Abstract
Atypical craniofacial clefts of the upper facial region have been well documented; however, the mandibular clefts remain rare and reported as isolated case reports. We report a case of a median mandibular cleft within the context of a Tessier 0-14 axis that we have followed over a 5-year period without surgical/orthodontic intervention. The mandibular symphysis cleft remained open without evidence of the fusion, in contrast to ossification of the metopic dysraphism. Within this context, we present a review of the median mandibular cleft cases from 1819 to 2015.
Introduction
Median mandibular cleft is an extremely rare congenital abnormality even among the atypical craniofacial cleft anomalies. It was described initially in 1819 by Couronne (cited in Monroe, 1966). Several hypotheses have been proposed regarding the formation of the midline mandibular cleft. Most authors believe that the mandible develops from the first pair of branchial arch embryologically, by the fusion of 2 mandibular prominences. Integration of the corresponding mandibular prominences forms the lower cheek and jaw, and the failure in fusion of paired mandibular prominences produces midline defect of the lower jaw (Morton and Jordon, 1935; Armstrong and Waterhouse, 1996). An alternative embryogenic theory suggested that solitary branchial arch develops during the early embryonic stage, instead of paired branchial arches. Two mandibular processes grow from the branchial arch, parted with a furrow in the middle. The deficient growth of the mandibular processes during the early embryonic stage leads to gross mandibular clefts extending into the cervical region. At the later embryonic stage, less severe median mandibular defects develop. The mandibular symphysis develops when the embryo is approximately 25 mm in length and ossifies postnatally during the first year (Oostrom et al., 1996). Postnatally, mandibular symphysis fuses by 7 to 8 months of age, with a comprehensive range of 6 to 9 months (Becker, 1986).
Although various classification schemes have been proposed for the variety of atypical clefts, the classification scheme of Tessier remains the standard. Tessier ordered the atypical cranio-maxillofacial clefts from 0 to 14, where the Tessier cleft 0 and 14 fall on the same midline axis. Because of the rarity of the mandibular clefts, Tessier assigned the number 30 cleft to the mandibular symphysis with the intention that as other mandibular paramedian clefts would be identified, they would be numbered 15 to 30 (Tessier, 1976).
The degree of skeletal and soft tissue involvement of the mandibular Tessier 30 clefts varies widely in the literature. The median cleft can be a minor notch in the vermillion or can extend up to the tongue, chin, hyoid, thyroid cartilage, and the manubrium sterni (Millard et al., 1971; Park and Takushima, 1993). Malformation in the heart, lungs, and other internal organs has also been described in Tessier 30 (Richieri-Costa and Pereira, 1993).
Case Report
A 27-month-old male child was referred to the Craniofacial Center at University of Illinois at Chicago for the management of a persistent large anterior fontanelle. This was the third child of healthy parents with no history of consanguinity. There was no previous history of genetic abnormalities in the family. The pregnancy was uneventful and without exposure to teratogenic elements during pregnancy. The child birth history too was uneventful. Parents were concerned about his delayed milestones, especially speech, and he was started on speech, occupational, and developmental therapy at 18 months of age.
The child at age 27 months presented without any obvious craniofacial anomaly and a normal facies. However, careful clinical examination with palpation revealed large anterior fontanelle extending into the metopic sutural region. Cranial vault indices showed a head circumference of 50.25 cm (50th-75th percentile). Lateral displacement of inner canthi was noticed, with 8.3 cm outer canthal distance (75th-97th percentile), 3.5 cm inner canthal distance (97th percentile), and 5 cm interpupillary distance (75th percentile). Examination of the ears showed a preauricular tag on the right ear and a normal left ear. The upper and lower lips were normal, without apparent mandibular cleft. Intraoral examination showed a narrow, deep, and high arched palate. In addition, there was evidence of prominent finger pads with sharp and pointy nail pads on examination. The chest was asymmetric, with the right side more prominent than the left.
