Surgical approaches to congenital atresia of the external auditory canal TIMOTHY B. MOLONY, MD, and ANTONIO DE LA CRUZ, MD, New Orleans. Louisiana. and Los Angeles. California
During the past 4 years, 22 patients with congenital atresia of the external aUditory canal underwent 24 Initial operations by either an anterior or transmastold approach. No attempt at randomization was made. but the two groups were similar In number and pathology (In 14 cases approach was anterior and In 10 cases approach was transmastoid). Followup ranged from 6 months to 4 years. Hearing results were similar in the two groups (71% with air-bone gap less than 30 dB). There were no Instances of facial nerve Injury or sensorineural hearing loss. Facial nerve monitoring was used. Complications of stenosis and drainage were more common with the transmastold approach. In both groups, hearing results were accomplished with the patients' Intact osslcles or prosthetic reconstructions. Meticulous soft-tissue technique, with splitthickness grafts covering all exposed bone. Is the key to preventing stenosis. For the three cases of patients with thick. acellular atresia plates, a different approach was developed. Maintaining proper orientation during the medial dissection Is more difficUlt In these cases. Byopening the antrum primarily and Identifying the lateral canal, Ossicles. and facial nerve. an ear canal can then be created anteriorly with these landmarks In view. An Intact canal wail-like procedure Iscarried out. Although hearing results are similar. the anterior approach. because of fewer postoperative complications. Is now our procedure of choice. Proper orientation and soft-tissue technique are the keys to successful correction of the congenitally atretic ear canal. (OTOLARYNGOL HEAD NECK SURG 1990;103:991.)
Obtaining consistent results in correcting congenital atresia of the external auditory canal remains a challenging task in otology. Complications, such as stenosis, drainage, and poor hearing results, can be minimized by adhering to well-established concepts and techniques. Thorough knowledge of modern tympanoplastic methods and of temporal bone anomalies in the atretic ear is a necessity. From Kiesselbach (1883), I to Cohen and Fox (1943),2 to Pattee (1947),.1 to Bellucci 4 (I 960), numerous approaches and procedures have been tried, with varying degrees of success. At present, two generally accepted techniques are used to recon-
~------------------
From the Department of Otolaryngology (Dr. Molony). Ochsner Clinic and Alton Ochsner Medical Foundation, and the House Ear Institute (Dr. de la Cruz). Presented at the Annual Meeting of the American Academy of OtOlaryngology_Head and Neck Surgery, New Orleans. La.• Sept. 24-28. 1989. Received for publication Sept. 24. 1989: revision received June 25. 1990; accepted July 10. 1990. Reprint requests: Timothy B. Molony. MD. Ochsner Clinic. 1514 Jefferson Highway. New Orleans. LA 70121.
23/1123668
struct the congenitally atretic ear canal-the anterior approach, as described by Jahrsdoerfer' in 1978 and by Mattox and Fisch" in 1985, and the transmastoid approach (with or without opening of the facial recess), as described by Bellucci," Shambaugh and Glasscock," and de la Cruz et al." (Figs. I and 2). In the past 4 years, the approach to correction of congenital atresias has changed considerably at the Otologic Medical Group. The senior author (A.D.C.) now uses the anterior approach in all atresia cases. For cases with very thick atresia plates and difficult anatomy, a modification of the anterior approach provides safer surgery and more predictable results. This report discusses and compares current methods, and describes significant modifications in technique. These modifications have made the final results more anatomically correct and more predictable. Indications, classification, and evaluation remain as discussed previously."
LITERAYURE REVIEW In 1947 Pattee.' described a technique for reconstruction of the meatus and mobilization of the stapes in cases of congenital atresia of the ear canal. This was 991
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992
OtolaryngologyHead and Neck Surgery
MOlONY and DE LA CRUZ
Anterior
NOR AL
J
I I I I
,./
ATRESIA
I
!r$i i ? .I-
-==::.:-
,.
I
Transmastold
I
)
(
Anterior Tran smastoid
+
~ 0
Fig . 2. Axial anterior and transmastoid approaches.
Fig. 1. Anterior and transmastoid approaches-lateral.
done by way of an endaural incision with a wall-down mastoidectomy. The incus and malleus were removed, leaving a mobile stapes . Split-thickness skin was used to line the cavity. No ossicular reconstruction was attempted, and results were similar to those of fenestration surgery. Also in 1947, Ombredanne? reported his results from the correction of congenital atresias by fenestration of the horizontal semicircular canal. With the advent of tympanoplasty, introduced by Wullstein' ? and Zollner, II hearing results gradually improved . Bellucci" and Crabtree" refined techniques, and described refined approaches to ossicular reconstruction and management of the cavity. Reports by Glasscock? and de la Cruz" have emphasized the safety of a transmastoid approach to identify the atresia plate and the level of the facial nerve . Hearing results with this approach are good, but occasional problems with the cavity and with late stenosis continue. Jahradoerfer' and Mattox and Fisch" have emphasized an approach to the ossicular chain by way of the atresia plate . This approach has the advantages of minimizing air-cell exposure and eliminating the drawbacks of canal walldown surgery. With no cavity to clean or drain, postoperative care is minimized. Obliteration with softtissue flaps or pate is unnecessary. Occasionally, however, this approach is technically difficult, as in
cases with a very thick atresia plate. With few landmarks in the acellular bone , orientation in these cases is difficult, and drilling and removal of the atresia plate with the ossicles intact is required . Approaching the ossicular chain by way of the atresia plate carries the potential for acoustic inner ear trauma, with subsequent sensorineural hearing loss. The approach to the atresia plate by way of the sinodural angle and mastoid antrum has the advantage of landmarks well-known to otologic surgeons. The level of the atresia plate and facial nerve is identified early in the procedure. Tympanoplasty and the creation of a new ear canal can be carried out with confidence . Acoustic trauma to the inner ear is minimized by early separation of the ossicular chain from the atresia plate . Both approaches were used in our series. Results are compared and a modification of the anterior approach is described.
