Mandibulofacial dysostosis: CT evaluation of the temporal bones for surgical risk assessment in patients of bilateral aural atresia

Pearls of Temporal Bone Imaging in Children with Hearing Loss

Hearing loss is one of the most common indications for temporal bone imaging in children. Hearing loss may be congenital or acquired, and it may be conductive, sensorineural, or mixed audiologically. Temporal bone imaging plays an important role in the assessment and management of this condition. An understanding of the embryology of ear structures better enables the radiologist to interpret abnormalities on imaging of the temporal bone. Here, we provide a general review of ear development and a description of known genetic defects that contribute to congenital ear anomalies associated with hearing loss. We provide appropriate imaging techniques for the temporal bone depending on the clinical presentation and a systematic approach to imaging for children with hearing loss. Diagnostic imaging for developmental anomalies of the ear and cholesteatoma will be discussed.

High-resolution computed tomography evaluation of congenital aural atresia - how useful is this?

OBJECTIVE

To depict various temporal bone abnormalities on high-resolution computed tomography in congenital aural atresia patients, and correlate these findings with auditory function test results and microtia subgroup.

METHODS

Forty patients (56 ears) with congenital malformation of the auricle and/or external auditory canal were evaluated. Auricles were graded according to Marx's classification, divided into subgroups of minor (grades I and II) and major (III and IV) microtia. Other associated anomalies of the external auditory canal, tympanic cavity, ossicular status, oval and round windows, facial nerve, and inner ear were evaluated.

RESULTS

Minor and major microtia were observed in 53.6 and 46.4 per cent of ears respectively. Mean hearing levels were 62.47 and 62.37 dB respectively (p = 0.98). The malleus was the most commonly dysplastic ossicle (73.3 vs 80.8 per cent of ears respectively, p = 0.53). Facial nerve (mastoid segment) abnormalities were associated (p = 0.04) with microtia subgroup (80 vs 100 per cent in minor vs major subgroups).

CONCLUSION

Microtia grade was not significantly associated with mean hearing levels or other ear malformations, except for external auditory canal and facial nerve (mastoid segment) anomalies. High-resolution computed tomography is essential in congenital aural atresia, before management strategy is decided.

Treacher Collins Syndrome: A Systematic Review of Evidence-Based Treatment and Recommendations

BACKGROUND

No reviews or guidelines are available on evidence-based treatment for the multidisciplinary approach in Treacher Collins syndrome. The authors' aim is to provide an evidence-based review of multidisciplinary treatment of Treacher Collins syndrome based on levels of evidence and supported with graded recommendations.

METHODS

A systematic search was performed by means of the PubMed, Web-of-Science, Embase, and Cochrane Central databases (1985 to January of 2014). Included were clinical studies (with five or more Treacher Collins syndrome patients) related to therapy, diagnosis, or risk of concomitant diseases. Level of evidence of the selected articles was rated according to the American Society of Plastic Surgeons evidence-based clinical practice guidelines. After two panelists had reviewed each abstract separately, a consensus method was used to solve any disagreements concerning article inclusion.

RESULTS

Of the 2433 identified articles, 63 studies (Level of Evidence II through V) were included. Conclusions and recommendations were extracted consecutively for the following items: upper airway; ear, hearing, and speech; the eye, eyelashes, and lacrimal system; growth, feeding, and swallowing; the nose; psychosocial factors; and craniofacial reconstruction.

CONCLUSIONS

In this systematic review, current evidence for the multidisciplinary treatment of Treacher Collins syndrome is provided, recommendations for treatment are made, and a proposed algorithm for treatment is presented. Although some topics are well supported, others, especially ocular, nasal, speech, feeding, and swallowing problems, lack sufficient evidence. In addition, craniofacial surgical reconstruction lacks a sufficient level of evidence to provide a sound basis for a full treatment protocol. Despite the rarity of the syndrome, more research is needed to compare outcomes of several surgical treatments, especially in orbitozygomatic/maxillary regions.

The Association of External and Middle Ear Anomaly and Mandibular Morphology in Congenital Microtia

OBJECTIVE

To investigate the relationship between the severity of ear anomaly and mandibular dysplasia in congenital microtia.

STUDY DESIGN

Retrospective case review.

SETTING

Sapporo Medical University Hospital.

