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Management of Troublesome Mastoid Cavity
Category : Otology » Mastoid cavity
The radical mastoid cavity (or canal down procedure) is a common surgical management of cholesteatoma and is often effective in eradicating this condition

MANAGEMENT OF TROUBLESOME MASTOID CAVITY

Jacques MAGNAN

ENT Department

HOPITAL NORD

13915 MARSEILLE Cedex 20


The radical mastoid cavity (or canal down procedure) is a common surgical management of cholesteatoma and is often effective in eradicating this condition. Unfortunately a proportion of cases is associated with persistent otorrhea and recurrent accumulation of epithelial debris, which means potential cholesteatoma.
In our opinion the reasons of a troublesome mastoid cavity are not always surgical failures, but mainly biological failures.
Using canal down procedure, the surgeon induces wrong conditions of cicatrization of both layers, epidermic and mucous.
Every otologist recognizes that to have a sure and good wound healing of epidermic layer, the skin must overlay an anatomical osseous auditory canal ; and to have a good and sure wound healing of the mucous layer, the middle ear must be closed and well ventilated by the Eustachian tube.
Thus, to manage a troublesome mastoid cavity the best way is to reconstruct the middle ear and to repair the posterior canal wall previously destroyed.
This anatomical reconstruction is more than a mere technical artifice, it is an absolute physio-pathological necessity. Three mean reasons for that are :
- anatomical : the external auditory canal bone and the eardrum constitute a harmonious curve, achieving a single anatomical unit ;
- biological : the harmonious size of the external auditory canal necessitates a good trophicity of the epidermic layer. The skin loses its self-cleaning capacity if the canal is stenotic or enlarged ;
- functional : the bottom of the osseous canal is the holding frame of the tympanic membrane. The respect or reconstruction of the attical wall preserves the tympano-ossicular physiology and prevents a marginal retraction pocket and a way of recurrent cholesteatoma.

Surgical indications

In our experience the concept of ear canal wall reconstruction after canal wall down mastoidectomy represents one of the best solution for curing problems in troublesome mastoid cavity. The technique of rehabilitation of middle ear by reconstruction of posterior canal wall always concerns failure of radical cavities, with resistant discharge and therefore wrong cicatrization. Otorrhea was present in 95% of our cases. Its origins was a cholesteatoma in 60% of cases .





Material and methods

During the last 20 years we performed more than 400 cases of middle ear rehabilitation by reconstruction of the posterior wall. In 1990 we published our long-term anatomical results which progressively increased from 57% to 80 % of good results in a one-stage procedure using mastoid cortical bone and Marquet’s technique. The challenge is to improve this result, and to reduce the 20 % of failures.
We have been using various materials for 20 years. At the beginning, we used cartilage and mastoid cortical bone. The shaping of the bone is technically difficult and time-consuming. The frequency of retraction around the newly formed ear canal wall is another reason for changing the method and for using a canal wall prosthesis. Later, we used a Ceravital canal wall prosthesis, but were disappointed by the results, and therefore started testing new alloplastic implants (hydroxylapatite and titanium).
We would like to present our experience and results in total reconstruction of the posterior canal wall using a new titanium prosthesis. This conductive ear canal prosthesis has been tested for five years in 80 cases of ear canal wall reconstruction.

Technique

The surgical steps of ear canal reconstruction are well known. Whatever the material used, the purpose of reconstruction of the ear canal wall is to restore as perfect an anatomy as possible.
The main points for a successful reconstruction are :
- cleaning of the radical cavity performed as cholesteatoma surgery ;
- making of a dissected finger-like large skin flap retained within the auditory canal ;
- estimation of the right size of the canal repair thanks to a model ;
- sliding in the titanium prosthesis between two grooves, one anterior attical, the other posterior on the facial bridge ;
- interposition of a conjunctive layer overlapping the entire canal graft, which is essential to promote successful growth over the raw area ;
- very careful replacement of the whole skin flap over the canal repair and the tympanic graft. This is the final and essential surgical step.