SURGICAL CONSIDERATIONS At the initial visit , the patient undergoes routine audiometry, and if necessary evoked-response audiometry. Patients younger than 4 years with bilateral atresias are immediately fitted with bone-conduction aids. Patients older than 4 or 5 years with bilateral atresias and adults with unilateral atresias are considered as candidates for surgery. Computed tomographic (CT) scans with high-resolution bone programs are done in the axial
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Volume 103 Number 6 December 1990
Surgical approaches to congenital atresia of the external auditory canal
993
Fig. 3. Well-pneumatized mastoid. middle ear. Normal facial nerve and inner ear.
and coronal planes . Children with unilateral atresias and evidence of cholesteatoma, infection, or very thin atresia plates are also considered surgical candidates . Bone conduction in the involved ear should average better than 45 dB . If it is worse than 45 dB, the possibility of improved hearing-aid performance with less distortion should be discussed with the patient. Good mastoid pneumatization, normal inner and middle ear morphology, adequate oval window size, and normal facial nerve anatomy visible on the CT scan indicate a good prognosis for surgical correction (Fig. 3). Patients with poor pneumatization, contracted middle ears , and absent oval window are not candidates . In cases with severe middle ear and mastoid anomalies, surgery is not recommended. These include patients with a middle ear anterior to the condyle of the mandible and those with poor pneumatization and a facial nerve anomalously passing through or directly lateral to the middle ear. These anomalies most commonly occur in the patient with Treacher Collins syndrome. Patients with bilateral atresias should undergo operation at the age of 4 to 5 years. In the patient younger than this, difficulty of postoperative care can compromise the final result. In the patient with unilateral atresia and a normal-hearing opposite ear, delay of surgery Until adulthood is recommended. If the patient, however, has very favorable anatomy-a very thin atresia plate with ecellent pneumatization and normal middle ear ossicles and facial nerve-surgery can be performed if the parents desire it. Selection of anterior or lransmastoid approach was according to surgeon pref-
erence. The initial cases were approached by way of the transmastoid approach. With encouraging initial results from the anterior approach, the remaining cases in this series were done by way of either the anterior or modified anterior approaches. APPROACHES Anterior
A postauricular incision is made. Subcutaneous tissue is elevated anteriorly to the temporomandibular joint. Care is necessary, since an anomalous facial nerve may exit the temporal bone in this area. T-shaped periosteal incisions are made and the mastoid cortex is exposed . If a remnant of the tympanic bone is present, the new ear canal is begun above it, at the level of the middle fossa dura . If no such remnant is present, drilling is begun at the level of the linea temporalis, just posterior to the glenoid fossa (Fig . 4). There are few landmarks through the atretic bone. The dissection is carried medially and anteriorly by means of cutting and with diamond burrs. The middle fossa dura is identified and followed. In all cases, the facial nerve is continuously monitored with the Nicolet NIM-2 (Nicolet Instruments , Madison, Wis.) . The anterior epitympanum is encountered, and the fused incus/ malleus mass is identified. The incus and malleus are carefully dissected away from the atresia plate. They are left intact, if possible . The horizontal facial nerve is always medial to these structures , and therefore is relatively protected . The atresia plate is removed with diamond microdrills
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994
OlolaryngologyHead and Neck Surgery
MOLONY and DE I..A CRUZ
Fig. 4. Anterior approach,
Skin Graft
Fascia Graft
Fig. 5. Preparation of fascia graft and skin graft.
Fig. 6. Mealoplasty,
and curettes to completely expose the ossicles. Care must be taken on dissction of the inferior and posterior aspect, since the aberrant facial nerve often passes laterally through the atresia plate in this area. The ossicular chain is left intact if complete. Identification of the stapes may be difficult because of overhanging or anomalousfacial nerve anatomy. Mastoid air-cell exposure is avoided if possible. A new ear canal approximately 11/ 2 times normal size is created. A 20- X IS-mm oval of temporalis fascia is cut to fashion a tympanic membrane graft. Small 3- x 6-mm "tabs" are cut in the anterior and superior aspects of the graft (Fig. 5). The new tympanic membrane is grafted with the fascia to either the lateral surface of the intact ossicular chain or with prosthetic partial ossicular replacement prosthesis (PORP) or total ossicular replacement prosthesis (TORP) covered with onlayed cartilage. The "tabs" are placed medially into the protympanum and epitympanum. A 0.012-inch split-thickness skin graft. 6 x 6 ern, is taken from the abdomen or thigh. One edge of the graft is cut in a zig-zag fashion approximately l.S-cm deep. The new ear canal is circumferentially lined with the split-thickness skin, with the zigzags totally overlapping the reconstructed eardrum.
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VOlume103 Number 6 December 1990
Surgical approaches to congenital atresia of the external aud itory canal
995
.Skln Graft Tr nsm
toid Appro ch
.. , ,
•
I
"
,
.. . '
Fascia Graft
Fig. 7. Placement of fascia and skin grafts.
Fig. 8. Transmastold approach.
