Evidence lacking to guide treatment for sudden hearing
loss
Editor: Well, this is certainly a surprise! We've heard for years that
steroids are the treatment of choice for sudden hearing loss. Now some
scientists are claiming that there's really no good evidence that steroids
are effective at all!
~~~~~~~~~~~~~~~~~
June 2007
Although steroids are the most widely used treatment for sudden hearing
loss, little scientific evidence supports their use or that of any other
therapies for this condition, according to a systematic review and
meta-analysis both published in the June issue of Archives of
Otolaryngology-Head & Neck Surgery, one of the JAMA/Archives journals.
Sudden sensorineural hearing loss is acute hearing impairment involving
loss of at least 30 decibels of hearing over at least three test
frequencies occurring within three days, according to background
information in the article. The condition affects about five to 20 of
every 100,000 individuals yearly. Treatment varies widely and includes
antiviral medications, vitamins, minerals, herbs, hyperbaric oxygen and
agents that dilute the blood. "In addition, some otolaryngologists choose
not to treat sudden sensorineural hearing loss at all, citing spontaneous
recovery rates of 32 percent to 70 percent," the authors write. "However,
the most common approach to treatment of sudden sensorineural hearing loss
in North America is with systemic steroids, which has been deemed by some
authors to be the gold standard of treatment."
Anne Elizabeth Conlin, B.A. & Sc., M.D., of the University of Ottawa,
Ontario, and Lorne S. Parnes, M.D., F.R.C.S.C., of the University of
Western Ontario, London, Canada, searched for all randomized clinical
trials evaluating treatments for sudden hearing loss published between
1966 and 2006.
For the systematic review, 21 trials were identified and evaluated, all
of which used measures from hearing tests to define treatment outcomes.
"Only two studies used identical criteria to define sudden sensorineural
hearing loss," the authors write. "The method of randomization was
described in two studies. Validity scores ranged from two to eight (of
nine). Positive results were reported favoring systemic steroids,
intratympanic [inside the inner ear] steroids, batroxobin, magnesium,
vitamin E and hyperbaric oxygen, although there were serious limitations
in each study with a positive finding."
This includes the article cited as the landmark study for the use of
steroids, which was not described as a randomized trial and therefore may
have produced exaggerated treatment effects, the authors note. The authors
suggest that this study also used inconsistent doses of steroids and did
not measure outcomes at the same time for all participants. "The study
therefore does not inform the otolaryngologist of what dose of steroids to
use, nor at what time after treatment to expect improvement," the authors
write.
"To our knowledge, no valid randomized controlled trial exists to
determine effective treatment of sudden sensorineural hearing loss," they
conclude. "Systemic steroids cannot be considered the gold standard of
treatment of sudden sensorineural hearing loss, given the severe
limitations of the landmark study supporting their use."
For the meta-analysis, data from the same trials were combined when
they covered the same therapies. Five trials were eligible for the
analysis. "Pooling of data from two randomized clinical trials that
compared steroids with placebo showed no difference between treatment
groups," the authors write. "No difference existed between patients
treated with antiviral plus steroid therapy vs. placebo plus steroid
therapy. Finally, there was no difference between subjects treated with
steroids vs. subjects treated with any other active treatment."
Treating sudden hearing loss is difficult because its cause is often
unknown, the authors note. However, it is still important to identify the
therapy that most benefits the patient. "At present, sudden sensorineural
hearing loss remains a medical emergency without a scientific
understanding of its cause or a rational approach to its treatment," they
conclude.
