The Journal of Laryngology and Otology September 1990. Vol. 104, pp. 685-689
Tympanosclerosis of the middle ear: Late results of surgical treatment MIRKOTOS, TORBEN LAU, HELGE ARNDAL, S0REN PLATE
(Copenhagen, Denmark)
Abstract The late results of one stage operation for middle ear tymanosclerosis in 73 patients during the period January 1965 to December 1980 are presented. Mean observation time was 11.2 years (range 3-20.2 years), with a follow-up rate 86 per cent. Among 64 patients with stapes fixation, 59 had removal of tympanosclerotic masses and stapes mobilization, and five cases underwent stapedectomy. The series was divided into six groups and the results analyzed. The best and most stable results occurred in the group with stapes mobilization and an intact ossicular chain followed by the group with stapes mobilization and Type II tympanoplasty with incus interposition. The poorest late results were obtained in ears with lacking stapes crura and stapes mobilization, and in ears subjected to stapedectomy. No case of post-operative sensorineural hearing loss occurred. We recommend that care is taken to preserve an intact ossicular chain at stapes mobilization performed at the same stage as myringoplasty. Also in ears with a defective ossicular chain but intact stapes with tympanosclerotic fixation we recommend stapes mobilization in one stage. In ears with fixation of the stapes footplate and defective crura, we recommend stapedectomy or stapedotomy in two stages.
piece by piece and stapediolysis, (b) stapedectomy, or (c) stapedotomy. Zollner (1963, 1969) recommended removal of tympanosclerotic masses piece by piece with mobilization of the stapes and reported a primary hearing gain of 10 dB or more in 93 per cent of the cases. Charachon et al. (1981) recommended removal of the tympanosclerotic masses from the ossicles, mobilization of the malleus and incus at the first operation, and mobilization of the stapes and interposition at the second stage. Following removal of the tympanosclerosis and stapes mobilization, Smyth (1972) reported closure of the airbone gap within 10 dB in 54 per cent of the ears. At the same time, sensorineural hearing impairment occurred in 17 per cent. Stapedectomy performed in two stages resulted primarily in closure of the air-bone gap within 10 dB in 85 per cent and no case of sensorineural hearing loss. Smyth (1972) also recommended that the stapedectomy should be performed at least six months after myringoplasty. Gibb (1976) achieved a primary air-bone gap closure within 10 dB in 65 per cent of ears undergoing stapedectomy. In a later series of ears treated with stapedectomy, with covering of the niche with perichondrium and an L-shaped cartilage columella, Smyth (1980) obtained a primary air-bone gap closure within 10 dB in 80 per cent of ears as opposed to 77 per cent using a TORP. The only study available on the late results in middle ear tympansoclerosis is a follow-up study of Smyth's stapedectomy series (Gormly, 1987), comprising 61 ears with large fenestra and six cases with small fenestra stapedectomy. The follow-up period exceeded five years in 72 per cent of cases and ten years in 54 per cent of the ears. Hearing deteriorated considerably during the
Introduction
Tympanosclerosis signifies a hyaline degeneration of the fibrous and elastic fibres in the lamina propria of the tympanic membrane and middle ear mucosa. It is extremely frequent in chronic otitis and its sequelae, as well as after secretory otitis (MacKinnon, 1971; Mawson and Fagan, 1972; Bonding and Lorenzen, 1974; Kokko, 1975; Tos and Poulsen, 1976, 1979), especially in ears treated with grommets (Kilby et al., 1972; Tos et al., 1983). The clinical term "tympanosclerosis of the middle ear' was first defined by Troltsch (1869) as a stiffness of the fibrous tissue in the deepest layer of the middle ear mucosafixingthe stapes in the oval niche and/or the malleus and incus in the attic. Actual clinical recognition of tympanosclerosis first began with Zollner and Beck (1955) and was followed by numerous clinical and histological reports on aetiology, pathogenesis, in relation to cholesteatoma as well as treatment methods (Zollner 1956, 1963, 1969; House and Sheehy, 1960; Goodhill, 1960; Sheehy and House, 1962; Chang, 1969; Friedmann, 1971; Smyth, 1972). Today, there is general agreement that tympanosclerosis is an irreversible, non-specific end-result of any chronic inflammation or infection of the middle ear (Friedmann, 1971; S0rensen and True, 1971; Tos and Bak-Pedersen, 1974; Friedmann and Galey, 1980; Mann et al., 1980; Schiff et al., 1980; Mailer, 1981). There is still disagreement, however, about the surgical treatment of the condition. The following surgical priniciples have been employed in middle ear tympanosclerosis in cases with stapes fixation: (a) removal of tympanosclerotic masses Accepted for publication: 30 June 1990. 685
686
M. TOS. T. LAU. H. ARNDAL. S. PLATE
TABLE I
TABLE II
AGE AT OPERATION
Tympanosclerosis—Pathology (73)
Years
No.
