Role of Pre Auricular Flap in Reconstruction of Acquired Meatal Stenosis Via Endaural Approach

Abstract

Acquired meatal stenosis is a difficult entity to treat with a significant recurrence rate. It is normally approached posteriorly via post aural approach and reconstructed using split thickness skin graft. We are presenting a novel method of surgery for acquired meatal stenosis using a pre auricular flap via endaural approach only. The aim was to evaluate the success rate of using a pre auricular flap in acquired atresia of the external auditory canal using the endaural approach. Twenty patients with acquired atresia of the external auditory canal that was surgically treated were retrospectively studied from July 2012 to July 2018. All cases were done using endaural approach only. During the surgery, the atretic tissue was removed, wide canaloplasty done and the stenotic segment widened. Reconstruction of the external auditory canal was done using a pedicled anteriorly based pre auricular flap rotating it into the external auditory canal to cover the bare bone. Of the 20 patrients there were good results in 18 patients with restenosis occurring only in 2 patients. However, a skin tag developed in 2 other patients which was excsiced as OPD procedure and patient was asymptomatic on further follow ups. In all the 20 cases preauricular flap was used for reconstruction along with use of Split thickness skin graft in 10 cases. All 20 cases were operated via endaural route only. Use of a Preauricular flap in surgical treatment of acquired aural stenosis gives good results with a wide dry cavity as the flap is pedicled with its vascular supply and it can be tailor made according to each case and requirement.

Introduction

Acquired meatal stenosis is a disorder of the external auditory canal characterized by formation of mature fibrous tissue in the external auditory meatus [1, 2] resulting in the narrowing of the external auditory meatus with its long term effects such ranging from deafness and impacted wax, keratosis obturans, external canal cholesteatoma and chronic otitis externa. Its incidence has been estimated at 0.6 cases per 100,000 by Becker and Tos [1, 2] in 1998. Acquired meatal stenosis commonly occurs after trauma, post ear surgery or due to inflammations [1, 2]. This poses a significant challenge for the surgeon for its notorious recurrence. Most studies stress and aim the role of SSG in reconstruction of acquired meatal stenosis [1, 2] using post aural approach, however we have found that using an endural approach along with a previously designed pre auricular flap in reconstruction in not only gives us a wide post operative healthy ear canal but also reduces the chances of recurrence and patient morbidity.

Materials and Methods

Twenty patients with acquired atresia of the external auditory canal that was surgically treated at our department were retrospectively studied from July 2012 to July 2018.

Inclusion Criteria

1. Acquired Meatal stenosis.

2. Cases operated using endaural approach only.

3. Use of anteriorly based preauricular flap for reconstruction (with or without SSG graft if required).

4. Follow up of at least 1 year.

Exclusion Criteria

1. Congenital aural atresia.

2. Cases operated using postaural approach or combined approach.

3. Exclusive use of split thickness skin graft alone.

4. Follow up less than 1 year.

Detailed history, Complete physical examination, otoscopy, probe test, pure-tone audiogram and HRCT Bilateral temporal bone was performed and noted in all the cases. After fitness for General anaesthesia and detailed consent, patients were posted for surgery. All cases included in this study were operated using endaural approach only. During the surgery, the atretic tissue was removed, wide canaloplasty done and the stenotic segment widened (Fig. 1). In cases where keratosis obturans or external canal cholesteatoma developed behind the stenotic segment, the disease was simultaneously removed and then reconstruction done. Reconstruction of the external auditory canal was done using a pedicled anteriorly based pre auricular flap (Fig. 2,3) rotating it into the External Auditory Canal to cover the bare bone. This pedicled anteriorly based pre auricular flap (Fig. 2,3) was designed in each case as per individual requirement for reconstruction but always following the basic principals of a pedicled flap so as to avoid its necrosis. Care was taken not to injure the superficial temporal artery during the graft harvesting. If any bare bone was present in the posterior canal it was covered with a small Split Thickness Skin Graft (SSG). However it was ensured that no external meatal skin or SSG was trapped under the pedicled skin flap. After the operation, the ear canal was packed with silastic sheet and a BIPP soaked merocel/ear wick was placed in ear canal for 14 days. A mastoid dressing was applied for 1 day. Follow up was done at 1 week (Fig. 4) for suture removal, 2 weeks for pack removal, 3 months (Fig. 5) and 1 year (Fig. 6). At least one year of postoperative follow-up was advocated to evaluate the results of surgery.

