|Year : 2019 | Volume
| Issue : 1 | Page : 8-12
Atresioplasty for congenital aural atresia: A not so gloomy outlook
Naresh K Panda, Niveditha Damodaran, Gyanranjan Nayak, Roshan Kumar Verma
Department of Otolaryngology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
|Date of Web Publication||22-Aug-2019|
Prof. Naresh K Panda
Department of Otolaryngology, Postgraduate Institute of Medical Education and Research, Chandigarh
Source of Support: None, Conflict of Interest: None
Introduction: Congenital aural atresia (CAA) is an abnormality of the external ear along with hypoplasia or aplasia of the external auditory canal. Surgery of aural atresia is not only challenging but also has not been accepted by the surgeons. Many surgeons hesitate to undertake the repair due to inadequate hearing outcome and probability of stenosis of the new canal. This report presents the authors' experience of surgical treatment of aural atresia. Materials and Methods: A retrospective analysis of 31 cases of CAA operated during 2002–2018 in a tertiary referral center was performed. Unilateral atresia was more common. A combined anterior and posterior approach was employed in all the cases. Postoperatively, the patients were evaluated for hearing improvement and any sequelae of surgery at varying period up to 3 months. Results: Twenty-eight patients underwent surgery after exclusion of three patients due to diploic mastoids. A postoperative air-bone closure of >25 dB was achieved in 15 out of 28 patients. Five patients had air-bone closure of 15–25 dB. Only 8 patients did not have any hearing improvement. Meatal stenosis occurred in 2 patients. There were no other complications. Conclusions: Patients with CAA of moderate grade favorable radiological findings may benefit with surgery for better hearing outcomes. Bone-anchored hearing devices can be advised if the surgery is not feasible, particularly in high-grade atresia and unfavorable radiology.
Keywords: Aural atresia, hearing outcomes, surgery
|How to cite this article:|
Panda NK, Damodaran N, Nayak G, Verma RK. Atresioplasty for congenital aural atresia: A not so gloomy outlook. Ann Indian Acad Otorhinolaryngol Head Neck Surg 2019;3:8-12
|How to cite this URL:|
Panda NK, Damodaran N, Nayak G, Verma RK. Atresioplasty for congenital aural atresia: A not so gloomy outlook. Ann Indian Acad Otorhinolaryngol Head Neck Surg [serial online] 2019 [cited 2019 Nov 16];3:8-12. Available from: http://www.aiaohns.in/text.asp?2019/3/1/8/265084
| Introduction|| |
Congenital aural atresia (CAA) is an abnormality of the external ear characterized by hypoplasia or aplasia of the external auditory canal (EAC). The incidence of CAA is 1 in 10,000–15,000 births. Up to 1%–3% of the cases occur concurrently with craniofacial syndromes. CAA has a predominance in unilateral cases, in a ratio of 3:1, and slightly more common on the right side. Bony atresia is more common than cartilaginous atresia. Bony atresia is usually associated with middle ear abnormalities. External-, middle-, and inner-ear develop independently and so the malformation of one can exist without any malformation in another. However, severe microtia usually correlates with a severe middle ear abnormality.
External ear forms earlier than the middle ear. Microtia and atresia basically imply an inadvertent arrest in development at any stage. EAC develops from ectoderm of the first branchial cleft which appears at 4 weeks of gestation. It extends medially toward the developing tympanic ring. Ossification of tympanic ring begins at 12 weeks of gestation. It forms the osseous portion of the auditory canal. Canalization of ectoderm starts at 28 weeks of gestation and progresses from medial-to-lateral direction. Failure of canalization leads to atresia. Separation of the mastoid from the mandible is usually complete at 28 weeks. In a patient with aural atresia, there is no mastoid growth. Mastoid growth principally affects the facial nerve position. Cremers et al. introduced the following classification of CAA.
- Grade 1: Tympanic membrane is present but hypoplastic. Tympanic bone is normal/hypoplastic. Various ossicular malformations were noted, but stapes is mobile
- Grade 2: An atretic plate is present. Tympanic bone is hypoplastic or absent. Abnormal course of facial nerve and tympanic cavity is normal
- Grade 3: Above abnormalities found with a severely hypoplastic tympanic cavity.
