Tóm tắt Luận án Evaluation of results of endoscopic transcanal canal wall down mastoidectomy for dangerous chronic otitis media

MINISTRY	
  OF	
  EDUCATION	
  AND	
  TRAINING	
   	
   	
  MINISTRY	
  OF	
  PUBLIC	
  HEALTH	
  	
  
HANOI	
  MEDICAL	
  UNIVERSITY	
  
NGUYEN	
  THI	
  TO	
  UYEN	
  
EVALUATION	
  OF	
  RESULTS	
  OF	
  ENDOSCOPIC	
  
TRANSCANAL	
  CANAL	
  WALL	
  DOWN	
  
MASTOIDECTOMY	
  FOR	
  DANGEROUS	
  
CHRONIC	
  OTITIS	
  MEDIA	
  	
  	
  	
   Specialization:	
  Ear	
  Nose	
  Throat	
  Code:	
  62720155	
  	
  
SUMMARY	
  OF	
  MEDICAL	
  DOCTORAL	
  THESIS	
  
HA	
  NOI	
  –	
  2018	
  	
  	
  	
  	
  
The work is completed at: 
HANOI MEDICAL UNIVERSITY 
Instructor: Assoc. Prof. PhD. NGUYEN TAN PHONG 
Reviewer 1: Assoc. Prof. PhD. NGHIEM HUU THUAN 
 Vietnam Military Medical Academy 
Reviewer 2: Assoc. Prof. PhD. NGUYEN THI NGOC DUNG 
 Pham Ngoc Thach University of Medicine 
Reviewer 3: Assoc. Prof. PhD. ĐOAN HONG HOA 
 National Otorhinolaryngology Hospital of Vietnam 
The Thesis will be protected at the Thesis-level dissertation board: 
Hanoi Medical University 
At: h month date year 
Can find thesis at: 
 National Library 
Hanoi Medical University Library 
Central Medical Information Library 
THE PUBLISHED RESEARCH WORKS 
RELATED TO THE THESIS TOPIC 
1. Nguyễn Thị Tố Uyên, Nguyễn Tấn Phong (2012), Kết quả ban 
đầu của phẫu thuật tiệt căn xương chũm tối thiểu đường xuyên 
ống tai, Tạp chí Nghiên cứu Y học, số 78 (1), tr 48-52. 
2. Nguyễn Thị Tố Uyên, Nguyễn Tấn Phong (2013), Kết quả 
phẫu thuật tiệt căn xương chũm tối thiểu đường xuyên ống tai, 
Tạp chí Nghiên cứu Y học, số 82 (2), tr 64-71. 
3. Nguyễn Thị Tố Uyên, Lương Hồng Châu, Nguyễn Tấn Phong 
(2017), Triệu chứng cơ năng của viêm tai giữa mạn tính nguy 
hiểm được phẫu thuật nội soi tiệt căn xương chũm đường xuyên 
ống tai, Tạp chí Tai Mũi Họng Việt Nam, Volume (62-37), N° 3, tr 
78-83. 
4. Nguyễn Thị Tố Uyên, Nguyễn Tấn Phong, Đoàn Thị Hồng 
Hoa, Lê Công Định (2018), Hình ảnh khám nội soi của viêm tai 
giữa mạn tính nguy hiểm được phẫu thuật nội soi tiệt căn xương 
chũm đường xuyên ống tai, Tạp chí Y học Việt Nam, tập 462, số 1, 
tr 161-164. 
5. Nguyễn Thị Tố Uyên, Nguyễn Tấn Phong, Cao Minh Thành, 
Lê Văn Khảng (2018), Đặc điểm ăn mòn xương trên phim cắt lớp 
vi tính của viêm tai giữa mạn tính nguy hiểm được phẫu thuật nội 
soi tiệt căn xương chũm đường xuyên ống tai, Tạp chí Y Dược học 
Quân sự, vol 43, số 4, tháng 4, tr 126-131. 
 1 
QUESTION 
Chronic otitis media (COM) is an inflammation that lasts more than 
3 months in the middle ear. According to the WHO, COM rate ranges 
from 1% to 4% depending on the region, Vietnam is 3% to 5%. COM can 
be dangerous by erosion of the bones which can cause serious 
complications, surgery indication is absolute, our research refers to 2 
diseases: cholesteatoma and grade IV retraction porket (uncontrolled or 
precholesteatoma). 
In the past, patients often come to treatment when lession damage 
and invasive enlargement of the mastoid region even during inflammation 
stage with serious complications such as meningitis, cerebral abscess ... 
Today dangerous COM is early diagnosis when the lesions are small and 
discreet; The CT scan of the temporal bone can determined extent of the 
lesions (focal or spread), mastoid structure. The change of disease and the 
development in diagnosis are motivation for improvement in treatment. 
With severe lesions on the sclerosis mastoid, small antre, post-auriculair or 
antero-auriculair mastoidectomy made a big and safe mastoid cavity which 
is too large for lesions with many disadvantages, on this case, the close 
technic mastoidectomy is difficult with high risk of complications and will 
be dangerous if patients do not return periodic examination and take the 
second look surgery when suspected recurrent cholesteatoma. 
Antrotomy transcanal under microscope was reported by Holt J.J in 
2008. When compare with post-auriculair and antero-auriculair, the 
transcanal is the shortest and direct entrance to antre, and well keeping 
propre mastoid cortex. Although the endoscopy (1990) was used on ear 