11-20 21-30 31-40 41-50 51-60 61-70 > 70
3 5 8 11 31 13 2
Total
73
observation period; thus, an air-bone gap closure within 10 dB was maintained in only 13 per cent of ears and within 20 dB in 40 per cent. Only 8 per cent had an absolute hearing within 20 dB, 22 per cent within 30 dB, and two ears were deaf. The aim of the present study is to present the late results obtained in a series of ears, in which stapediolysis was performed as a rule in one stage, and compare them with the well-documented late results of stapedectomy reported in the above-mentioned study (Gormly, 1987). We hope in this way to provide a more differentiated view of the treatment of tympanosclerosis.
Series and methods The present series comprises 73 patients consecutively undergoing surgery in one stage for middle ear tympanosclerosis from January 1965 to December 1980. Postoperatively, the patients were seen regularly in the outpatients' clinic for up to two years and since then at follow-up several times, most recently in December
Drum:
Perforation Intact
—60 —13
Stapes:
Mobile ( 9), Fixed (64)
Type I (3) Type II (6) Stapedectomy (5) Stapediolysis (59)
Intact chain (28): Remained intact Disrupted Disrupted Crura intact (28) Crura missing (8)
Type I Type 11 Stapedectomy Type II Type III Type IV
(12) (11) (5) (28) (7) (1)
1989. A total of 86 per cent appeared for reevaluation. Mean observation time was 11.2 years, range 3-20.2 years. The time elapsing from surgery to last follow-up was 3-5 years in 10 per cent of the cases, 6-10 years in 33 per cent, 11-15 years in 23 per cent, and 16-21 years in 21 per cent of the ears. The series shows a preponderance of women (52 vs. 21 men). More than half of the patients were over 50 years of age at the time of surgery (Table I); median age was 54.5 years. The pathological findings varied greatly (Table II) and were subdivided into eardrum perforation, tympanosclerosis, stapes fixation, and ossicular chain defects. Sixty patients with eardrum perforation, mainly posterior, underwent myringoplasty with fascia. Nine cases had a mobile stapes but tympanosclerotic fixation of the incus and malleus in the attic. The tympanosclerotic masses were removed at atticotomy. The ossicular chain was intact in three of these cases and
TABLE III TYMPANOSCLEROSIS OF THE MIDDLE EAR, PRIMARY AND LATE RESULTS
Absolute hearing
SRT
0-20 dB %
0-30 dB %
0-40 dB %
0-20 dB %
0-30 dB %
9 9 9
11 33 22
11 44 44
11 33 11
22
22 11
Preopr. Prim. Late
12 12 10
_ 17 10
_ 67 30
8 83 60
Preopr. 3. Intact Chain Prim. Interupted Late
11 11 10
_ 9 -
_ 27 10
4. Defective Incus
Preopr. Prim. Late
28 28 23
_ 14 9
5. Defective Stapes
Preopr. Prim. Late
8 8 7
6. Stapedectomy
Preopr. Prim. Late
5 5 4
Total material
Preopr. Prim. Late
73 73 63
Pathology groups
No.
