Facial canal anatomy in patients with microtia: evaluation of the temporal bones with thin-section CT

PURPOSE

To ascertain the location of the facial nerve in patients with microtia by using thin-section computed tomography (CT).

MATERIALS AND METHODS

Thin-section CT was performed in 66 ears of patients with microtia (unilateral, n = 12; bilateral, n = 34) and mandibulofacial dysostosis (MFD, n = 20). Findings were compared with those in 22 ears with normal auricles (control group) by using the Dunnett two-sided t test.

RESULTS

The facial nerve at the mastoid portion in patients with MFD was 2 mm more lateral and 3 mm more anterior than that in control subjects (P <.01). The same portion in patients with microtia was 3 mm more anterior than that in the control subjects (P <.01). The distance between the facial nerve and the most lateral point of the temporal bone in patients with MFD was 10 mm shorter and that in patients with bilateral microtia was 3 mm shorter than that in the control subjects (P <.01).

CONCLUSION

The facial nerve in patients with microtia was not more lateral from the Bill bar (vertical crest) than that in control subjects. The facial nerve in patients with MFD was different from that in patients with microtia who had no other head anomalies.

Prenatal diagnosis and confirmation of the acrofacial dysostosis syndrome type Rodriguez

The group of acrofacial dysostosis (AFD) syndromes is very heterogeneous and contains many different entities. In 1990, Rodriguez et al. [1990: Am J Med Genet 35:484-489] described a new type of AFD characterized by severe mandibular hypoplasia, phocomelia and oligodactyly of the upper limbs, absence of fibulae, microtia, cleft palate, internal organ anomalies including arrhinencephaly and abnormal lung lobulation, and early lethality. We describe another case of AFD type Rodriguez, identified by prenatal ultrasonography at 25 weeks of gestation.

Effect of distraction osteogenesis of the mandible on upper airway volume and resistance in children with micrognathia

Children with craniofacial anomalies often have compromise of the upper airway, a condition with potential for morbidity and mortality. In children with microretrognathia, the diminutive size and retruded position of the mandible reduces the size of the oropharynx, thereby predisposing to glossoptosis and airway obstruction. Although several authors have reported successful use of mandibular distraction osteogenesis to alleviate this type of upper airway obstruction, the physiologic relationship between changes in mandibular shape, size, and position and upper airway dynamics remains undefined. The purpose of this study was to develop methodologies to quantitatively evaluate upper airway dynamics in children with micrognathia both before and after mandibular distraction osteogenesis. The patient population consisted of four children with micrognathia who had successfully undergone upper airway stabilization by bilateral mandibular distraction osteogenesis. The data used were digitally archived computed tomographic scan data from high-resolution, thin-slice head computed tomographic scans obtained before and after mandibular distraction. Upper airway evaluation was performed in two ways: static and dynamic. Static analysis consisted of computer quantification of predistraction and postdistraction mandibular and upper airway volumes using Analyze imaging software. Dynamic analysis consisted of fabrication of rigid stereolithographic hollow cast models of the upper airway produced from computed tomographic scan data. Models were used for characterization of upper airway resistance and flow patterns as related to respiration. After distraction osteogenesis, mandibular total volume increased 32, 32, 18, and 25 percent (mean, 27 percent) and upper airway volume increased by 20, 31, 23, and 71 percent (mean, 37 percent). A significant decrease in flow resistance, both inspiratory and expiratory, was observed in the patient with the greatest upper airway volume increase (71 percent) after distraction. After distraction, the inspiratory resistance was diminished by 51 percent and the expiratory resistance diminished by 85 percent. However, the three patients with more modest upper airway volume increases of 20 to 31 percent demonstrated no statistically significant change in flow resistance after distraction. Results of this study support the conclusion that distraction osteogenesis of the micrognathic mandible increases the volume of the upper airway, roughly paralleling the increase in mandibular volume. In the biomechanical airway model studied, upper airway volume expansion has been shown to be able to decrease the flow resistance over the length of the airway, presumably secondary to an increase in the average cross-sectional area. The artificial rigidity of the stereolithographic "airway" compared with the elasticity of the human upper airway may account for the insensitivity of this model to smaller but clinically significant airway changes.

Syndromic ear anomalies and renal ultrasounds

OBJECTIVE

Although many pediatricians pursue renal ultrasonography when patients are noted to have external ear malformations, there is much confusion over which specific ear malformations do and do not require imaging. The objective of this study was to delineate characteristics of a child with external ear malformations that suggest a greater risk of renal anomalies. We highlight several multiple congenital anomaly (MCA) syndromes that should be considered in a patient who has both ear and renal anomalies.

