Tympanoplasty--conchal cavum approach

Abstract

The three well recognized tympanoplasty approaches: permeatal, postaural, and endaural, each have advantages and disadvantages. The permeatal approach is suitable only for ears with adequate canal size. The postaural approach limits visualization of the posterior eardrum margin. The endaural approach limits the view of the eardrum's anterior margin. This study describes a modified endaural approach, developed to overcome these limitations. A retrospective case series review and collection of a prospective cohort of patient reported outcome data were undertaken to assess the technique.

Method: Standard incisions as used in an endaural approach are placed within the ear canal. The novel incision extends from the superior canal incision into the conchal cavum. This allows a flap of the thick, hairbearing skin from both the bony and cartilaginous portions of the canal to be raised, and everted, to provide an excellent view of the entire drum. Perichondrium can be harvested for grafting from the conchal cavum. The clinical charts of all patients operated on by the first author using this technique from 2010-2012 were retrospectively reviewed. The size and position of the perforation, size of the canal, whether primary or revision surgery, graft take rate, hearing results and the occurrence of chondritis/perichondritis were recorded. To investigate the morbidities and the acceptance by the patients of the incision/scar in the conchal cavum, all patients undergoing the procedure in the 8 months up to the end of August 2013 were prospectively recruited to complete a self-assessment Likert scale questionnaire recording postoperative pain, and satisfaction with the cosmesis of the operative site. The clinician recorded if there was any evidence of chondritis/perichondritis.

Results: A 100% graft take rate was achieved in the 75 adults treated by the first author from 2010 to 2012 regardless of the size and position of the perforation, configuration of the canal, primary or revision surgery. Preoperative Pure Tone Audiometric (PTA) Air Bone Gap (ABG) averaged over 3 frequencies (0.5, 1 and 2 K Hz) was 19.4dB (standard deviation = 9.6, range 2 to 50). Postoperative PTA ABG average was 6.2 dB (standard deviation = 8.3, range -7 to 37), demonstrating a statistically significant post-surgery mean improvement of 13.2 dB (paired T-test, p < 0.001). Twenty-one patients who underwent the procedure in 2013, reported minimal postoperative analgesic use, and scored the acceptability of the incision scar highly (4.8 out of a maximum of 5). There was no case of chondritis/perichondritis in the 96 cases.

Conclusion: Whilst it is the surgeon's decision to use a permeatal, postaural or endaural approach, the endaural approach with the conchal cavum modification is an excellent alternative to the traditionally described approaches.

Clinical trial number: NCT02000843 at ClinicalTrials.gov.

Figures

Fig. 1

Circumferential in the ear canal incision. Legend- This illustrates the circumferential incision c. It is a half circle, 180°, on the posterior bony wall, which can be extended to 270° if indicated. It separates the thick hair bearing canal from the thin squamous epithelial lining

Fig. 2

Radial ear canal incisions. Legend- The lower radial incision a1 and the upper radial incision a 2 are illustrated

Fig. 3

Conchal incision. Legend- The novel incision b, made at the superficial end of upper radial incision a2, extends into the conchal cavum, which allows eversion of the posterior canal skin

Fig. 4

Bony ear canal exposure. Legend: The bony canal is exposed by everting the skin flap which consists of canal skin from both the bony and cartilaginous portions of the canal

Fig. 5

Cuff shape tympanomeatal flap. Legend: A cuff shape medial tympanomeatal flap is raised. The middle ear cavity can then be entered by lifting of the annulus from the tympanic ring

Fig. 6

Conchal cartilage harvest. Legend: The harvesting of the conchal cartilage for grafting is shown