Results

Caution is advised in reading the literature on tympanic membrane repair because of uncontrolled variations in patient selection, and reporting methods (Table 3-1). Prospective, randomized, controlled clinical trials comparing groups undergoing underlay versus overlay tympanic membrane grafting do not exist. In author Monsell's experience, the socioeconomic status of the patient is an important factor in success with chronic ear surgery generally.

In 1995, the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) Committee on Hearing and Equilibrium recommended uniform reporting methods.28 Under the reporting guidelines, the pure tone average (PTA) is evaluated at 500, 1000, 2000, and 3000 Hz for air and bone conduction postoperatively. The 4000-Hz threshold can replace the 3000-Hz threshold in the calculation of the PTA. The postoperative air-bone gap (ABG) is determined by subtracting the postoperative bone PTA from postoperative air PTA. Sensorineural hearing loss as a complication of the procedure is defined as changes in the bone conduction PTA at 1000, 2000, and 4000 Hz.28 Patients should be followed for at least 12 months.

Postoperative reperforation of the tympanic membrane occurs in some cases. The postoperative interval chosen to assess successful graft closure

Tympanic Sulcus

Back of anterior canal skin flap

FIGURE 3-4 To facilitate exposure for repairing larger and anterior perforations, a postauricular incision is made and a tympanoplasty retractor is placed (not shown). No additional exposure is needed if the anterior tympanic sulcus can be seen (A). If additional exposure is needed, an anterior canaloplasty can be performed by drilling the anterior canal wall bone with a diamond bur behind a medially based flap of anterior canal wall skin (B). The skin flap is returned to its original position after the canal bulge has been removed (C).

Back of anterior canal skin flap

FIGURE 3-4 To facilitate exposure for repairing larger and anterior perforations, a postauricular incision is made and a tympanoplasty retractor is placed (not shown). No additional exposure is needed if the anterior tympanic sulcus can be seen (A). If additional exposure is needed, an anterior canaloplasty can be performed by drilling the anterior canal wall bone with a diamond bur behind a medially based flap of anterior canal wall skin (B). The skin flap is returned to its original position after the canal bulge has been removed (C).

varied among published studies. Thus, the same case might be reported as a success, a failure, or a complication depending on the postoperative interval chosen for assessment. Many published studies predated the AAO-HNS guidelines, or the guidelines were not consistently followed. Most reports have included the postoperative ABG and complications.

Most cases in the series listed in Table 3-1 involved tympanoplasty without ossicular repair or mastoidectomy. Rates of complete closure of the tympanic membrane are generally greater than 90% in most series. In centers that use overlay grafting techniques predominantly, the rate of closure for overlay grafts tends to be higher, about 97%, than with underlay grafting techniques, 93 to 95%. Patients were followed for at least 6 months post-operatively in most series reported here. Most graft failures occurred 6 to 12 months postoperatively.

Some reports of personal series cannot be generalized to compare the merits of underlay versus overlay techniques except as used by those authors. For example, one study compared the results of underlay tympanoplasty on 79 ears versus overlay techniques in 52 ears.17 The authors reported a lower failure rate and better postoperative hearing result (closure of ABG) with the underlay technique. However, they exclusively employed the endaural approach for both underlay and overlay techniques. Exposure of the anterior tympanic sulcus, which is important to the success of lateral grafting techniques, is restricted with the endaural approach. Also, the operations were often performed by residents, who may not have been experienced with the more technically demanding overlay grafting technique. Another prevalent source of bias in published personal series is that surgeons may use underlay techniques for healthier ears and smaller perforations (selection bias).

Hough4 reported a series of 208 cases with medial grafting and the transcanal approach. perforations were closed in more than 99%, with 81% ABG closure to within 10 dB. The cause of perforation and middle ear pathology did not influence the result. Lee and Schuknecht29 reported similar hearing results in their series. They also noted slightly less success with vein and split-thickness skin grafts in comparison with fascia grafts. They reported

Underlay Technique Tympanoplasty

FIGURE 3-5 Supplemental techniques may improve the success rate in large and anterior perforations. To create a larger surface of raw tissue for graft healing, elevate the annulus and up to 1 mm of medial canal wall skin (A).34 The graft can then be placed between the fibrous and bony annulus. For large perforations the graft can be placed lateral to the malleus and superior scutum (B).35 The superior and inferior flaps of canal wall skin are placed over the fascia graft. A 4 x /4 mm tab of fascia can be placed through a tunnel under the anterior canal wall skin to help ensure adequate coverage of the perforation and retention of the graft in the desired position (C).

FIGURE 3-5 Supplemental techniques may improve the success rate in large and anterior perforations. To create a larger surface of raw tissue for graft healing, elevate the annulus and up to 1 mm of medial canal wall skin (A).34 The graft can then be placed between the fibrous and bony annulus. For large perforations the graft can be placed lateral to the malleus and superior scutum (B).35 The superior and inferior flaps of canal wall skin are placed over the fascia graft. A 4 x /4 mm tab of fascia can be placed through a tunnel under the anterior canal wall skin to help ensure adequate coverage of the perforation and retention of the graft in the desired position (C).

significantly different success rates between attending surgeons and residents (89% vs. 68%).