PATIENTS

Congenital microtia: 44 patients over a period of 4 years.

INTERVENTIONS

The height of the condylar process of the mandible was assessed by three-dimensional computed tomography (CT), and the patients were divided into three groups based on the ratio of the condylar process height on the affected side to that on the unaffected side: Group A, ≥1.00; Group B, 0.99 to 0.85; Group C, <0.85. Developmental abnormalities of the ear were evaluated using Jahrsdoerfer's scoring system on high-resolution CT scans.

MAIN OUTCOME MEASURES

Nonparametric statistical tests were used to determine correlations between the height of the condylar process of the mandible and Jahrsdoerfer's score.

RESULTS

The total Jahrsdoerfer's score for each group was 7.36 ± 2.23, 7.28 ± 0.10, and 4.52 ± 0.30, respectively; this value was significantly lower in Group C than in the other groups. In terms of subtotal points, oval window open, middle ear aeration, and mastoid pneumatization correlated significantly with mandibular dysplasia. Patients in Group C tended to have grade III microtia, by Marx's classification. Facial nerve weakness was not significantly correlated with mandibular dysplasia.

CONCLUSIONS

In congenital microtia, mandibular development correlated significantly with aeration of the middle ear space, pneumatization of the mastoid, and formation of the oval window, but not with the presence of a bony part of the external auditory canal or with ossicular development.

Prospective blinded study of computed tomography in congenital aural atresia

OBJECTIVE

To report a preliminary descriptive study of new and refined anatomic considerations for computed tomography (CT) in congenital aural atresia (CAA).

DESIGN/PATIENTS

Thirty-two temporal bone CT scans from 26 patients (6 bilateral cases) with CAA were graded in a prospective blinded manner with both Jahrsdoerfer's system and the new/refined anatomic considerations. In addition to Jahrsdoerfer's grading, new and refined considerations graded included the presence or absence of: (1) inferiorly displaced tegmen mastoideum, (2) malleus/incus complex directly lateral versus anterolateral to stapes, which may make surgical stapes access much more difficult, and (3) possible facial nerve obstruction of surgical access at two sites: oval window and middle ear.

SETTING

Tertiary-care children's hospital.

RESULTS

Inferiorly displaced tegmen mastoideum occurred in 5 ears (16%), the malleus/incus complex was directly lateral to the stapes in 12 ears (38%), the facial nerve possibly obstructed access to the oval window in 17 ears (53%), and it possibly obstructed access to the middle ear in 5 ears (16%).

CONCLUSION

New and refined anatomic/radiographic considerations for CT in CAA are reported for a series of temporal bones. The presence of these anatomic variants may influence the decision against atresiaplasty since these anatomic factors may possibly make atresiaplasty more difficult or impossible. Precise determination of atresiaplasty candidacy is important since Bone Anchored Hearing Aid is also a valuable option.

Hearing levels in patients with microtia: correlation with temporal bone malformation

OBJECTIVE

To evaluate the relationship between hearing level and temporal bone abnormalities in patients with microtia.

STUDY DESIGN

Retrospective case series study between 1992 and 2004.

SETTING

Academic, tertiary care referral medical center.

PATIENTS

We evaluated 115 ears of 89 patients (68 males, 21 females; mean age, 11 yr; range, 5-44 yr) with microtia.

MAIN OUTCOME MEASURES

Hearing level was examined in patients with microtia. Developmental abnormalities of the temporal bone were evaluated by Jahrsdoerfer's computed tomography (CT) scoring system using high-resolution CT (HRCT) scans of the temporal bone. Temporal bone malformation scores were divided into four subgroups: ossicular development, windows connected to the cochlea, aeration of the middle ear cavity, and facial nerve aberration. Patients were divided into the stenosis and atresia groups on the basis of the appearance of the external auditory canal (EAC). We also evaluated the relationships between hearing level and four subtotal scores of the HRCT findings in the stenosis and atresia groups.

