Abstract
Objectives
To facilitate the diagnosis, treatment and surgical options for congenital bony atresia of external auditory canal (EAC) with temporal-mandibular joint (TMJ) retroposition by analyzing its audiological features and the morphology of temporal bone on CT scan.
Materials and methods
Two cohorts of patients with congenital EAC bony atresia with (n = 23) or without (n = 21) TMJ retroposition were recruited from September 2012 to July 2014 at Beijing Tongren Hospital, Capital Medical University. The patients with TMJ retroposition were set as the group A and those without as group B. Based on the degree of TMJ retroposition, group A was further divided into two sub-groups A1 (n = 13) and A2 (n = 10). The temporal bone CT scan, pure tone average (PTA) and air-bone gap (ABG) were obtained for the main outcome measurements. SPSS 17.0 was used for the statistics analysis with t and t test.
Results
For group A, the average air conduction (AC) was 55.22 ± 12.53 dBHL, the average bone conduction (BC) was 7.07 ± 3.34 dBHL, and the average ABG was 50.69 ± 8.60 dBHL. For the sub-groups A1 and A2, the average AC was respectively 45.77 ± 8.43 dBHL and 59.50 ± 7.43 dBHL, BC 7.07 ± 3.34 dBHL and 6.89 ± 4.37 dBHL, and ABG 47.31 ± 7.92 dBHL and 53.00 ± 7.91 dBHL. For group B, the average AC was 70.24 ± 5.63 dBHL, BC 6.78 ± 4.37 dBHL, and ABG 60.19 ± 6.09 dBHL.
Conclusions
The degree of TMJ retroposition is negatively related to the severity of hearing loss among patients with congenital EAC bony atresia, and those with TMJ have suffered less severe hearing loss than those without. Although TMJ retroposition might be a disadvantage for patients undergoing EAC plasty and tympanoplasty, it must be considered for its influence on hearing loss severity and auditory canal abnormality when planning the surgical treatment. Different from normal surgical protocol for congenital EAC bony atresia, we commend other hearing reconstruction methods such as BAHA and VSB, even without intervention.
1
Introduction
Clinical manifestations of congenital malformation of external and middle ear are various, including auricle deformity, external auditory canal (EAC) malformation (atresia or stenosis), and middle ear malformation with or without maxillofacial deformity. Congenital aural atresia (CAA) is an abnormality in which the external auditory canal failed to develop . It occurs in one of every 20,000 births . Some of the cases with aural atresia have temporal-mandibular joint (TMJ) abnormal position, especially retroposition. It is very important to determine the clinical audiology features and the relationship between aural atresia and TMJ abnormality for making treatment plan. Due to the limited reports on relevant cases, there is usually a lack of clear and accurate understanding among clinical otologists and radiologists. Through the analysis of CT images and audiology characteristics of 23 patients with congenital EAC bony atresia with TMJ retroposition, the authors have recommended several clinical treatment strategies.
2
Methods
A cohort of 23 patients with congenital EAC atresia was recruited from September 2012 to July 2014 at Beijing Tongren Hospital for this study. The minimum age in the cohort was 6 years old. All the 23 patients were examined by computed tomography of temporal bone (CT,64 MDCT TKLight speed, GE Medical System) in our hospital, with contiguous 0.7-mm-thick sections and a bone algorithm. Based on the setting of axial and coronal planes in CT scan, the following standards were employed. The axial plane was adjusted so that the basal turn and/or the posterior semicircular canal level was on the same level. The coronal scan was adjusted so that the incudostapedial joint complex or the long crus of the incus show completely at the level. All the 23 patients were categorized as group A and further divided into two sub-groups A1 and A2 according to the degree of the TMJ retroposition. Another cohort of 21 patients with unilateral congenital EAC atresia and normal position of TMJ was recruited as the contrast group B. The basic demographic information of group A and group B was shown in Table 1 . For both group A and group B, all patients underwent the pure tone auditory (PTA) to test the average of the air conduction (AC), bone conduction (BC) and the air-bone gap (ABG) at each of four tested frequencies (500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz).
| Group | Lateral | Gender | Age | |||
|---|---|---|---|---|---|---|
| Left | Right | Male | Female | |||
| A | 5 | 18 | 13 | 10 | 11.21 ± 6.35 | |
| A1 | 4 | 9 | 7 | 6 | 11.54 ± 3.57 | |
| A2 | 1 | 9 | 6 | 4 | 9.50 ± 4.78 | |
| B | 7 | 14 | 14 | 7 | 12.02 ± 3.39 | |
| Total | 12 | 32 | 27 | 17 | ||
The data were analyzed with statistic software SPSS 17.0, (SPSS, Inc, Chicago, IL) using the statistic method t and t test.