Glasscock11 reported the results of 180 ears with underlay techniques versus 57 ears with overlay techniques. The areolar fascia was used instead of true temporalis fascia. All procedures employed a postauricular approach. The graft take rate was better with the underlay technique (96%) versus with the overlay technique (91%). Glasscock et al12 later reported an overall graft success rate of over 93% in his series of 1556 ears, all performed with postauricular incisions and underlay techniques. There were 19 cases of early graft failure and 91 cases of graft failure noted 3 months after surgery. Success with cholesteatomatous ears was slightly less (92%) compared with those without cholestea-toma (93.2%). There was no difference in the rate of graft healing between draining and dry ears. The graft closure rate for children under age 12 was 91.5%, and 93.3% for those 12 and older.12 Various graft materials were used, including aerolar tempor-

alis tissue, true temporalis fascia, perichondrium, and cartilage. In general, the postauricular approach was associated with a slightly better success rate than transcanal techniques. In contrast, Sheehy10,27 reported better success rate, 97%, with overlay techniques.

Rizer16 addressed the question of whether differences in success rates in comparative studies may reflect the surgeon's preference for a particular technique. He reported results of 551 procedures with underlay techniques versus 158 ears with overlay techniques. The location and size of the perforations, the middle ear status, and the causes of perforation (infection or trauma) were evenly distributed in both groups. All operations were performed by the same surgeons, who were experienced with both techniques. Rizer concluded that both techniques have high success rates, although drum healing was more successful with overlay grafting (95.6%) versus underlay techniques (88.8%), p = 0.050.16 There were no statistically sig

Table 3—1 Illustrative Results

Author

Air-Bone

Gap

Comments

Complications: Reperforation, Retraction, SNHL

Lee 197129

Underlay

81

<10 dB: 78%

Included various

3% (estimated)

n =1 235

graft materials

Hough 19704

Underlay

99.63

<10 dB: 81%

Transcanal

2%

n =1 208

<|40 dB: 92.3%

Myringoplasty

only from a larger

series of 644

Children

included

Austin 19768

Underlay

94

<10 dB: 59%

Transcanal

Less than 1%

n = / 52

< /20 dB: 76%

< /30 dB: 96%

Sheehy 198010

Overlay

97.4

<10 dB: 88%

Loss of BC of more than

n = ll53

< /20 dB: 97%

10 dB at 2 kHz

and 4 kHz =1 3%

Shelton and

Overlay

97

<10 dB: 31 to 45%

Myringoplasty only

As SNHL, including

Sheehy 199027

n =l 39

< /20 dB: 68 to 80%

from a larger

cases with

< /30 dB: 79 to 85%

series of 400

mastoidectomy:

Tested after second

<|2%, mostly from

stage

cholesteatomatous

ears with

mastoidectomies

Doyle 197217

Underlay

86

<15 dB: 62%

Mostly endaural

10%

n =l 79

<15 dB: 27%

approaches

Overlay

64

with both

38%

n = / 52

techniques

Glasscock

Underlay,

93

Not reported

Aerolar fascia,

6-8%

198212

postauricular

true fascia,

n =l 1556

allograft,

perichondrium,

and cartilage

used

Children

included

Koch 199030

Underlay,

73

<10 dB: 42%

Children only;

Estimated to 12%:

endaural

< /20 dB: 50%

mostly fascia

infection,

mostly

< /30 dB: 72%

with perichon-

cholesteatoma,

n =l 64

drium

atelectasis

Shih 199136

Overlay

78

<10 dB: 17%

Children from 6 to

Not reported

n = / 59

< /30 dB: 68%

16 years of age

Rizer 199716

Underlay

89

<15 dB: 90%

Overall results

8%

n = / 554

<15 dB: 89%

Overlay

96

n =l 158

BC, bone conduction threshold; SNHL, sensorineural hearing loss.

BC, bone conduction threshold; SNHL, sensorineural hearing loss.

nificant relationships between the hearing results or complications with techniques used.

Special considerations may apply to tympanoplasty in children. Recommended ages for pediatric tympanoplasty and success rates vary widely. Some authors have proposed that tympanoplasty in children should be deferred until eustachian tube maturation is achieved and the risk of infection is

Middle Ear and Mastoid Surgery lessened, typically age 8 to 10. Others have argued that closing the perforations would better protect the middle ear from further infections and minimize delay in speech development from hearing loss.

Koch et al30 reported complete healing of 73% in one series of 64 pediatric cases. Graft failures were more common in children under 8 years of age. The middle ear status, the condition of the contralateral ear, and the size and location of the perforation did not influence results. In contrast, Raine and Singh31 noted a statistically lower success rate with bilateral perforations. They also reported better success with children older than 8 years of age in their 114 cases.

In 170 pediatric cases (124 underlay, 46 overlay), Rizer16 found no correlation between age and success rate; however, 75% of patients were older than 9 years of age in his series. The success rate for 35 patients under age 9 was 100% for overlay grafts and 89% for underlay grafts. Lau and Tos13 concluded that long-term success, which was 92% in their series, depended on whether the ear remained dry, rather than on the age at surgery.

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