Direct Perfusion of Steroids Into the Inner Ear Safe, Effective for Sudden Hearing Loss Patients

Sudden sensorineural hearing loss (SSNHL) is the loss of greater than 30 decibels (dB) in three consecutive frequencies over a period of three days or less. The hearing loss occurs in five to 20 of every 100,000, with approximately 4,000 new cases occurring annually in the United States and 15,000 cases occurring worldwide. Uncertainty about the true cause of this disease makes the development of effective treatment difficult. Viruses are commonly cited as the cause for this hearing disorder; other potential causes include blood flow disturbances, immune disorders, cochlear membrane rupture, and toxic and metabolic processes. Still, there are occurrences of sudden hearing loss that cannot be linked to other disorders.

Of the medical therapies recommended for idiopathic (of unknown cause) sudden hearing loss, systemic steroid therapy is advocated as the only treatment demonstrating effectiveness. The success of steroids has been attributed to the potent anti-inflammatory action of this class of drugs. However, systemic steroids can have significant side effects, and are contraindicated in patients with diabetes, peptic ulcer disease, and immunosuppression.

Other studies found that topical application of corticosteroids into inner ear fluids achieves a significantly higher penetration when compared with systemic administration. A research team has reported some success with transtympanic steroid therapy for treatment of hearing loss in patients with various inner ear problems. They have concluded that direct inner ear steroid perfusion helps to achieve higher inner ear concentrations while minimizing systemic side effects.

This direct inner ear perfusion was performed with the MicroWickTM, a device that allows the patient to periodically self-instill medication for inner ear perfusion over a prolonged period of time. The purpose of this study was to determine the safety and efficacy of transtympanic dexamethasone application via the MicroWickTM for the treatment of SSNHL. The authors of "Dexamethasone Inner Ear Perfusion for the Treatment of Sudden Deafness," are Herbert Silverstein, MD FACS, Joshua P. Light MD, Lance E. Jackson, MD, and Karen K. Hoffmann MD, all from the Ear Research Foundation, Sarasota, FL. Their findings are to be presented at the American Academy of Otolaryngology--Head and Neck Surgery Foundation Annual Meeting and OTO EXPO, September 22-25, 2002, at the San Diego Convention Center, San Diego, CA.

Methodology: This nonrandomized, prospective study assessed the results of dexamethasone inner ear perfusion for the treatment of SSNHL in patients between July, 1998, and July, 2002. Patients were diagnosed with SSNHL based on the following criteria: hearing loss occurring suddenly (< 12 hours), a loss of at least 30 dB in three contiguous frequencies, and/or greater than 20 percent loss in speech discrimination score (SDS). If there were no prior audiograms available for comparison, the degree of hearing loss was determined by comparing the affected ear with the hearing results of the good ear.

Initial treatment included oral prednisone at 60 mg/day for two weeks, followed by a tapering dose. Patients were evaluated on an individual basis for medical contraindications to high dose oral prednisone, and all patients were advised of the risks and potential side effects of steroid therapy. Patients were offered dexamethasone perfusion via the MicroWickTM if they had a persistent hearing loss following steroid therapy, if they had medical contraindications preventing the use of high dose oral steroids, or if they refused oral steroids.

Following insertion of the MicroWickTM, patients were instructed to instill three drops of dexamethasone solution three times a day. Patients were also asked to instill an antibiotic drop once daily to control any infections. The concentration of dexamethasone that was initially used was 24 mg/cc. However, after observing persistent tympanic membrane (TM) perforations at the tympanostomy site in almost 17 percent of patients, the dexamethasone concentration was reduced to a current preferred dosage of four mg/cc.

Patient data was entered into a Microsoft Excel 2000 spreadsheet for analysis. When comparing groups of data, chi-squared analysis was utilized to determine if a statistically significant difference exists.

Results: Forty-eight patients, 17 females and 31 males with an average age of 66 years old (range 45 to 85 years old), were treated with dexamethasone inner ear perfusion for SSNHL during the study period. The average duration before treatment was initiated was seven weeks (range one day-56 weeks). Sixteen of the patients did not take oral prednisone due to medical contraindications or patient preference.

Of those treated with dexamethasone at 4-10 mg/cc, 44 percent had improvement in PTA. Those patients initially responding to oral steroids had a better post perfusion response. Those perfused within four weeks of onset of SSNHL had a better response; those treated after a > four week delay still exhibited positive responses. Of the responders to perfusion, 11 patients demonstrated an average 43 dB improvement in pure tone average, and 17 patients had a mean 51 percent improvement in discrimination.

Conclusions: In patients who fail oral steroid therapy, steroid perfusion remains a secondary option. For those patients in whom oral steroids are contraindicated, steroid perfusion is a viable alternative. The researchers contend that the MicroWickTM delivers a high concentration to the round window, facilitating perfusion into the inner ear fluids. Not only does transtympanic administration of steroids result in superior perilymph levels within an hour of administration, it helps to minimize systemic absorption.

Patients that had an initial response to oral steroids had the greatest response to transtympanic steroid therapy, with a statistically significant increase in pure tone average. Of those patients who responded to treatment, the mean change in PTA was 43 dB.

Steroid perfusion of the inner ear via the MicroWickTM appears to improve hearing in some patients with SSNHL. A low concentration of dexamethasone (4 mg/cc) produces better hearing results with less chance of complications, especially when the patient is treated within a four-week period. Those who initially respond to oral steroids have a higher likelihood of responding to steroid perfusion of the inner ear. Overall, the treatment is recommended when oral steroids are not practical due to other health reasons, the patient refuses oral steroids, the patient has a partial response to oral steroids, and possibly in cases when oral steroids fail the patient.