Discussion

This is the first study to investigate the current practice and opinions of the UK ENT consultant body on Eustachian tube balloon dilatation. Current National Institute for Health and Care Excellence (NICE) UK guidelines regarding Eustachian tube balloon dilatation note a lack of existing high-quality evidence regarding the efficacy and safety of the procedure, and recommend its application for research purposes only.⁶

In our survey, insufficient evidence of efficacy was the most cited reason for not performing the procedure. Similarly, a US-based study by Micucci et al.^{Reference Micucci, Keschner and Liang7} highlighted the need for higher level studies to ascertain the role of Eustachian tube balloon dilatation in the treatment of Eustachian tube dysfunction. Yet uptake of the procedure in the USA has been greater than in the UK, with 49.7 per cent (n = 143) of US consultants surveyed by Micucci et al. reported to be practising Eustachian tube balloon dilatation, compared to 23 per cent (n = 31) of UK consultants in our current study.^{Reference Micucci, Keschner and Liang7} The approval of the procedure by the Food and Drug Administration for the treatment of persistent Eustachian tube dysfunction may explain the discrepancy in uptake and experience levels between US and UK ENT surgeons, with only 23 per cent (n = 33) of US consultants practising Eustachian tube balloon dilatation having performed less than five procedures, compared to 67 per cent (n = 24) in the UK.^{Reference Micucci, Keschner and Liang7}

The majority (83 per cent) of respondents to our survey who currently practise Eustachian tube balloon dilatation had less than two years’ experience. However, over 1 in 10 respondents (10 per cent) expressed an intention to start performing the procedure, suggesting that it is gaining interest in the UK. The survey found an even split of ENT surgeons performing Eustachian tube balloon dilatation almost exclusively (in more than 95 per cent of cases) in the private sector and those performing it almost exclusively in their NHS practice (n = 13, 36 per cent in each category), with the remainder of those performing the procedure in both the NHS and privately in equal proportion. This may be partly accounted for by each responding surgeon's experience of the procedure to date, and whether they are currently involved in Eustachian tube balloon dilatation research activity.

Pre-operative planning and investigation used in the context of Eustachian tube balloon dilatation has been a subject of debate. Abded-Aziz et al. showed that pre-operative high-resolution CT temporal bone scans were not able to predict intra-operative difficulties or post-operative complications of the procedure.^{Reference Abdel-Aziz, Schröder, Lehmann, Gehl, Ebmeyer and Sudhoff8} Most of the UK consultants surveyed request pre-operative symptom questionnaires and tympanometry (or tubomanometry), with only 28 per cent requesting a pre-operative CT scan. The most common pre-operative investigation performed in this cohort was tympanometry, followed by patient-reported questionnaires, in line with the 2015 consensus statement on Eustachian tube dysfunction diagnosis.^{Reference Schilder, Bhutta, Butler, Holy, Levine and Kvaerner1} Additional investigations reported in the literature include pure tone audiometry^{Reference Abdel-Aziz, Schröder, Lehmann, Gehl, Ebmeyer and Sudhoff8} and ‘successful Valsalva manoeuvre’.^{Reference Poe, Anand, Dean, Roberts, Stolovitzky and Hoffmann9,Reference Meyer, O'Malley, Schlosser, Soler, Cai and Hoy10}

The effective management of Eustachian tube dysfunction symptoms poses a clinical challenge. Randomised, controlled trials investigating the effects of decongestants and intranasal steroids in the management of Eustachian tube dysfunction have shown no statistically significant difference when compared to placebo.^{Reference Shapiro, Bierman, Furukawa, Pierson, Berman and Donaldson11,Reference Gluth, McDonald, Weaver, Bauch, Beatty and Orvidas12} Randomised, controlled trials investigating the use of autoinflation devices in children have shown statistically significant improvements in tympanograms and ear-related symptoms compared to controls, yet evidence for their use in adult populations is lacking.^{Reference Williamson, Vennik, Harnden, Voysey, Perera and Kelly13}