surgery much later than micoscopy (1950), it become the usefull 
manipulation for endoral and transcanal entrance thanks for small tip and 
wide fild. Nguyen Tan Phong (2009), Tarabachi M. (2010) reported 
endoscopy transcanal atticotomy, antrotomy. Nguyen Tan Phong (2010), 
Tarabachi M. (2013) continue to down the posterior canal wall for the 
endoscopic transcanal canal wall down (ET CWD) mastoidectomy. This 
operation is addapted with cholesteatoma or grade IV retraction pocket 
base on schlerose mastoid and small antre which made a small size of 
 2 
mastoid cavity but ensure control of disease and drainage, rapid recovery 
time, high aesthetics, can improve hearing. To improve the theoretical, 
indicative, technical contribution to disseminate surgery in ENT specialist 
we carry out the topic: “Evaluation of results of endoscopic transcanal 
canal wall down mastoidectomy for dangerous chronic otitis media” 
with 2 target: 
1. Describe the clinical, subclinical characteristics of patients with 
dangerous chronic otitis media. 
2. Evaluation of the results of endoscopic transcanal canal wall 
down mastoidectomy in patients with chronic otitis media. 
THE NEWS CONTRIBUTIONS OF THE THESIS 
1. Suggest the indication of ET CWD based on endoscopic exam and 
temporal bone CT Scan. 
2. Contribute to the scientific reasoning, point out the advantages of ET 
CWD, the difficulties and how to overcome when practice. 
3. Confirmed success of improving the hearing by tympanoplasty on the 
ET CWD at the first surgery. 
LAYOUT OF THE THESIS 
 The thesis includes 132 pages: Question 2 pages; Overview 28 
pages; Research subjects and methods 17 pages; Results 37 pages; 
Discussion 45 pages; Conclusion 2 pages; Recommendations and new 
contributions of the thesis 1 page. There are 28 pictures, 34 tables, 29 
charts. There are 106 references: Vietnamese: 21, English: 72, French: 13. 
CHAPTER 1: STUDY OVERVIEW 
1.1. Dangerous chronic otitis media: 
1.1.1. The concept: Dangerous chronic otitis media is a type of COM 
that is invasive, destroys the surrounding bone and is at risk for 
complications. Research refers to two prominent diseases are 
cholesteatoma and grade IV retraction pocket. Cholesteatoma is a 
development of epithelial squamous keratinaze (with epidermal origin) in 
the middle ear. The retraction pocket, also known as the local atelectasis, 
 3 
is divided into four degrees, in which the fourth degree is uncontrollable, 
considered cholesteatoma and the majority of surgeons have a therapeutic 
view like cholesteatoma. Through reserch decades, many authors agree 
with the view that retraction pocket are one of the pathological 
mechanisms of cholesteatoma Three characteristics are mobility, self-
cleaning, and superinfection that assess the risk of cholesteatoma, with 
patches of superficial patches and superinfection showing the highest risk. 
1.1.3. The formation and progression of cholesteatoma: the squamous 
cell of the inner layer of cover breaks into the centre, accumulates, grows, 
and invades the middle ear passively. On the other hand, the outer layer of 
the shell produces an enzyme that eats away the bone in an active way, 
cholesteatoma can gradually destroy middle ear structures by passive 
developing and active destruction of neighboring bone structures. 
1.1.5. Clinical characteristics of dangerous chronic otitis media 
1.1.5.2. Functional Symptoms: In addition to the classic symptoms can 
meet dry ear, mild hearing loss or normal hearing in dry cholesteatoma, 
grade IV retraction porket. 
1.1.5.3. Physical symptoms: Endoscopy can detect dangerous lesions but 
does not measure the extent of the lesion, but the following images are 
often present in the	
  localized lesions: 
Perforation of eardrum: Pars tensa: postero-supperior, marginal or just 
below the anteror malleus-atrium ligaments; Pars flaccida: can be erossion 
the attic wall (solid bone), sometimes scaly (brown, firmly attached). 
Perforation of the attic wall: Spongy bone, which may have granule, pus. 
Polyp: usually from attic, characteristic, covered with cholesteatoma. 
Grade IV retraction pocket: Pars flaccida: “naturally opened attic”,	
  
