DISCUSSION
Adenoidectomy has been the hallmark treatment in children suffering from otitis media with effusion since past many decades(1). There have been various expansion in research in the field of adenoidectomy and its outcomes, but sparse literature is available studying the outcome of adenoidectomy on middle ear functions. There is a paucity of literature available in testing middle ear functions post adenoidectomy and thus we conducted this study to critically appraise the results comparing the middle ear functions post conventional and endoscopic microdebrider assisted adenoidectomy.
Adenoid hypertrophy in children is the most common cause of eustachian tube blockage leading to fluid collection in the middle ear i.e otitis media with effusion leading to derangement of middle ear functions and various modalities of treatment have been in use since time immemorial in treating it.
In a recent Cochrane review by Van den Aardweg et al. [2] they reported that there is a significant benefit of adenoidectomy in the resolution of middle ear effusion in children with OME, but the benefit to hearing is small and the effects on changes in the tympanic membrane are unknown.
Coyle et al (3) also concluded in his study that adenoidectomy is a useful procedure for correction of medically resistant chronic OME and should be considered as the first line procedure when surgical treatment is chosen.
However the dissatisfaction over the widely used conventional curettage adenoidectomy since many years has prompted the use of endoscopic assisted powered shaver adenoidectomy with microbebrider in recent times.
Setliff and parsons introduced microdebrider use in nasal surgery in 1994. The unique design equipped with powered shaver, continuous irrigation device and suction port makes this instrument superior in clearing tissue from the field under direct vision with minimal complications.
Stainslaw et al(4) found that tissue dissection was more complete and of appropriate depth with a microdebrider as compared to the depth being too shallow in conventional method leaving behind significant tissue post procedure.
Various studies conducted by Murray et al. Rodigruez et al. Costantini et al. proved that endoscopic assisted powered shaver adenoidectomy is more effective in cleaning adenoid tissue under direct visualization; thus requiring less operating time, causing less blood loss, and providing more complete removal of the adenoid tissue and less post-operative pain. ( 5, 6 )
By using endoscopic assisted adenoidectomy with a microdebrider, the adenoid remnants along the superior portion of the nasopharynx, the choanae and the peritubal region, can be clearly visualized easily and thus removed completely. Moreover, the likelihood of damage to the Eustachian tube and/or to the pharyngeal muscles is reduced, thereby reducing the post-operative scarring. Hemorrhage can also be effectively controlled by direct identification of the bleeding points (7, 8).
Tympanometry has been a novel approach in studying the function of middle ear including middle ear pressures, volume and compliance. This study also states the use of these modalities in testing middle ear function. According to Renvall et al (9) stapedial reflex is considered too sensitive to be used as a screening test in the diagnosis of OME thus we excluded it from our criteria.
The patients included in our study showed a significant improvement in hearing thresholds post endoscopic microdebrider assisted adenoidectomy resulting in only 4 % patients with abnormal hearing threshold in comparison to the conventional method being 24 % ( p value 0.004 ). There was not much statistical difference seen in the peak compliance comparing the two groups but however the peak middle pressures were found to be significantly improved post surgery in children undergoing endoscopic microdebrider assisted adenoidectomy compared to conventional method .
The initial preoperative tympanograms of patients presenting showed B and C type of curves which were found to have significantly improved (normal A type) in children who underwent endoscopic microdebrider assisted adenoidectomy in our study.
Similar studies have been conducted in evaluating the conversion rates of tympanograms by Sarafoleanu et al. in 2010 which revealed a type-B curve in 41% of cases, compared with type-A in 22% and type-C curve in 37% of cases. Re-evaluation performed after 4 weeks of surgery (classical adenoidectomy) in their study also documented very good relief of disease on subjective as well as objective evaluation (10). Another study by Mori et al. in 1980 also observed a type-B tympanogram in 50% of cases preoperatively with post-operative conversion to type-A. (11)
Thus the clinical outcome and improvement in middle ear functions was found to have improved drastically in the children who underwent microdebrider assisted adenoidectomy as compared to the conventional method .