Effect of orthognathic surgery on middle ear condition

Effect of orthognathic surgery on middle ear condition

Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 24 (2012) 75–79 Contents lists available at SciVerse ScienceDirect Journal of Ora...

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Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 24 (2012) 75–79

Contents lists available at SciVerse ScienceDirect

Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology journal homepage: www.elsevier.com/locate/jomsmp

Original research

Effect of orthognathic surgery on middle ear condition Hideki Sato, Tadaharu Kobayashi ∗ , Hiroyuki Takatsuji, Akinori Funayama, Toshihiko Mikami, Chikara Saito Division of Reconstructive Surgery for Oral and Maxillofacial Region, Department of Tissue Regeneration and Reconstruction, Course for Oral Life Science, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-Dori, Cyuo-Ku, Niigata City 951-8514, Japan

a r t i c l e

i n f o

Article history: Received 3 July 2011 Received in revised form 3 September 2011 Accepted 7 October 2011 Available online 8 November 2011 Keywords: Orthognathic surgery Tympanometry Middle ear condition

a b s t r a c t Objectives: The aim of this study was to determine the effects of orthognathic surgery on middle ear condition assessed by tympanometry. Materials and methods: The subjects were 239 patients in whom jaw deformities were surgically corrected. Bilateral sagittal split osteotomies were performed in 80 patients and a combination of Le Fort I osteotomy and bilateral sagittal split osteotomies was used in 159 patients. Tympanometry was performed before surgery and one day, three days, five days, seven days and nine days after surgery. Tympanometric peak pressure and static compliance were used to assess Eustachian tube function, and the tympanograms were divided into three basic types. Results: Tympanometric peak pressure significantly decreased one day after surgery and gradually recovered within nine days after surgery. Tympanometric peak pressure immediately after surgery in the two-jaw surgery group was significantly lower than those in the one-jaw surgery group. The percentage of normal tympanogram decreased immediately after surgery, especially in the two jaw surgery group, and gradually recovered by nine days after surgery. The percentages of normal tympanogram in the patients with ear symptoms were significantly lower than those in the patients without ear symptoms for the entire period. Conclusion: Orthognathic surgery, especially maxillary osteotomy, can cause Eustachian tube dysfunction, though it is mild and transient and requires no intervention in most cases. However, 13% of patients had Eustachian tube dysfunction at the end of the study. These results suggest the importance of careful monitoring middle ear condition in patients undergoing orthognathic surgery. © 2011 Asian Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

1. Introduction Orthognathic surgery is a common treatment for jaw deformities that results in both functional and esthetic improvements. Numerous complications, however, have been reported [1–3], including middle ear changes [4–7]. It has been suggested that surgical compromise and positional changes of the palatal muscles and surgical edema of soft tissues in the nasopharyngeal area interfere with the function of the Eustachian tube following orthognathic surgery, resulting in absorption of gas in the middle ear, negative pressure, and development of middle ear effusion [4–7]. Tympanometry is an examination used to test the condition of the middle ear and to test the mobility of the tympanic membrane and conduction bones by creating variations of air pressure in the ear canal. Tympanometry is a simple, valid and objective test that

∗ Corresponding author. Tel.: +81 25 227 2880; fax: +81 25 223 6516. E-mail address: [email protected] (T. Kobayashi).

is sensitive for detecting middle ear ventilatory abnormalities [8], though there are the other audiometric examinations such as pure tone audiometry and Eustachian tube function test. Some investigators have reported negative middle ear pressure in patients shortly after maxillary osteotomy [4,5,9]. In the present study, middle ear conditions were assessed longitudinally by tympanometry in patients in whom jaw deformities were surgically corrected, and the effect of orthognathic surgery on middle ear condition was evaluated.