Preopr. 1. Without Fixation of Prim. Stapes Late 2. Intact Chain
Hearing gain
Air-bone gap 0-10 dB %
0-20 dB %
0-30 dB %
>20 dB %
>10 dB %
1-10 dB %
no gain in dB %
deterioration in dB %
44 33
67 22
_ 89 89
44 89 100
67 44
89 89
11 11
-
_ -
_ 42 20
_ 75 50
_ 58 30
_ 100 60
8 100 100
75 50
83 80
17 -
-
20
_ 45 20
_ 18 -
_ 55 20
_ 36 20
_ 45 40
27 82 70
55 20
64 50
27 30
9 20
-
_ 39 17
_ 54 30
_ 25 13
_ 43 22
_ 39 22
_ 61 35
4 79 64
71 30
79 52
18 26
4 -
22
_ -
_ 25 -
50 -
_ -
25 -
_ 50 -
_ 75 29
13 88 71
75 29
75 71
13 14
-
13 14
_ 20 _ 14 6
_ 40 -
_ 40 -
_ -
20 25
80 25
100 25
100 100
100 25
100 75
25
-
-
1 40 16
3 56 32
1 23 10
3 47 25
_ 49 21
_ 73 46
14 86 78
70 35
79 62
16 22
3 3
1 13
687
TYMPANOSCLEROSIS OF THE MIDDLE EAR
dB k SRT 20 :
Tympanosclerosis
P—°
2 Operation Gr. Gr. Gr. Gr. Gr. Gr.
10
15
20
Years, postoperativeiy 1 2 3 4 5 6
• • O O X X • • O-•••O A A
Without stapes fixation Intact chain Intact chain -» disrupted Stapes crura intact Stapes crura missing Stapedectomy
with stapes fixation
Air-bone gap
T2
5
10
Operation
15 20 Years, postoperativeiy
1 Long-term correlation of mean SRT and mean air-bone gap in various groups of tympanosclerosis. FIG.
defective in six which underwent tympanoplasty Type II with incus interposition (Table II). In 64 cases with stapes fixation, the tympanosclerotic masses were removed piecemeal and stapes was mobilized; infivecases a large fenestra stapedectomy was performed, with covering of the niche with fascia and placement of a steel wire on the intact long process of the incus (Table II). In 28 ears with stapes fixation, the ossicular chain was intact primarily and could be preserved intact in 12 ears. In 11 cases it was disrupted in order to ease resection of tympanosclerosis from the stapes and stapedial niche. An autologous incus was interposed between the mobilized stapes and the tympanic membrane (Table II). In five other cases the ossicular chain was disrupted at stapedectomy. In 28 cases with a defective incus, the tympanosclerotic masses were removed from the stapedial niche and stapes, and the latter was mobilized. An autologous incus was interposed between the mobilized stapes and the tympanic membrane (Table II). Finally, in eight cases with defective stapedial crura the footplate was cleaned and mobilized. In seven cases a columella of autologous incus was positioned between the footplate and the tympanic membrane, and in one case a Type IV was performed (Table II).
Results The series could be divided into six groups that were analyzed separately (Table III). The hearing results were evaluated in the frequency range 500-2000 Hz using four different methods in addition to speech audiometry. Here, the primary result refers to the last audiogram taken within the first two years post-operatively and the late result to the audiogram at the last follow-up. Group I: Ears without stapes fixation (nine ears). The late results are fairly good, especially as evaluated by the air-bone gap method (Table HI). Group II: Ears with intact chain and stapes fixation; stapes was mobilized and the chain preserved. This group shows the best results (Table III). Group III: Ears with stapes fixation; stapes was mobilized but the chain disrupted. The results are somewhat inferior to those obtained in group II, indicating that it should be attempted to remove tympanosclerotic masses without disrupting the ossicular chain (Table III). Group IV: Ears with fixation of the stapes which otherwise was intact; the long process of the incus was defective. The incus was interposed on the mobilized stapes. The results are slightly poorer than in group III (Table III). Group V: Ears with defective stapedial crura and fixation of the footplate which was cleaned and mobilized; a columella was inserted between the footplate and the tympanic membrane. The results are unfavourable; thus, no ear showed a hearing exceeding 40 dB (Table III). Middle ear tympanosclerosis dB 0-
Air-bone gap
1020-
-o
__ _ „ _ _ — - O stapes present X stapes absent
304050No. of ears Intact cliain 15 I 15 St. present 45 45 St. absent 13 13
Operation '
8 30 10
6 16 5
11
31 7
10
3 10 2
15 20 Years, postoperativeiy
Middle ear tympanosclerosis •
SRT
intact chain ^ O stapes present ___. _ » . —x stapes absent
Intact chain 15 St. present 45 St. absent 13
Operation
10
15
20
Years, postoperativeiy
FIG. 2 Long-term deterioration of mean air-bone gap and mean SRT in ears with intact ossicular chain, stapes present and stapes absent.
