defined as a sudden hearing loss that has no known cause, and it occurs in 3 days or more with 30 dB of sensorineural hearing loss at 3 or more consecutive frequencies on pure-tone audiometry (PTA).1 Initially, patients may complain of tinnitus or ear fullness, and accompanying dizziness may occur in approximately 20-60% of patients; however, these symptoms are not severe and usually disappear within a few days.2,3 Therapies for unexplained sudden hearing loss are unclear. [...]anti-inflammatory drugs, blood circulation improvers, vasodilators, antiviral drugs, and diuretics may be used.4,5 Among them, steroids are the only ones recognized for their effectiveness in sudden hearing loss.6 They may be used in combination with one or more agents, such as acyclovir, dextran, Ginkgo biloba, nifedipine, magnesium, vitamins (B, E, and C), pentoxifylline, carbogen, heparin, or histamine, as well as other therapies, such as stellate ganglion block or hyperbaric oxygen therapy (HBOT).7,8 Many clinical practice guidelines have recommended HBOT as a combination treatment for ISSNHL.9-" Although the exact mechanisms underlying the effect of HBOT on ISSNHL are unclear, HBOT can enhance the positive effects of steroids in reducing vascular permeability, edema, and inflammatory responses7. In accordance with the International Organization for Standardization in 1964, the degrees of hearing loss are classified as follows: less than 25 dB HL (normal), 26-40 dB HL (mild hearing loss), 41-55 dB HL (moderate hearing loss), 56-70 dB HL (moderate to severe hearing loss), 71-90 dB HL (severe hearing loss), and greater than 91 dB HL (profound hearing loss).12 The more severe the hearing loss on an initial test or the more the hearing loss over the whole frequencies of the test, the poorer the prognosis of recovery for ISSNHL.13-14 Children and elderly people have a relatively low recovery rate, and patients with long-term ISSNHL may show less recovery.15 In this study, we investigated the necessity of routine application of combined steroid therapy and HBOT for severe or profound ISSNHL and attempted to