2. Materials and methods 2.1. Subjects The subjects consisted of 239 patients (75 males and 164 females) in whom jaw deformities were surgically corrected in the clinic of Oral and Maxillofacial Surgery, Niigata University Medical and Dental Hospital. Bilateral sagittal split osteotomies were performed in 80 patients and a combination of Le Fort I osteotomy

2212-5558/$ – see front matter © 2011 Asian Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ajoms.2011.10.003

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H. Sato et al. / Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 24 (2012) 75–79

2.3. Statistical analysis

Compliance value (ml) 1.0

Type C

Type A

0.5 Type B 0 -300

-200

-100

0

100

200 daPa

First, univariate analyses were done for all measured parameters. Since it could be assumed that the parameters have normal distributions, one-way repeated measures analysis of variance was used to determine whether changes in each parameter have significance and two-way repeated measures analysis of variance was used to determine whether there are significant differences between groups. The statistical differences between right and left ears were assessed by the paired t-test, and the frequency distributions of types of tympanograms were assessed by the Chi-square (2 ) test. The data were analyzed using SPSS ver.18 for Windows (SPSS Japan Inc., Japan).

Middle ear pressure 3. Results Fig. 1. Typical tympanograms. A type A tympanogram, in which maximum compliance occurs in the range of plus or minus 100 daPa, represents normal middle ear function. A type B tympanogram has little or no point of maximum mobility and reduced compliance (<0.2 ml), which is usually suggestive of middle ear fluid, a perforated tympanic membrane, or immobility of the middle ear space. A type C tympanogram, in which maximum compliance occurs at a pressure more negative than −100 daPa, represents poor Eustachian tube function.

and bilateral sagittal split osteotomies was used in 159 patients. No cases of cleft palate or craniofacial syndrome were included. The mean age at surgery was 23 years (range: 15–52 years). All of the subjects received pre- and postoperative orthodontic treatment and they received dexamethasone, 8 mg intraoperatively and two 4-mg postoperative doses. Maxillomandibular fixation was performed one day after surgery and maintained for 14 days. Twelve patients complained of ear symptoms such as aural fullness or auditory disturbance after surgery.

2.2. Tympanometry Tympanometry using an impedance audiometer RS-31 (RION Co. Ltd., Japan) was performed before surgery and one day, three days, five days, seven days and nine days after surgery. When performing tympanometry, a patient sits on a dental chair in closed-mouth position and a microphone probe is placed in the ear canal. A 226 Hz probe tone is presented through an earphone to measure acoustic admittance of the middle ear system as a function of air pressure in the ear canal, which is systematically varied from +200 daPa to −400 daPa. Acoustic admittance of the ear canal and middle ear system is determined at the probe tip by the ratio of acoustic volume velocity to acoustic pressure. A graphic display of the measurement is called a tympanogram (Fig. 1). Compliance is plotted vertically on the tympanogram and maximum compliance of the middle ear system occurs when the pressure in the middle ear cavity is equal to the pressure in the external auditory canal. Tympanometric peak pressure (TPP) and static compliance (SC) were used in this study to assess middle ear condition. Tympanograms are commonly classified as three basic types based on their quantitative pattern and shape. A type A tympanogram, in which maximum compliance occurs in the range of plus or minus 100 daPa, represents normal middle ear condition. A type B tympanogram represents restricted tympanic membrane mobility, which is usually suggestive of middle ear fluid, a perforated tympanic membrane, or immobility of the middle ear space. Type B curves have little or no point of maximum mobility and reduced compliance (<0.2 ml). A type C tympanogram represents negative middle ear pressure caused by poor Eustachian tube function and may be presented in the early stages of otitis media without effusion. In type C, maximum compliance occurs at a pressure more negative than −100 daPa.

