Comments to authors

Introductory paragraph

The authors aimed to measure middle ear pressure improvement following eustachian tube (ET) dilation in patients with chronic ET dysfunction. This was accomplished by comparing pre- and post-operative tympanogram values by retrospective chart review. The authors state that their results indicated that postoperatively, Jerger tympanogram type improved significantly (p=0.04) and a statistically significant improvement in measured middle ear pressure (p=0.003) was observed. From the reviewer’s perspective, there is no proof of efficacy in this case series because of the lack of an internal control group using ET function as an outcome measure. Moreover, the limited longitudinal follow-up and small sample size are significant limitations of this study.

General comments: major vs. minor points

Major points

1. The information in this manuscript is consistent with the journal’s mission and is relevant to the readership.
2. Aims are stated in the background. The authors state that the primary outcome of the present study was middle ear pressure improvement following ET dilation in patients with chronic ET dysfunction. However, in the abstract, they state that the aim of this study was to objectively measure the success of eustachian tube balloon dilation. The meaning of “success” is vague and needs to be defined.
3. In terms of descriptive statistics, for “significant” findings, the authors did not describe effect size (e.g., odds ratio, relative risk, correlation coefficient) and did not discuss the clinical importance of their findings.
4. The authors did not account for uncertainty by providing a 95% confidence interval (CI) to give a range of values considered plausible for the target population.
5. The level of evidence is determined as level no. 4; Case series without an internal control group (reviews, uncontrolled cohort).
6. The authors mention that approval for this study was obtained from the Nova Scotia Health Authority Research Ethics Board. They also declare that they have no competing interests. However, they have not included a clear statement about funding bodies and have not declared that the funders did not influence the conclusion of the study.

Minor points

1. This manuscript is correctly labeled ‘original research’ because it is a before-and-after study despite its comparatively small case series.

Specific comments

Disclosures

1. This paper needs a clear statement regarding funding.

Abstract

1. Background; “The aim of our study is to objectively measure the success of Eustachian tube balloon dilation by comparing pre and post-operative middle ear pressures using tympanometric testing.” Here, it would be better if “success” were changed to “outcomes”.
2. Conclusion; “and produces significant improvement in tympanogram values up to 15 months post-operatively.” The conclusion in the abstract does not correspond with the conclusion in the main body of the text. The authors refer to “15 months” postoperative follow-up period in the abstract’s conclusion and “14 months” in the main text’s conclusion. Moreover, in the abstract’s conclusion, the authors refer to “significant” improvement in tympanogram scores but in the main text, the authors conclude that a “modest” improvement was produced.

Background

1. The literature review is verbose. I would like to recommend condensing the Background section. Please focus on (1) The immediate context and background of the study (not an extended review of literature, or textbook outline), (2) The gap, lacunae, or what is lacking/inconsistent in previous studies/ present knowledge or practice (which gives the reason for the study) supported by a limited number of references, (3) The aim or objective of the study (and underlying hypothesis if any).
2. Page 1. “Eustachian tube dysfunction is a common medical issue, occurring in at least 1% of the adult population.” Here, “1%” should be corrected to “0.9%” as mentioned in reference no. 1.
3. Page 1. “ET dysfunction can lead to impaired quality of life due to persistent sensation of ear fullness, ear pain, and inability to tolerate air travel or scuba diving.” This sentence requires a reference. Please see the following quote: “The symptoms are classic of dysfunction of the ET, such as fluctuating hearing, tinnitus characterized by popping and cracking sounds in the ear, occasional mild recurrent vertigo, and mild recurrent otalgia.” from ‘Eustachian tube: Structure, function, and role in Middle-Ear Disease, 2nd edition’ by Charles D. Bluestone in 2018.
4. Page 2. The authors introduced a few methods for treating ET dysfunction. However, they omitted ET catheterization which is the most important and necessary treatment of ET dysfunction. Transnasal catheterization of the ET with the classic metal cannula has been used to inflate the middle ear for more than a century. Although this technique has lost some of its popularity among the majority of today’s otolaryngologists, the valuable contribution of earlier researchers provides sufficient evidence to rationalize the application of ET catheterization even now. The eustachian tube catheter is identified by the U.S. Food and Drug Administration Code of Federal Regulations Title 21 (revised April 1, 2017), under section 874.4175 Nasopharyngeal catheter, which states, “A nasopharyngeal catheter is a device consisting of a bougie of filiform catheter that is intended for use in probing or dilating the Eustachian tube. This generic type of device includes Eustachian catheters.”
5. Most researchers incorrectly exclude vertigo from the list of possible symptoms caused by ET dysfunction. To introduce both ‘vertigo caused by ET dysfunction’ and ‘ET catheterization’, the authors may refer to the following article: ‘Vertigo due to obstruction of the eustachian tubes; a clinical study based on one hundred and thirty-five cases’ by F.W. Merica M.D. (April 11, 1942.) [ JAMA. 1942;118(15):1282-1284. doi:10.1001/jama.1942.02830150018006]

Methods

1. Page 2. “Patients were selected for ET balloon dilatation if they had long-standing Eustachian tube dysfunction (ETD) treated with multiple sets of tympanostomy tubes, and were interested in pursuing a longer-term solution.” Here, the criteria of long-standing ETD are unclear. The authors need to clarify the ranges for ‘long-standing’ and ‘longer-term’.
2. Page 3. “Success was defined by an improvement in type of tympanogram: Type B or C to Type A, or Type B to Type C.” Here, the authors explain “Type C tympanogram” as a success of improvement” (from Type B), when “Type C” is not ‘within normal limit.’ It is necessary for the authors to describe what change of tympanogram values are considered ‘effective’, or ‘successful’ or ‘a demonstration of change’.

Results

1. I am unsure whether the statistics are sound. Please consult a biostatistician.
2. I am unable to comment on the Kaplan Meier curve plot as this is beyond the scope of my statistical knowledge.

Discussion

1. Strengths; The authors discussed the strengths and limitations of their study.

Conclusion

1. Page 5. “Eustachian tube balloon dilation produces ‘modest’ improvement in tympanogram scores up to ‘14’ months post-operatively.” This statement is not consistent with the evidence generated by the study. In both the Abstract and Results sections, the authors state that ET balloon dilation produces “significant” improvement in tympanogram values for up to 15 months post-operatively.

References

1. Reference no. 1 is from 1992 which is outdated. Nevertheless, it is useful.
2. As a foundational article, I suggest the following article: ‘Eustachian tube dysfunction: consensus statement on definition, types, clinical presentation and diagnosis’ A.G.M. Schilder, M.F. Bhutta, C.C. Butler, C. Holy, L.H. Levine, K.J. Kvaerner, G. Norman, R.J. Pennings, D. Poe, J.T. Silvola, H. Sudhoff, V.J. Lund (First published: 07 September 2015) [https://doi.org/10.1111/coa.12475]

Concluding paragraph

1. This paper reports exciting results but needs a few amendments.