Helen Witherow

Spectrum of Antley-Bixler syndrome.

Antley-Bixler syndrome (ABS) is an exceptionally rare craniosynostosis syndrome characterized by radiohumeral synostosis present from the perinatal period. There is a wide spectrum of anomalies seen within ABS, and other features include midface hypoplasia; choanal stenosis or atresia; multiple joint contractures; visceral anomalies, particularly of the genitourinary system; and impaired steroidogenesis.The condition of ABS is curious in that mutations of 2 separate genes have been identified and that there seem to be subtle phenotypic differences between the 2 genotypes. Mutations of the P450 oxidoreductase gene have been reported in those patients with genital anomalies and/or impaired steroidogenesis, and the S351C mutation of the fibroblast growth factor receptor 2 gene has been reported predominantly in those patients with normal genitalia and steroidogenesis. We report a series of 4 patients with ABS and review their main findings and management.

Three-dimensional image analysis of facial skeletal changes after monobloc and bipartition distraction.

Background: Both monobloc and facial bipartition distraction are important tools for correcting functional and aesthetic problems in patients with syndromic craniosynostosis. Three-dimensional computed tomographic reconstructions have become increasingly useful in planning and analyzing surgical results. This study measured the differential deformation of the facial skeleton following distraction osteogenesis with the rigid external distractor frame, looking especially at correction of the midface concavity. Correction of the midface concavity aims to not only improve the appearance but also increase the upper airway volume. Methods: Ten children with syndromic craniosynostoses were studied. Seven children with Crouzon syndrome underwent monobloc distraction and three with Apert syndrome underwent facial bipartition distraction using the rigid external distractor frame. The patients’ ages ranged from 4 months to 15 years. The medial advancement and the lateral advancement of the facial skeleton were compared by landmarking three-dimensional computed tomographic reconstructions using the sella turcica as the fixed point. To compare the shape of the monobloc segment from the preoperative to postoperative scans, a color map was generated. Results: Of the seven patients who underwent monobloc distraction, the mean medial advancement of the face was 4.9 mm greater than the lateral advancement. With the bipartition distraction, the mean central area advancement was 11.4 mm farther than the lateral aspect of the facial skeleton. Conclusions: Both monobloc and in particular the facial bipartition distraction differentially advance the central part of the face more than the lateral areas. This bending of the face appears to have both cosmetic and functional advantages.

Long term results of mandibular distraction.

Mandibular distraction osteogenesis has become a popular surgical modality due to its many advantages over conventional orthognathic surgical procedures. However, in spite of the technique having been used for over 15 years, no concrete long term results are available regarding the stability of results. We discuss the various studies which have reported either in favour or against the stablility of results after distraction. We report a series of 6 cases (3 unilateral and 3 bilateral distraction) where distraction was carried out before puberty and followed them up to seven years after removal of distractors. This case series shows that results achieved by distraction osteogenesis are unstable or best unpredictable with respect to producing a permanent size increase in the mandible. The role of the distraction osteogenesis in overcoming the pterygomassetric sling is questionable. We suggest a multicenter study with adequate patient numbers treated with a similar protocol and documented after growth cessation to have meaningful conclusions on the debate of distraction osteogenesis versus orthognathic surgery.

Relapse following frontofacial advancement using the rigid external distractor.

Multisutural synostosis may result in frontofacial hypoplasia. The aesthetic and function problems arising from this can be corrected by frontofacial advancement, either by monobloc or bipartition osteotomy. Significantly larger, safer advancements can be achieved using distraction osteogenesis when compared to conventional osteotomy. However, the stability of this technique has been questioned. A retrospective study of 21 patients with craniofacial dysostosis who underwent frontofacial advancement osteotomies using the rigid external distractor system was undertaken. Twelve were distracted on protocol 1 (24 hours after surgery at 1.5 mm/d). Nine were distracted on protocol 2 (7 days after surgery at 1 mm/d). A 6-week consolidation period was used. Changes in frontofacial advancement in the sagittal plane were measured preoperatively, immediately, at 6 months, and where possible thereafter annually using lateral cephalograms and three-dimensional computed tomography scans. The midface was distracted an average of 16.4 mm with a range of 12 to 22 mm as measured in the sagittal plain. Relapse was seen only in 3 of 21 patients, and all of these patients were distracted using protocol 1. Distraction osteogenesis of the frontofacial skeleton using the rigid external distractor frame is generally stable. In this series, a longer latency period and reduced distraction rate resulted in greater stability. Overdistraction in the growing infant is recommended to allow for completion of growth. Overdistraction is not needed to compensate for potential relapse.