3.1. Tympanometric peak pressure (Table 1) The mean values of preoperative TPP in the right and left sides were −16 daPa (SD, 39 daPa) and −17 daPa (SD, 42 daPa), respectively. The values significantly decreased one day after surgery to −123 daPa (SD, 115 daPa) and −123 daPa (SD, 116 daPa), respectively. Thereafter, the values gradually recovered and were −21 daPa (SD, 51 daPa) and −18 daPa (SD, 54 daPa), respectively, at nine days after surgery. By one-way repeated measures analysis of variance, significant changes of TPP following orthognathic surgery were found on both sides. There were no significant differences between the mean values of TPP on the right and left sides by the paired t-test. The mean values of TPP immediately after surgery in the twojaw surgery group were significantly lower than those in the one-jaw surgery group, though there were no significant differences between the values in the two groups before surgery and nine days after surgery. The mean values of TPP in patients with ear symptoms were significantly lower than those in patients without ear symptoms for the entire period. 3.2. Static compliance (Table 2) The mean values of preoperative SC in the right and left sides were 0.65 ml (SD, 0.43 ml) and 0.70 ml (SD, 0.45 ml), respectively. There was no significant difference between the mean values of SC in the right and left sides by the paired t-test, and the values did not show significant changes after surgery. There were no significant differences between the mean values of SC in the two-jaw surgery group and one-jaw surgery group before and after surgery. There were also no significant differences between the mean values of SC in patients with ear symptoms and those without ear symptoms for the entire period. 3.3. Types of tympanograms (Table 3) Preoperatively, 94.4% (451 ears) of all ears (478 ears) had normal (type A) tympanograms, 3.1% (15 ears) had type B tympanograms and 2.5% (12 ears) had type C tympanograms. One day after surgery, the percentage of type A tympanogram decreased to 47.7% (228 ears) and the percentages of type B and type C tympanograms increased to 10.9% (52 ears) and 41.4% (198 ears), respectively. Thereafter, the percentage of type A tympanograms gradually increased and was 91.0% (435 ears) nine days after surgery, but 13.4% of the 239 patients had Eustachian tube dysfunction (type B or C) at the end of the study. There was no significant difference between the percentages of types of tympanogram before surgery and nine days after surgery. There were significant differences between the percentages of types of tympanograms at one day, three days and five days after

H. Sato et al. / Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 24 (2012) 75–79

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Table 1 Results of tympanometric peak pressure.

Before

1 day after

3 days after

5 days after

7 days after

9 days after

surgery

surgery

surgery

surgery

surgery

surgery

Right **

-16±39

-123±115

-70±90

-42±77

-26±57

-21±51

Left *

-17±42

-123±116

-60±85

-31±70

-21±53

-18±54

-18±40

-92±96

-52±71

-27±57

-14±35

-16±53

-21±50

-99±103

-31±65

-12±42

-18±51

-19±61

Side

All patients (N=239) One jaw surgery group (N=80 )

**

Left *

Two jaw surgery group (N=159) With ear symptoms (N=12 )

-15±39

-139±120

-79±97

-49±84

-32±65

-23±50

Left*

Right **

**

-16±37

-134±121

-75±90

-41±79

-22±53

-18±51

Right **

-29±43

-208±87

-148±117

-97±105

-70±94

-53±61

-43±85

-233±83

-140±96

-87±103

-70±103

-56±87

-15±39

-119±114

-66±87

-39±74

-23±54

-19±50

-16±38

-117±115

-56±83

-28±67

-18±47

-16±51

Left **

Without ear symptoms (N= 227) *

Right **

Right **

*

Left **

p < 0.05 (Mean ± SD) (daPa). p < 0.01 (Mean ± SD) (daPa).

**

surgery in the one-jaw surgery group and two-jaw surgery group by the 2 test. The percentages of type A tympanograms in the twojaw surgery group were lower than those in the one-jaw surgery group. The percentages of type A tympanograms in patients with ear symptoms were significantly lower than those in patients without ear symptoms for the entire period.

was used to assess the condition of the middle ear and the mobility of the tympanic membrane following orthognathic surgery. On the tympanograms, deleterious effects on Eustachian tube function such as lower average values of TTP and SC were found after surgery. Similar changes were found in previous studies [4–7]. It has been suggested that surgical compromise of the soft palate musculature and nasopharyngeal soft tissue interferes with intermittent opening of the Eustachian tube, resulting in absorption of gas in the middle ear, negative pressure, and development of middle ear effusion [10,13]. Several theories have been advanced to explain the pathogenesis of disturbance in Eustachian tube function after orthognathic surgery. Most of the changes in Eustachian tube function were observed one day or three days after surgery. This might be due to the effect of edema on para-tubular muscles. Edema blocks the orifice of the Eustachian tube in the nasopharynx as a result of the surgery. It is likely that retrograde flow of blood and debris into the Eustachian tube causes blockage and dysfunction. This condition possibly leads to a buildup of fluid in the middle ear, which is suggested by changes in tympanometric curve patterns immediately after surgery. The gradual recovery in tube function may be due to edema diminishing and improvement in the function of paratubular muscles, though 9.0% of the 435 ears in this study had poor Eustachain tube function nine days after surgery. The tensor veli palatini muscle, which is attached to the lateral cartilaginous lamina of the Eustachian tube, is usually considered to be the main muscle for opening the Eustachian tube with the levator veli palatini muscle. If these muscles are impaired as a result