All bone in the ear canal should be covered. There should be 2 to 3 cm of excess skin laterally to line the soft tissue meatoplasty. A single layer of antibioticsoaked Gelfoam is used to hold the skin and fascia of the new eardrum in place. A disc ofO.040-inch silicone rubber is placed over this . Next, 1.5 x 6 em gauze strips impregnated with Vaseline (Sherwood Medical CO./Hospital Products D, Greenwich, Conn.) are placed in the canal lateral to the silicone rubber to make a rosebud dressing. The center is filled with small Vaseline-impregnated gauze pieces. Meatoplasty is then performed, and skin and subcutaneous cartilage and tissue are removed in a 2-cm diameter area over the new meatus (Fig. 6). The ear is turned and the skin of the canal is brought through the meatoplasty. The skin graft is attached circumferentially to the meatal skin with absorbable sutures (Fig. 7). The soft tissue of the meatus should be completely lined . The meatus is packed open widely with a rolled-up strip of Vaselineimpregnated gauze. The postauricular incision is then closed. Tran_mastold
A postauricular incision is made and continued down to the mastoid cortex. Soft tissue is elevated anteriorly, and the glenoid fossa is explored. Dissection is begun at the level of the linea temporalis, well posterior to the
temporomandibular joint. The sinodural angle is identified and followed medially to the antrum. The facial nerve is monitored continuously with the Nicolet NIM2. The lateral semicircular canal and the atresia plate are identified. The atresia plate is carefully removed. At this point incudostapedial joint separation if possible , is recommended to prevent acoustic trauma to the inner ear. Mastoid air-cell exenteration, with lowering of the facial ridge to the level of the facial nerve, is then carried out (Fig. 8). If the ossicles are intact, the temporal is fascia is grafted directly to them. If not, reconstruction is done with a PORP or TORP, with cartilage overlay followed by mastoid air-cell obliteration with soft-tissue flaps or bone pate, meatoplasty, and canal skin grafting as described previously. Anterior Approach Modlftcatlon
In patients with thick, bony atresia plates, orientation in the anterior approach is often difficult during the medial dissection . These patients typically have few air cells , making this approach particularly challenging (Fig . 9). Dissection too far in either the inferior or posterior direction risks inadvertent carotid, lateral canal, or facial nerve injury. Orientation can be achieved in these cases with initial posterior dissection and an-
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996
OtolaryngologyHead and Neck Surgery
MOLONY and DE LA CRUZ
Fig. 9. Thick atresia plate .
1
Modified Anterior Appro ch
(Fig. 10). The lateral canal can be used as a landmark to indicate depth and anterior-posterior and superiorinferior directionality, thus expediting the dissection . An intact canal wall-like procedure is carried out. Tympanic membrane grafting, meatoplasty, ossiculoplasty and ear canal grafting are carried out as described previously. CASE REPORT: MODIFIED ANTERIOR APPROACH
Fig. 10. Modified ante rior approach.
trotomy to identify the levels of the lateral canal, facial nerve, and atresia plate. A new ear canal can then be created anteriorly by drilling just posterior to the glenoid fossa and following the tegmen mastoidum medially
A 16-year-old boy had a right- sided congenital atresia of the ear canal, with a grade II microtia on that side and a rudimentary blind-sac ear canal. His left auricle and ear canal were normal. He had normal hearing on the left and a bone conduction level of 15 dB on the right , with an air conduction level of 42 dB . CT scanning indicated a very thick atresia plate and a well-pneumatized mastoid on the right (Fig. II) . Facial nerve anatomy and middle ear were normal. The right ear was approached by postauricular incis ion . A short vascular strip was made in the rudimentary ear canal and the ear was reflected forward. Drilling was begun in the ear canal at the anterior and superior aspect . Solid bone that was quite thick and acellular was encountered. There were no visible landmarks to follow . At this point attention was turned to the mastoid , where drilling was begun posteriorly and the sinodural angle was identified . The dissection was continued medially and the antrum was entered . The lateral semicircular canal was identified , the facial recess was opened. and the facial nerve was identified . With these landmarks in view . attention was directed to the ear canal. where the atresia plate was then removed. The epitympanum and the fixed, fused ossicular mass were identified . With diamond burrs, bone
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VOlume103 Number 6 December 1990
Surgical approaches to congenital atresia of the external auditory canal
997
Fig. 11. Reported case. Thick atresia plate, pneumatized mastoid.
Over the cssicular mass was carefully removed to expose the middle ear. Stapes mobility could not be determined because of the size and position of the ossicular mass. Removal of this mass revealed a mobile stapes. The middle ear was filled with Gelfoam, and a PORP was placed over the stapes with atresiaplate cartilagecovering the platform. Temporalis fascia Was used as a tympanic membrane overlay graft with a "tab" into the protympanum. Split-thickness skin was used to line the new ear canal. Gelfoam was packed lateral to the graft, followed by a disc of silicone rubber. Antibiotic-impregnated gauze was used to fill the new ear canal. Meatoplasty was carried out by incising a 2-cm circle in the skin and deep soft tissue lateral to the newly created bony meatus. Ear canal skin graft was brought out through the meatus and attached laterallyto the meatoplastyedge with absorbablesutures. The postauricular incision was closed after a wedge had been incised to retract the auricular remnant posteriorly and superiorly.The postoperativecourse was uneventful. When seen 6 months after surgery, the patient had a well-formed ear canal, with an air-bone gap of 13 dB and a speech reception threshold (SRT) of 25 dB.