Surgical treatment for Eustachian tube dysfunction includes the use of ventilation tubes, and methods of Eustachian tube dilatation such as balloon dilatation and laser. Early results from published studies have suggested that Eustachian tube balloon dilatation is effective in treating symptoms of Eustachian tube dysfunction.^{Reference Tisch, Maier and Sudhoff4,Reference Schmitt, Akkari, Mura, Mondain, Uziel and Venail14–Reference Schröder, Lehmann, Ebmeyer, Upile and Sudhoff16} However, these are mostly retrospective, single-centre case series in small sample populations, with limited long-term follow up. Randomised, controlled trials comparing Eustachian tube balloon dilatation to medical therapy^{Reference Poe, Anand, Dean, Roberts, Stolovitzky and Hoffmann9,Reference Meyer, O'Malley, Schlosser, Soler, Cai and Hoy10} have also been encouraging, yet it is relevant to note that there is a lack of evidence to support the efficacy of medical management of Eustachian tube dysfunction. A meta-analysis of prospective and retrospective studies comparing Eustachian tube balloon dilatation and laser Eustachian tuboplasty in Taiwan showed no inferiority of Eustachian tube balloon dilatation results, but also noted the need for further studies to assess its efficacy.^{Reference Wang, Lin, Shih, Chung, Wang and Tsou17}

A recent retrospective study of 60 adults with chronic secretory otitis media showed that a combination of Eustachian tube balloon dilatation and ventilation tubes resulted in significantly better Eustachian tube function scores (based on a Eustachian tube dysfunction questionnaire, an effective Valsalva manoeuvre and tympanometry) compared to ventilation tubes alone.^{Reference Li, Chen, Yin and Zeng18} Patient satisfaction ratings at 24 months following the procedure were 81 per cent, compared to 70 per cent in the ventilation tube group. Six patients in the combination group and 10 patients in the ventilation tube group reported no improvement.^{Reference Li, Chen, Yin and Zeng18}

While results from the abovementioned studies are encouraging, high-level randomised, controlled studies comparing the efficacy of Eustachian tube balloon dilatation alone with established treatments such as ventilation tubes are lacking.^{Reference Schröder, Lehmann, Ebmeyer, Upile and Sudhoff16} A systematic review by Huisman et al., conducted in 2017, similarly concluded that Eustachian tube balloon dilatation may be a helpful treatment for Eustachian tube dysfunction, but stated that the literature is still heterogeneous with a lack of placebo-controlled trials, making it difficult to draw a conclusion for best practice.^{Reference Huisman, Verdam, Stegeman and de Ru19} Our survey findings showed that uptake of Eustachian tube balloon dilatation in the UK remains limited because of insufficient evidence of efficacy and long-term outcomes.

While Eustachian tube balloon dilatation has mainly been reported as a treatment for obstructive Eustachian tube dysfunction,^{Reference Dalchow, Loewenthal, Kappo, Jenckel, Loerincz and Knecht20} it has also been suggested as a potential treatment for adhesive otitis media with effusion, and as an adjunct to tympanomastoid surgery.^{Reference Bowles, Agrawal and Salam21} The indications reported for performing the procedure in UK practice were variable. Treatment of Eustachian tube dysfunction symptoms was the most common indication, followed by otitis media with effusion or obstructive Eustachian tube dysfunction, retraction pockets, and baro-challenge-induced Eustachian tube dysfunction symptoms (i.e. symptoms caused by changes in atmospheric pressure such as when flying or diving).

Several databases exist in the US ENT community, notably those concerning cancer outcomes, as well as an international database of middle-ear operations (Common Otology Database), which facilitates participation in audit and research.^{Reference Van Rompaey, Yung and Van de Heyning22} The variation in practice regarding indications for Eustachian tube balloon dilatation found in our survey is also reported in other studies. The application of Eustachian tube balloon dilatation to different pathologies, for which outcome measures may vary, suggests that a national or international database, to record and promote transparency and learning, may be beneficial in terms of developing evidence-based patient selection criteria and outcome measures. Consultants responding to our survey supported the proposal of a national database of Eustachian tube balloon dilatation procedures, through which to combine results, promote audit and research, and develop the evidence base.

The main limitation of this study is the low response rate of 31.3 per cent, although this does compare favourably with the response rate reported in a similar web-based questionnaire study, of 9.1 per cent.^{Reference Micucci, Keschner and Liang7} A further limitation is that the survey is limited to the ENT-UK membership and does not include the practice of those UK ENT consultants who are not members. The retrospective nature of this survey-based study subjects it to recall bias.