The degree of microtia also indicates an arrest in development and abnormalities of the middle ear. The grade of microtia serves as an indicator of middle ear development.
Surgery for aural atresia is not only challenging but also has not been accepted by the surgeons. Many surgeons hesitate to undertake the repair for mainly two reasons, namely inadequate hearing improvement and probability of stenosis of the neocanal. This report reviews the author's experience of treating aural atresia with surgical intervention.
| Materials and Methods|| |
A retrospective analysis of 31 cases of CAA operated during the years from 2002 to 2018 in a tertiary referral center was performed. All of them were either Type 2 or Type 3 according to the Cremer's classification. A computerized tomography in axial and coronal planes was done in all the cases. Patients with diploic mastoid air cells were excluded [Figure 1]. Unilateral cases were 20 in number, and there were 11 bilateral cases. Male:female ratio was 1.5:1. Unilateral atresia was more common than bilateral atresia. Computed tomography was done to assess the status of the ossicles. Bilateral atresia was taken for surgery at 5–6 years of age. Unilateral cases were operated at 15–17 years of age. In cases of bilateral atresia, atresioplasty followed pinna reconstruction by a plastic surgeon. Postoperatively, the patients were evaluated at 1 week, 4 weeks, and 12 weeks following surgery. Pure-tone audiometry (PTA) was performed at the end of 3 months to assess hearing improvement. The patients were evaluated for any sequelae of surgery during the follow-up.
In general, there are three possible approaches to be followed for CAA repair, namely anterior, posterior transmastoid approach, and combined anterior-posterior approach. The authors used the combined anterior and posterior approach.
Anterior approach described by Jahrsdoerfer is the most common approach, wherein a postauricular incision is made, and the subcutaneous tissue and periosteum are raised anteriorly up to the level of the glenoid fossa. The drilling is done based on the overlying remnants of the tympanic bone. If no tympanic bone is present, the drilling begins at the temporal line just posterior to the glenoid fossa. It is continued anteriorly and medially till the epitympanum is entered. The most commonly encountered anomaly in the middle ear is a fused malleo-incudal joint, termed as an ossicular mass.
The atretic bone is carefully removed thereby uncovering the ossicles, during which the facial nerve underlying the ossicular mass, must be protected with caution to avoid complications. Drilling is continued till the canal is about 10 mm in size, and ossicular chain reconstruction is performed. Temporalis fascia graft is used for the neotympanum. A groove is created with a 1 mm polishing burr for tucking in the temporalis fascia graft. Split-thickness graft is used to line the EAC. A wide meatoplasty is fashioned, and a large wick is inserted to stent the canal.
Posterior transmastoid approach
This approach is used in patients with a thick atretic plate. The orientation in such patients could be achieved with an initial posterior dissection up to the level of sinodural angle. Further exposure enables the surgeon to identify the level of lateral canal and ossicular mass. From here on, the approach is similar to that of the anterior approach.
The authors have used a combined anterior and posterior approach in the present study. The middle ear is approached through the atretic bone with a limited mastoid opening. The posterior wall of the glenoid fossa becomes the anterior wall of the new ear canal. The epitympanum is the first part of the middle ear encountered. The fused ossicles are identified. Majority of the times, the ossicular mass comprises fused malleus and incus with the short process of incus identifiable. It is not feasible to look for the stapes which could be rudimentary. The atretic bone is removed initially with small diamond or polishing burr, and the last part of the paper, thin atretic plate is removed with curette. The globular mass is separated from the stapes to avoid cochlear trauma. It is very important to determine the facial nerve course to avoid injury to the same. The senior author (NKP) believes in creating an inner sulcus for the temporalis graft which overlies the fused ossicular mass. The neocanal is lined by a split-thickness skin graft (0.008 inch) [Figure 2]. The skin graft is stabilized with Merocel wicks hydrated with antibiotic ear drops [Figure 3].