METHODS AND RESULTS From 1984 to 1988, 86 patients with congenital atresia of the external auditory canal were evaluated at the Otologic Medical Group. Charts were reviewed retrospectively for data on first visit, surgical procedure, postoperative results, and complications. Surgical correction was recommended in 39 cases. From the 22 patients who underwent surgical correction, results are available in 24 ears (Table I). No
patients were unavailable for followup. There were 15 male and 7 female patients, aged 4 to 61 years. Fifteen patients had unilateral atresias and 7 had bilateral atresias. Average preoperative air-bone gap was 51 dB. Average preoperative SRT was 65 dB. Of 15 right ears and 9 left ears, 10 initial procedures were performed by way of a trans mastoid approach. Fourteen were performed by way of an anterior approach, with three of these through the modified anterior approach. Length of followup ranged from 6 months to 4 years. Success in this series is defined as a closure of the air-bone gap to within 30 dB at the last follow-up examination. Results are also reported for closure of the air-bone gap to within 20 dB. Of the 24 initial surgical procedures, 17 were eventually classified as successful, with 71 % of the patients having air-bone gaps of less than 30 dB and 50% having air-bone gaps of less than 20 dB (Table 2). SRT in the larger group ranged from 20 to 50 dB, with an average SRT of 31 dB. There were no instances of sensorineural losses. Six of the 10 transmastoid operations and 11 of the 14 anterior operations were successful. Fourteen of the 24 ears were reconstructed to their intact ossicular chain; nine of these reconstructions were successful (Table 3). Seven of eight prosthetic reconstructions were successful. In two cases, reconstruction was not performed. There were no cases of postoperative facial weakness. There were seven failures in this series. Three cases
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998 MOLONY and
OtolaryngologyHead and Neck Surgery
D! LA CRUZ
Table 1. Case descriptions
Patient
Age (yr)
6
2
3
14
Op side
Atresia
Pathology
Procedure
L
81
Pneumatized, soft-tissue stenosis. FN over OW Pneumatized, 5 rnrn atresia plate, hypoplastic malleus, normal ME Left -~ pneumatized; normal ME, FN, OW; 3 mm atresia plate: fixed stapes pneumatized; Right normal ME, FN, OW: 3 mm atresia plate: fixed stapes Pneumatized, no plate anterior FN, narrow ME, abnormal ossicles Pneumatized; normal ME, FN, OW; cholesteatom a medial to mid canal Pneumatized; bony canal stenosis: normal ME, ossicles, FN Bony canal stenosis, soft-tissue atresia, normal ME Pneumatized, thin atresia plate, ME normal Pneumatized; thin bony plate; normal FN, ME Pneumatized, normal ME, malformed ossicles Drainage, softtissue stenosis, 4 mm atresia plate. cholesteatoma in ME staoes Pneumatized; normal OW. ME. FN: thick atresia plate
ANT
R
UNI
L
BI
6 R
4
5
6
7
61
17
20
16
R
R
R
L
BI
UNI
UNI
UNI
UNI
8
12
R
UNI
9
14
L
UNI
10
18
R
UNI
11
7
12
25
L
R
BI
UNI
Reconstruction
Result [preop. AC, postop. AC/BC (ABGll*
New OW with stapes prosthesis
70,45/20
ANT
To ossicles
55, 36/10 (26)
ANT
Stapes prosthesis, incus to OW
72,47/20
Stapes prosthesis, Incus to OW
72,47/20
To ossicles. secend procedure with TORP
83,41/26
To ossicles: removal of cholesteatoma
58,24/10
To ossicles
65,45/25
ANT
ANT
ANT
ANT
Comments
(25)
(27)
(27)
(15) late fixation
2 proce-
cures. corrected With TORP at 1 year
(14)
(20)
ANT
To ossicles
72, 69/25 (44)
ANT
To ossicles
66,59/18 (41)
ANT
To ossicles
54,39/9 (20)
ANT
To ossicles
69, 69/20 (49)
Modified ANT
Modified ANT
Staged with TORP
To ossicles
60, 22110 (12)
Lateralized graft
Lateralized graft
Failure, unknown cause Staged with TORPsecond procedure
100, 65/54 (11 )
Op, Side operated on: AC, air conduction. BC, bono conoucncn: BI, [)ilateriJl Ow. oval Window, ANI, anterior, UNI, unilateral, ME, rniodle ear, EAC, external aUditory canal. TRANS, transmastoid. 'Pure-tone average, American National Standards Institute (1969)
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VOlume 103 Number6 December 1990
Surgical approaches to congenital atresia of the external auditory canal
999
Table 1. Case descriptions-(cont)
Patient
Age (yrl
Op side
Atresia
13
16
R
UNI
14
10
L
BI
-
15
5
R
BI
16
5
L
BI
17
18
R
UNI
18
18
L
UNI
19
26
R
UNI
20
30
R
UNI
21
18
R
UNI
5
R
BI
6
L
BI
22
Pathology Pneumatized thick atresia plate. normal FN. ME Pneumatized: no ear canal, 2 rnm atresia plate: normal FN. ME: cholesteotoma in ME Pneumatized: normal ME, FN
Result [preop. AC. postop. AC/BC (ABGIl*
Procedure
Reconstruction
Modified ANT
PORP
38,29/16 (13)
To ossicles
47. 38/20 (18)
TRANS
TRANS
None
60, 60/20 (40)
Pneumatized. 12 rnrn bony plate, abnormal FN (over OW) Pneumatized; soft tissue in EAC: normal ME. FN
TRANS
None
65.65/15 (50)
TRANS
To ossicles
66, 24/4 (20)
Pneumatized: 4 mm atresia plate; normal FN. ME Pneumatized: normal ME, FN
TRANS
To ossicles
69, 50/31 (19)
TRANS
To ossicles
77.67/20 (47)
TRANS
To ossicles
65,30/15 (15)
TRANS
To ossicles
80, 65/35 (30)
Pneumatized; normal ME, FN
TRANS
PORP
59 49/6 (43)
Borderline pneumatization, lateral FN
TRANS
PORP
59,17/1 (16)
Pneumatized; deformed ossicles: normal ME. FN Pneumatized; normal ME, FN; abnormal ossicles
showed varying degrees of lateralization and stenosis30-dB air-bone gap)
During the past 4 years, 22 patients with congenital atresia of the external aUditory canal underwent 24 Initial operations by either an anterior or transmastold approach. No attempt at randomization was made. but the two groups were similar In number and pathology (In 14 cases approach was anterior and In 10 cases approach was transmastoid). Followup ranged from 6 months to 4 years. Hearing results were similar in the two groups (71% with air-bone gap less than 30 dB). There were no Instances of facial nerve Injury or sensorineural hearing loss. Facial nerve monitoring was used. Complications of stenosis and drainage were more common with the transmastold approach. In both groups, hearing results were accomplished with the patients' Intact osslcles or prosthetic reconstructions. Meticulous soft-tissue technique, with splitthickness grafts covering all exposed bone. Is the key to preventing stenosis. For the three cases of patients with thick. acellular atresia plates, a different approach was developed. Maintaining proper orientation during the medial dissection Is more difficUlt In these cases. Byopening the antrum primarily and Identifying the lateral canal, Ossicles. and facial nerve. an ear canal can then be created anteriorly with these landmarks In view. An Intact canal wail-like procedure Iscarried out. Although hearing results are similar. the anterior approach. because of fewer postoperative complications. Is now our procedure of choice. Proper orientation and soft-tissue technique are the keys to successful correction of the congenitally atretic ear canal. (OTOLARYNGOL HEAD NECK SURG 1990;103:991.)
