Cerebro-costo-mandibular syndrome: Clinical, radiological, and genetic findings.

Cerebro-Costo-Mandibular syndrome (CCMS) is a rare autosomal dominant condition comprising branchial arch-derivative malformations with striking rib-gaps. Affected patients often have respiratory difficulties, associated with upper airway obstruction, reduced thoracic capacity, and scoliosis. We describe a series of 12 sporadic and 4 familial patients including 13 infants/children and 3 adults. Severe micrognathia and reduced numbers of ribs with gaps are consistent findings. Cleft palate, feeding difficulties, respiratory distress, tracheostomy requirement, and scoliosis are common. Additional malformations such as horseshoe kidney, hypospadias, and septal heart defect may occur. Microcephaly and significant developmental delay are present in a small minority of patients. Key radiological findings are of a narrow thorax, multiple posterior rib gaps and abnormal costo-transverse articulation. A novel finding in 2 patients is bilateral accessory ossicles arising from the hyoid bone. Recently, specific mutations in SNRPB, which encodes components of the major spliceosome, have been found to cause CCMS. These mutations cluster in an alternatively spliced regulatory exon and result in altered SNRPB expression. DNA was available from 14 patients and SNRPB mutations were identified in 12 (4 previously reported). Eleven had recurrent mutations previously described in patients with CCMS and one had a novel mutation in the alternative exon. These results confirm the specificity of SNRPB mutations in CCMS and provide further evidence for the role of spliceosomal proteins in craniofacial and thoracic development.

Does a true knowledge of dental crowding affect orthodontic treatment decisions?

OBJECTIVES: To assess whether a true knowledge of crowding alters treatment decisions compared with estimates of crowding. MATERIALS AND METHODS: Thirty-six orthodontists were asked to estimate crowding using visualization on eight mandibular arch study models and to indicate possible extraction choices. For each model, the intermolar widths, intercanine widths, and clinical scenarios were identical, but the true crowding varied from 0.2 to 8.4mm as to a lesser extent did the curve of Spee. Eleven orthodontists repeated the visualization exercise after 2 weeks to assess reliability. All 36 of the orthodontists were asked to repeat the treatment planning exercise on the same models, but this time was provided with the true amount of crowding in each case. RESULTS: When the 36 orthodontists used direct visualization of the models to assess crowding, the range of their estimates of crowding increased as the crowding increased. As might be expected, they also tended to move towards extraction treatments as the crowding increased (P = 0.013, odds ratio = 3). Although the reliability of the repeat estimates of crowding were moderate, the mean estimates were greater than the true crowding for each model. When orthodontists were presented with the true amount of crowding, rather than their estimate of crowding, it had a significant effect on the decision to extract, with fewer orthodontists recommending extractions. LIMITATIONS: The principal limitation of this study is that it was a laboratory-based study and utilized just the mandibular arch model for estimation and treatment planning. CONCLUSIONS: Direct visualization may overestimate the amount of crowding present. When the true amount of crowding is known, it can lead to more consistent treatment planning, with the decision to extract fewer teeth in the borderline cases. A formal space analysis is likely to assist with treatment planning.

How good are we at estimating crowding and how does it affect our treatment decisions?

OBJECTIVES: To assess the estimation of crowding by orthodontists and their subsequent extraction choices. MATERIALS AND METHODS: Sixty-two orthodontists were asked to quantify crowding on eight lower arch study models using their preferred method and also to indicate possible extraction choices. For each model, the intermolar widths, intercanine widths, and clinical scenarios were identical, but the true crowding varied from 0.1 to 7.5mm across the eight models as to a lesser extent did the curve of Spee. Eleven orthodontists repeated the exercise after 9 months to assess reliability. RESULTS: The preferred method of space estimation by all of the orthodontists was direct visualization. However, the estimates of crowding were very variable. For the most crowded lower model with 7.5mm of crowding, the estimates ranged from 5 to 20mm. Extraction choices were less variable than estimates of crowding and shifted from second to first premolars as crowding increased. Estimates of crowding and treatment decisions changed with time in 28 of 33 repeat measures. Estimates of crowding were unrelated to clinical experience. LIMITATIONS: The principal limitation of this study is that it was a laboratory-based study and utilized just the lower arch model for estimation and treatment planning. CONCLUSIONS: Extraction decisions and estimates of crowding tended to vary both initially and over time but were less varied in the case of the extraction decisions. Although this may have been a reflection of the limited treatment options, perhaps reassuringly, as the degree of crowding increased, so did the likelihood of prescribing extractions and the decisions generally shifted from second to first premolars. How orthodontists estimate crowding and make subsequent extraction choices is important and has potential medico-legal implications.

The role of the nasopharyngeal prong in craniofacial disorders in particular the Pierre Robin sequence.

There are a wide range of surgical and maxillofacial options to alleviate upper airway obstruction in children with craniofacial disorders. The nasopharyngeal prong (NPP) is a simple idea where the airway obstruction arising from the posteriorly placed tongue secondary to a small mandible can be overcome quickly and without resorting to more invasive surgical procedures. The role of the NPP is of particular interest in Robin sequence (RS). RS describes a congenital anomaly with retrognathia (often with associated U-shaped cleft palate) where in some children the tongue and small jaw can significantly impact on airway patency with upper airway obstruction. The NPP is a modified endotracheal tube, of ideal diameter and cut to a desired length that can bypass the airway obstruction and regain patency to the upper airway. RS has a natural history of mandibular growth and resolution of the symptoms with time and thus the NPP presents a medium term solution precluding the need in selected children of more permanent and potentially unnecessary surgical procedures. The role of the NPP in other craniofacial disorders (either as a temporary solution or longer term option) requires further research.

Managing infants with craniofacial malformations - Where to go next?

Treatment of infants with craniofacial malformations, e.g. Robin sequence, is characterized by considerable heterogeneity and a lack of randomized trials to identify an optimal approach. We propose to establish an international register using a common minimal dataset that will better allow for a comparison between key determinants and outcomes in these patients. In infants, this should include an assessment of mandibular micrognathia, glossoptosis, upper airway obstruction, weight gain and mode of feeding. Later on, neurocognition, speech development, hearing and quality of life should also be included. Together, these data will help better to advice parents on which treatment to choose for their baby with a craniofacial malformation.