Craniofacial team management in Apert syndrome

Introduction

Apert syndrome is one of the rarest of the craniosynostosis syndromes. Affected persons have extensive structural and functional impairments, some of which can be life threatening. Management requires team care from infancy to adulthood. The purposes of this article are to assess the outcomes in individuals with Apert syndrome after completion of treatment and to review current protocols for craniofacial team care and dental, orthodontic, and orthognathic surgical management.

Methods

This was a retrospective cohort study of 8 subjects with Apert syndrome. Cephalograms at 2 time points were compared: adolescence (before midface advancement) and at least 1 year after advancement. The cephalometric values were compared with paired t tests. Team protocols are delineated.

Results

Measurements indicating forward positioning of the maxilla increased significantly: SNA by 10.7° ( P = 0.002) and midface length by 9.6 mm ( P = 0.002). Sagittal jaw relationship improved significantly as well: ANB by 14° ( P = 0.004) and the Wits appraisal by 8 mm ( P = 0.003). Vertical dimensions also increased.

Conclusions

All individuals had significantly improved and stable positions of the midface and normalized facial profiles after treatment.

Apert syndrome (OMIM [Online Mendelian Inheritance in Man] #101200) is a rare craniosynostosis syndrome with an estimated incidence of 1 in every 160,000 live births; it accounts for 4% to 5% of all craniosynostosis syndromes. The syndrome is characterized by irregular craniosynostosis, midface hypoplasia, and syndactyly of the fingers and toes. Although most are sporadic, many are associated with high paternal age. The disorder is associated with a mutation in the FGFR2 gene that maps to chromosome 10q25-10q26 and follows an autosomal dominant inheritance pattern. The recurrence risk for an unaffected parent of a child with Apert syndrome is minor, but an affected person has a 50% risk of having a baby with the syndrome.

The sagittal and metopic sutures are incompletely formed, often with a broad defect in the midline from glabella to the posterior fontanel that might gradually fill in over time. The premature suture closures can result in acrobrachycephaly or turribrachycephaly, large, late-closing fontanels, and macrocephaly. Premature fusion might restrict brain growth and central nervous system development. Those with Apert syndrome have been reported to have a mean IQ of 74 and significant mental deficiencies not readily explained by suture closures. Other central nervous system characteristics include agenesis of the corpus callosum, ventriculomegaly, and hydrocephalus. Spinal fusions are frequently found in C3-4 and C5-6. If there is synostosis of the radius and humerus, limb mobility might be limited.

The maxilla is retruded and hypoplastic. and the palate is high arched and narrow with bulbous palatal swellings, mostly consisting of mucopolysaccharides. This excessive soft-tissue buildup can give the appearance of a pseudocleft. A 30% incidence of soft-palate clefting has been reported. Other findings include shallow orbits, hypertelorism, down-slanting palpebral fissures, strabismus, proptosis, depressed nasal bridge, and deviated nasal septum. Chronic otitis media, hearing loss, and abnormal semicircular canals are common findings. Increased ocular pressure can result in blindness.

Both the primary and permanent dentitions are characterized by impaction, severe crowding, delayed eruption, thick gingival swellings, and congenitally missing teeth. The development of the primary dentition is delayed by a year (mean, 0.96 years), with increased delays in dental development and eruption during preadolescent and adolescent growth. Ectopic eruption of the maxillary permanent first molars, which occurs in about half of individuals, causes premature loss of the deciduous second molars and mesial drifting of the molars. Often, a second premolar will erupt palatally, contributing to further impaction and crowding. Unilateral and bilateral posterior crossbites are prevalent in two thirds of affected persons. These individuals experience high caries risks due to lack of motivation and mobility restrictions from fused shoulder and elbow joints, and hand anomalies, making it difficult to maintain adequate oral hygiene.

The purpose of this study was to evaluate the final treatment outcomes of the team care provided for individuals with Apert syndrome.

Material and methods

This was a retrospective study conducted with records from the University of California at San Francisco’s Center for Craniofacial Anomalies Filemaker database by using the keywords “Apert syndrome” and “craniosynostosis.” There were 46 subjects in the initial sample. Of these, 25 met the inclusion criterion of having had the final midface advancement. Additional inclusion criteria were complete clinical and radiographic records and no previously published articles about these individuals. Eight subjects met these criteria ( Table I ). Cephalometric films taken before midface advancement and after completion of all treatment were compared.

Table I
Number, age, and sex of subjects at both time points
T1 T2
Mean age 14.9 y 17.9 y
Age range 13-16 y 15-20 y
Sex 1 male, 7 females 1 male, 7 females

T1 , Before surgery; T2 , time point farthest from surgery.

The lateral cephalograms obtained before 2006 were taken on a cephalostat with magnification of 9.8%. These images were then scanned (U Max Power Look 1100; UMAX Technologies Inc, Dallas, Tex), and the magnification was calibrated to the digital images that were obtained between 2006 and 2010 with no magnification, and stored in Dimaxis Pro (version 3.3.1; Planmeca, Roselle, Ill). Fifty-three hard-tissue and soft-tissue landmarks were digitized by an orthodontist (S.O.) using Dolphin software (version 10.5; Dolphin Imaging and Management Solutions, Canoga Park, Calif). Thirty-five angular and linear measurements were analyzed. The landmarks and measurements are described in Table II .

