TITLE: Cartilage Tympanoplasty

TITLE: Cartilage Tympanoplasty
SOURCE: Grand Rounds Presentation, UTMB, Dept. of Otolaryngology
DATE: March 19, 2007
RESIDENT PHYSICIAN: Ki-Hong Kevin Ho, MD
FACULTY PHYSICIAN: Tomoko Makishima, MD, PhD
SERIES EDITORS: Francis B. Quinn,= Jr., MD

"This materia= l was prepared by resident physicians in partial fulfillment of educational requirements established for the Postgraduate Training Program of the UTMB Department of Otolaryngology/Head and Neck Surgery and was not intended for clinical use in its present form. It was prepared for the purpose of stimulating group discussion in a conference setting. No warranties, either express or implied, are made with respect to its accuracy, completeness, or timeliness. The material does not necessarily reflect the current or past opinions of members of the UTMB faculty and should not be used for purposes= of diagnosis or treatment without consulting appropriate literature sources and informed professional opinion."

Introduction

Since Wullstein and Zoeller popularized tympanop= lasty in the 1950s, various materials have been used for the procedure, including fascia, skin, vein, dura, and cartilage. At present, the most common materi= al used in tympanoplasty is temporalis fascia. In cases like revision tympanoplasty and atelectatic ear, cartilage has been used with great succe= ss to reconstruct the tympanic membrane (TM).

Tympanic Membrane

The tympanic membrane is oval in shape with dime= nsions of approximately 8 mm X 10 mm. It is oriented at approximately 55 degrees with the floor of the meatus. The greater part of the circumfere= nce is thickened, and forms a fibrocartilaginous ring (also known as the annulus or annular ligament) which is attached to the tympanic sulcus at the medial en= d of the meatus (scutum). The annu= lus and sulcus are deficient superiorly which is known as the notch of Rivinus. The anterior and pos= terior malleolar folds extend to the lateral process of the malleus from the two e= nds of this notch. The triangular= area created above these folds is known as the pars flaccida and is called such because it lacks the middle fibrous layer that gives tensile strength to the rest of the membrane. This characteristic makes it vulnerable to retraction under negative pressure. The rest of the membrane is called= the pars tensa. The handle of the malleus is firmly attached to the inner surface of the TM as far as its cen= ter, which projects towards the tympanic cavity giving the TM a conical shape. The point of the cone is called the umbo. The membrane is approxi= mately 130 microns thick. As mention= ed before, it is a three layered structure consisting of an outer ectodermal l= ayer composed of keratinizing squamous epithelium, an intermediate mesodermal fibrous layer (which consists of a superficial layer of radial fibers and d= eep layer of circular fibers), and an inner endodermal mucosal layer. The epidermal layer has migratory properties which gives the TM its self cleaning ability. The epidermis migrates centrifugal= ly from the umbo outward in a posterosuperior direction at about 131 microns p= er day.

Etiology of TM perforation

Perforations in the TM are most commonly caused = by infections of the middle ear and less commonly the external auditory canal. Other causes are traum= a, and iatrogenic. The vast majority= of perforations due to infection is small and heals spontaneously; however, recurrent infections may impair the regenerative process and result in a chronic perforation. Beta-hem= olytic streptococci are associated with large central perforations secondary to its necrotizing toxins and proteolytic enzymes. Viruses, mycobacterium species and external otitis have also been associated with TM perforations

Prognostic factors of TM re-perforation

Larger perforation is associated with significant lower rate (56 vs. 74% in smaller perforation)of success of tympanoplasty. Success rate is lower in anterior (67%) perforation than posterior location (90%). Presence of middle ear mucosal and contralateral disease is also significant predictors for outcome. A finding of otorrhea at surgery is a p= oor prognostic factor for tympanoplasty. Smoking is associated with worse middle ear status and delayed graft failure according to Becvaroski’s study = in 2001. Despite concerns about operating on young children who are pro= ne to otitis media, Albera’s study shows that TM closure and re-perforat= ion rates are similar among patients aged less than 18, 18-50, and greater than= 50.

Advantages of Cartilage graft

Cartilage has been shown to be well tolerated by= the middle ear. Long term survival is achieved since cartilage grafts are nouri= shed largely by diffusion. Even in the cases of severe Eustachian tube dysfuncti= on, cartilage maintains its rigid quality and resists resorption and retraction= .

Indications of cartilage tympanoplasty

Ø At= electatic ear

Ø Re= traction pocket/ Cholesteatoma

Ø Hi= gh Risk Perforation

l Re= vision

l An= terior perforation

l &g= t; 50%

l Ot= orrhea at the time of surgery

l Bi= lateral

Techniques of cartilage tympanoplasty

Four techniques have been described for cartilage tympanoplasty, namely the inlay butterfly graft, Perichondrium/cartilage is= land flap, palisade flap, and cartilage shield tympanoplasty. The choice of technique is dictated by surgeon’s preference, size of the perforatio= n, integrity of the ossicular chain, and the presence of cholesteatoma.

Inlay butterfly graft

This technique was originally described for smal= l TM perforation myringoplasty. The tragal cartilage graft is harvested with int= act perichondrium on both sides. Using a beaver blade, a 2 mm circumferential incision can be made on the cartilage to create a groove with an appearance similar to the wings of a butterfly. After the perforation rim is freshened, the cartilage graft can then be anchored onto the perforation similar to a tympanostomy tube. A split thickness skin graft can be placed over the graf= t if the perforation is large. For perforation greater than 1/3 of TM or close to the annulus, the graft can be anchored onto the bony annulus, as described = by Ghanem et al in 2006.