often. Pars tensa: postero-supperior: can invade the pars flaccida; ½ 
posterior:	
   Easy to skinned the posteiror tympanic cavity, type “faux 
perforation”; postero-inferior, anterio-supperior or total are rare. 
1.1.6. The paraclinical characteristics of dangerous COM 
1.1.6.1. Tonal audiometry: Frequent transmission or mixt hearing loss, 
may be normal hearing: ossicular chain is continue or tympan - stape fix. 
1.1.6.2. Temporal CT Scanner:	
  cholesteatoma lesions with opaque region 
in the middle ear or grade IV retraction pocket with hollow (may be partial 
 4 
opaque) in the attic, the trend is spreading into the adittus, antre;	
  regular 
erode	
  bones around, rounded bow; erode part or all ossicular. 
1.2. Canal wall down mastoidectomy: 
1.2.1. History of surgical treatment dangerous COM 
CWD mastoidectomy: Zaufal (1890) propose, Bondy (1910)	
  modify,	
  
widely used in cholesteatoma	
  safe, less recurrence, however, the posterior 
access	
   create a wide cavity with many disadvantages.	
   Thanks to the 
microscope (1950), canal wall up mastoidectomy (CWU) developt with 
highlights of listening function overwhelmed CWD until 1980, when the 
defect of recurrence of cholesteatoma and second surgery become clearly, 
the surgeons comback CWD with many improvement. Luong Sy Can 
(1975) discusses overcoming the defect of wide cavity. 
CT Scan support the transcanal access under microscope: atticotomy 
by Tos (19820, Morimitsu (1989); antrotomy by Holt J.J. (2008). 
Endoscopy ear surgery: began at 1990 by Takahashi and Thomassin 
J.M., now it's already popular in the world. Nguyen Tan Phong (2009), 
Tarabachi M. (2010): transcanal attico-addito-antrotomy. Continue 
lowering the facial nerve wall, Nguyen Tan Phong (2010), Tarabachi M. 
(2013) had done ET CWD mastoidectomy. Some Vietnamese surgeons 
(Cao Minh Thanh, Ho Le Hoai Nhan) also use endoscopy ear surgery for 
dangerous COM. 
1.2.2. Concept of CWD: destroy postero-superior ear canal wall and attic 
wall, unify mastoid, tympanic cavity and ear canal in unique cavity, 
lowering the facial nerve wall, meatoplasty; Radical mastoidectomy: 
remove the eardrum, malleus and enclume, keep the stape, clamped 
eustachian tube; Modify radical mastoidectomy: keep the eardrum, 
ossicular chain or tympanoplasty. 
1.2.3. The entrance of CWD: 3 types are postaural (drill through mastoid 
cortex to antre), preaural (drill at the same time the mastoid cortex and 
postero-anterior ear canal) and transcanal (direct drilling at attic wall and 
postero-anterior ear canal without removing the mastoid shell). 
 5 
1.2.4. Endoscopic transcanal canal wall down mastoidectomy 
1.2.4.3. Anatomical basis of ET CWD mastoidectomy 
According to Legent, Ngo Manh Son, Tran To Dung average 
mastoid cortex thickness is 12.41 ± 1.6 mm and split wall between antre 
and ear canal thickness is just about 2 – 4 mm. Compared to the classic 
postaural entrance, transcanal is the shortest access to antre. 
Figure 1.6. Vertical horizontal slice temporal bone and middle ear: 1. 
Access to antre from ouside of the mastoid; 2. Access to antre transcanal.	
  
