Idiopathic Sudden Sensorineural Hearing Loss


Idiopathic sudden sensorineural hearing loss is classically defined as a hearing loss of at least 30 dB occurring within three days over at least three contiguous frequencies. The most common clinical presentation involves an individual experiencing a sudden unilateral hearing loss, tinnitus, a sensation of aural fullness and vertigo. The incidence is estimated at 5 to 20 cases per 100,000 annually in the United States. However, the incidence may be higher, as many cases are likely unreported. Additionally, it has been estimated that as many as 65% of cases may resolve spontaneously.

Rationale for HBO2

The etiologies and pathologies of ISSHL remain unclear. Several pathophysiological mechanisms have been described including:vascular occlusion, viral infections, labyrinthine membrane breaks,immune associated disease, abnormal cochlear stress response,trauma, abnormal tissue growth, toxins, ototoxic drugs and cochlear membrane damage.

The rationale for the use of hyperbaric oxygen to treat ISSHL is supported by an understanding of the high metabolism and paucity of vascularity to the cochlea. The cochlea and the structures within it require a high oxygen supply. The direct vascular supply, particularly to the organ of Corti, is minimal. Tissue oxygenation to the structures within the cochlea occurs via oxygen diffusion from cochlear capillary networks into the perilymph and the cortilymph. The perilymph is the primary oxygen source for these intracochlear structures.  Unfortunately, perilymph oxygen tension is decreased significantly in patients with ISSHL. To achieve a consistent rise of perilymph oxygen content, the arterial-perilymphatic oxygen concentration difference must be extremely high. This can be restored with hyperbaric oxygen therapy.
Evidence-based medicine While there is a large body of literature comparing therapeutic interventions for the treatment of ISSHL, only a small number of controlled studies have been performed. Moreover, there is no clear consensus for the treatment. More than 60 protocols have been described. However, when the three most prominent and efficacious
treatments (steroids, vasodilators and HBO2) were systematically reviewed by meta-analyses from the Cochrane Collaboration, only the use of HBO2 received a positive, objective, critical review (Cochrane Review, 2010).  Both steroids and vasodilator treatments were found to have "no good evidence to suggest the effectiveness or lack thereof”  in the treatment of ISSHL. By contrast, the Cochrane Review concluded  that "for people with acute ISSHL, the application of HBO2  significantly improved hearing . . .”   Multiple controlled studies have also demonstrated a greater degree of hearing improvement when patients receive early intervention with HBO2 and oral steroids concomitantly. The use of HBO2 for the treatment of ISSHL is Class IIa (AHA Evidence-Based Scoring System) with an "A” Level of Evidence (data derived from multiple randomized clinical trials). Patient selection criteria

Patients with moderate to profound ISSHL (≥ 41 dB) who present within 14 days of symptom onset should be considered for HBO2. While patients presenting after this time may experience improvement when treated with HBO2, the medical literature suggests that early intervention is associated with improved outcomes. The best evidence supports the use of HBO2 within two weeks of symptom onset.

Clinical management

Patients who present with ISSHL should undergo a complete evaluation by an otolaryngologist and audiologist, inclusive of appropriate audiological and imaging studies, to determine the degree and potential etiology of disease. Patients determined to have ISSHL and meet the selection criteria may benefit from HBO2.  The recommended treatment profile consists of 100% O2 at 2.0 to 2.5 atmospheres absolute for 90 minutes daily for 10 to 20 treatments.  The 2.4 ATA treatment pressure is probably most practical, especially for facilities with multiplace chamber operations. Patientswith no known contraindications to steroid therapy should also be treated concomitantly with oral corticosteroids. Continued consultation and follow-up with an otolaryngologist is recommended

The above information was obtained from:
Piper SM, Murphy-Lavoie H, LeGros TL. Idiopathic Sudden Sensorineural Hearing Loss in Hyperbaric Oxygen Therapy Indications, 13th Edition, Undersea and Hyperbaric Medical Society, Best Publishing Comapany, FL; 2014


Additional indications for hyperbaric oxygen therapy may be discussed with your doctor and the Hyperbaric Medicine Team. Hyperbaric oxygen  therapy is usually used as an adjunct to additional care the patient is receiving. Additional treatments may also include antibiotic therapy, nutritional support, and surgical procedures, if indicated.  Our Hyperbaric Medicine Team will work closely with your physician(s) to coordinate any additional care needed.

Contact the Department of Hyperbaric Medicine at MemorialCare, Long Beach Medical Center for more information.


MemorialCare, Long Beach Medical Center
Department of Hyperbaric Medicine
2801 Atlantic Avenue
Long Beach, California 90806

Telephone: (562) 933-6960

 Fax: (562) 933-6060