Transmigration of a maxillary canine. A case report.

In the oral cavity, transmigration is defined as a tooth that crosses the mid-line by more than half its length. Following extensive literature review, it was found that, although well documented with respect to mandibular canines, there were only two publications detailing maxillary cuspid transmigration. This report presents a case of transmigration where the left maxillary canine gradually crossed the mid-line and migrated to the right side in a patient with hemifacial microsomia and cleft palate. The Mupparapu classification of the migratory pattern of the mandibular canines is discussed. Various clinical considerations, as well as guidelines for general practitioners to diagnose and manage such a condition, are also discussed.

Correcting the typical Apert face: combining bipartition with monobloc distraction.

Background: Bipartition distraction is a novel procedure combining frontofacial bipartition and monobloc distraction. Apert syndrome and other syndromic craniofacial dysostoses are often characterized by hypertelorism, with a negative canthal axis and counterrotated orbits. Central midface hypoplasia can result in a biconcave face in both midsagittal and axial planes. Bipartition distraction can correct these facial abnormalities. Methods: Twenty patients (19 Apert syndrome patients and one Pfeiffer syndrome patient, aged 1.6 to 21 years) underwent bipartition distraction. Severity of appearance was graded preoperatively and postoperatively as mild, moderate, or severe. Functional problems were documented by a multidisciplinary team. Central and lateral midface skeletal advancement were measured. Follow-up ranged from 15 months to 7 years. Results: Bipartition distraction consistently produced more central than lateral facial advancement. Mean central advancement was 13.2 ± 5.9 mm at sella-nasion and 11.7 ± 5.4 mm at sella-A point. Lateral advancement was 4.7 ± 2.8 mm. Unbending the face improved aesthetic appearance. Airway function, eye exposure, and elevated intracranial pressure were improved. Complications included six temporary cerebrospinal fluid leaks (four needing a lumbar drain), five patients with postoperative seizures, five patients requiring Rigid External Distraction frame repositioning, one palatal fistula, one velopharyngeal incompetence, five pin-site infections, one abscess under frontal bone, three cases of sepsis, nine patients with worsened strabismus, two patients with enophthalmos, one patient with partial visual field loss, and three patients who required reintubation because of aspiration. Conclusions: Bipartition distraction is an effective procedure with which to differentially advance the central face in Apert syndrome. It improves both function and aesthetics. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Ocular advancement in monobloc distraction.

Background: Monobloc distraction has been demonstrated to be an efficacious, safe, and stable method of providing functional and aesthetic improvement in children with syndromic craniosynostosis. Although the movement of bony structures following monobloc distraction has been quantitatively assessed before, objective analysis of the movement of soft tissues, such as the globe, has not been published previously. The authors present a method that assesses globe movement following monobloc distraction, using computed tomographic scan data. Methods: The preoperative and postoperative computed tomographic scans of 10 patients with Pfeiffer’s and Crouzon’s syndromes, undergoing monobloc distraction, were assessed. Scan data were loaded into voxel image-rendering software that produced a three-dimensional reconstruction. Direct measurements between preoperative and postoperative images were taken. Results: An average upper face osseous distraction distance of 12.94 mm, with an average lower face distraction of 14.19 mm, was achieved in all 10 children. The authors measured average globe movements on three planes and calculated an average left eye forward movement of 5.28 mm and average right eye forward movement of 6.33 mm. In all, globe advancement was approximately two fifths of the distance advanced by the surrounding bone. Conclusions: Forward movement of the globe following monobloc distraction has not previously been described. Although there is no current evidence for optic nerve stretch and compromise in monobloc surgery, the functional implications of these findings should be formally assessed.