Because of the significant size and persistence of the anterior fontanel defect that was clinically palpable, a craniofacial CT scan was ordered. The CT scan confirmed the large anterior frontal defect (metopic dysraphism) with multiple biparietal and occipital sutures. However, the CT scan in addition revealed that the child had a midline cleft of the mandible (Figure 1) that was not clinically evident. Noncontrast computed tomography scan at the age of 27 months shows nondeveloped frontal bone with osseous defect and midline cleft of the mandible. At 7 years, the remnant small front defect and median symphyseal defect is seen on the CT scan. Morphologically, no gross craniofacial defect is present, with panoramic radiograph showing deficient mandible with dental arch crowding at 7 years of age. Intraoral pictures showing dental arch crowding before orthodontic treatment.
Genetic testing for chromosomal microarray, fragile X, osteogenesis imperfecta, and cleidocranial dysplasia was normal.
At 2.5 years of age, the team’s decision was not to perform either a cranioplasty or autogenous bone graft of the mandibular symphysis. The child was managed conservatively, with annual follow-up for growth and development.
At 7 years of age, 3D craniofacial CT scan was repeated and it revealed progressive ossification of the median frontal region defect. However, the median symphyseal cleft persisted. He presented with severe maxillary-mandibular transverse dental arch crowding. The Bolton discrepancy measurement for the upper dental arch was 15 mm, and for the lower dental arch, it was 18.5 mm.
The archived scans were analyzed by using the Dolphin Imaging system (Chatsworth, California). Landmarks were identified manually and was evaluated by 2 observers to minimize the bias (Figures 2 and 3; Tables 1 and 2). Defined landmarks for 3D skeletal cephalometric analysis. Graphical representation of the mandibular growth on the basis of predefined landmarks. All the measurements are in millimeters. Co, Condylion; Go, gonion; L, left; R, right.) Comparison of the Asymmetry of Anatomical Points at the Age of 27 Months and 7 Years on the x, y, and z Axes, Showing the Distance From the Landmarks That Projected to the Frontal, Coronal, and Midsagittal Planes. Abbreviations: ANS, anterior nasal spine; L, left; Md1, first mandibular incisor; Mx1, first maxillary incisor; PNS, posterior nasal spine; R, right. Three-Dimensional Measurements of the Maxilla and Mandible to Monitor the Growth and Development. Abbreviations: L, left; R, right.
Discussion
Spectrum of the Clinical Features Described in the Review of Literature.
As there was no functional indication to reconstruct at the initial presentation, the craniofacial team/orthodontic elected to follow the child without immediate intervention. The eventual surgical plan was frontal cranioplasty when there was sufficient diplopic space for autogenous cranial bone graft and autogenous mandibular bone grafting at mixed dentition with the formalized orthodontic treatment. We monitored the growth of our patient by clinical examination and objective studies. The craniofacial CT scans at age 27 months and 7 years were available to assess change in growth and development of the natural history of this child with atypical cleft. We found that there was continued ossification of the cranial vault median defect, and that by 7 years of age the small areas of remaining full thickness defects did not warrant surgical intervention. Mandibular bigonial width increased by 3.6% per year, the bicondylar width increased by 1.3% per year, and the bimenton width decreased by 0.4%. In contrast, there was no postnatal ossification of the mandibular symphysis. We chose not to intervene by early bone grafting that would fuse the mandibular symphysis so as to allow orthodontic management at an appropriate age that would involve maxillary and mandibular expansion to increase the alveolar arch length to accommodate the dental crowding. The mandibular cleft was stabilized by autogenous bone graft once the desired arch length and inter-arch width were achieved.
The mode of management and surgical treatment of this condition remains not clearly defined, owing to its rareness and variation in severity. Millard et al. (1979) reported the closure of the mandibular cleft at the age of 8 years, because premature correction of the mandible would risk injury to the developing tooth buds. On the contrary, another case reported that careful earlier correction of the mandibular cleft does not damage the tooth buds but can instead enhance the occlusion (Oostrom et al., 1996). Armstrong and Waterhouse (1996) grafted the mandibular defect at 4 years followed by orthodontic correction of the occlusal cross bite. Ibrahim et al. (2002) treated a case of median mandibular cleft by using the cartilage from the 2 hamartoma associated on the both sides of the median mandibular cleft.
This case illustrates the importance of clinical examination supported by complete radiographic documentation when there is evidence of any component of an atypical cleft. The typical CT scan limited to the skull and orbit to assess the median frontal defect would have missed the mandibular cleft. Atypical clefts do not necessarily manifest fully involving all tissue planes but should be sought along the fault lines described by Tessier (1976).
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
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