Antiviral drugs for sudden hearing loss (without known cause)

Idiopathic sudden sensorineural hearing loss (ISSHL) is sudden loss of hearing where clinical assessment has failed to reveal a cause. Patients may also suffer from additional symptoms such as tinnitus (a background ringing noise), together with dizziness and a sensation of fullness in the ear. Prompt investigation is essential to identify and treat the hearing impairment. In a large proportion of patients, however, no cause can be found.

Antiviral drugs are often used, usually in conjunction with steroids, to treat sudden hearing loss of unknown cause, based on the theory that the deafness is caused by a viral infection. We searched for randomised controlled trials (RCTs) which compared treatment of sudden hearing loss with antiviral drugs (either alone or in combination with another treatment) with placebo or no antiviral drug, in patients of any age. We found four RCTs (257 patients). The overall risk of bias in the studies was low. All four trials compared steroid treatment (either alone or plus a placebo drug) with steroid plus antiviral treatment. None of the trials found a statistically significant difference between groups. No trial documented any serious adverse effects related to using antiviral treatments. One study reported slight to moderate nausea equally in the acyclovir and placebo groups (one patient in each), both attributable to the steroid treatment. Another reported insomnia, nervousness and weight gain with valacyclovir (number not specified).

The effectiveness of antiviral drugs in the treatment of sudden hearing loss of unknown origin is questionable. Certainly, this review of the clinical trials did not identify any substantial evidence to support their use. Further research is required with larger patient numbers and standardised inclusion criteria, antiviral regimes and outcome measures.

Authors' conclusions: 

There is currently no evidence to support the use of antiviral drugs in the treatment of ISSHL. The four trials included in this review were, however, small and with a low risk of bias. Further randomised controlled trials with larger patient populations, using standardised inclusion criteria, antiviral regimes and outcome measures, are needed in order for adequate meta-analysis to be performed to reach definitive conclusions. A uniform definition of ISSHL should also be established, together with what constitutes adequate recovery.

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Background: 

Idiopathic sudden sensorineural hearing loss (ISSHL) is characterised by sudden loss of hearing of cochlear or retro-cochlear origin without an identifiable cause. Antivirals are commonly prescribed, but there is no consensus on the treatment regimen or their effectiveness.

Objectives: 

To determine the effectiveness and side effect profile of antivirals in the treatment of ISSHL.

Search strategy: 

We systematically searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 5), PubMed, EMBASE, CINAHL and other databases to 12 June 2012. We also scanned the reference lists of identified studies for further trials.

Selection criteria: 

Randomised controlled trials comparing different antivirals versus placebo (both with or without other treatment).

Data collection and analysis: 

Two authors independently extracted data, met to resolve disagreements and contacted study authors for further information. We assessed study risk of bias independently. We considered meta-analysis inappropriate and ultimately not possible due to differing treatment protocols of varying dose and duration, together with differing inclusion criteria and outcome measures between studies. The results of each study are reported individually.

Main results: 

We included four randomised trials (257 participants). The overall risk of bias in the included studies was low. Two trials compared the addition of intravenous acyclovir to a steroid (prednisolone). One included 43 participants, the other 70 patients. Neither demonstrated any hearing improvement with ISSHL. Another (84 patients) did not show any statistically significant difference between groups with the addition of valacyclovir to prednisolone (compared to steroid plus placebo) with respect to change in pure-tone audiogram. Comparing the addition of intravenous acyclovir to hydrocortisone with hydrocortisone alone, the final trial did not show any statistically significant difference between groups (60 patients). No trial documented any serious adverse effects related to the use of antiviral treatment. One study reported slight to moderate nausea equally in the acyclovir and placebo groups (one patient in each). Another reported insomnia, nervousness and weight gain with valacyclovir (number not specified). Even though no meta-analysis was possible, evidence from the four RCTs has demonstrated no statistically significant advantage in the use of antivirals in the treatment of ISSHL.

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