Obtaining consistent results in correcting congenital atresia of the external auditory canal remains a challenging task in otology. Complications, such as stenosis, drainage, and poor hearing results, can be minimized by adhering to well-established concepts and techniques. Thorough knowledge of modern tympanoplastic methods and of temporal bone anomalies in the atretic ear is a necessity. From Kiesselbach (1883), I to Cohen and Fox (1943),2 to Pattee (1947),.1 to Bellucci 4 (I 960), numerous approaches and procedures have been tried, with varying degrees of success. At present, two generally accepted techniques are used to recon-
~------------------
From the Department of Otolaryngology (Dr. Molony). Ochsner Clinic and Alton Ochsner Medical Foundation, and the House Ear Institute (Dr. de la Cruz). Presented at the Annual Meeting of the American Academy of OtOlaryngology_Head and Neck Surgery, New Orleans. La.• Sept. 24-28. 1989. Received for publication Sept. 24. 1989: revision received June 25. 1990; accepted July 10. 1990. Reprint requests: Timothy B. Molony. MD. Ochsner Clinic. 1514 Jefferson Highway. New Orleans. LA 70121.
23/1123668
struct the congenitally atretic ear canal-the anterior approach, as described by Jahrsdoerfer' in 1978 and by Mattox and Fisch" in 1985, and the transmastoid approach (with or without opening of the facial recess), as described by Bellucci," Shambaugh and Glasscock," and de la Cruz et al." (Figs. I and 2). In the past 4 years, the approach to correction of congenital atresias has changed considerably at the Otologic Medical Group. The senior author (A.D.C.) now uses the anterior approach in all atresia cases. For cases with very thick atresia plates and difficult anatomy, a modification of the anterior approach provides safer surgery and more predictable results. This report discusses and compares current methods, and describes significant modifications in technique. These modifications have made the final results more anatomically correct and more predictable. Indications, classification, and evaluation remain as discussed previously."
LITERAYURE REVIEW In 1947 Pattee.' described a technique for reconstruction of the meatus and mobilization of the stapes in cases of congenital atresia of the ear canal. This was 991
Downloaded from oto.sagepub.com at NANYANG TECH UNIV LIBRARY on June 5, 2016
992
OtolaryngologyHead and Neck Surgery
MOlONY and DE LA CRUZ
Anterior
NOR AL
J
I I I I
,./
ATRESIA
I
!r$i i ? .I-
-==::.:-
,.
I
Transmastold
I
)
(
Anterior Tran smastoid
+
~ 0
Fig . 2. Axial anterior and transmastoid approaches.
Fig. 1. Anterior and transmastoid approaches-lateral.
done by way of an endaural incision with a wall-down mastoidectomy. The incus and malleus were removed, leaving a mobile stapes . Split-thickness skin was used to line the cavity. No ossicular reconstruction was attempted, and results were similar to those of fenestration surgery. Also in 1947, Ombredanne? reported his results from the correction of congenital atresias by fenestration of the horizontal semicircular canal. With the advent of tympanoplasty, introduced by Wullstein' ? and Zollner, II hearing results gradually improved . Bellucci" and Crabtree" refined techniques, and described refined approaches to ossicular reconstruction and management of the cavity. Reports by Glasscock? and de la Cruz" have emphasized the safety of a transmastoid approach to identify the atresia plate and the level of the facial nerve . Hearing results with this approach are good, but occasional problems with the cavity and with late stenosis continue. Jahradoerfer' and Mattox and Fisch" have emphasized an approach to the ossicular chain by way of the atresia plate . This approach has the advantages of minimizing air-cell exposure and eliminating the drawbacks of canal walldown surgery. With no cavity to clean or drain, postoperative care is minimized. Obliteration with softtissue flaps or pate is unnecessary. Occasionally, however, this approach is technically difficult, as in
cases with a very thick atresia plate. With few landmarks in the acellular bone , orientation in these cases is difficult, and drilling and removal of the atresia plate with the ossicles intact is required . Approaching the ossicular chain by way of the atresia plate carries the potential for acoustic inner ear trauma, with subsequent sensorineural hearing loss. The approach to the atresia plate by way of the sinodural angle and mastoid antrum has the advantage of landmarks well-known to otologic surgeons. The level of the atresia plate and facial nerve is identified early in the procedure. Tympanoplasty and the creation of a new ear canal can be carried out with confidence . Acoustic trauma to the inner ear is minimized by early separation of the ossicular chain from the atresia plate . Both approaches were used in our series. Results are compared and a modification of the anterior approach is described.