METHODS

Charts of patients who had ear anomalies and were seen for clinical genetics evaluations between 1981 and 2000 at Cedars-Sinai Medical Center in Los Angeles and Dartmouth-Hitchcock Medical Center in New Hampshire were reviewed retrospectively. Only patients who underwent renal ultrasound were included in the chart review. The literature was reviewed for the epidemiology of renal anomalies in the general population and in MCA syndromes with external ear anomalies. We defined a child as having an external ear anomaly when he or she had any of the following: preauricular pits and tags; microtia; anotia; or cup, lop, and other forms of dysplastic ears. A child was defined as having a renal anomaly if an ultrasound revealed any of the following: unilateral or bilateral renal agenesis; hypoplasia; crossed ectopia; horseshoe, pelvic, cystic kidney; hydronephrosis; duplicated ureters; megaureter; or vesicoureteric reflux.

RESULTS

Because clinical genetics assessments were made by the same clinician at both sites (J.M.G.), data were combined. A total of 42 patients with ear anomalies received renal ultrasound; 12 (29%) of them displayed renal anomalies. Of the 12 patients with renal anomalies, 11 (92%) also received a diagnosis of MCA syndrome. Eleven of 33 patients (33%) with MCA syndromes had renal anomalies, whereas 1 of 9 patients (11%) with isolated ear anomalies had renal anomalies. Specific disorders seen were CHARGE association, Townes-Brocks syndrome, branchio-oto-renal syndrome, Nager syndrome, and diabetic embryopathy.

CONCLUSIONS

We conclude that ear malformations are associated with an increased frequency of clinically significant structural renal anomalies compared with the general population. This is due to the observation that auricular malformations often are associated with specific MCA syndromes that have high incidences of renal anomalies. These include CHARGE association, Townes-Brocks syndrome, branchio-oto-renal syndrome, Nager syndrome, Miller syndrome, and diabetic embryopathy. Patients with auricular anomalies should be assessed carefully for accompanying dysmorphic features, including facial asymmetry; colobomas of the lid, iris, and retina; choanal atresia; jaw hypoplasia; branchial cysts or sinuses; cardiac murmurs; distal limb anomalies; and imperforate or anteriorly placed anus. If any of these features are present, then a renal ultrasound is useful not only in discovering renal anomalies but also in the diagnosis and management of MCA syndromes themselves. A renal ultrasound should be performed in patients with isolated preauricular pits, cup ears, or any other ear anomaly accompanied by 1 or more of the following: other malformations or dysmorphic features, a family history of deafness, auricular and/or renal malformations, or a maternal history of gestational diabetes. In the absence of these findings, renal ultrasonography is not indicated.

Imaging the neonatal mandible for accurate distraction osteogenesis

The position of mandibular teeth is difficult to document in the neonatal patient. Panorex images are difficult to obtain in an uncooperative pediatric patient. The new technique presented by the authors uses computed tomographic data to create a curved, reformatted image of the mandible, and generates an image similar to a panorex image. This curved, reformatted mandibular image provides accurate visualization of the mandible and mandibular teeth. This technique allows for precise pin placement and osteotomy in distraction osteogenesis.

Three-dimensional spiral CT of craniofacial malformations in children

OBJECTIVE

To assess the value of three-dimensional CT (3D CT) in the diagnosis and management of suspected paediatric craniofacial malformations.

MATERIALS AND METHODS

Twenty-eight children (12 girls, 16 boys) with a mean age of 4 years, suffering from craniofacial or cervical malformations, underwent craniofacial spiral CT. 3D reformatting was performed using an independent work-station.

RESULTS

3D CT allowed the preoperative evaluation of 16 patients with craniosynostosis and the post-surgical management of 2 patients. 3D CT clearly depicted malformations of the skull base involving the petrous bone in seven patients (four cases of Goldenhar-Gorlin syndrome, one case of Treacher-Collins syndrome and two cases of Crouzon's disease). Four patients with craniofacial clefts were also evaluated. Radiological findings were confirmed by the clinical and intraoperative findings in all patients that underwent surgical treatment. Movement artefacts and "Lego effect" related to abrupt change of cranial vault border were encountered and are discussed.

CONCLUSIONS

3D CT of the skull can safely and reliably identify paediatric craniofacial malformations involving bone, and it should be used as morphological mapping to help the surgeon in planning surgical treatment.