Source: Nguyen Tan Phong (2010) miniradical mastoidectomy with 
tympanoplasty, YHTH magazine 730(8). 
Prolonged inflammation restricts the development of cells, osteitis 
lead to bone formation reaction, calcium deposition make higher bone 
density. Tran To Dung: more than 80% solid mastoid have antral bottom 
higher than canal floor (62,5% in the middle 1/3 canal wall). Solid mastoid 
often included small antre with bottom higher than canal floor so the 
CWD cavity will be small, easily ensure drainage. 
1.2.4.5. Application endoscope in CWD mastoidectomy: With wide 
viewing angles and flexible viewing position, endoscopy has made the 
transcanal more effective. When applied in CWD, instead of	
   destroy 
normal bone of mastoid cortex, just direct drilling at attic wall and postero-
anterior canal wall, it was revealed all the attique, adittus, antre. Down the 
facial nerve wall and do tympanoplasty are easy with endoscopy surgery. 
However, ET CWD only for the solid mastoid with small antre. Difference 
point with microscopy surgery also the difficulty of endoscopy is having 
only one hand for used micro instrument but it were overcomed by own 
technique. For successful application, the surgeons should be updated need 
to improve the anatomical knowledge. 
1	
  
2	
  
 6 
CHAPTER 2: OBJECTIVES AND RESEARCH METHODS 
2.1. Research subjects: 54 patients with 57 ears are diagnosed COM with 
cholesteatoma or grade IV retraction porket which are performed 
endoscopy transcanal canal wall down mastoidectomy at the ENT National 
Hospital from September 2010 to September 2013. 
2.1.1. Selection criteria 
- Patients are diagnosed COM with cholesteatoma or grade IV retraction 
porket: 
+ Clinical: at least 1 of endoscopic lesions: Pars tensa: marginal 
perforation, nacre pus	
   or uncontrolled retraction porket; Pars flaccida: 
perforation or uncontrolled retraction porket; Erosion of attical wall. 
+ Tonal audiograms: no limit of type and level of hearing loss but 
does not include progressive lesions of cochlear or auditory nerve or 
intracranial. 
+ CT Scan: Translucent blocks or hollow cavity in the middle ear 
which erosion bone: ossicular chain, attical wall, middle ear, external 
semi-circular canal, fallop; mastoid structure: compact or poor cell (but 
compact in facial wall for transcanal entrance, small antre. 
+ Evaluation in operation: local lesion, solid mastoid, small antre. 
- Be done ET CWD mastoidectomy, followed and evaluated post-op. 
- Patients and caregivers (if ≤ 18 years) agree to participate in the study. 
2.1.2. Exclusion criteria: are in inflammatory or dangerous complication 
such as meningitis, brain abscess, atrial fibrillation ; have deformed 
outer ear, middle ear; don’t follow up until the operation stable, not 
evaluated at 3 months post operation. 
2.2. Research methods 
2.2.1. Research design: prospective, intervention. 
2.2.2. Choose a convenient template: There were 54 patients with 57 
diseases ears, 3 patients were bilateral operated. All 57 ears were evaluated 
at 3 months; 50/57 at least 1 year of follow up. 
2.2.4. Research steps 
2.2.4.1. Data collection before surgery: Functional symptoms; Endoscopy 
for ear surgery and ear opposite; Tonal audiometry; Temporal bone CT. 
2.2.4.2. Steps of endoscopy transcanal CWD mastoidectomy 
 7 
Incision: Endaural access: creating a V flap at postero-superior of 
external auditory canal  ...  the ET CWD mastoidectomy for the cases which antre is 
smaller, equal or slightly larger than the ear canal and the antral bottom 
is as high as possible or equal to the ear canal floor level. 