The advantages of a titanium canal wall prosthesis are :
- its well known biocompatibility ;
- its respect of the anatomical shape, with a right and a left side, with a lower inclined part to restore the scutum and obtain an harmonious junction with the tympanic graft ;
- it cannot be modeled, and thus different sizes of prosthesis are required.

At first, a one piece no-modeled prosthesis seems to be a disadvantage. We now know that this is a great advantage. The prosthesis retains the surface and machine finished qualities, thereby reducing the risk of inflammation and improving the growth of the skin flap. Shaping is performed on the surrounding bony structures and the prosthesis is pressed into the defect by wedging it between two grooves.

Results

80 patients operated on from 1994 to 1999, were analysed . After first stage surgery we observed 68 cases (85%) with dry ear, and 60 cases (75%) with good anatomical results, i.e., perfect wound healing of the covering skin with a self cleaning and waterproof ear canal . 17 losses of cicatrization with the canal prosthesis denuded requiring revision surgery performed under local anaesthesia .We recorded 93% of good results in two stages A recurrent attical cholesteatoma was observed in 2 cases (3%) . The titanium canal wall had to be removed in 3 cases (one myringitis, two surgical failures).

Discussion

Firstly, our failures have to be analysed according a technical inadequacy or imperfect material, not to the inevitable evolution of the chronic otitis .

Secondly, all our cases concern failures of the mastoid cavity with resistant discharge, cholesteatoma recurrence . We therefore tested the titanium prosthesis in terrible conditions and the postoperative status was dry ears and only one case of granulation tissue. The preoperative inflammatory process did not modify the skin growth over the prosthesis.

Thirdly, in 15 cases the titanium prosthesis was partially exposed . But, in four cases, two months later the skin grew spontaneously over the titanium prosthesis, finally covering the whole newly formed ear canal. This was the main feature of our study. We never encountered this using mastoid cortical bone, ceravital or hydroxylapatite canal wall prosthesis. The titanium prosthesis is a truly biocompatible material ensuring good conditions for wound healing of the epidermic layer.


Conclusions

Reconstruction of the posterior canal wall represents the optimal method to manage a troublesome mastoid cavity and confirms the sound basis of the concept of the closed technique.
This surgery is a source of considerable reward for patient and surgeon alike.

References

1 – Portmann N, Austin D, Jansen C, Perkins R, Smith M : reconstruction of the mastoidectomized ear. Arch Otolaryngol 97 : 74-76, 1973
2 – Poll J : Reconstruction of bony canal with autogenous bone graft. Laryngoscope 87 : 1826-1932, 1977
3 – Reck R : Bioactive glass ceramics in ear surgery. Animal studies and clinical results. Laryngoscope (suppl 33) 94 : 1984
4 – Slim C, Tos M : Partial and total reconstruction of old radical cavities. Arch Oto-Laryngol 113 : 635-643, 1987
5 – Grote J : Reconstruction of the middle ear with hydroxylapatite implants. Long Term Result. Ann Otol Rhinol (Suppl 144) 1990, 99 : 12-16
6 – Magnan J, Chays A, Gignac D, Bremond G : Reconstruction of posterior canal wall : long-term results in Charachon R, Garcia-Ibanez E : Long-Term Results and Indication in Otology and Otoneurosurgery. Kugler α Ghedini Amsterdam 1991, 57-61.
7 – Magnan J, Chays A, Pencroffi E : Reconstruction for the ear canal wall in Portmann M, Transplants and Implants in Otology. Kugler Publication Amsterdam 1996, 251-255
8 – Black B : Mastoidectomy elimination. Laryngoscope (suppl 76) 1995, 105, 1-30
9 – Black B : Mastoidectomy elimination : Obliterate Reconstruction or ablate ? Am J Otol 1998, 19, 551-558
Prepared by : Prof. Jacques Magnan