Abstract
Objective
To describe the technique for canalplasty as performed in the Academic Medical Center, Amsterdam, the Netherlands and to present the results of this technique.
Study design
Retrospective chart analysis.
Subjects and methods
Charts of patients who underwent a canalplasty prodedure between 2001 and 2010 were reviewed for indication for surgery, side of surgery, age at the time of surgery, gender, smoking habits, surgical outcome, results of pure tone audiometry pre-and post-operatively and the occurrence of complications.
Results
193 canalplasty procedures with or without more extensive otosurgery in 174 patients were performed for various indications in the Academic Medical Center, Amsterdam, the Netherlands between 2001 and 2010. Complete re-epithelialization took approximately 6.7 weeks and was influenced by smoking and the surface needed to re-epithelialize. Complications occurred in 28.0% of cases, of which most (98%) could be regarded as transient. No significant changes in pure tone bone conduction levels at 1, 2 and 4 kHz were observed.
Conclusion
This retrospective study shows that technique for canalplasty as used in the Academic Medical Center, Amsterdam, the Netherlands can be used for a wide variety of indications, highlighting its added value in otosurgery.
1
Introduction
Widening of the bony ear canal (i.e. canalplasty) is an established technique for the treatment of several diseases of the osseous external auditory canal (OEAC). Several techniques to widen the OEAC have been advocated in literature, all based on the same principle (i.e. creating a sufficiently wide, disease free and self cleansing ear canal) . Next to sufficient width, the quality of epithelial lining of the OEAC plays a pivotal role in the outcome of canalplasty. A healthy, dry and water resistant bony ear canal is completely lined with keratinizing squamous epithelium with normal migratory characteristics and the capacity of producing cerumen . These features enable the external auditory canal to fight water-borne pathogens (thus reducing the risk of infection) and prevent accumulation of debris. The skin of the ear canal is unique as it lacks subcutaneous tissue and adheres directly to the periost of the external auditory canal. These two factors make the skin of the bony external auditory canal extremely vulnerable and hard to replace .
A canalplasty can be a standalone procedure or can be part of more complex otosurgery. Performing a canalplasty has been shown to be both an effective and useful tool in otosurgery to optimize surgical view of the middle ear and the treatment of primary OEAC disease . This manuscript focuses on interventions in which an existing external auditory canal is present. The creation of an entirely new ear canal (as is the case in congenital aural atresia) will not be discussed. The technique for canalplasty as performed in the Academic Medical Center, Amsterdam, the Netherlands is described, results of this technique are presented and suggestions are made on how to handle skin deficits.
2
Patients and methods
2.1
Patients
A retrospective chart analysis was performed identifying 225 individuals who underwent a canalplasty procedure in one or two ears between September 2001 and May 2010 in the Academic Medical Center, Amsterdam, the Netherlands, a tertiary center for otorhinolaryngology. Of these 225 individuals, canalplasty was part of revision radical cavity surgery in 51 cases. These cases were excluded because of enormous abnormalities in shape of the OEAC. In the remaining 174 patients, 193 canalplasty procedures were performed by either the first or the third author of this manuscript. All charts were reviewed for indication for surgery, side of surgery, age at the time of surgery, gender, smoking habits, surgical outcome (i.e. complete epithelialization of the external auditory canal alias time to heal), results of pure tone audiometry (PTA) pre-and post-operatively and the occurrence of complications.
2.2
Surgical technique
The surgical technique for canalplasty as used in the Academic Medical Center, Amsterdam, the Netherlands is a slight modification of the technique as described by Prof. U. Fisch in 1994 . Fig. 1 is a representation of all steps of the procedure as are performed in our center. All steps are described as if a right ear is involved. Briefly, one starts with a post-aural incision and the creation of a periosteal flap, thus allowing adequate exposure of the bony external auditory canal. Once the periostial flap is created, the external auditory canal is opened at the level of the transition between the bony and cartilaginous external auditory canal . This incision is extended forward along the anterior wall to the 3 o’clock position . At the 3 o’clock position, a second incision is made starting as close as possible to the tympanic annulus and reaching laterally to connect with the first incision at the level of the transition of the bony and cartilaginous external auditory canal . If an inadequate amount of meatal skin is expected (as is the case in acquired medial canal fibrosis, AMCF), the technique as described above can be modified. This modification is a ‘lateral steal’ of skin covering the cartilaginous auditory canal using sharp dissection [3; blue lines]. Upon the first and second incision, the skin covering the bony external auditory canal is elevated starting at the 3 o’clock position in a counter clock wise manner until the 5 o’clock position is reached . The skin should be elevated as medially as possible leaving only a small skin cuff near the tympanic annulus. Following elevation of this skin flap, the skin covering the external auditory canal is circularly cut using micro-scissors just medial to the bony overhang until the tympanosquamous suture is reached (anterior limb) . The posterior limb of the circular incision is initiated by cutting through the elevated meatal skin . The posterior and anterior limbs of the circular incision are connected along the superior canal wall. The circular incision is completed inferiorly . Once the third incision is completed, one can elevate the antero-inferior pedicled skin flap out of the bony external auditory canal using a Rosen microraspatory and Williger raspatory , thus revealing the entire meatal skin flap . One can fixate this meatal skin flap outside the operation field using spreaders. If necessary, the flap can be thinned sparing the epithelial layer. Next, the external bony canal is enlarged exposing the entire tympanic annulus using sharp and diamond burrs, eliminating all bony overhangs, particularly anterior and inferior using the tympanic annulus as a margin . One should take care not to open any of the mastoid air cells or temporo-mandibular joint. When a bluish hue is observed, the bone overlying the temporo-mandibular joint is maximally thinned. Care should be taken not to damage the skin cuff near the tympanic annulus .