* Narrow mastoidectomy entrance: When the mastoid is compact, the 
small antre may experience lowering meninge, encroached sigma sinus... 
making it difficult for the posterior mastoidectomy entrance. 
- Meninge down low: On the Coronal plane, use the middle ear ceiling 
and the superior wall of ear canal to compare the position of the meninges. 
There are 70% meninges which outside the antre lower than the middle ear 
ceiling, and even 14% of them close to the ear canal. 
- Sigma sinus encroachment forward: on the Axial plane, an imaginary 
line passing through the posterior wall of the antre parallel to the posterior 
wall of the ear canal, the sigma sinus as far away from this line means that 
more behind the posterior wall of antre, drilling the mastoid as easy. There 
are no difficult to apply transcanal entrance for 31.6% of sigma sinus 
encroachment forward with 17.6% same lever and 14% crossing this line. 
In summary, in the CT Scan that the meninge close to ear canal and 
the sigmoid sinus encroache on the front of posterior wall of the antre, the 
transcanal radical mastoidectomy with endoscopy is the optimal choice 
because of avoiding meninges, sigmoid sinus and still control of lesions. 
4.2. Treatment results of ET CWD mastoidectomy 
4.2.1. Surgical process 
4.2.1.1. Skin incision and meatotomy: 100% of the incision are in the ear 
canal make a V skin flap, 33.3% of the incision are pulled to anterior ear 
groove for a wider operative view and and also “meatotomy outside the 
cartilage”, do not deform the ear, ensure aesthetics, suitable for small 
radical mastoid cavity (Va/S rational). 
4.2.1.2. Drill technic of transcanal entrance 
Advantages of transcanal entrance: expressed in the safety. The posterior 
entrance should be noted within the surgical triangle to avoid expose the 
temporal lobe (superior), sigmoid sinus (posterior), the elbow and the 3rd 
 19 
segment of facial nerve (anterior) while the transcanal entrance starts from 
the attical wall (usually at the corroded bones) to adittus – antre, plus a 
wide angle viewer of endoscope should avoid the PT incident on. 
Difficulties and how to fix: the anatomical points is different with 
microscopic surgery, should be update the anatomical knowledge of 
endoscopic surgery. In the endoscopy, there is only one hand to use 
microsurgical instruments but it will be easier when apply the endoscopic 
ear surgery technique. The drilling speed should be slow to control and 
avoid collision with the optic. (We did’nt meet this problem and the 
surgical time is short because the bone have to removed less than the 
postauricular entrance). There is a risk of skin erosion due to drilling, for 
the apprentice should be longer the incision to the ear anterior groove. 
4.2.1.6. Middle ear reconstruction: recovery partial anatomy, physiology. 
* Tympanic membrane: most used under-lay techniques (except the 
external ear canal - eardrum flap) which are not only suitable for unique 
hand using microsurgical instruments but also avoids epidermal ectopic. 
* Ossicular reconstruction: There are 35 ears in which 21 
interrupted, 12 continuous and vibrant but can’t clean the cholesteatoma or 
retraction pocket, and 2 intact bone but immovable except the stape. In 
addition, 2 cases which ossicular chains were partial worn but continuous 
and vibrant are retained after total remove of cholesteatoma. Obholzer R.: 
32 cholesteatoma with continuous and vibrant chains: 53.2% displacement 
(for radical removal of cholesteatoma), 46.8% remain the ossicular. 
Ossicular reconstructive materials: 9 ears using bio-ceramic pillar 
