Abstract
The aim of this study was to evaluate changes to the Eustachian tube and middle ear function and hearing level in individuals undergoing Le Fort I osteotomy. 20 consecutive patients underwent Le Fort I maxillary osteotomy with advancement, impaction or a combination of both. All individuals underwent hearing sensitivity tests, including pure tone audiometry and acoustic impedance measurements (middle ear pressure and compliance), which were carried out by an audiologist 1 week before surgery ( t 0 ), and then again 1 week ( t 1 ) and 4 weeks ( t 2 ) after surgery. Regarding pure tone audiometry, the differences between t 0 and t 2 at a frequency of 125 Hz ( P = .002), between t 0 and t 1 and between t 0 and t 2 at a frequency of 250 Hz, and between t 0 and t 1 at a frequency of 1000 Hz ( P = .006) were statistically significant. There was no statistically significant difference at any other frequency. Regarding middle ear pressure, no statistically significant difference was observed between t 0 and t 1 , and t 0 and t 2 . Following Le Fort I osteotomy, mild changes in hearing sensitivity and middle ear pressure are possible, but these changes were clinically insignificant.
Patients with dentofacial deformities, such as congenital and acquired abnormal position of the maxilla, mandible or both, can experience problems with facial aesthetics, mastication and speech. Correction of midfacial deformities often involves Le Fort I osteotomy with advancement, impaction or a combination of these movements. The osteotomy and movement of the maxilla often result in changes in the position and shape of the surrounding soft tissues, including the nasopharyngeal area. The muscles of the Eustachian tube originate from the pterygoid processes, which are one of the major sites of Le Fort I osteotomy. Trauma or structural changes to the tensor veli palatini and levator veli palatini muscles may alter function of the Eustachian tube and hearing sensitivity.
The purpose of this study was to understand the potential alteration in Eustachian tube function, middle ear pressure and hearing levels in individuals who underwent Le Fort I osteotomy.
Materials and methods
This study was approved by Baskent University Institutional Review Board and Ethics Committee (Project no: D-KA 09/05) and supported by the Baskent University Research Fund. 20 consecutive patients (8 males and 12 females aged 18–32 years) undergoing Le Fort I osteotomy were identified for this clinical study. During the preoperative evaluation, patients with a history of cleft palate, signs or symptoms of upper respiratory tract infection, chronic nasal inflammation, or otitis media were excluded from the study.
All patients underwent Le Fort I maxillary osteotomy with advancement, impaction, or a combination of both (15 double jaw surgery, 5 Le Fort I only) ( Table 1 ). All procedures were performed by the same surgeon. The amount of advancement ranged from 4 to 8 mm. To reduce oedema, all patients were given 1 mg/kg intravenous (i.v.) methylprednisolone sodium succinate (Prednol-L enjektable ampul Mustafa Nevzat İlaç Sanayii A.Ş, Turkey) intraoperatively and 0.5 mg/kg on postoperative day 1.
| Surgical type | Number of patients |
|---|---|
| Le Fort I | 3 |
| Le Fort I, genioplasty | 2 |
| Le Fort I, sagittal split ramus osteotomy (SSRO) | 6 |
| Le Fort I, SSRO, genioplasty | 9 |
| Total | 20 |
Audiological evaluations, including pure tone audiometry and acoustic impedance, were performed bilaterally by an audiologist 1 week before surgery ( t 0 ), and then 1 week ( t 1 ) and 4 weeks ( t 2 ) after surgery.
In pure tone audiometry, a graphic representation of the auditory threshold responses to pure tone stimulus application is made in the form of an audiogram. The parameters of the audiogram are frequency, which is measured in Hertz (Hz), and intensity, measured in decibels (db). A typical audiogram is determined by establishing hearing thresholds for single-frequency sounds at different frequencies (125–8000 Hz). A hearing threshold level, as measured by pure tone audiometry, is considered to be within normal limits when it ranges from 0 to 20 db.
Acoustic impedance is an objective test that measures Eustachian tube function and middle ear pressure. These test results are represented by air pressure/compliance graphs known as tympanograms. One of the most commonly used classification schemes for tympanogram shapes was described by Liden ; it was later modified. Type A tympanograms indicate normal middle ear pressure. Type B tympanograms indicate nonmobility of the tympanic membrane (e.g. middle ear effusion and tympanic membrane perforations). Type C tympanograms show negative middle ear pressure indicating poor Eustachian tube function. The peak air pressure of the tympanogram is equal to the patient’s middle ear pressure. The range of normal middle ear pressure is between 100 daPa and −100 daPa and represents normal Eustachian tube function. Middle ear pressure below −100 daPa indicates poor Eustachian function.
Compliance indicates the transmission of sound through the middle ear. When air pressure on both sides of the eardrum is equal, compliance of the tympanic membrane is at its maximum.
Statistical analysis
The auditory tests results from each follow-up examination were compared with the results of the previous examination. The hearing measurements taken at t 0 , t 1 , and t 2 were calculated and statistically evaluated. Whether the distributions of continuous variables were normal or not was determined by using the Shapiro–Wilk test. The Bonferroni adjusted Wilcoxon sign rank test was used to calculate the statistical significance between the pure tone audiometry, middle ear pressure, and the compliance results. The Bonferroni adjusted McNemar test was used to evaluate the differences in the types of tympanogram. The level of statistical significance was set at P < .017. Data analysis was performed using the Statistical Package for Social Sciences (SPSS) version 11.5 software (SPSS Inc., Chicago, IL, USA).
Results
Regarding pure tone audiometry, the differences between t 0 and t 2 at a frequency of 125 Hz ( P = .002), between t 0 and t 1 and between t 0 and t 2 at a frequency of 250 Hz, and between t 0 and t 1 at a frequency of 1000 Hz ( P = .006) were statistically significant. There was no statistically significant difference at any other frequency ( Table 2 ).
| Frequency (Hz) | t 0 Mean/SD |
t 1 Mean/SD |
t 2 Mean/SD |
t 0 − t 1 | t 0 − t 2 |
|---|---|---|---|---|---|
| 125 | 15.2 (8.08) a | 12.1 (6.39) | 11.5 (6.43) a | −3.1 (7.90) | −3.7 (7.05) |
| 250 | 14.1 (7.06) a.b | 11.4 (5.88) b | 11.2 (6.77) a | −2.7 (6.60) | −2.9 (6.88) |
| 500 | 10.9 (6.69) | 10.1 (5.49) | 9.0 (6.22) | −0.8 (6.66) | −1.9 (6.57) |
| 1000 | 9.0 (5.80) b | 6.6 (4.14) b | 8.5 (5.21) | −2.4 (5.06) | −0.5 (4.78) |
| 2000 | 7.6 (7.25) | 6.4 (6.10) | 6.2 (7.05) | −1.2 (6.07) | −1.4 (6.89) |
| 4000 | 9.2 (6.46) | 7.5 (5.99) | 7.9 (6.69) | −1.7 (5.83) | −1.3 (5.19) |
| 6000 | 13.2 (8.96) | 15.1 (8.43) | 11.7 (6.85) | 1.9 (8.75) | −1.5 (8.49) |
| 8000 | 9.7 (8.91) | 10.4 (8.50) | 7.5 (7.25) | 0.7 (7.27) | −2.2 (7.42) |
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