688
M. TOS. T. LAU. H. ARNDAL. S. PLATE
TABLE IV TIME AND REASONS FOR REOPERATIONS AND FINDINGS AT REOPERATION
Years postoperatively
Tympanosclerosis of the middle ear: Late results of surgical treatment MIRKOTOS, TORBEN LAU, HELGE ARNDAL, S0REN PLATE
(Copenhagen, Denmark)
Abstract The late results of one stage operation for middle ear tymanosclerosis in 73 patients during the period January 1965 to December 1980 are presented. Mean observation time was 11.2 years (range 3-20.2 years), with a follow-up rate 86 per cent. Among 64 patients with stapes fixation, 59 had removal of tympanosclerotic masses and stapes mobilization, and five cases underwent stapedectomy. The series was divided into six groups and the results analyzed. The best and most stable results occurred in the group with stapes mobilization and an intact ossicular chain followed by the group with stapes mobilization and Type II tympanoplasty with incus interposition. The poorest late results were obtained in ears with lacking stapes crura and stapes mobilization, and in ears subjected to stapedectomy. No case of post-operative sensorineural hearing loss occurred. We recommend that care is taken to preserve an intact ossicular chain at stapes mobilization performed at the same stage as myringoplasty. Also in ears with a defective ossicular chain but intact stapes with tympanosclerotic fixation we recommend stapes mobilization in one stage. In ears with fixation of the stapes footplate and defective crura, we recommend stapedectomy or stapedotomy in two stages.
piece by piece and stapediolysis, (b) stapedectomy, or (c) stapedotomy. Zollner (1963, 1969) recommended removal of tympanosclerotic masses piece by piece with mobilization of the stapes and reported a primary hearing gain of 10 dB or more in 93 per cent of the cases. Charachon et al. (1981) recommended removal of the tympanosclerotic masses from the ossicles, mobilization of the malleus and incus at the first operation, and mobilization of the stapes and interposition at the second stage. Following removal of the tympanosclerosis and stapes mobilization, Smyth (1972) reported closure of the airbone gap within 10 dB in 54 per cent of the ears. At the same time, sensorineural hearing impairment occurred in 17 per cent. Stapedectomy performed in two stages resulted primarily in closure of the air-bone gap within 10 dB in 85 per cent and no case of sensorineural hearing loss. Smyth (1972) also recommended that the stapedectomy should be performed at least six months after myringoplasty. Gibb (1976) achieved a primary air-bone gap closure within 10 dB in 65 per cent of ears undergoing stapedectomy. In a later series of ears treated with stapedectomy, with covering of the niche with perichondrium and an L-shaped cartilage columella, Smyth (1980) obtained a primary air-bone gap closure within 10 dB in 80 per cent of ears as opposed to 77 per cent using a TORP. The only study available on the late results in middle ear tympansoclerosis is a follow-up study of Smyth's stapedectomy series (Gormly, 1987), comprising 61 ears with large fenestra and six cases with small fenestra stapedectomy. The follow-up period exceeded five years in 72 per cent of cases and ten years in 54 per cent of the ears. Hearing deteriorated considerably during the
Introduction
Tympanosclerosis signifies a hyaline degeneration of the fibrous and elastic fibres in the lamina propria of the tympanic membrane and middle ear mucosa. It is extremely frequent in chronic otitis and its sequelae, as well as after secretory otitis (MacKinnon, 1971; Mawson and Fagan, 1972; Bonding and Lorenzen, 1974; Kokko, 1975; Tos and Poulsen, 1976, 1979), especially in ears treated with grommets (Kilby et al., 1972; Tos et al., 1983). The clinical term "tympanosclerosis of the middle ear' was first defined by Troltsch (1869) as a stiffness of the fibrous tissue in the deepest layer of the middle ear mucosafixingthe stapes in the oval niche and/or the malleus and incus in the attic. Actual clinical recognition of tympanosclerosis first began with Zollner and Beck (1955) and was followed by numerous clinical and histological reports on aetiology, pathogenesis, in relation to cholesteatoma as well as treatment methods (Zollner 1956, 1963, 1969; House and Sheehy, 1960; Goodhill, 1960; Sheehy and House, 1962; Chang, 1969; Friedmann, 1971; Smyth, 1972). Today, there is general agreement that tympanosclerosis is an irreversible, non-specific end-result of any chronic inflammation or infection of the middle ear (Friedmann, 1971; S0rensen and True, 1971; Tos and Bak-Pedersen, 1974; Friedmann and Galey, 1980; Mann et al., 1980; Schiff et al., 1980; Mailer, 1981). There is still disagreement, however, about the surgical treatment of the condition. The following surgical priniciples have been employed in middle ear tympanosclerosis in cases with stapes fixation: (a) removal of tympanosclerotic masses Accepted for publication: 30 June 1990. 685
686
M. TOS. T. LAU. H. ARNDAL. S. PLATE
TABLE I
TABLE II
AGE AT OPERATION
Tympanosclerosis—Pathology (73)
Years
No.