(successfully applied by Nguyen Tan Phong, Cao Minh Thanh and Le 
Cong Dinh). In order to limit grafted rejection due to inflammatory in the 
middle ear, we use cartilage to lay-over the crest of staped and in contact 
with the eardrum, it help to supporting and strengthening the eardrum. 
Obholzer R. and Becvarovski also reconstruct the acoustic system with 
cartilage or eardrums placing directly on the stape. 
4.2.2. Follow up the results of surgery 
4.2.2.1. Catastrophe and complication: There is 1 case (1.8%) of paralysis 
peripheral facial nerve grade 4 which completely recovered after 1 month. 
Kos M.I.: 0.3% but failed to recover, Mukherjee P.: 3% with recovered 
 20 
after 2 months. Transcanal entrance is outside of the facial nerve so it 
relatively safe. However when lowering the wall should be drill carefully 
and pump enough water to avoid heating the nerve. 
4.2.2.2. Evaluation in the postoperative period 
- Inflammatory exudate flow: 77.2% does not flow. The incidence and 
timing of flow was much less than that of the posterior or anterior CWD 
technic (thanks to using a small cavity (≈ twice of the ear canal volume). 
- Time for skin covering the cavity: over half of cases in 5 weeks and 
82.4% in 6 weeks, significantly shorter than other CWD technic. Beside 
the small cavity advantage, we use temporal fascia or pericartilage or 
cartilage to lining and maximum reuse the ear canal skin flap to cover. 
4.2.2.3. Stability of CWD cavity: assessed at 50 ears which follow at least 
1 year with functional symptoms, endoscopy, audiometry. 
- Postoperative follow-up time: mean 35.1 ± 9.3 months (≈ 3 years, 12 to 
50 months), of which 86% followed at least 2 years, more than half (54%) 
followed at least 3 years (including 6 ears (12%) over 4 years (Figure 3)). 
- Improvement of functional symptoms: relatively clear, pre-op are 94% 
otorrhea and 78% earache, but post-op there are any symptom. Tinnitus 
was reduced from 72% to 6% and dizziness decreased from 24% to 6%. 
- Endoscopic evaluation of CWD cavity: 82% stable (clean or little ear 
wax), Maniu A.: 87.5% stable. Medial results: 2% (1 ear) moist, 16% 
fungal infection (local treatment only). No case of failure due to recurrent 
cholesteatoma. Stability cavity demonstrated that ET CWD 
mastoidectomy has ensured the technical standards such as lowering the 
facial nerve wall so that the antre drain into the ear canal, opening all 
narrow corners and making sure ear orifice width (Va/S	
  reasonable). 
4.2.2.4. Status of tympanic membrane in the tympanoplasty group: 
Tympanoplasty type I, II, III: N = 35. 57.2% good results with 
normal eardrums that indicate steady state of the tympanic mucosa and 
Eustachian function. 34.2% quite good with grade I, II atelectasis (without 
grade III, IV), recurrent atelectasis is difficult problems, Holt J.J.: 12.7% 
of atelectasis and 12.7% of effusion otitis. Medial results: 3 ears (8.6%) 
had small perforations that equivalent to 7.3% of Kos M.I. 
 21 
Type IV: Tympanic cavity is very small so easily affected by 
Eustachian tube function: tympanic membrane tends to pull on, 4/11 ears 
the tympanic membrane cover the Eustachian hole. 
4.2.2.5. Cholesteatoma recurrence: assessed by endoscopy, MRI 
diffusion and 2nd surgery. With an average follow-up of 3 years, we have 
not detected any case of cholesteatoma recurrence, while Kos M.I.: 6.1% 
(follow-up from 1 to 24 years, average 7 years), Chang CC. & Chen MK.: 
3.8% (follow-up over 1 year), Young M.: 3.7% (follow-up for 5 years). 
4.2.2.6. Change in audiometry post-op: 50 ears follow-up at least a year. 