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

We present the results of detailed CT investigation of nine patients with mandibulofacial dysostosis (MFD). We also graded the severity of microtia according to Marx's classification system. The results revealed a positive correlation between the severity of microtia and the severity of deformity of the external auditory canal, and attic formation. In 13 ears, the stapes was not adequately visualized to allow any comment on its form. The angle of the first genu of the facial nerve ranged from 55.0 to 123.6 degrees (mean +/-S.D.; 99.5 +/-18.5 degrees ), indicating that this angle is more obtuse in MFD patients than in normal subjects. The eustachian tube and tympanic sinus were present in all the ears examined. None of the patients had mastoid pneumatization. In four ears, the lateral semicircular canal was dysplastic. Eleven ears of six patients scored less than 5 in the grading system developed by Jahrsdoerfer for assessment of the suitability for atresia surgery. These findings indicate that most patients with mandibulofacial dysostosis are poor surgical candidates.

Mandibulofacial dysostosis--variability in facial morphology and growth: a long-term profile roentgenographic and roentgen stereometric analysis of three patients

OBJECTIVE

To monitor and compare facial morphology and growth in three individuals with variable expression of mandibulofacial dysostosis (MFD) in terms of changes in the skeletal profile and in terms of growth in the circummaxillary sutures and temporomandibular joints (TMJs).

DESIGN

Retrospective conventional profile roentgenography (mean age 9 to 18 years) and prospective roentgen stereometric analysis (RSA) (mean age 7 to 17 years).

SETTING

Center for Craniofacial Anomalies and Department of Plastic and Reconstructive Surgery, Malmö University Hospital, Sweden.

PATIENTS

The first three MFD patients seen by one of the authors (B.R.).

INTERVENTIONS

Surgery was performed at the Department of Plastic and Reconstructive Surgery. Implants were inserted at surgery under general anesthesia. Roentgen examinations were performed in connection with continued clinical evaluations and treatment.

MAIN OUTCOME MEASURES

All profile roentgenograms were traced and measured by one of the authors (K.-V.S.) using a conventional point-based analysis.

RESULTS

The more afflicted patient showed a greater total difference in profile morphology and growth from the norm and more pronounced effects of articular growth restriction. Little change in the skeletal profile was associated with considerable displacement of the jaws.

CONCLUSIONS

The variability in MFD expression and surgical procedures in our patients is reflected less in the skeletal profile morphology and growth and more in the displacement of the jaws.

Multi-facial anomalies in mandibulofacial dysostosis. A report of three cases

Mandibulofacial dysostosis is readily recognized on the basis of a characteristic facial appearance caused by hard and soft tissue abnormalities of the face, including malformations of the ear. Generally, the abnormality is symmetrical. The psychological and social stigma associated with severe facial deformity makes this syndrome one of the most challenging reconstructive problems presented to the craniomaxillofacial surgeon.

Radiocephalometric evaluation of a family with mandibulofacial dysostosis

Persons from four generations of a family with mandibulofacial dysostosis (MFD), known as Treacher Collins (TC) Syndrome, were examined for the presence of clinical signs traditionally associated with this syndrome. In this family, 14 adults, who had been judged trait bearers by an earlier family study were included in this study. Maxillary and mandibular study models were taken of affected and unaffected family members. Panoramic cephalograms and lateral radiographs were taken. The lateral cephalograms were traced and digitized on a computer system and compared. The 117 cephalometric values of the trait bearers were compared with known standard values and nontrait bearing family members. In the trait bearing group, 81 of the 117 values and, in the nontrait bearing group, 72 of the 117 values were significantly different (p < 0.05) when comparing mean values to the accepted normal range. The interfamily comparison between trait-bearing and nontrait members revealed nine values to be significantly different. This indicates that cephalometric analysis of these patients, some of whom have minimal clinical expression of the gene, may have potential value for screening and further characterization of this condition. The results also suggest that intrafamily comparisons may be of greater value for diagnostic confirmation of TC than comparison with literature norms.

Mandibulofacial dysostosis: CT findings of the temporal bones

Six patients of two families with clinically suspected and genetically proven Treacher Collins syndrome and hearing loss were studied by CT of the temporal bone. The objective of this study was to detect the abnormalities and to show the variation of expression of abnormalities. We found a high incidence of asymmetry in the different ear malformations and a slightly lower incidence of some other classical features, probably due to our patient selection.