| Results|| |
Out of 31 patients, 3 had their surgery abandoned due to diploic mastoid air cells. Twenty-eight patients had successful surgery performed for hearing improvement. Successful hearing result was defined as postoperative AB gap closure of 25 dB or more. Twenty patients (71%) had hearing improvement. Of these, 15 patients (54%) had postoperative AB gap closure of 25 dB or more. Five patients had AB gap closure between 15 and 25 dB (18%). Eight patients had no hearing improvement [Table 1]. Rate of complications was also evaluated. Twenty-nine patients had a wide neocanal with well taken up graft [Figure 4]. There was no case of facial paralysis or postoperative disequilibrium. Two patients had meatal stenosis (7.1%). One patient underwent successful resurgery. One had restenosis [Figure 5].
| Discussion|| |
The first attempt to surgically correct aural atresia was by Thomson in 1843. After the efforts of Patee and Ombredanne, surgical repair of atresia began to be widely popularized. Later on, Shambaugh, 1967, recommended unilateral surgery only if the cochlear reserve allowed hearing to improve by 25 dB. Jahrsdoerfer, 1978, advocated the first large surgery series involving the anterior approach. Treatment is heavily reliant on the evaluation of CAA followed by surgical correction. Despite vast improvements in canaloplasty, meatoplasty, tympanoplasty, and ossiculoplasty, surgical correction of CAA remains an arduous task. The otologic surgeons are also averse to go ahead with atresioplasty due to adverse anatomy, facial nerve anomalies, and chances of cavity stenosis that occurs postoperatively.
The altered anatomy of the facial nerve and the middle ear allows little space for reconstruction, and problems in postoperative healing make it one of the most demanding surgeries in otology. The aim of surgery is to provide the patient with a clean, dry, epithelialized, and an infection-free wide meatus canal with serviceable hearing. It is important that atresioplasty procedures are done in hospitals with considerable amount of cases owing to the steep learning curve. Patel and Shelton concluded that a minimum operative experience of 32 and 48 ears is necessary to provide short-term and long-term improvement in hearing results. Furthermore, it is essential for the surgeon to have a fair knowledge of the normal anatomy and complications that may arise due to surgery.
Amongst other variables, middle ear aeration is the most crucial factor in determining better prognosis postoperatively It is imperative in the manner that a better middle ear anatomy correlates with better postoperative hearing. Other considerations of surgery include the caution of avoiding canaloplasty in certain situations. A computerized tomography of the temporal bone in axial and coronal plane ensures adequate evaluation of middle ear aeration, state of mastoid pneumatization, and presence or absence of the ossicles along with the position of the atretic plate. A computerized tomography scan also helps to note the presence of aberrant facial nerve, the situation in which surgery cannot be performed. A low tegmen, poorly pneumatized mastoid, and a constricted middle ear space may prevent surgical access to the ossicles/atretic plate, which ultimately results in poor outcomes. It further stresses the importance of surgical skills with the goal of creating a reliable ear canal and middle ear system that allows for normal hearing without the need of hearing aids.
As far as the surgical approach is concerned, most surgeons choose the anterior approach to avoid the mastoid cavity to avoid neocanal narrowing. Forty percent of patients with unilateral atresia are not surgical candidates as such as those with severe aplasia as in Treacher–Collins syndrome. The timing of surgery is very essential, commonly performed after the age of 6–7 years for bilateral atresia. This allows for microtia repair to be done at first. Canaloplasty can be done before microtia repair if medpor is used. Unilateral atresioplasty is usually deferred till 15–16 years of age to allow for involving the patient in the decision-making process. Unilateral atresioplasty helps in binaural stimulation and improved sound localization if performed in a child.
In this study, we compared the postoperative AB gap and the rate of complications with other comparable studies. It is worth commenting on the complication rates as we reflect on the not so gloomy outcome of a dedicated surgical management through atresioplasty. We did not have any complications, e.g., facial palsy or giddiness in any of our patients. The hearing outcomes have also been optimum.
Chang et al. reported a mean postoperative air-bone gap of 30 dB with no significant difference among the types of CAA and the types of tympanoplasty. The mean air-bone gap comparison done in the study exhibited that it was possible to get an ABG of 20 dB or better in only four of the cases while 52% of cases showed 30 dB or better. The complication that was most commonly observed was meatal stenosis which accounted for 12 patients in a sample size of 25 patients. Our study has revealed postoperative air-bone closure of up to 25 dB in around 75% of our patients. More moderate hearing results were reported by De la Cruz and Teufert.
