Analysis of 60 patients after tympanotomy and sealing of the round window membrane after acute unilateral sensorineural hearing loss

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To the Editor:

I read with great interest the article titled “Analysis of 60 patients after tympanotomy and sealing of the round window membrane after acute unilateral sensorineural hearing loss” by Gedlicka et al [1]. Sudden sensorineural hearing loss (SSNHL) is not fatal, but patient's psychologic stress and social disability may be significant if not recovered. Although the spontaneous recovery rate is 30% to 60% and the recovery rate can be more increased when treated [1], [2], the novel treatment option that can raise the recovery rate is still needed. Therefore, the authors' trial gave valuable clinical data to the readers; but I raise some questions in their article.

The first issue is the ethical aspect of the tympanotomy with sealing of the round window, which the authors performed to patients with 3 types of SSNHL during 8 years. Because they did not state the surgical indications or inclusion/exclusion criteria of their study, the readers did not know why the tympanotomy was performed in patients with idiopathic SSNHL. Although the authors reviewed the history of tympanotomy with sealing of round window membrane in cases of perilymphatic fistula (PLF) in the introduction section, they did not suggest the rationale of the invasive surgery for patients whose PLF was not diagnosed. Most references cited in their article are on cases of PLF. In addition, they are old-fashioned and not evidence based.

The second issue is the absence of statistical analysis of their data. I doubt how the authors deducted the conclusions without statistical process. Maybe for that reason, the authors misinterpreted the data of Table 3 in their article. They stated that PLF group might show a better hearing outcome in barotraumas cases, but not in idiopathic or acoustic trauma cases. When I reorganized and analyzed their data of Table 3, I found that there was no significant difference of improvement rate according to presence/absence of PLF in 3 types of acute hearing loss (Table 1; χ² test, P = .656 in barotrauma, P = 1.000 in idiopathic hearing loss, and P = 1.000 in acoustic trauma).

Table 1. Improvement rate according to presence of a perilymphatic leakage

The authors demonstrated that the hearing level improved 63.1% in patients with barotrauma, 50% in patients with acoustic trauma, and 70.3% in patients with idiopathic hearing loss after tympanotomy with sealing of the round window. From these results, they concluded that it is recommended in cases of acute hearing loss after failure of conservative treatment. However, I think that their results were too weak to support their conclusions. First, their article failed to show any statistical difference of the recovery rate. Even in the cases of barotrauma, which is one of the most frequent indications of the tympanotomy, the recovery rate was 63.2%, compared with 80% in its counterpart control (χ² test, P = .631). The recovery rate was 50% in cases of acoustic trauma as well as in its counterpart control (χ² test, P = 1.000). The authors failed to show the superiority of their surgical treatment to established medical treatment. The second weak point is that they did not compare the results of idiopathic cases with those of its counterpart control. Because idiopathic one is the most common cause of “acute unilateral sensorineural hearing loss” and the authors did not analyze the idiopathic cases in case-control fashion, their results ought not to have been generalized to “acute unilateral sensorineural hearing loss.” The third weak point is the time when the tympanotomy was performed in the cases of idiopathic SSNHL and acoustic trauma. The authors performed the tympanotomy within 2 weeks (range, 3-60 days) after primary medical therapy and recommended that the tympanotomy should be delayed 10 days. However, I think that their tympanotomy timing after sudden hearing loss may be too fast in most cases of idiopathic SSNHL and acoustic trauma. Yeo et al [2] reported the delayed recovery after conservative medical therapy for idiopathic SSNHL. They reported that a delayed recovery after a 10-day course of conservative medical therapy occurred in 45.5% of patients who recovered over 3 months of follow-up. Therefore, I think that their recovery rate may be overestimated by adding otherwise recovered patients.

As discussed in the most recent article [3] that showed the efficacy of exploratory tympanotomy after sudden hearing loss, the only argument is the determination of a more likely pathology (hidden PLF vs idiopathic); and the only problem is low diagnosis rate of PLF. Maier et al [3] admitted that tympanotomy is indeed beneficial for patients with PLF. Their results should not be interpreted too broadly; tympanotomy may be beneficial only for patients with PLF as a cause of SSNHL, but not for all patients complaining of “acute unilateral sensorineural hearing loss.”

Otologists should make enough effort to rule out possible surgically correctable causes including PLF using many advanced diagnostic tools including imaging modalities. I think that exploratory tympanotomy should be performed in selected cases in which PLF is strongly suspicious. In this aspect, the authors' article has its own value; some patients who have a hidden PLF as a cause of SSNHL can be recovered by the exploratory tympanotomy. I worry that the readers might misunderstand the tympanotomy with sealing of the round window membrane as one of the principal treatment options for acute unilateral sensorineural hearing loss.

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References 

1. Gedlicka C, Formanek M, Ehrenberger K. Analysis of 60 patients after tympanotomy and sealing of the round window membrane after acute unilateral sensorineural hearing loss. Am J Otolaryngol. 2009;30:157–161
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2. Yeo SW, Lee DH, Jun BC, et al. Hearing outcome of sudden sensorineural hearing loss: long-term follow-up. Otolaryngol Head Neck Surg. 2007;136:221–224
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3. Maier W, Fradis M, Kimpel S, et al. Results of exploratory tympanotomy following sudden unilateral deafness and its effects on hearing restoration. Ear Nose Throat J. 2008;87:438–451
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