SURGICAL CONSIDERATIONS At the initial visit , the patient undergoes routine audiometry, and if necessary evoked-response audiometry. Patients younger than 4 years with bilateral atresias are immediately fitted with bone-conduction aids. Patients older than 4 or 5 years with bilateral atresias and adults with unilateral atresias are considered as candidates for surgery. Computed tomographic (CT) scans with high-resolution bone programs are done in the axial
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Volume 103 Number 6 December 1990
Surgical approaches to congenital atresia of the external auditory canal
993
Fig. 3. Well-pneumatized mastoid. middle ear. Normal facial nerve and inner ear.
and coronal planes . Children with unilateral atresias and evidence of cholesteatoma, infection, or very thin atresia plates are also considered surgical candidates . Bone conduction in the involved ear should average better than 45 dB . If it is worse than 45 dB, the possibility of improved hearing-aid performance with less distortion should be discussed with the patient. Good mastoid pneumatization, normal inner and middle ear morphology, adequate oval window size, and normal facial nerve anatomy visible on the CT scan indicate a good prognosis for surgical correction (Fig. 3). Patients with poor pneumatization, contracted middle ears , and absent oval window are not candidates . In cases with severe middle ear and mastoid anomalies, surgery is not recommended. These include patients with a middle ear anterior to the condyle of the mandible and those with poor pneumatization and a facial nerve anomalously passing through or directly lateral to the middle ear. These anomalies most commonly occur in the patient with Treacher Collins syndrome. Patients with bilateral atresias should undergo operation at the age of 4 to 5 years. In the patient younger than this, difficulty of postoperative care can compromise the final result. In the patient with unilateral atresia and a normal-hearing opposite ear, delay of surgery Until adulthood is recommended. If the patient, however, has very favorable anatomy-a very thin atresia plate with ecellent pneumatization and normal middle ear ossicles and facial nerve-surgery can be performed if the parents desire it. Selection of anterior or lransmastoid approach was according to surgeon pref-
erence. The initial cases were approached by way of the transmastoid approach. With encouraging initial results from the anterior approach, the remaining cases in this series were done by way of either the anterior or modified anterior approaches. APPROACHES Anterior
A postauricular incision is made. Subcutaneous tissue is elevated anteriorly to the temporomandibular joint. Care is necessary, since an anomalous facial nerve may exit the temporal bone in this area. T-shaped periosteal incisions are made and the mastoid cortex is exposed . If a remnant of the tympanic bone is present, the new ear canal is begun above it, at the level of the middle fossa dura . If no such remnant is present, drilling is begun at the level of the linea temporalis, just posterior to the glenoid fossa (Fig . 4). There are few landmarks through the atretic bone. The dissection is carried medially and anteriorly by means of cutting and with diamond burrs. The middle fossa dura is identified and followed. In all cases, the facial nerve is continuously monitored with the Nicolet NIM-2 (Nicolet Instruments , Madison, Wis.) . The anterior epitympanum is encountered, and the fused incus/ malleus mass is identified. The incus and malleus are carefully dissected away from the atresia plate. They are left intact, if possible . The horizontal facial nerve is always medial to these structures , and therefore is relatively protected . The atresia plate is removed with diamond microdrills
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994
OlolaryngologyHead and Neck Surgery
MOLONY and DE I..A CRUZ
Fig. 4. Anterior approach,
Skin Graft
Fascia Graft
Fig. 5. Preparation of fascia graft and skin graft.
Fig. 6. Mealoplasty,
and curettes to completely expose the ossicles. Care must be taken on dissction of the inferior and posterior aspect, since the aberrant facial nerve often passes laterally through the atresia plate in this area. The ossicular chain is left intact if complete. Identification of the stapes may be difficult because of overhanging or anomalousfacial nerve anatomy. Mastoid air-cell exposure is avoided if possible. A new ear canal approximately 11/ 2 times normal size is created. A 20- X IS-mm oval of temporalis fascia is cut to fashion a tympanic membrane graft. Small 3- x 6-mm "tabs" are cut in the anterior and superior aspects of the graft (Fig. 5). The new tympanic membrane is grafted with the fascia to either the lateral surface of the intact ossicular chain or with prosthetic partial ossicular replacement prosthesis (PORP) or total ossicular replacement prosthesis (TORP) covered with onlayed cartilage. The "tabs" are placed medially into the protympanum and epitympanum. A 0.012-inch split-thickness skin graft. 6 x 6 ern, is taken from the abdomen or thigh. One edge of the graft is cut in a zig-zag fashion approximately l.S-cm deep. The new ear canal is circumferentially lined with the split-thickness skin, with the zigzags totally overlapping the reconstructed eardrum.
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VOlume103 Number 6 December 1990
Surgical approaches to congenital atresia of the external aud itory canal
995
.Skln Graft Tr nsm
toid Appro ch
.. , ,
•
I
"
,
.. . '
Fascia Graft
Fig. 7. Placement of fascia and skin grafts.
Fig. 8. Transmastold approach.