11-20 21-30 31-40 41-50 51-60 61-70 > 70
3 5 8 11 31 13 2
Total
73
observation period; thus, an air-bone gap closure within 10 dB was maintained in only 13 per cent of ears and within 20 dB in 40 per cent. Only 8 per cent had an absolute hearing within 20 dB, 22 per cent within 30 dB, and two ears were deaf. The aim of the present study is to present the late results obtained in a series of ears, in which stapediolysis was performed as a rule in one stage, and compare them with the well-documented late results of stapedectomy reported in the above-mentioned study (Gormly, 1987). We hope in this way to provide a more differentiated view of the treatment of tympanosclerosis.
Series and methods The present series comprises 73 patients consecutively undergoing surgery in one stage for middle ear tympanosclerosis from January 1965 to December 1980. Postoperatively, the patients were seen regularly in the outpatients' clinic for up to two years and since then at follow-up several times, most recently in December
Drum:
Perforation Intact
—60 —13
Stapes:
Mobile ( 9), Fixed (64)
Type I (3) Type II (6) Stapedectomy (5) Stapediolysis (59)
Intact chain (28): Remained intact Disrupted Disrupted Crura intact (28) Crura missing (8)
Type I Type 11 Stapedectomy Type II Type III Type IV
(12) (11) (5) (28) (7) (1)
1989. A total of 86 per cent appeared for reevaluation. Mean observation time was 11.2 years, range 3-20.2 years. The time elapsing from surgery to last follow-up was 3-5 years in 10 per cent of the cases, 6-10 years in 33 per cent, 11-15 years in 23 per cent, and 16-21 years in 21 per cent of the ears. The series shows a preponderance of women (52 vs. 21 men). More than half of the patients were over 50 years of age at the time of surgery (Table I); median age was 54.5 years. The pathological findings varied greatly (Table II) and were subdivided into eardrum perforation, tympanosclerosis, stapes fixation, and ossicular chain defects. Sixty patients with eardrum perforation, mainly posterior, underwent myringoplasty with fascia. Nine cases had a mobile stapes but tympanosclerotic fixation of the incus and malleus in the attic. The tympanosclerotic masses were removed at atticotomy. The ossicular chain was intact in three of these cases and
TABLE III TYMPANOSCLEROSIS OF THE MIDDLE EAR, PRIMARY AND LATE RESULTS
Absolute hearing
SRT
0-20 dB %
0-30 dB %
0-40 dB %
0-20 dB %
0-30 dB %
9 9 9
11 33 22
11 44 44
11 33 11
22
22 11
Preopr. Prim. Late
12 12 10
_ 17 10
_ 67 30
8 83 60
Preopr. 3. Intact Chain Prim. Interupted Late
11 11 10
_ 9 -
_ 27 10
4. Defective Incus
Preopr. Prim. Late
28 28 23
_ 14 9
5. Defective Stapes
Preopr. Prim. Late
8 8 7
6. Stapedectomy
Preopr. Prim. Late
5 5 4
Total material
Preopr. Prim. Late
73 73 63
Pathology groups
No.
Preopr. 1. Without Fixation of Prim. Stapes Late 2. Intact Chain
Hearing gain
Air-bone gap 0-10 dB %
0-20 dB %
0-30 dB %
>20 dB %
>10 dB %
1-10 dB %
no gain in dB %
deterioration in dB %
44 33
67 22
_ 89 89
44 89 100
67 44
89 89
11 11
-
_ -
_ 42 20
_ 75 50
_ 58 30
_ 100 60
8 100 100
75 50
83 80
17 -
-
20
_ 45 20
_ 18 -
_ 55 20
_ 36 20
_ 45 40
27 82 70
55 20
64 50
27 30
9 20
-
_ 39 17
_ 54 30
_ 25 13
_ 43 22
_ 39 22
_ 61 35
4 79 64
71 30
79 52
18 26
4 -
22
_ -
_ 25 -
50 -
_ -
25 -
_ 50 -
_ 75 29
13 88 71
75 29
75 71
13 14
-
13 14
_ 20 _ 14 6
_ 40 -
_ 40 -
_ -
20 25
80 25
100 25
100 100
100 25
100 75
25
-
-
1 40 16
3 56 32
1 23 10
3 47 25
_ 49 21
_ 73 46
14 86 78
70 35
79 62
16 22
3 3
1 13
687
TYMPANOSCLEROSIS OF THE MIDDLE EAR
dB k SRT 20 :