2
Methods
A cohort of 23 patients with congenital EAC atresia was recruited from September 2012 to July 2014 at Beijing Tongren Hospital for this study. The minimum age in the cohort was 6 years old. All the 23 patients were examined by computed tomography of temporal bone (CT,64 MDCT TKLight speed, GE Medical System) in our hospital, with contiguous 0.7-mm-thick sections and a bone algorithm. Based on the setting of axial and coronal planes in CT scan, the following standards were employed. The axial plane was adjusted so that the basal turn and/or the posterior semicircular canal level was on the same level. The coronal scan was adjusted so that the incudostapedial joint complex or the long crus of the incus show completely at the level. All the 23 patients were categorized as group A and further divided into two sub-groups A1 and A2 according to the degree of the TMJ retroposition. Another cohort of 21 patients with unilateral congenital EAC atresia and normal position of TMJ was recruited as the contrast group B. The basic demographic information of group A and group B was shown in Table 1 . For both group A and group B, all patients underwent the pure tone auditory (PTA) to test the average of the air conduction (AC), bone conduction (BC) and the air-bone gap (ABG) at each of four tested frequencies (500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz).
| Group | Lateral | Gender | Age | |||
|---|---|---|---|---|---|---|
| Left | Right | Male | Female | |||
| A | 5 | 18 | 13 | 10 | 11.21 ± 6.35 | |
| A1 | 4 | 9 | 7 | 6 | 11.54 ± 3.57 | |
| A2 | 1 | 9 | 6 | 4 | 9.50 ± 4.78 | |
| B | 7 | 14 | 14 | 7 | 12.02 ± 3.39 | |
| Total | 12 | 32 | 27 | 17 | ||
The data were analyzed with statistic software SPSS 17.0, (SPSS, Inc, Chicago, IL) using the statistic method t and t test.
3
Results
3.1
Age distribution
The average age in group A was 11.21 ± 6.35 years old (in group A1 11.54 ± 3.57 and in group A2 9.50 ± 4.78) and in group B 12.02 ± 3.39 years old, and no statistical and significant difference was found between the groups.
3.2
Computer tomography
Compared to that in common osseous EAC atresia ( Fig. 1 A and E ), the normal structure of the EAC for the patients in group A was partially or totally occupied by TMJ, i.e. on the CT image, the soft tissues partially or wholly covered the structure of EAC and the anterior (axial) or the inferior (coronal) wall was absent, which was referred to as TMJ retroposition ( Fig. 1 B, C, F and G). The structure of the EAC in group B was also abnormal, and the atresia plank, rather than the soft tissues, was filling the malformation bony structure. The structure of TMJ was at physical location ( Fig. 1 D and H).
3.3
Pure tone auditory
All patients underwent pure tone auditory (PTA) test at each of four tested frequencies (500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz).
The means of AC and of BC were respectively 55.22 ± 12.53 dBHL and 7.07 ± 3.34 dBHL, and that of ABG was 50.69 ± 8.60 dBHL in group A. In group B, the means of AC and of BC were respectively 70.24 ± 5.63 dBHL and 6.78 ± 4.37 dBHL, and that of ABG was 60.19 ± 6.09 dBHL. Table 2 showed the comparison between groups A and B, and Table 3 showed that between sub-groups A1 and A2. Four cases had the mean of the ABG less than 30 dBHL. In Table 4 , there was another contrast between groups A and B in terms of 7 and 8 of Jahrsdoerfer score system.
| Group A | Group B | P value | |
|---|---|---|---|
| AC ± Mean (dBHL) | 55.22 ± 12.53 | 70.24 ± 5.63 | 0.001 |
| BC ± Mean (dBHL) | 7.07 ± 3.34 | 6.78 ± 4.37 | >0.05 |
| ABG ± Mean (dBHL) | 50.69 ± 8.60 | 60.19 ± 6.09 | <0.05 |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