RESULTS

There was no relationship between hearing level and total points of HRCT scoring system or between hearing level and severity of microtia scored by Marx classification. With regard to subtotal points related to ossicles (4 points), the hearing level in ears with low scores (<2) (64.7 +/- 1.6 dB) was significantly different (P = .03) from that in ears with high scores (> or =2) (54.0 +/- 2.8 dB) in the stenosis group. In the atresia group, the hearing level was 64.3 +/- 2.2 dB in ears with low scores and 62.3 +/- 1.1 in ears with high scores (P > .5). As for subtotal points related to the windows connected to cochlea (2 points), the hearing level was 64.8 +/- 2.6 dB in ears with low scores (0) and 55.9 +/- 2.4 dB in ears with high scores (> = 1) in the stenosis group. In the atresia group, the hearing level was 67.7 +/- 2.3 dB in ears with low scores and 61.5 +/- 1.0 in ears with high scores. There was significant difference between ears with low and high scores in the stenosis group (P = .03) and atresia group (P = .009). There was no significant difference between ears with low and high scores with respect to the subtotal points related to aeration of the middle ear cavity and aberration of the facial nerve.

CONCLUSION

The hearing level in microtic ears correlated with the formation of oval/round windows and ossicular development but not with the degree of middle ear aeration, facial nerve aberration, or severity of microtia. The hearing level can also serve as an indictor, such as the HRCT findings, to determine whether a subject's hearing will likely improve after reconstructive surgery.

Joint formation in the middle ear: Lessons from the mouse and guinea pig

The malleus, incus and stapes form an ossicle chain in the mammalian middle ear. These ossicles are articulated by joints that link the chain together. In humans and mice, fusion of the ossicles leads to hearing loss. However, in the adult guinea pig the malleus and incus are normally found as a single complex. In this report, we investigate how the malleus and incus form during mouse and guinea pig development. The murine malleus and incus develop from a single condensation that splits to form the two ossicles. Even before a morphological split, we show that the ossicles have distinct genetic identities and joint markers are expressed. In the guinea pig embryo, joint formation is initiated but no cavitation is observed, resulting in a single complex divided by a thin suture. The malleal-incudo complex in the guinea pig is, therefore, not caused by a defect in joint initiation.

Correlation between microtia and temporal bone malformation evaluated using grading systems

OBJECTIVE

To evaluate the relationships between temporal bone abnormalities and the severity of microtia in Japanese patients using objective grading systems.

DESIGN

Retrospective case series study conducted between 1992 and 2003.

SETTING

Academic, tertiary care, referral medical center.

PATIENTS

One hundred forty-two ears of 109 Japanese patients (85 male and 24 female patients; mean age, 12.8 years [range, 2-36 years]) with microtia.

MAIN OUTCOME MEASURES

The severity of microtia was classified according to Marx classification. Developmental abnormalities of the temporal bone were evaluated by a computed tomographic (CT) scoring system modified after the system used by Jahrsdoerfer and colleagues, using high-resolution CT scans of the temporal bone. Correlations between the scores obtained from these 2 grading systems were evaluated using a nonparametric statistical method.

RESULTS

Male preponderance and incidence of bilateral cases of approximately 30% were observed in our Japanese patients with microtia. There was no significant difference in the severity of microtia between unilateral and bilateral cases. The mean +/- SEM total points in the CT scoring system (full marks, 10) was 7.9 +/- 0.4 for grade I microtia, 6.6 +/- 0.6 for grade II, and 6.4 +/- 0.3 for grade III; the total points correlated inversely with the microtia grade. Development of the auricle correlated significantly with aeration in the middle ear spaces but not with ossicular development or formation of the oval/round windows. Proportion of acceptable surgical candidates according to the CT scoring system (>5 points) was 79% for grade I microtia, 52% for grade II microtia, and 65% for grade III microtia.

CONCLUSION

The principle "the better developed the auricle, the better developed middle ear" was confirmed in Japanese patients with microtia; however, even with grade II/III microtia, more than half of the patients were considered suitable for atresia surgery.

Aplasia of zygomatic arch and dislocation of temporomandibular joint capsule in Treacher-Collins syndrome: three-dimensional reconstruction of computed tomographic scans

Seven patients with Treacher-Collins syndrome were studied. All of patients were children or teenagers. Helical CT scanner (Toshiba) was used to reconstruct zygomatic arch and temporomandibular joint capsule on lateral aspect of temporal bone in five patients of microtia and atresia of both ears and two patients of narrow ear canals of both ears without microtia.Three-dimensional reconstructions of computed tomography on lateral aspect of temporal bone demonstrated various congenital abnormality including aplasia of zygomatic arch in seven patients and dislocation of temporomandibular joint capsule in seven patients.