All bone in the ear canal should be covered. There should be 2 to 3 cm of excess skin laterally to line the soft tissue meatoplasty. A single layer of antibioticsoaked Gelfoam is used to hold the skin and fascia of the new eardrum in place. A disc ofO.040-inch silicone rubber is placed over this . Next, 1.5 x 6 em gauze strips impregnated with Vaseline (Sherwood Medical CO./Hospital Products D, Greenwich, Conn.) are placed in the canal lateral to the silicone rubber to make a rosebud dressing. The center is filled with small Vaseline-impregnated gauze pieces. Meatoplasty is then performed, and skin and subcutaneous cartilage and tissue are removed in a 2-cm diameter area over the new meatus (Fig. 6). The ear is turned and the skin of the canal is brought through the meatoplasty. The skin graft is attached circumferentially to the meatal skin with absorbable sutures (Fig. 7). The soft tissue of the meatus should be completely lined . The meatus is packed open widely with a rolled-up strip of Vaselineimpregnated gauze. The postauricular incision is then closed. Tran_mastold
A postauricular incision is made and continued down to the mastoid cortex. Soft tissue is elevated anteriorly, and the glenoid fossa is explored. Dissection is begun at the level of the linea temporalis, well posterior to the
temporomandibular joint. The sinodural angle is identified and followed medially to the antrum. The facial nerve is monitored continuously with the Nicolet NIM2. The lateral semicircular canal and the atresia plate are identified. The atresia plate is carefully removed. At this point incudostapedial joint separation if possible , is recommended to prevent acoustic trauma to the inner ear. Mastoid air-cell exenteration, with lowering of the facial ridge to the level of the facial nerve, is then carried out (Fig. 8). If the ossicles are intact, the temporal is fascia is grafted directly to them. If not, reconstruction is done with a PORP or TORP, with cartilage overlay followed by mastoid air-cell obliteration with soft-tissue flaps or bone pate, meatoplasty, and canal skin grafting as described previously. Anterior Approach Modlftcatlon
In patients with thick, bony atresia plates, orientation in the anterior approach is often difficult during the medial dissection . These patients typically have few air cells , making this approach particularly challenging (Fig . 9). Dissection too far in either the inferior or posterior direction risks inadvertent carotid, lateral canal, or facial nerve injury. Orientation can be achieved in these cases with initial posterior dissection and an-
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996
OtolaryngologyHead and Neck Surgery
MOLONY and DE LA CRUZ
Fig. 9. Thick atresia plate .
1
Modified Anterior Appro ch
(Fig. 10). The lateral canal can be used as a landmark to indicate depth and anterior-posterior and superiorinferior directionality, thus expediting the dissection . An intact canal wall-like procedure is carried out. Tympanic membrane grafting, meatoplasty, ossiculoplasty and ear canal grafting are carried out as described previously. CASE REPORT: MODIFIED ANTERIOR APPROACH
Fig. 10. Modified ante rior approach.
trotomy to identify the levels of the lateral canal, facial nerve, and atresia plate. A new ear canal can then be created anteriorly by drilling just posterior to the glenoid fossa and following the tegmen mastoidum medially
A 16-year-old boy had a right- sided congenital atresia of the ear canal, with a grade II microtia on that side and a rudimentary blind-sac ear canal. His left auricle and ear canal were normal. He had normal hearing on the left and a bone conduction level of 15 dB on the right , with an air conduction level of 42 dB . CT scanning indicated a very thick atresia plate and a well-pneumatized mastoid on the right (Fig. II) . Facial nerve anatomy and middle ear were normal. The right ear was approached by postauricular incis ion . A short vascular strip was made in the rudimentary ear canal and the ear was reflected forward. Drilling was begun in the ear canal at the anterior and superior aspect . Solid bone that was quite thick and acellular was encountered. There were no visible landmarks to follow . At this point attention was turned to the mastoid , where drilling was begun posteriorly and the sinodural angle was identified . The dissection was continued medially and the antrum was entered . The lateral semicircular canal was identified , the facial recess was opened. and the facial nerve was identified . With these landmarks in view . attention was directed to the ear canal. where the atresia plate was then removed. The epitympanum and the fixed, fused ossicular mass were identified . With diamond burrs, bone
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VOlume103 Number 6 December 1990
Surgical approaches to congenital atresia of the external auditory canal
997
Fig. 11. Reported case. Thick atresia plate, pneumatized mastoid.
Over the cssicular mass was carefully removed to expose the middle ear. Stapes mobility could not be determined because of the size and position of the ossicular mass. Removal of this mass revealed a mobile stapes. The middle ear was filled with Gelfoam, and a PORP was placed over the stapes with atresiaplate cartilagecovering the platform. Temporalis fascia Was used as a tympanic membrane overlay graft with a "tab" into the protympanum. Split-thickness skin was used to line the new ear canal. Gelfoam was packed lateral to the graft, followed by a disc of silicone rubber. Antibiotic-impregnated gauze was used to fill the new ear canal. Meatoplasty was carried out by incising a 2-cm circle in the skin and deep soft tissue lateral to the newly created bony meatus. Ear canal skin graft was brought out through the meatus and attached laterallyto the meatoplastyedge with absorbablesutures. The postauricular incision was closed after a wedge had been incised to retract the auricular remnant posteriorly and superiorly.The postoperativecourse was uneventful. When seen 6 months after surgery, the patient had a well-formed ear canal, with an air-bone gap of 13 dB and a speech reception threshold (SRT) of 25 dB.
