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Steroids for Treatment of Sudden Hearing Loss

ALEXANDRIA, VA -- September 19, 2006 -- Sudden sensorineural hearing loss (SSNHL) can occur suddenly in one ear, and generally within three days, cause a 30+ decibel (dB) hearing loss at three consecutive frequencies. The cause for this disorder is unclear, but research has indicated that viral infection, vascular compromise, and immunologic diseases could be key reasons for this hearing disorder.

A few celebrities have reported experiencing sudden hearing loss. In recent years, radio personality Rush Limbaugh and Rapper Foxy Brown both reported experiencing sudden hearing loss.

Treatment of SSNHL remains controversial. Different approaches such as steroids, vasodilator, antiviral agents, diuretics, and low-salt diets have been suggested. Nevertheless, spontaneous recovery rate without treatment ranges from 30 to 60%, most resolving within two weeks after onset.

As a result of its anti-inflammatory effect, high-dosage systemic steroid therapy is currently the mainstay of the treatment for SSNHL. Despite oral or intravenous steroid therapy for two weeks, approximately 30% to 50% of patients show no response. Animal studies have found that intratympanic steroid injections, introducing steroids through the tympanic membrane, results in reduced systemic steroid toxicity and higher perilymph steroid level selectively.

Past research has focused on use of these injections as a secondary-line therapy in SSNHL refractory cases. Other clinicians promote its use as first-line therapy in all SSNHL cases. Nevertheless, few controlled studies have been published comparing the results between intratympanic steroid treatment and other approaches.

A New Study
A new study evaluates the effect of intratympanic steroid injections in patients with SSNHL after failure to respond to systemic steroid treatment. Patients who refused this regimen were used as controls in this research. The authors of "Intratympanic Steroids for Treatment of Sudden Hearing Loss After Failure of Intravenous Therapy," are Guillermo Plaza MD PhD, from the Otolaryngology Department, Hospital de Fuenlabrada, and Carlos Herráiz MD PhD, with the Otolaryngology Department, Fundación Hospital Alcorcón, both in Madrid, Spain. Their findings are being presented at the 110th Annual Meeting & OTO EXPO of the American Academy of Otolaryngology—Head and Neck Surgery Foundation, being held September 17-20, 2006, at the Metro Toronto Convention Centre, Toronto, Canada.

Methodology
From January 2000 to December 2004, a non-randomized prospective clinical trial was conducted for 50 patients diagnosed with unilateral (affecting one ear) SSNHL due to unknown reasons. All patients underwent a complete clinical history, physical and audiologic examination, syphilis serology, autoimmune antibody test, and magnetic resonance imaging, producing negative results. Patients were excluded if SSNHL might be caused by trauma, Meniere's disease, tumors, or autoimmune diseases. Also, those cases that were treated later than 30 days after onset of SSNHL were also excluded.

All cases were intravenously treated, with 120 mg of methlyprednisolone per day, for five days. Rest, stop smoking, and low-salt diet were also advised. Although antiviral agents or diuretic were not included in the standard protocol, intravenous pentoxyphylline was sometimes used with the steroids. After five days of intravenous treatment, pure-tone audiometry and speech discrimination tests (SDT) were performed. Pure-tone average (PTA) was calculated as the average of the thresholds at 0.5, 1, 2 and 3 kHz.

After this period of intravenous therapy, failures (18 cases) were offered intratympanic steroid treatment. Nine patients refused, and were treated with oral steroid tapering during 15 days. They were considered as internal controls, whereas the other nine patients received three weekly intratympanic injections of methylprednisolone. Intratympanic steroid treatment was started 5-7 days after onset of conservative treatment.

Pure-tone audiometry and SDT were performed just before each injection, and one week, one month and six months after the last injection. In the control group that refused intratympanic treatment, pure-tone audiometry and SDT were performed one month and six months after onset. Recovery of hearing was defined as improvement of more than 15 dBs in PTA or an increase in speech discrimination score (SDS) of 15% or more. Threshold differences were also analyzed at each frequency in PTA. Side effects and subjective symptoms were also recorded.

Results
The average age of the study patients the patients was 52.0 ± 15.8 years. Male to female ratio was 22:28. Time of onset to start of intravenous therapy averaged 5.6 ± 7.7 days. Tinnitus was present in 58% of the cases, whereas vertigo presented in 24%. Thirty-2% of cases had hypertension, and 14% had diabetes mellitus. Initial hearing impairment was average 76.5 ± 21.2 dB PTA, and 38 ± 12%.

After standard intravenous treatment, hearing improvement of 15 dB or more in PTA was noted in 32 cases (64%). In these responders, the mean improvement of the value of PTAs before and after intravenous treatment was 35.0 ± 16.56 dB. For the 18 failures, nine patients accepted intratympanic treatment, and were enrolled in the treatment group, whereas the other nine served as internal controls. There were no statistical differences in age, sex ratio, time of onset to therapy, presence of vertigo and tinnitus, initial hearing level, and final hearing level after intravenous treatment between the two groups.

In the treatment group, hearing improvement of 15 dB or more in PTA was noted in five cases (55%). The mean value of PTA before and one month after intratympanic injections treatment were 73.3 ± 20.8 dB and 40.2 ± 17.3 dB, respectively, so that an improvement in mean PTA after intratympanic treatment was 33 ± 12.55 dB.

Conclusions
This non-randomized prospective clinical trial shows that intratympanic methylprednisolone significantly improved the outcome of SSNHL after intravenous steroid treatment. As previously reported, intratympanic steroids actually are an effective and safe therapy in SSNHL cases that are refractory to standard treatment.

The researchers suggest that the number of injections, the type of steroid, and the most adequate doses must be defined in randomized prospective clinical trials. Also, these randomized studies will allow establishing an evidence-based treatment for idiopathic SSNHL. These trials should also evaluate outcomes after initial therapy for SSNHL comparing steroids that are administrated systemically or by intratympanic injections.


SOURCE: American Academy of Otolaryngology Head and Neck Surgery

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