Monobloc distraction in an infant, using the rigid external distractor: Problems and solutions - A case report

INTRODUCTION Patients with craniofacial dysostosis frequently develop functional problems including raised intracranial pressure, ocular dysfunction, obstructive sleep apnoeas and failure to thrive. These functional problems can be treated by a number of different techniques. The monobloc frontofacial advancement has the ability to correct all of these functional problems in one procedure, but can be associated with high morbidity particularly in the young infant. AIM A case report of a 4-month-old infant with Pfeiffers syndrome and severe functional problems treated by monobloc osteotomy and distraction using the rigid external distractor is reported. The management, problems and complications encountered with this patient are discussed together with the role of monobloc distraction in the infant. Adaptation of the rigid external distraction (RED) technique using two titanium mesh sheets to prevent penetration of the skull by the cranial pins is described. CONCLUSIONS Monobloc frontofacial advancement in the very young can be successfully achieved using the RED frame, thus treating exophthalmus, raised intracranial pressure and upper airway problems in one operation. However, it may be associated with significant complications and should only be used for those extreme cases where the severity of the functional problems prevent treatment being delayed.

The evaluation of bony union after frontofacial distraction.

Frontofacial advancement by distraction osteogenesis using the rigid external distraction device has become an accepted treatment for the deformity associated with craniofacial dysostoses (e.g., Crouzon, Apert, and Pfeiffer syndromes). The technical and physiological principles of osteogenesis distraction are well understood. This study documents the pattern of calcification at the osteotomy sites after distraction by analysis of serial three-dimensional computed tomography (CT) scans. The CT scans of 25 patients (11 with Crouzon, 6 with Apert, and 8 with Pfeiffer syndrome) were analyzed. Eleven individual areas along the osteotomy lines were assessed for evidence of bone formation. Scores were assigned within 4 categories ranging from no bone, calcification without bridge formation, a bony bridge, to complete bony infill (>95%). The scans were reviewed on 2 separate occasions by 2 independent assessors. There was high concordance both for intraobserver and interobserver scores. Rigid external distraction frame removal was undertaken after a 6-week consolidation period. All CT scan timings were calculated from this date. Of the 25 patients studied, 16 patients had CT scans available at 3 to 6 months, 12 at 9 to 12 months, and 7 at or more than 18 months. The scans were available in standard coronal slices with three-dimensional reconstructions. Bone formation is most consistently seen in the pterygoid region with calcification consistently occurring earlier and more completely in this area. Bone formation was often delayed in the orbital region and severely delayed or absent in the frontal region and zygomatic arches. There was no significant difference in the order or quality of bony union for the 3 underlying craniofacial dysostoses. This preliminary study confirms the clinical impression that bone formation after distraction is greatest in the pterygoid regions. The clinical implications of these findings are discussed.

The danger of using metallic plate and screw fixation in the young

A 13-year-old boy with Apert Syndrome was admitted for bipartition and rigid external distraction. This was done for functional and cosmetic correction of his mid-facial retrusion that had led to speech disturbances, breathing difficulties and obstructive sleep apnoea. At the age of 10 months he had skull vault expansion performed with the bones being held with metallic screws and plates. During the current surgery it was noticed that the metallic screws and the plates that had been used for skull vault expansion had gone through the outer cortex, had embedded into the inner cortex of the skull bone and was pressing on the dura (Figs. 1 and 2). Migration of the metal plate and screws, wellrecognized by paediatric neurosurgeons, can also penetrate the dura and become embedded in the underlying cerebral cortex. Plating systems must be selected properly with due consideration to long-term safety in both traumatic and elective cranial fixation in children. Nonabsorbable plates and screws should be avoided wherever possible.