Table II
Abbreviations, descriptions, and definitions of points and measurements used on lateral cephalograms
Abbreviation Description Definition
A A-point Deepest point of the curve of the maxilla, between anterior nasal spine (ANS) and the dental alveolus
B B-point Most posterior point in the concavity along the anterior border of the symphysis
ANS Anterior nasal spine The tip of the anterior nasal spine
PNS Posterior nasal spine The tip of the posterior nasal spine
Ba Basion Most inferior posterior point of the occipital bone at the anterior margin of the occipital foramen
Ar Articulare Posterior border of the condyle
Co Condylion Most posterior superior point of the condyle
Me Menton Most interior point of the symphysis of the mandible
Pg Pogonion Most anterior point of the mandible
OP Occlusal plane Functional occlusal plane located between the first molars and the first premolars
PT Pterygomaxillary fissure point Intersection of the inferior border of the foramen rotundum with the posterior wall of the pterygomaxillary fissure
Or Orbitale Lowest point of the orbital rim
S Sella Center of the pituitary fossa of the sphenoid bone
N Nasion Intersection of theinternasal suture with the frontonasal suture in the \midsagittal plane
Gn Gonion Most convex point along the inferior border of the ramus
SNA Maxillary prognathism Angle formed between sella, nasion, and A-point
N-A Maxillary prognathism Linear measurement between nasion perpendicular and A-point
N-B Mandibular prognathism Linear measurement between nasion perpendicular and B-point
SNB Mandibular prognathism Angle formed between sella, nasion, and B-point
N-Pg Mandibular prognathism Linear measurement between nasion perpendicular and B-point
ANB Sagittal jaw relationship Angle formed between A-point, nasion, and B-point
MP-SN Mandibular plane angle Angle formed between the mandibular plane and the sella-nasion plane
MP Mandibular plane Plane from menton to gonion
OP-SN Occlusal plane-sella-nasion Angle formed between the occlusal plane and the sella-nasion plane
FMA Mandibular plane angle Angle formed between the Frankfort horizontal plane and the mandibular plane
Y-axis Y-axis Angle formed between S-Gn and S-N
LFH Lower face height Linear measurement of ANS-Me
A-Po Lower incisor protrusion Linear measurement of lower incisor tip to A-Po line
E-plane Ricketts’ E-line Line between the nasal tip and soft-tissue chin point
Palate plane Palatal plane
U1 Upper incisor Tip of the maxillary central incisor edge
L1 Lower incisor Tip of the mandibular central incisor edge

Statistical analysis

Measurements taken at the 2 time points were compared and tested for statistically significant differences with paired t tests. Two-tailed P values of less than or equal to 0.05 were reported as statistically significant.

Lin’s concordance was used to assess intrarater reliability of the orthodontist’s duplicate measurements. Five randomly selected cephalograms were traced twice 3 weeks later.

Results

Analysis of the digitizing errors produced Lin’s concordance values between 0.8 and 0.9 for all intraclass correlation measurements across 35 variables on the repeated measurements, indicating good to excellent intrarater reliability.

Cephalometric measurements and comparisons are shown in Table III . The anterior cranial base length showed no difference between the 2 time points, as expected.

Table III
Cephalometric measurement comparisons between Apert individuals at the 2 time points
Measurement T1 T2 P value
Cranial base measurements
Anterior cranial base (SN) (mm) 64.8 66.9 0.139
Sagittal maxillary measurements
SNA (°) 71.6 82.3 0.002
Maxillary length (Co-ANS) (mm) 63.8 73.4 0.001
Sagittal mandibular measurements
SNB (°) 85.1 82.9 0.274
Mandibular length (Co-Pg) 103 104 0.268
Sagittal jaw relationships
ANB (°) −13.5 −0.613 0.004
Wits appraisal (mm) −12.0 −4.76 0.003
Vertical maxillary and mandibular measurements
FMA (MP-FH) (°) 25. 3 30.8 0.009
Lower face height (ANS-Me) (mm) 70.1 71.6 0.241
Upper incisor-palatal plane (°) 43.5 32.1 0.030
Dentoalveolar measurements
U1-NA (°) 43.5 32.1 0.030
U1-NA (mm) 17.4 10.9 0.021
L1 protrusion (L1-APo) (mm) 8.86 3.74 0.001
L1-NB (mm) 4.48 4.81 0.654
Interincisal angle (U1-L1) (°) 125 123 0.378
Soft-tissue measurements
Upper lip to E-plane (mm) −9.80 −6.20 0.0001
Lower lip to E-plane (mm) −4.16 −4.18 0.992
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Apr 8, 2017 | Posted by in Orthodontics | Comments Off on Craniofacial team management in Apert syndrome
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