CWU, CWD – RECONSTRUCTION OR OBLITERATION? CANAL-WALL-DOWN MASTOIDECTOMY FOR CHOLESTEATOMA
Introduction
The incidence of cholesteatoma in the Indian sub-continent is higher than that reported by western literature. In the past, most cholesteatoma patients reported late, which resulted in a late diagnosis and many patients with complications due to extensive cholesteatoma. There is a recent trend in the early diagnosis of cho-lesteatoma due to improved diagnostic procedures and improved patient literacy. Nowadays, more cases of cholesteatoma are being diagnosed and operated in Indian clinics. In this author’s clinical practice, the same trend has been observed recently times and cholesteatoma seems to have an incidence rate of 15–20% among all chronic otitis media cases.
The intricate anatomy around the sinus tympani and the posterior mesotympanum poses surgical challenges to the otologist, who often relies upon his surgical experience to fully eradicate the disease while preserving the vital structures in its vicinity.1 There is an inherent risk of spread of mesotympanic cholesteatoma in a variety of ways, a.o. the risk of ossicular involvement including stapes supra-structure, facial nerve and labyrinthine windows. In many cases, the foot plate is found to be spared and this provides the possibility of using the mobile footplate for hearing reconstruction as a single-stage procedure.2
A one-stage dissection of all cholesteatoma matrix in the mesotympanum and hearing reconstruction as above would be most ideal in the Indian context, due to problems of patient follow up. It is prudent to do a complete canal-wall-down (CWD) mastoidectomy with adequate lowering of the facial ridge and clearance of all disease covering the sinus tympani and vertical segment of the facial nerve course.2 The surgeon needs to emphasize the need for diligent follow-up with oto-microscopy in these patients to identify any recurrence or recidivism at the earliest.
Principles of cholesteatoma surgery
The basic goal of cholesteatoma surgery is the complete removal of squamous epithelium to minimize the risk of recurrence while maximizing hearing gain / preservation. The best method would be a CWD mastoidectomy, in which the posterior wall of the external auditory canal is removed and the mastoid and external auditory canal become a common communicating cavity exposed to the outside. This approach in management of cholesteatoma has been well emphasized in literature published since the last century.3 Bezold and Hartmann stated this in their manuscript on ‘Office management of discharging ears’ in the 1880s. Schwartz, Kuster and Zaufal (1889 emphasized the need for ‘exteriorization and fistulization’ in ear surgery and Hartmann, Jansen and Stacke (1890–91) proposed the true beginnings of CWD surgery, which still remains the ‘Gold-standard’ operation for unsafe ears, since then till date.3
The basic indications for CWD mastoidectomy include: extensive cholesteatoma involving mastoid air cells, sclerotic, contracted mastoid with limited access to epitympanum, cholesteatoma in the only hearing ear, recurrence of cholesteatoma after closed-cavity procedure, non-reconstructable posterior canal wall, otologic or CNS complications, labyrinthine fistula, poor ET function, patients with unreliable follow up, cases of extensive pediatric cholesteatoma.3 The fact that CWD mastoidectomy is still an important tool in managing cholesteatoma is testament to certain clear advantages.
The salient investigations would include otomicroscopy, radiological and audiological tests. Cholesteatoma surgery requires the nuances of an experienced otologist in order to completely eradicate the disease from the entire middle ear cleft, while taking utmost care for preserving and reconstructing the hearing mechanism of the disease-free ear either in the same sitting or as a staged procedure. These decisions lie with the operating surgeon and intra-operative decisions must be made judiciously with concern towards the patient factors like age, pre-op hearing thresholds, presence of co-morbidities, and financial status.
The major advantages of CWD mastoidectomy include: better access to meso- and epitympanum, facial recess gets exteriorized well, there is decreased incidence of residual/recurrent disease, CWD facilitates better post-operative inspection and second-look surgery is usually not required. CWD mastoidectomy may be performed by retro-auricular or endaural approach with trans-cortical or trans-meatal route. There are a few demerits to CWD mastoidectomy, e.g., the open cavity needs frequent ear canal cleaning and shallow middle ear space makes ossiculoplasty difficult with a possibility of increasing loss of hearing over time.4 In the Indian sub-continent, residual disease and recurrent disease occur in an estimated 11–27% and 5–13% of patients undergoing the closed procedure, whereas residual or recurrent disease occurs in 2–10% of patients undergoing the open procedure.