At the end of the procedure both skin flaps are repositioned. To allow adequate alignment of skin within the new bony ear canal, the most medial skin flap (the skin cuff near the tympanic annulus) is incised partially at several locations . The lateral skin flap is repositioned in a clockwise manner. One should make sure that the epithelial side of the skin flap is facing the lumen of the OEAC. Part of the OEAC canal will not be covered by skin as a result of its increased diameter . After repositioning both skin flaps, antibiotic gauzes are applied for fixation .
Postoperatively, special care should be taken not to displace the skin flaps as antibiotic gauzes are changed every other week until complete re-epithelisation of the OEAC has occurred.
2.3
Statistical analysis
Statistical analysis was carried out using SPSS 16.0.2 (Chicago, IL, USA). Data are expressed as number (%) and mean (SD). Paired-samples T-tests and one-way ANOVA tests were performed to check for significant changes from baseline in pure tone audiometry (both air and bone conduction thresholds, at 1, 2 and 4 kHz), the occurrence of a dry ear post-operatively, time to heal (i.e. time to complete re-epithelialization) and the influence of smoking. P values of less than 0.05 were considered statistically significant.
2
Patients and methods
2.1
Patients
A retrospective chart analysis was performed identifying 225 individuals who underwent a canalplasty procedure in one or two ears between September 2001 and May 2010 in the Academic Medical Center, Amsterdam, the Netherlands, a tertiary center for otorhinolaryngology. Of these 225 individuals, canalplasty was part of revision radical cavity surgery in 51 cases. These cases were excluded because of enormous abnormalities in shape of the OEAC. In the remaining 174 patients, 193 canalplasty procedures were performed by either the first or the third author of this manuscript. All charts were reviewed for indication for surgery, side of surgery, age at the time of surgery, gender, smoking habits, surgical outcome (i.e. complete epithelialization of the external auditory canal alias time to heal), results of pure tone audiometry (PTA) pre-and post-operatively and the occurrence of complications.
2.2
Surgical technique
The surgical technique for canalplasty as used in the Academic Medical Center, Amsterdam, the Netherlands is a slight modification of the technique as described by Prof. U. Fisch in 1994 . Fig. 1 is a representation of all steps of the procedure as are performed in our center. All steps are described as if a right ear is involved. Briefly, one starts with a post-aural incision and the creation of a periosteal flap, thus allowing adequate exposure of the bony external auditory canal. Once the periostial flap is created, the external auditory canal is opened at the level of the transition between the bony and cartilaginous external auditory canal . This incision is extended forward along the anterior wall to the 3 o’clock position . At the 3 o’clock position, a second incision is made starting as close as possible to the tympanic annulus and reaching laterally to connect with the first incision at the level of the transition of the bony and cartilaginous external auditory canal . If an inadequate amount of meatal skin is expected (as is the case in acquired medial canal fibrosis, AMCF), the technique as described above can be modified. This modification is a ‘lateral steal’ of skin covering the cartilaginous auditory canal using sharp dissection [3; blue lines]. Upon the first and second incision, the skin covering the bony external auditory canal is elevated starting at the 3 o’clock position in a counter clock wise manner until the 5 o’clock position is reached . The skin should be elevated as medially as possible leaving only a small skin cuff near the tympanic annulus. Following elevation of this skin flap, the skin covering the external auditory canal is circularly cut using micro-scissors just medial to the bony overhang until the tympanosquamous suture is reached (anterior limb) . The posterior limb of the circular incision is initiated by cutting through the elevated meatal skin . The posterior and anterior limbs of the circular incision are connected along the superior canal wall. The circular incision is completed inferiorly . Once the third incision is completed, one can elevate the antero-inferior pedicled skin flap out of the bony external auditory canal using a Rosen microraspatory and Williger raspatory , thus revealing the entire meatal skin flap . One can fixate this meatal skin flap outside the operation field using spreaders. If necessary, the flap can be thinned sparing the epithelial layer. Next, the external bony canal is enlarged exposing the entire tympanic annulus using sharp and diamond burrs, eliminating all bony overhangs, particularly anterior and inferior using the tympanic annulus as a margin . One should take care not to open any of the mastoid air cells or temporo-mandibular joint. When a bluish hue is observed, the bone overlying the temporo-mandibular joint is maximally thinned. Care should be taken not to damage the skin cuff near the tympanic annulus .