- Bone conduction reserve (threshold): with N = 50, almost unchanged 
between before and after surgery (deviation of 0.05 ± 8.2 dB with p> 0.05) 
so there aren’t inner ear’s complications no damage to the hearing cells. 
This result partly confirms the safety of ET CWD mastoidectomy. 
- Hearing changes in tympanoplasty type I, II, and III: N = 34, 
eardrum reconstruction with ossicular preservation or reconstruction are 
initially successful. 
Improvement of PTA: The average PTA pre-op is 46.6 ± 16.3 dB 
and post-op is 41.3 ± 17.9 dB so PTA improved 5.3 ± 13.5 dB. 
PTA evaluation pre-op and post-op according to value range: Table 
5, no case less than 10 dB. With the PTA in the range of 11 - 20 dB 
(normal hearing): pre-op any case but post-op has 3 ears (8.8%). With 
PTA ≤ 30 dB (slight hearing loss, according to Commitee on Hearing and 
Equilibrium guideines for the evaluation of results of conductive hearing 
loss, patients can integrate into social life without hearing aids): 26.5% 
pre-op and 35.3% post-op. PTA ≤ 50 dB (mild hearing loss): 44.1% pre-op 
and increased to 70.6% post-op. 
Improvement of ABG: ABG	
  efficiency 6.5 ± 13.5 dB is not high in 
functional surgery but is good at CWD mastoidectomy. Moreover, ABG 
30.6 ± 11.1 dB pre-op is not easy to improve so 24,0 ± 9,8 dB post-op is 
relatively good. 
Looking at table 6, no case with ABG ≤ 10 dB, ABG from 11 - 20 
dB from 20.6% pre-op increase to 50% post-op. ABG ≤ 20 dB (considered 
good) so over half of cases is successful tympanoplasty. ABG ≤ 30 dB 
pre-op is 55.9% and post-op increase to 70.6%. Our hearing efficiency is 
 22 
modest in comparing with Holt J.J’s, equivalent with Minovi A.’s (42.9% 
ABG ≤ 20 dB, 9.3%> 30 dB), better than Zinis’s (30.7% ABG ≤ 20 dB). 
- Hearing variation in tympanoplasty type IV and Eustachian clog up: 
PTA’s efficiency of type IV is 3.0 ± 10.8 dB, ABG efficiency is 0.2 ± 9.6 
dB. Eustachian clog group have PTA and ABG are lower than pre-op that 
in turn -5.9 ± 24.3 dB and -8.4 ± 22.3 dB. Clog up the Eustachian tube 
equivalent to delete middle ear’s anatomy, physiology and function. The 
improvement of PTA and ABG in type IV is trivial but in comparing with 
the clog up group we can see the hearing loss is better maintained, 
suggesting that the small cavity in hypotympanic maintain phase different 
operation between round and oval window. That is worthwhile indication 
even though more complex and slightly longer than clog up Eustachian. 
CONCLUSION 
1. Clinical, subclinical characteristics of dangerous chronic otitis 
media are done endoscopic transcanal canal wall down mastoidectomy 
- Clinical: diagnosis is easy but difficult to define the limits. 
+ Functional symptoms: almost otorrhea (94.7%) and earache (75.4%) 
but some have not characteristic of cholesteatoma (20.4% transparent 
fluid, 42.6% no fetid). 
+ Endoscopy: suspicion lesion of cholesteatoma or grad IV of retraction 
pocket. The most is in the par flacida (94.7%) and attical wall (93%), the 
least at pars tensa (38,6%). 
- Audiotonal: Most are conductive and mixed hearing loss (42.1% and 
54.4%). Although 70% discontinued ossicular but ABG <35 dB (= 32.5 ± 
11.6 dB). 
- CT Scan: Very important in diagnosis and surgery. 
+ Diagnosis of dangerous chronic otitis: Translucent blocks or hollow 
cavity limited to tympany – attic – aditus – antre with: 
Bone erosion: attical wall 94.7%; ossicular chain 84.2%. 
The complicational risks by opening: meningeal middle ear roof 
17.6%, external semi-circular canal 12.3%, 2nd facial nerve 35.1%. 
+ Characteristics of mastoid and antre: important for surgical 
indications. 
 23 