4. Discussion Jaw deformities pose both esthetic and functional problems, and orthognathic surgery is commonly performed to correct the position of the maxilla and/or the mandible with the aim of improving speech, mastication and appearance. However, numerous complications have been reported [1–3], including ear symptoms [4–7] such as aural fullness or auditory disturbance after orthognathic surgery. The Eustachian tube plays an important role in middle ear condition as it provides ventilation and drainage as well as protection of the middle ear [10]. We have been interested in the effects of orthognathic surgery on patients’ middle ear condition. Tympanometry has been a broadly accepted method to assess middle ear condition [3,11,12]. It is not a hearing test but rather a measure of energy transmission through the middle ear. A tympanogram is a graphic representation of the change in compliance (vertical axis) of the middle ear system as air pressure (horizontal axis) is varied. Valuable diagnostic information is obtained from both graphic and quantitative data. In this study, tympanometry Table 2 Results of static compliance.

All patients (N = 239) One jaw surgery group (N = 80) Two jaw surgery group (N = 159) With ear symptoms (N = 12) Without ear symptoms (N = 227) Mean ± SD (ml).

Side

Before surgery

Right Left Right Left Right Left Right Left Right Left

0.65 0.70 0.71 0.68 0.63 0.70 0.65 0.74 0.65 0.70

± ± ± ± ± ± ± ± ± ±

0.43 0.45 0.45 0.41 0.42 0.47 0.48 0.75 0.43 0.43

1 day after surgery 0.57 0.67 0.66 0.73 0.52 0.63 0.44 0.50 0.57 0.67

± ± ± ± ± ± ± ± ± ±

0.49 0.71 0.37 0.66 0.54 0.74 0.30 0.40 0.50 0.73

3 days after surgery 0.62 0.64 0.68 0.67 0.60 0.62 0.53 0.62 0.63 0.64

± ± ± ± ± ± ± ± ± ±

0.48 0.42 0.40 0.40 0.51 0.44 0.38 0.51 0.49 0.42

5 days after surgery 0.64 0.69 0.73 0.75 0.59 0.66 0.64 0.59 0.64 0.70

± ± ± ± ± ± ± ± ± ±

0.56 0.58 0.64 0.65 0.51 0.55 0.52 0.41 0.56 0.59

7 days after surgery 0.62 0.67 0.67 0.72 0.60 0.64 0.59 0.52 0.63 0.68

± ± ± ± ± ± ± ± ± ±

0.44 0.49 0.40 0.64 0.45 0.40 0.43 0.31 0.44 0.50

9 days after surgery 0.63 0.67 0.71 0.72 0.59 0.65 0.52 0.54 0.64 0.68

± ± ± ± ± ± ± ± ± ±

0.41 0.47 0.43 0.59 0.39 0.40 0.32 0.30 0.41 0.48

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H. Sato et al. / Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 24 (2012) 75–79 Table 3 Percentages of tympanogram types.

Side All patients

Right:**

(N=239)

Left **

One jaw surgery Group

Right **

(N=80 )

Left **

Two jaw surgery group

Right **

(N=159)

Left **

With ear symptpms

Right **

(N=12 )

Left **

Without ear s

Right **

ymptpms (N= 227)