Tympanosclerosis
P—°
2 Operation Gr. Gr. Gr. Gr. Gr. Gr.
10
15
20
Years, postoperativeiy 1 2 3 4 5 6
• • O O X X • • O-•••O A A
Without stapes fixation Intact chain Intact chain -» disrupted Stapes crura intact Stapes crura missing Stapedectomy
with stapes fixation
Air-bone gap
T2
5
10
Operation
15 20 Years, postoperativeiy
1 Long-term correlation of mean SRT and mean air-bone gap in various groups of tympanosclerosis. FIG.
defective in six which underwent tympanoplasty Type II with incus interposition (Table II). In 64 cases with stapes fixation, the tympanosclerotic masses were removed piecemeal and stapes was mobilized; infivecases a large fenestra stapedectomy was performed, with covering of the niche with fascia and placement of a steel wire on the intact long process of the incus (Table II). In 28 ears with stapes fixation, the ossicular chain was intact primarily and could be preserved intact in 12 ears. In 11 cases it was disrupted in order to ease resection of tympanosclerosis from the stapes and stapedial niche. An autologous incus was interposed between the mobilized stapes and the tympanic membrane (Table II). In five other cases the ossicular chain was disrupted at stapedectomy. In 28 cases with a defective incus, the tympanosclerotic masses were removed from the stapedial niche and stapes, and the latter was mobilized. An autologous incus was interposed between the mobilized stapes and the tympanic membrane (Table II). Finally, in eight cases with defective stapedial crura the footplate was cleaned and mobilized. In seven cases a columella of autologous incus was positioned between the footplate and the tympanic membrane, and in one case a Type IV was performed (Table II).
Results The series could be divided into six groups that were analyzed separately (Table III). The hearing results were evaluated in the frequency range 500-2000 Hz using four different methods in addition to speech audiometry. Here, the primary result refers to the last audiogram taken within the first two years post-operatively and the late result to the audiogram at the last follow-up. Group I: Ears without stapes fixation (nine ears). The late results are fairly good, especially as evaluated by the air-bone gap method (Table HI). Group II: Ears with intact chain and stapes fixation; stapes was mobilized and the chain preserved. This group shows the best results (Table III). Group III: Ears with stapes fixation; stapes was mobilized but the chain disrupted. The results are somewhat inferior to those obtained in group II, indicating that it should be attempted to remove tympanosclerotic masses without disrupting the ossicular chain (Table III). Group IV: Ears with fixation of the stapes which otherwise was intact; the long process of the incus was defective. The incus was interposed on the mobilized stapes. The results are slightly poorer than in group III (Table III). Group V: Ears with defective stapedial crura and fixation of the footplate which was cleaned and mobilized; a columella was inserted between the footplate and the tympanic membrane. The results are unfavourable; thus, no ear showed a hearing exceeding 40 dB (Table III). Middle ear tympanosclerosis dB 0-
Air-bone gap
1020-
-o
__ _ „ _ _ — - O stapes present X stapes absent
304050No. of ears Intact cliain 15 I 15 St. present 45 45 St. absent 13 13
Operation '
8 30 10
6 16 5
11
31 7
10
3 10 2
15 20 Years, postoperativeiy
Middle ear tympanosclerosis •
SRT
intact chain ^ O stapes present ___. _ » . —x stapes absent
Intact chain 15 St. present 45 St. absent 13
Operation
10
15
20
Years, postoperativeiy
FIG. 2 Long-term deterioration of mean air-bone gap and mean SRT in ears with intact ossicular chain, stapes present and stapes absent.
688
M. TOS. T. LAU. H. ARNDAL. S. PLATE
TABLE IV TIME AND REASONS FOR REOPERATIONS AND FINDINGS AT REOPERATION
Years postoperatively