Prenatal sonographic diagnosis of Treacher Collins syndrome: a case and review of the literature

We report the prenatal ultrasonographic diagnosis of a fetus with mandibulofacial dysostosis (Treacher Collins syndrome). Sonographic findings included: polyhydramnios, microcephaly, abnormal fetal facial features (slanting forehead, microphthalmos, micrognathia), and abnormal fetal swallowing. A review of the current literature pertaining to prenatal diagnosis of this condition is presented.

Cranio-orbito-zygomatic measurements from standard CT scans in unoperated Treacher Collins syndrome patients: comparison with normal controls

Fourteen reproducible cranio-orbito-zygomatic measurements taken from 26 standard axial computed tomographic (CT) scans of unoperated individuals with symmetric forms of Treacher Collins syndrome (TCS) were compared to age-matched controls. The interorbital measurements of the TCS patients were at the mean when compared to their cohort group (medial and lateral orbital wall separation), while the zygomatic measurements were significantly less than normal confirming the extent of malar hypoplasia. The congenitally deficient lateral aspect of the orbits in TCS patients was confirmed by the greater than normal values measured for globe protrusion and medial orbital wall protrusion in conjunction with the diminished lateral orbital wall lengths, all of which use the lateral orbital rim as a reference point. The abnormal shape of the anterior cranial vault in patients with TCS was documented as a diminished intercoronal distance (width) and decreased cephalic length when compared to normal age-matched controls.

[Modern imaging of maxillofacial deformities]

Facial malformations make a wide chapter of maxillofacial abnormalities whose treatment needs an accurate clinical-instrumental analysis to quantify malformation entity and to agree on precise lesion classification and subsequent management. Maxillofacial abnormalities are classified as congenital, growth-related and acquired. Congenital deformities include the alterations present at birth, i.e., craniofacial stenosis, oto-mandibular syndrome. Treacher-Collins and Goldenhar syndrome, facial clefts and lip-palate clefts. Growth-related malformations include the deformities appearing during growth and which are called maxillary dysmorphosis, e.g., hemimandibular hyperplasia, prognathism, maxillary hypoplasia, etc. Acquired malformations are those remaining after trauma or cancer surgery and those which are secondary to fibrous dysplasias of the craniofacial complex. May 1990 through May 1993, forty-two patients with different malformations were examined. The malformations secondary to cancer surgery were not included in our series. A radiologic study including conventional skull radiography, teleradiography and panoramic tomography had been performed for preliminary assessment before axial CT studies and 2D and 3D reconstructions. As for our series, in 20 patients coventional radiology was exhaustive to diagnose the disorder and to supply essential elements for treatment planning while axial CT and 3D reconstructions added no further piece of information. Only in the most complex malformations and in all cases of congenital malformations was axial CT needed to assess the type, extent and entity of the malformations allowing both the diagnosis and adequate surgical planning.

[High resolution computerized tomography of the temporal bone in mandibulofacial dysostosis]

High resolution CT (HR-CT) scanning of the temporal bone was performed in three patients with a fully expressed mandibulofacial dysostosis for preoperative assessment of temporal bone abnormalities. The external auditory canal was absent in five of six ears. Scans revealed a dysplastic middle ear cleft with dysplastic and partly dislocated ossicles. The ossicles were absent in two temporal bones. In no patient was the mastoid bone pneumatised. The inner ear was affected in only one patient in whom a shortening of the lateral semicircular canal could be found bilaterally. The role of HR-CT of the temporal bone as a preoperative diagnostic tool for the assessment of abnormalities of surgical import is discussed.

Fetal micrognathia: associated anomalies and outcome

The purpose of this study was to evaluate the spectrum of sonographic findings, karyotypic abnormalities, and clinical outcome in cases of fetal micrognathia. Twenty fetuses with sonographically identified micrognathia were identified between 15 weeks' gestation and term. Five of 20 fetuses (25%) had abnormal karyotypes, including three with trisomy 18 and one each with trisomy 13 and trisomy 9. Sixteen of the 20 fetuses (80%) did not survive: Ten died in utero or during the neonatal period, and six pregnancies were terminated electively. Three of 20 fetuses (15%) had micrognathia as the sole sonographic finding. Two of these fetuses survived, one with growth retardation and one with Pierre Robin syndrome. Thirteen of 20 pregnancies were complicated by polyhydramnios. The diversity of the syndromes represented in our cases of micrognathia indicates a wide breadth of possible diagnoses when micrognathia is encountered prenatally. The poor prognosis and associated karyotypic and lethal anomalies are remarkable, with survival of only four of 20 fetuses in this report.