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Reply to the Letter to the Editor

Intratympanic Steroid Injection for Bell's Palsy

Some Issues Highlighted

Chung, Jae Ho M.D.; Cho, Seok Hyun M.D.

Author Information
doi: 10.1097/MAO.0000000000000844
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In Reply: We appreciate your interest in our study of intratympanic injection in Bell's palsy and we will answer for the issues of which Dr Annabelle C. Leong has pointed out. We understand the concerning about statistical power. This investigation was designed as a pilot study to explore the potential effect of intratympanic steroid injection before the large-scale clinical study. The sample size of over than 12 per group was determined based on the article discussing rule of thumb for the determination of sample size in the pilot study (1). The patients were enrolled until the number of subjects who completed the trial was over 12 in each group. According to our results, the recovery rates of the test and control groups were not significantly different. However, we found that the intratympanic steroid injection might speed up the recovery of facial palsy. Although we have tested the similarity between test and control group, the placebo effect might influence the results. We will consider another version of an analysis using propensity score matching to reduce biases in control group selection in the future.

Administration time of steroid could be an important confounding factor. Because patients did not visit the clinic at the onset of facial palsy, the gap between onset and treatment might obscure the results. In this study, intratympanic steroid therapy started with oral steroid at the initial presentation and there was no significant difference in the duration between groups. Therefore, we believe that our study will be safe in this issue of the starting time of treatment.

Number needed to treat (NNT) is the number of patients we might need to treat to prevent one additional bad outcome (nonrecovery in this article). Accordingly, 10 patients with Bell's palsy would need to be treated with oral and intratympanic steroid therapy to prevent one additional patient of permanent facial palsy. However, the primary outcome of this study did not show any significance in regarding “complete recovery,” those values of NNT were not significant. We have presented the value of NNT referentially according to the advice of peer-reviewers.

Because intratympanic drug can leak out through the Eustachian tube with swallowing activities, it is generally recommended to avoid swallowing after intratympanic injection. A recent review article discussed that “after intratympanic injection, patients usually instructed postinjection to keep their heads still and turned to the opposite side for 20 to 45 minutes, and to refrain from swallowing in that time. The above measures may serve as a useful guide for clinicians performing intratympanic steroid injections” (2). However, it is difficult to suppress a swallowing for half an hour, patients usually spit out their saliva. So, we gave them handkerchief or tissues to wipe the saliva on perioral area.

We hope that those answers are helpful. Thank you for your interests in our study once again.


1. Julious SA. Sample size of 12 per group rule of thumb for a pilot study. Pharmaceut Statist 2005; 4:287–291.
2. Ng JH, Ho RC, Cheong C, et al. Intratympanic steroids as a salvage treatment for sudden sensorineural hearing loss? A meta-analysis. Eur Arch Otorhinolaryngol 2015; 272:2777–2782.
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