Abstract There is no consensus regarding treatment modalities for idiopathic sudden sensorineural hearing loss (SNHL). In order to evaluate the effectiveness of steroid or carbogen inhalation therapies, a prospective double-blind placebo controlled study was designed. All 41 patients en- rolled in the study had unilateral SNHL with no prior his- tory of SNHL, otological pathological history or otoscopic findings. Patients were assigned to four treatment groups: prednisone tablets, placebo tablets, carbogen inhalation or room air inhalation. All were treated for 5 days. The au- diometric data at admission was compared to that at day 6 and to data collected at follow-up (average 33 days). Re- sults revealed no significant difference between the groups for early or late audiometric outcome. Age, time from on- set of symptoms to initiation of treatment, tinnitus, audio- gram configuration, and the presence of vertigo at onset did not significantly affect the outcome. The discrimina- tion scores that were poor in all patient groups on admis- sion improved within days in all groups. These findings suggest that steroids or carbogen inhalation have no ther- apeutic advantage over placebo. Also, regardless of treat- ment modality, hearing continued to improve for at least a month after treatment was stopped. Keywords Sudden hearing loss · Steroid treatment · Carbogen inhalation Introduction Various theories have been proposed for the etiology of idiopathic sudden sensorineural hearing loss (SNHL). These include blood flow disturbances, viral infections, immune disorders, membrane rupture of the inner ear, and toxic and metabolic causes. Due to the problematic identifica- tion of the cause, many regimens have been used to treat SNHL. In a prospective study by Mattox and Simmons, 65% of patients were found to recover spontaneously, in- dependently of the type of medical therapy [9]. The effec- tiveness of steroid treatment was emphasized by Wilson et al. and later by Moskowitz et al. [10, 15], while others found that steroids had no advantage over other therapies [5, 8]. The blood flow disturbance theory, with the condi- tion regarded as a thromboembolic, vasospasm or hemor- rhagic event, means that plasma expanders, anticoagulants and vasodilators are also used as common medical treat- ments. Carbogen inhalation (5% carbon dioxide and 95% oxygen) as a treatment for sudden hearing loss was de- scribed by Fisch et al., as carbogen has a vasodilating ef- fect on intracranial blood vessels [3, 11]. In this study we compared two common therapies for sudden hearing loss: steroids and carbogen inhalation. Our study was conducted in a prospective, double-blind, placebo controlled fashion. Patients and methods Forty-one consecutive patients were enrolled in the study, which was approved by the Helsinki Committee of the Chaim Sheba Medical Center. All the patients were members of the general community suffering from unilateral SNHL who were referred to and hospital- ized in our tertiary medical center. Their ages ranged between 12 and 71 years (average 36). There were 22 females and 19 males, with 24 left and 17 right ears affected. The average duration from onset to initiation of treatment was 4 days. The earliest time ther- apy began was on the day of hearing loss and the latest was 9 days after onset (Table 1). In order to participate in the study patients had to meet strict criteria: Sudden hearing loss was defined as a sensorineural impair- ment of immediate onset. The deterioration had to be 20 dB or more Udi Cinamon · Erez Bendet · Jona Kronenberg Steroids, carbogen or placebo for sudden hearing loss: a prospective double-blind study Eur Arch Otorhinolaryngol (2001) 258 : 477–480 © Springer-Verlag 2001 Received: 6 April 2001 / Accepted: 9 May 2001 OTOLOGY Text presented at the annual meeting of The Israeli Otolaryngology, Head and Neck Surgery Society, 26 March 1998, Eilat, Israel U. Cinamon · E. Bendet · J. Kronenberg Department of Otolaryngology, Head and Neck Surgery, The Chaim Sheba Medical Center, Tel-Hashomer, Sackler School of Medicine, Tel-Aviv University, Israel Present address: U. Cinamon () Department of Otolaryngology, Head and Neck Surgery. The Edith Wolfson Medical Center, Holon 58100, Israel, and The Ear Research Laboratory, Department of Biomedical Engineering, Tel-Aviv University, Israel e-mail: udicin@hotmail.co.il Tel.: +972-3-5028653, Fax: +972-9-7679605