METHODS AND RESULTS From 1984 to 1988, 86 patients with congenital atresia of the external auditory canal were evaluated at the Otologic Medical Group. Charts were reviewed retrospectively for data on first visit, surgical procedure, postoperative results, and complications. Surgical correction was recommended in 39 cases. From the 22 patients who underwent surgical correction, results are available in 24 ears (Table I). No
patients were unavailable for followup. There were 15 male and 7 female patients, aged 4 to 61 years. Fifteen patients had unilateral atresias and 7 had bilateral atresias. Average preoperative air-bone gap was 51 dB. Average preoperative SRT was 65 dB. Of 15 right ears and 9 left ears, 10 initial procedures were performed by way of a trans mastoid approach. Fourteen were performed by way of an anterior approach, with three of these through the modified anterior approach. Length of followup ranged from 6 months to 4 years. Success in this series is defined as a closure of the air-bone gap to within 30 dB at the last follow-up examination. Results are also reported for closure of the air-bone gap to within 20 dB. Of the 24 initial surgical procedures, 17 were eventually classified as successful, with 71 % of the patients having air-bone gaps of less than 30 dB and 50% having air-bone gaps of less than 20 dB (Table 2). SRT in the larger group ranged from 20 to 50 dB, with an average SRT of 31 dB. There were no instances of sensorineural losses. Six of the 10 transmastoid operations and 11 of the 14 anterior operations were successful. Fourteen of the 24 ears were reconstructed to their intact ossicular chain; nine of these reconstructions were successful (Table 3). Seven of eight prosthetic reconstructions were successful. In two cases, reconstruction was not performed. There were no cases of postoperative facial weakness. There were seven failures in this series. Three cases
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998 MOLONY and
OtolaryngologyHead and Neck Surgery
D! LA CRUZ
Table 1. Case descriptions
Patient
Age (yr)
6
2
3
14
Op side
Atresia
Pathology
Procedure
L
81
Pneumatized, soft-tissue stenosis. FN over OW Pneumatized, 5 rnrn atresia plate, hypoplastic malleus, normal ME Left -~ pneumatized; normal ME, FN, OW; 3 mm atresia plate: fixed stapes pneumatized; Right normal ME, FN, OW: 3 mm atresia plate: fixed stapes Pneumatized, no plate anterior FN, narrow ME, abnormal ossicles Pneumatized; normal ME, FN, OW; cholesteatom a medial to mid canal Pneumatized; bony canal stenosis: normal ME, ossicles, FN Bony canal stenosis, soft-tissue atresia, normal ME Pneumatized, thin atresia plate, ME normal Pneumatized; thin bony plate; normal FN, ME Pneumatized, normal ME, malformed ossicles Drainage, softtissue stenosis, 4 mm atresia plate. cholesteatoma in ME staoes Pneumatized; normal OW. ME. FN: thick atresia plate
ANT
R
UNI
L
BI
6 R
4
5
6
7
61
17
20
16
R
R
R
L
BI
UNI
UNI
UNI
UNI
8
12
R
UNI
9
14
L
UNI
10
18
R
UNI
11
7
12
25
L
R
BI
UNI
Reconstruction
Result [preop. AC, postop. AC/BC (ABGll*
New OW with stapes prosthesis
70,45/20
ANT
To ossicles
55, 36/10 (26)
ANT
Stapes prosthesis, incus to OW
72,47/20
Stapes prosthesis, Incus to OW
72,47/20
To ossicles. secend procedure with TORP
83,41/26
To ossicles: removal of cholesteatoma
58,24/10
To ossicles
65,45/25
ANT
ANT
ANT
ANT
Comments
(25)
(27)
(27)
(15) late fixation
2 proce-
cures. corrected With TORP at 1 year
(14)
(20)
ANT
To ossicles
72, 69/25 (44)
ANT
To ossicles
66,59/18 (41)
ANT
To ossicles
54,39/9 (20)
ANT
To ossicles
69, 69/20 (49)
Modified ANT
Modified ANT
Staged with TORP
To ossicles
60, 22110 (12)
Lateralized graft
Lateralized graft
Failure, unknown cause Staged with TORPsecond procedure
100, 65/54 (11 )
Op, Side operated on: AC, air conduction. BC, bono conoucncn: BI, [)ilateriJl Ow. oval Window, ANI, anterior, UNI, unilateral, ME, rniodle ear, EAC, external aUditory canal. TRANS, transmastoid. 'Pure-tone average, American National Standards Institute (1969)
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VOlume 103 Number6 December 1990
Surgical approaches to congenital atresia of the external auditory canal
999
Table 1. Case descriptions-(cont)
Patient
Age (yrl
Op side
Atresia
13
16
R
UNI
14
10
L
BI
-
15
5
R
BI
16
5
L
BI
17
18
R
UNI
18
18
L
UNI
19
26
R
UNI
20
30
R
UNI
21
18
R
UNI
5
R
BI
6
L
BI
22
Pathology Pneumatized thick atresia plate. normal FN. ME Pneumatized: no ear canal, 2 rnm atresia plate: normal FN. ME: cholesteotoma in ME Pneumatized: normal ME, FN
Result [preop. AC. postop. AC/BC (ABGIl*
Procedure
Reconstruction
Modified ANT
PORP
38,29/16 (13)
To ossicles
47. 38/20 (18)
TRANS
TRANS
None
60, 60/20 (40)
Pneumatized. 12 rnrn bony plate, abnormal FN (over OW) Pneumatized; soft tissue in EAC: normal ME. FN
TRANS
None
65.65/15 (50)
TRANS
To ossicles
66, 24/4 (20)
Pneumatized: 4 mm atresia plate; normal FN. ME Pneumatized: normal ME, FN
TRANS
To ossicles
69, 50/31 (19)
TRANS
To ossicles
77.67/20 (47)
TRANS
To ossicles
65,30/15 (15)
TRANS
To ossicles
80, 65/35 (30)
Pneumatized; normal ME, FN
TRANS
PORP
59 49/6 (43)
Borderline pneumatization, lateral FN
TRANS
PORP
59,17/1 (16)
Pneumatized; deformed ossicles: normal ME. FN Pneumatized; normal ME, FN; abnormal ossicles
showed varying degrees of lateralization and stenosis