Perichondrium/ cartilage island flap

Tragal cartilage graft is harvested because it is flat, thin (~ 1mm) and abundant. Perichondrium from the side away from the external auditory canal is removed. A flap of perichondrium is produced posteriorly that will eventually drape over the posterior canal wall. Next,= a complete strip of cartilage 2 mm in width is removed vertically from the ce= nter of the cartilage to accommodate the entire malleus handle. The entire graft= is placed in an underlay fashion, with the malleus fitting in the groove.

Palisade technique

Cartilage graft can be harvested from either the tragus or concha cymba. The latter is used when a post-auricular incision is planned, as in the case of mastoidectomy. For conchal cartilage graft, perichondrium is removed from the post-auricular side. Cartilage graft is c= ut into several slices or strips, which are subsequently pieced together media= l to the malleus to reconstruct the TM. This technique is favored when ossicular chain reconstruction is performed because it provides a better visualizatio= n of the prosthesis and precise placement of graft onto the prosthesis. In cases= of posterior perforation, the anterior half of the TM can be left alone to all= ow postoperative surveillance and future myringotomy tube placement.

Cartilage shield technique

A vascular strip incision is made in the ear can= al, followed by a post-auricular incision. Areolar tissue overlying temporalis fascia is harvested. A round = piece of conchal cartilage is harvested and perichondrium on both sides is remove= d. A small wedge of cartilage is removed to accommodate the handle of the malleu= s. The graft is then placed medial to the malleus and the remnants of the TM. The areolar graft is then placed in between the cartilage graft and the remnant= s of the TM.

Postoperative care

Topical antibiotic drop is initiated for 2 weeks= after surgery. 2 weeks after the surgery, all gelfoam in the EAC is removed. Audiogram is obtained in 3-4 months postop, mainly to evaluate air-bone gap since tympanometry is no longer reliable given the rigidity of the cartilage graft. If the entire TM is reconstructed with cartilage, surveillance by otoscopy might be difficult due to its opaque appearance. Air-bone gap is a good tool to assess the presence of middle ear effusion. CT temporal bone c= an be obtained and a second look procedure can be performed especially in the = case of cholesteatoma.

Hearing results after cartilage tympanoplasty

Dornhoffer et al reports 96 patients who failed = at least 1 temporalis fascia graft tympanoplasty, of which 29 of them also underwent ossicular chain reconstruction. TM closure was achieved in about = 95% of patients. There was a significant improvement in pure tone average (PTA) from 24.6 to 12.2 dB.

Gerber et al compared hearing results after temp= oralis fascia and cartilage graft. All eleven patients had normal ossicular chain function. The primary indication of the surgeries was retraction pocket. Wi= th an average follow-up period of 12 months, they found no significant differe= nce between the improvement of speech reception threshold (approximately 10 dB)= in the temporalis fascia group and the cartilage group. In addition, the carti= lage group also shows significant reduction in air-bone gaps across various frequencies. (500, 1k, 2k, and 4k Hz).&nbs= p;

Acoustic properties of various graft materials

Using a cartilage graft thinner than 1 mm or sma= ller cartilage pieces (palisade technique) may improve sound transmission proper= ties of the reconstructed TM, as demonstrated by Murbe et al. Using scanning las= er Doppler vibrometry, various thicknesses and sizes of cadaveric conchal cartilage were used. The sound-induced vibration of the 1-mm cartilage plate showed a first resonance frequency at 1188 Hz with amplitude of 30 nm/Pa. Slicing this plate into palisades decreased the first resonance frequency a= nd increased its amplitude, reflecting improved sound transmission properties = of the transplant. Reduction of the thickness of a cartilage plate to 0.7 mm revealed a similar effect on vibration characteristics. The 0.5- and 0.3-mm plate transplants showed results that were acoustically superior to the palisades or the 0.7-mm plate.

Conclusions <= /span>

Cartilage tympanoplasty offers otologists a reli= able armamentarium in TM reconstruction. The choice of techniques depends on surgeon’s preference, the integrity of the ossicular chain, the size = of the perforation, and the presence of cholesteatoma. Despite its rigid quali= ty, cartilage tympanoplasty achieves good audiologic results comparable to temporalis fascia graft.

References

1. Cartilage tympanoplasty. Dornhoffer JL 2006

2. Butterfly cartilage graft inlay tympanoplasty for large perforations.Ghanem MA 2006

3. Hearing results after primary cartilage tympanoplasty. Gerber MJ 2000

4. Cartilage tympanoplasty for posterosuperior retraction pockets of the pars tensa in children. Couloigner V 2003

5. Tympanic reperforation in myringoplasty: evaluation of prognostic factors. Albera R = 2006

6. Acoustic properties of different cartilage reconstruction techniques of the tympanic membrane. Murbe D 2002

7. Type III cartilage shield tympanoplasty: an effective procedure for hearing impairment. Kyrodimos E 2007

8. Cartilage shield tympanoplasty: a reliable technique. Aidonis I 2005

9. Palisade cartilage tympanoplasty for management of subtotal perforations: a comparis= on with the temporalis fascia technique. Kazikdas KC 2007