Left **

*

Before

1 day after

3 days after

5 days after

7 days after

9 days after

surgery

surgery

surgery

surgery

surgery

surgery

Types A

93.3

45.2

71.5

80.3

87.9

90.8

B

4.2

10.5

6.3

8.4

6.7

6.3

C

2.5

44.4

22.2

11.3

5.4

2.9

A

95.4

50.2

72.0

82.8

90.0

91.2

B

2.1

11.3

5.0

5.9

4.2

5.0

C

2.5

38.5

23.0

11.3

5.9

3.8

A

95.0

57.5

77.5

91.3

95.0

93.8

B

2.5

2.5

3.8

3.8

5.0

5.0

C

2.5

40.0

18.8

5.0

0.0

1.3

A

92.5

63.8

90.0

90.0

3.8

6.3

86.3

**

1.3

93.8

**

B

3.8

2.5

C

3.8

33.8

12.5

1.3

6.3

3.8

A

92.5

39.0

68.6

74.8

84.3

89.3

B

5.0

14.5

7.5

**10.7

** 7.5

6.9

C

2.5

46.5

23.9

14.5

8.2

3.8

A

96.9

43.4

64.8

77.4

89.9

91.8

B

1.3

15.7

6.9

6.3

4.4

4.4

C

1.9

40.9

28.3

16.4

5.7

3.8

A

83.3

8.3

8.3

41.7

66.7

66.7

B

8.3

25.0

25.0

16.7

8.3

16.7

C

8.3

66.7

66.7

41.7

25.0

16.7

A

83.3

16.7

**

25.0

*

16.7

5.0

**

58.3

**

8.3

75.0

*

B

8.3

33.3

C

8.3

50.0

58.3

33.3

25.0

16.7

A

93.8

47.1

74.9

82.4

89.0

92.1

B

4.0

9.7

5.3

** 7.9

** 6.6

C

2.2

43.2

19.8

9.7

4.4

2.2

A

96.0

52.0

74.4

84.1

91.2

92.1

B

1.8

10.1

4.4

5.7

4.0

4.8

C

2.2

37.9

21.1

10.1

4.8

3.1

*

8.3

66.7

**

8.3

*

5.7

*

*

p < 0.05 (%). p < 0.01 (%).

**

of surgery, then the Eustachian tube opening patterns will become inconsistent. Two types of operations were taken into consideration in the present study, and Eustachian tube dysfunctions in patients who underwent a combination of Le Fort I osteotomy and bilateral sagittal split osteotomies were recognized more frequently than those in patients who underwent only bilateral sagittal split osteotomies. One of the reasons for this difference might be that maxillary osteotomy results in more severe edema of para-tubular muscles. Another possibility is that the mechanical impairment of

para-tubular muscles may lead to poor function of the tube and loss of middle ear integrity [6,7]. Moreover, muscle attachments to the Eustachian tube change in direction and tension following maxillary osteotomy, especially maxillary advancement, and these changes may cause Eustachian tube dysfunction [6]. The effect of maxillomandibular fixation on Eustachian tube function has also been investigated, and significant changes in hearing status and Eustachian tube function have been observed after maxillomandibular fixation removal [6]. In this study,

H. Sato et al. / Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 24 (2012) 75–79

maxillomandibular fixations were maintained at the end of the study in all patients, and 13.4% of the patients had Eustachian tube dysfunction at the end of the study. Further extended follow-up study is required to assess the effects of jaw movements on auditory impairment. As expected, a high rate (92%) of Eustachian tube dysfunctions was found in patients with ear symptoms, and one patient had examinations by otolaryngologists. However, the prevalence of ear symptoms was 5% in all patients and was lower than that of Eustachian tube dysfunction. It is conceivable that the patients studied might have experienced otologic problems postoperatively that simply were not detected by the protocol employed because the symptoms were mild and transient. On the other hand, one patient with ear symptom did not have Eustachian tube dysfunction. It was reported that patients with temporomandibular disorder had high incidences of otologic complaints [14,15], and TMJ signs and symptoms with or without ear symptoms sometimes appear after orthognathic surgery [16]. Therefore, increased tension of the muscles of mastication and excessive force on the TMJ after surgery might result in temporomandibular dysfunction and ear symptoms. 5. Conclusion Orthognathic surgery, especially maxillary osteotomy, can cause Eustachian tube dysfunction, though it is mild and transient and requires no intervention in most cases, but 13.4% of the patients had Eustachian tube dysfunction at the end of this study. These results suggest the importance of careful monitoring of middle ear condition in patients undergoing orthognathic surgery. Conflict of interest There is no conflict of interest.

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