Management philosophy in cholesteatoma surgery
In this author’s extensive experience with cholesteatoma surgery over the past thirty years, small cholesteatomas limited to the post-mesotympanum are best treated with canal-wall-up mastoidectomy with reconstruction of scutum with cartilage, while large cholesteatomas in a small sclerotic mastoid should be treated with the retrograde approach or inside-out CWD mastoidectomy. Extensive cholesteatoma in a well-pneumatized mastoid should be treated with a thorough CWD mastoidectomy. In this author’s experience, there is a bias towards CWD mastoidectomy, due to the following results: MERF experience: January 1999-December 2006 (eight years); total number of cholesteatoma surgeries: 480 - CWD = 390, intact CW = 90.
Table 1. MERF Experience with Cholesteatoma Surgery (Jan 1999 - Dec 2006)
Type of Surgery | Recurrence of Disease | Residual Disease | Total % |
|
CWU | 9 (10%) | 5 (6%) | 14 (15%) | |
CWD | 12 (3%) | 6 (1.5%) | 18 (4.5%) |
Operating pearls for Cholesteatoma Surgery
In this survey, salient steps while performing cholesteatoma surgery have been highlighted and the identification of important anatomical landmarks – like the second genu of the facial nerve which is located infero-medial to the prominence of the lateral semicircular canal, and the cochleariform process which is a reliable landmark for tympanic segment of facial nerve – have been emphasized. The author also pointed out that the micro-drill burr should be moved parallel to important structures, e.g., facial nerve, sigmoid sinus, LSCC; and drilling over the facial nerve must be with large burrs and with continuous irrigation to cool the drilled area. Special care needs to be taken while the anterior buttress is removed, when the facial ridge is lowered to the level of the nerve, and when the perilabyrinthine cells in the attic are drilled out.5,6
The importance of saucerization of the entire cavity and removal of overhanging edges which allows soft tissue to fill in the bony defect which makes the cavity smaller, and the fact that an adequate meatoplasty is an essential prerequisite to CWD procedures are also points that have been described. Performing such a meticulous dissection would essentially create the ideal CWD cavity which will be small, rounded in shape, self-cleansing, smooth, without niches, with low facial ridge, having a wide meatoplasty which is dry and well epithelialized. This cavity should essentially be disease-free for a life time.6
Incomplete exteriorization of cellular tracts, inadequate removal of the bone over the middle fossa dura, sig-moid sinus, facial nerve, or mastoid tip and inadequate meatoplasty are the major causes for cavity problems in most of the CWD procedures. Since diagnostic modalities to identify early cholesteatomas accurately have advanced in the present day, operative techniques should also be further refined by otologists, in order to cure the patients of all disease by the best possible approach and provide them with the best audiological outcomes. A correctly performed CWD technique together with a sufficiently large meatoplasty, has proven to be successful in the management of extensive cholesteatomas and has paved the way for achieving the above-mentioned desired goals.
References
1.Chole RA, Sudhoff HH. Chronic otitis media, mastoiditis and petrositis. In: Otolaryngology: Head & Neck Surgery 5th ed. Cum-mings CW, Flint PW, Haughey BH, et al (eds.), chapter 139. Philadelphia, Pa: Mosby Elsevier; 2010
2.Semaan MT, Megerian CA. The pathophysiology of cholesteatoma. Otolaryngol Clin North Am 39(6):1143–1159, 2006
3.Osborn AJ, Papsin BC, James AL. Clinical Indications for Canal Wall-down Mastoidectomy in a Pediatric Population. Otolaryngol Head Neck Surg 147(2):316–322, 2012
4.Roland PS, Meyerhoff WL. Open-cavity tympanomastoidectomy. Otolaryngol Clin North Am 32(3):525–546, 1999
5.Kemppainen HO, Puhakka HJ, Laippala PJ , Sipilä MM, Manninen MP, Karma PH. Epidemiology and aetiology of middle ear cholesteatoma. Acta Otolaryngol 119(5):568–572, 1999
6.De la Cruz A, Fayad JN. Detection and management of childhood cholesteatoma. Pediatr Ann 28(6):370–373, 1999
Address for Correspondence: Prof. Mohan Kameswaran,Madras ENT Research Foundation, No.1, 1st Cross Street, Off 2nd Main Road, Raja Annamalaipuram, Chennai – 600028, India. merfmk30@yahoo.com
Cholesteatoma and Ear Surgery – An Update, pp. 55–57
Edited by Haruo Takahashi
2013 © Kugler Publications, Amsterdam, The Netherlands