Fig. 1.

Wide canaloplasty

Fig. 2.

Marked preauricular flap incisions

Fig. 3.

Harvested pedicled pre auricular flap

Fig. 4.

Post operative day 7 results

Fig. 5.

Follow up results at 3 months

Fig. 6.

Follow up of healthy preauricular flap with wide patent ear canal at 1 year

Statistical analysis was performed with SPSS 21 (IBM, Atlanta, USA) software using Mann–Whitney U and Chi squared tests. Ethics committee approval, as well as informed consent, was obtained prior to the study.

Results

Of the 20 patients, 12 were males and 8 were females. The average age was 43 years (range 22–68). The study was conducted over a period of 6 years from July 2012 to July 2018.

Chief Complaints

All the 20 cases presented with complaints of decrease hearing followed by ear discharge in 11 cases and cosmetic complaints in 6 cases (Table 1).

Table 1.

Presenting complaints of the patients

Complaints	Number of cases
Decrease hearing	20
Ear discharge	11
Cosmetic/not able to use hearing aid or ear phones	6

Causes

Most common cause encountered in our study is trauma to EAC in 8 cases followed by surgical trauma in 7 cases, inflammations in 4 cases. In one case no obvious cause could be ascertained despite careful detailed history and examination (Table 2).

Table 2.

Causes of acquired meatal stenosis encountered

Ear trauma (RTA, fall from height, Cut Injuries, CLW)	8
Previous ear surgery	7
Inflammations (Otitis Externa, COM)	4
No. obvious cause	1

Pure Tone Audiogram

Average mean pre op Air–bone–gap is 42 decibles. This was reduced to 24 decibles in post operative cases (Table 3).

Table 3.

Hearing results pre and post surgery

Pure tone audiogram	Average air–bone–gap in decibles (dB)
Pre operative	42
Post operative	24

Location of Stenosis

Most common place of stenosis in external auditory cansal was both bony and cartilaginous canal in 9 cases followed by cartilaginous canal only in 6 cases, bony cartilaginous junction in 4 cases and bony canal only in 1 case (Table 4).

Table 4.

Location of stenosis in external auditory canal

Location of acquired meatal stenosis	Number of cases
Bony cartilagenous junction	4
Cartilagenous canal only	6
Bony canal only	1
Both bony and cartilaginous canal	9

Use of Pre Auricular and/Split Thickness Skin Graft

Pre auricular graft was used for reconstruction in all the 20 cases. Split thickness skin graft (SSG) was required in 10 cases along with the use of pre auricular flap to cover the bare bone circumferentially in external auditory canal specially in cases of bony canal involvement (Table 5).

Table 5.

Graft used for reconstruction

Type of graft used	No. of cases
Pre auricular flap	20
Split thickness skin graft	10

Restenosis

Total 4 cases had restenosis (Fig. 7). Out of these 4 cases 2 cases required revision surgery and in 2 other cases a superficial external skin tag developed which was excised locally as opd procedure and patients were asymptomatic thereafter (Table 6).

Fig. 7.

Failure: restenosis requiring revision surgery

Table 6.

Complications and failure on followup

Restenosis (Fig. 7)

4 cases

2 cases required revision surgery 2 cases a superficial external skin tag developed which was excised locally in opd and were asymptomatic thereafter

Discussion

External Auditory Canal (EAC) stenosis can be congenital or acquired [1, 2]. Acquired stenosis of external auditory canal is also known as acquired aural stenosis, post inflammatory medial meatal fibrosis, post inflammatory medial canal fibrosis, post inflammatory acquired atresia or acquired canal stenosis [2].

Acquired stenosis of EAC is a clinical condition in which there is formation of granulation tissue in external auditory canal after birth [3]. It can be broadly classified into partial or complete types. In Complete or Circumferential obliteration there is granulation tissue or fibrosis of the EAC in all the four quadrants leading to a false appearance of lateralized tympanic membrane. In Partial obliteration there is fibrosis of the anterior tympanomeatal angle [3].