Mastoid: compact (79%) or poor cell but compact in entrance (21%). 
Small antre is advantage point for transcanal entrance: 8.8% without 
antre, 91.2% with antre; Antral size and ear canal: less than 51.9%, equal 
to 40.4%, slightly larger than 7.7%; The antral base is as higher than ear 
canal base as easier for surgery: 76.9% at 1/3 supperior, 17.3% at 1/3 
middle 5.8% at 1/3 inferior of extern ear canal. 
Narrow mastoid entrance: lowered meninge 70.2% (below the 
middle ear ceiling 56.2%, close to ear canal 14%); TMB lie front 31.6% ( 
equal with posterior antral wall 17.6%, lay front of 14%). 
- Anatomopathology: some time difficult to take, 73,7% are 
cholesteatoma. 
2. Results of endoscopic transcanal canal wall down mastoidectomy 
- Surgery process: Despite have to operate by one hand but the small 
endoscope tip can flexibility put into the surgical field, the field of view is 
wider than the microscope, thus creating a complete CWD cavity to ensure 
control of lesions, drainage and tympanoplasty. 
+ Incision: Mainstream is the inside ear canal but should coordinate the 
front ear to wider operative view and do "the meatoplasty out of cartilage". 
+ Opening attic-aditus-antre: attical wall and postero-superior of ear 
canal is the safe drilling area. 
+ Lowering facial nerve wall: use anatomy points and manipulation as 
the other entrance. 
+ Tympanoplasty in 93%, clog up the Eustachian hole for 7%. 
Eardrum reconstruction: cartilage or pericartilage 66%, ear canal skin 
– eardrum flap 32.1%. 
Ossicular reconstruction: 35 ears, PORP 97.1%; 25.7% ceramic, 
74.3% cartilage. 
- Postoperative: good recovery with short time due to small cavity. 
+ Low complication rates: 1 case facial paralysis (1.8%) recovered 
completly after a month. 
+ Less inflammatory secretion: 77.2% dry ears, 22.8% less than 2 weeks. 
+ Shortest skin covering time: average 5.44 ± 0.14 weeks (4 to 8 weeks). 
- Monitoring over a year: N = 50, average time 35.1 ± 9.3 months ≈ 3 
years. 
 24 
+ Functional symptoms improved: no otorrhea and no earache; tinnitus 
and dizziness reduced. 
+ CWD cavity: 82% stable, 18% with once inflammation. 
+ Eardrum: most stable; 34.2% atelectasis grade I, II; 8.6% safe 
perforation. 
+ Cholesteatoma recurrence: any case detected. 
+ Audiometry: good results in hearing 
Safe for inner ear: no difference of bone conduction pre and post-op 
0.05 ± 8.2 dB. 
Tympanoplasty type I, II, III (34 ears): PTA efficiency 5.3 ± 13.5 
dB; PTA ≤ 20 dB (normal hearing): 8.8%; PTA ≤ 30 dB (mild hearing 
loss): 35.3%. The average ABG post-op: 24.0 ± 9.8 dB, ABG efficiency 
was 6.5 ± 13.5 dB, 50% good with ABG ≤ 20 dB, 70.6% good with ABG 
≤ 30 dB. 
Tympanoplasty type IV: PTA and ABG improve slightly but better 
than clog up Eustachian hole. 
REQUEST 
1. Dangerous chronic otitis cholesteatoma or grade IV retraction pocket 
have been indicated canal wall down mastoidectomy should use the 
endoscopic transcanal if CT Scan have some characteristics below: lesion 
reach to antre, compact mastoid or poor cell mastoid but compact in 
transcanal entrance and small antre. 
2. To perform safety and efficacy of endoscopic transcanal canal wall 
down mastoidectomy, surgeon needs to update the knowledge of ear and 
mastoid anatomy and to practice techniques of ear endoscopic surgery (use 
instrument with one hand). 
3. In general, in the canal wall down mastoidectomy and endoscopic 
transcanal canal wall down mastoidectomy if the hypotympanic cavity 
(including round windows) clean, Eustachian hole open should use the 
type IV instead of clog up the Estachian tube because of better hearing 
performance and still safe.