Atresioplasty may be performed at 4–5 years of age for the occasional patient with CAA without microtia. However, it is advisable in most children that have microtia, atresioplasty follows microtia reconstruction, which avoids potential compromise of temporal blood supply and gives a better chance of successful microtia reconstruction. Microtia reconstruction is best delayed until at least 7 years of age.
Over the last 35 years, in which numerous surgical techniques have evolved, the osseointegrated bone-conduction device, otherwise known as the BAHA system, has been developed adhering to the safety guidelines and precautions. BAHA serves as an alternative to atresioplasty. Hearing results are fairly good, although the cosmetic burden it poses to the patient. The added attention of proper wound care is very essential for the patient. The decision of BAHA versus surgical management has to be carefully explained to the patient and has to be individualized for each patient due to the potential complications for BAHA. Wound care is especially essential in a younger child as it is very challenging. Complications include loss of the BAHA fixture from infection and need for revision surgeries with surgical site infections that cause flap thickening.
However, the option of bone-anchored devices has to be considered with patients' affordability. For a country like ours, bone-anchored device may an expensive preposition compared to atresioplasty notwithstanding the complications associated with surgery.
A retrospective review was done by Evans and Kazahaya on 36 ears in 29 patients and 6 patients who underwent BAHA placement with the assessment of surgical and audiological outcomes. The groups of patients that underwent EAC reconstruction had an average postoperative hearing of 34.3 dB and 31.6 dB in the right and left ear, respectively. The audiological results from the group of patients with the BAHA system revealed an average postoperative hearing of 17 dB at 500 Hz and 20 dB at 2000 and 4000 Hz. The complications in those who underwent EAC reconstruction were both early and late. Recurrent canal stenosis was observed in 22.2% of ears, recurrent otitis externa in 19.4% of ears and two cases of canal prolapse (5.5%) and one case of canal cholesteatoma (2.8%). Whereas, in the BAHA system, complications had ensued in only one patient who experienced hypertrophic scarring at the site of skin-graft incision. In addition, the bone conduction hearing implants offer a better treatment option for conductive hearing loss patients, especially in patients with a high-grade aural atresia and those who do not fulfill surgical candidacy.
BAHA is considered as the gold standard in terms of closure of the air-bone gap and the air-conduction PTA gain in children with CAA. It is advocated in children with CAA who have unfavorable anatomy for reconstruction and are poor candidates for a lengthy atresioplasty procedure for medical reasons or with families that desire good hearing with lesser surgical risk. The standard surgical procedure includes the placement of a titanium fixture in the temporal bone with the reduction of the subcutaneous tissue and creation of a zone of alopecia around the abutment. The planned site for BAHA placement is 5.5 mm posterosuperior to the EAC or planned site of the EAC.
A recent alternative by the name of BAHA soft band serves as an effective means of hearing rehabilitation for children with congenital bilateral aural atresia who are too young for the conventional BAHA implant. The hearing threshold with a BAHA soft band is comparable to that of a conventional bone conductor. It is shown in experience that the BAHA soft band is comfortably worn by children, and they are not troubled often by the pressure points.
A recent implementation in the name of bone bridge transcutaneous bone conduction implant exhibited the ease of surgery compared to middle ear implants with the added advantage of magnetic resonance imaging compatibility.
Surgery for aural atresia requires a steep learning curve. Results can improve by operating on favorable cases. In cases of failure, hearing improvement can be accomplished by BAHA. Our report has shown that an air-bone gap closure of >25 dB can be achieved by atresioplasty.
| Conclusions|| |
Patients with CAA with favorable radiological findings and moderate grade atresia may benefit with surgery for attaining better hearing outcomes. This has some economic considerations in a particularly developing country like ours. However, bone-anchored hearing devices can be used in high-grade atresia and unfavorable radiology. Both the options of atresioplasty and bone-anchored hearing devices should be offered to the patients depending on the clinical situation.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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