Any insult to the external auditory canal in form of infections, trauma or de novo initiates the process of fibrosis and granulation tissue formation leading to acquired stenosis of EAC [3].The most common cause of acquired EAC stenosis is infections i.e., otitis externa. Chronic inflammation of the EAC results in subepithelial infiltration of inflammatory cells; this inflammatory process results in fibrotic changes to the canal leading to EAC stenosis [1–3]. Trauma is another possible cause of EAC stenosis. Iatrogenic trauma from prior otologic surgery is a common inciting event, however, direct trauma to EAC is a rare cause of stenosis. In one of the largest series on this subject, there was only one acquired EAC stenosis due to previous trauma in a total of 49 patients [1–3]. Rarely this can also arise de novo and can be iatrogenic as we have encountered one case in our study.

Acquired stenosis can be treated medically or surgically, however, medical management plays a limited role in the treatment of post traumatic stenosis since the goal of medical therapy is to control the underlying infection and prevent the formation of granulation tissue [1–3].Surgery should be the treatment of choice in post traumatic EAC stenosis.

The goal of the surgery is to remove the fibrous plug/debris, widen the bony EAC, expose the tympanic membrane, and recreate an epithelial-lined EAC [1–3]. Published recurrence rates range from 6 to 27% in different studies, with 100% in patients where only the fibrous plug is removed [1–3].

Acquired meatal stenosis whatever the cause is usually managed surgically by a post auricular approach [3]. According to McDonald [4], the essential step in canalplasty involves the generous widening of the posterior bony canal wall until mastoid cells are encountered. Cremers [5] prefer to widen the auditory canal as much as possible without opening the mastoid, to increase the chance of achieving a sufficiently wide and dry auditory canal. This widening of external auditory canal leads to bare bone which needs to be covered properly to avoid recurrence.

Soliman [6] removed a wedge of skin from the meatal floor and achieved a good result in 13 of 16 patients. Adkins [7] covered the skin-deficient canal with a transposition flap in eight cases with no recurrence. Moore [8] lined the canal with a full-thickness skin graft in one case with no recurrence. Bell [9] used bilateral rotational skin flaps in nine cases with no recurrence. McCary [10] used split-thickness grafts in 18 cases with one recurrence. Despite all these efforts skin graft shrinks leading to bare bone causing granulation tissue ultimately leading to stenosis. Also most of these graft are also free grafts which can lead to necrosis easily as they do not have their own vascular supply. Restenosis often occurs in such cases leading to a frustrating time for the doctor and the patient.

To overcome the problem of restenosis and to give a wide dry cavity to the patient use of a preauricular flap which is rotated from preauricular region via endaural route into the EAC via insisura terminalis is tried and recommended. The incusura terminalis is a natural cleavage in the auricular cartilage where the meatus can be widened thus widening the opening also. This is frequently done in an endaural approach in an inside out mastoidectomy to create a wide meatoplasty.

A preauriclar flap is used by the ENT and plastic surgeons to repair defects of the tragus, antitragus and the lobule. It is a well vascularised, robust flap which is conveniently available. It can be harvested and made of variable length which fits in neatly in the endaural incison thus keeping it widened and does not allow it to the meatal stenosis to recur.In all the cases where there was cartilagenous narrowing it effectively opened the meatus and canal and did not allow subsequent restonsis.

Conclusion

Restenosis often occurs in acquired meatal stenosis due to scar tissue and granulation formation, leading to a frustrating time for the doctor and the patient. We have presented a novel approach for the surgery of acquired

meatal stenosis using an endaural approach and utilising a preauricular skin flap to hold the meatus wide open with less chance of restenosis. Use of endaural approach also reduces the patients morbidity.

Funding

There are no financial interests the authors may have in companies or other entities that have an interest in the information in the Contribution (e.g., grants, advisory boards, employment, consultancies, contracts, honoraria, royalties, expert testimony, partnerships, or stock ownership in medically related fields). The authors have no financial interest.

Compliance with Ethical Standards

Conflict of interest

The author declares that they have no conflict of interest.