Beyond Pierre Robin sequence

Parental experiences and genetic counsellor roles in Pierre Robin sequence

Pierre Robin sequence (PRS) is a craniofacial abnormality comprising micrognathia, glossoptosis and airway obstruction, which can impair the newborn's feeding and breathing. While there has been much research around the cause of PRS and most appropriate methods of care, understanding the psychosocial aspects of a PRS diagnosis from the parents' perspective is lacking. The aim of this study is to understand parental experiences of having a child diagnosed with PRS, as well as the role of genetic counselling in PRS. Fourteen semi-structured interviews were conducted with parents of children diagnosed with isolated PRS between 2 and 5 years prior. From these 14 interviews, eleven transcripts were analysed to find common themes and experiences. The diagnosis was confusing and overwhelming for participants during emotionally sensitive periods and little was understood about the cause of their child's PRS. Those participants who did recall experiences with genetic services reported that they were minimal and uninformative. According to participant recollection, genetic counselling was rarely offered, despite there being a potential for this service in PRS. Genetic counselling would be a valuable source of information and support for parents both at the time of antenatal diagnosis, and potentially 6 to 12 months later in the outpatient environment when these children are all routinely reviewed by their clinical care team.

Floating Bone Phenomenon in Pierre Robin Sequence

After a failed mandibular osteodistraction, the wrong positioned mandible of a few patients with Pierre Robin sequence returned in the most functional position and regained a proper symmetry, without external intervention. The study aims to explain this self-adjustment and introduce the floating bone phenomenon.The inclusion criteria were severe micrognathia, Fast and Early Mandibular Distraction Osteogenesis protocol, postoperative mandibular wrong positioning, presurgery, immediate postsurgery, and long-term computed tomography scan. Five patients were included. The considered parameters were the distance between mandibular dental centerline and midsagittal facial axis, the rotation of the mandibular body, the magnitude of elongation, and the lowering of the mandibular body.Three patients went from a decentralization >4 mm in the activation phase to a normalization of the said value in the follow-up. In the same period, the interincisal point of 2 patients moved respectively from 0.5 mm on the left and 0.8 mm on the right to 1.2 mm and 1.6 mm on the right, respectively. The rotation of the mandibular body was meanly 25.6° among all patients. The mean value of the distraction was 14.1 mm. A difference of about 4.4 mm between the left and the right side was measured. The lowering of the mandible varied between 2.8 and 12.6 mm.All patients improved their symmetry. Four of them improved in all the measured parameters, while 1 patient presented a worsening in the decentralization of the interincisal point.The floating bone phenomenon could break new grounds in the management of patients with Pierre Robin sequence.

The etiology of cleft palate formation in BMP7-deficient mice

Palatogenesis is a complex process implying growth, elevation and fusion of the two lateral palatal shelves during embryogenesis. This process is tightly controlled by genetic and mechanistic cues that also coordinate the growth of other orofacial structures. Failure at any of these steps can result in cleft palate, which is a frequent craniofacial malformation in humans. To understand the etiology of cleft palate linked to the BMP signaling pathway, we studied palatogenesis in Bmp7-deficient mouse embryos. Bmp7 expression was found in several orofacial structures including the edges of the palatal shelves prior and during their fusion. Bmp7 deletion resulted in a general alteration of oral cavity morphology, unpaired palatal shelf elevation, delayed shelf approximation, and subsequent lack of fusion. Cell proliferation and expression of specific genes involved in palatogenesis were not altered in Bmp7-deficient embryos. Conditional ablation of Bmp7 with Keratin14-Cre or Wnt1-Cre revealed that neither epithelial nor neural crest-specific loss of Bmp7 alone could recapitulate the cleft palate phenotype. Palatal shelves from mutant embryos were able to fuse when cultured in vitro as isolated shelves in proximity, but not when cultured as whole upper jaw explants. Thus, deformations in the oral cavity of Bmp7-deficient embryos such as the shorter and wider mandible were not solely responsible for cleft palate formation. These findings indicate a requirement for Bmp7 for the coordination of both developmental and mechanistic aspects of palatogenesis.

Neonates with Tongue-Based Airway Obstruction

Objective. In this systematic review, the authors summarize the current evidence in the literature regarding diagnosis, treatment, and long-term outcomes in neonates with tongue-based airway obstruction (TBAO) and assess the level of evidence of included studies.

Data Sources. The terms Pierre Robin syndrome/sequence, micrognathia, retrognathia, and cleft palate were combined with airway obstruction, treatment, tongue-lip plication, and osteogenesis distraction to perform an Ovid literature search, yielding 341 references. The authors excluded references containing patients with isolated choanal/nasal obstruction, patients older than 12 months, and expert opinion papers, yielding 126 articles.

Review Methods. The authors searched 3 electronic databases and reference lists of existing reviews from 1980 to October 2010 for articles pertaining to the diagnosis, treatment, and outcomes of TBAO. Reviewers assigned a level of evidence score based on Oxford’s Centre for Evidence Based Medicine scoring system and recorded relevant information.

Results. Most studies were case studies and single-center findings. The lack of standardization of diagnostic and treatment protocols and the heterogeneity of cohorts both within and between studies precluded a meta-analysis. There was little evidence beyond expert opinion and single-center evaluation regarding diagnosis, treatment, and long-term outcomes of neonates with TBAO.

Conclusions. The variability in the phenotype of the cohorts studied and the absence of standardized indications for intervention preclude deriving any definitive conclusions regarding diagnostic tools to evaluate this patient population, treatment choices, or long-term outcomes. A coordinated multicenter study with a standardized diagnostic and treatment algorithm is recommended to develop evidence for the diagnosis and treatment of neonates with TBAO.

Cleft lip and palate genetics and application in early embryological development

The development of the head involves the interaction of several cell populations and coordination of cell signalling pathways, which when disrupted can cause defects such as facial clefts. This review concentrates on genetic contributions to facial clefts with and without cleft palate (CP). An overview of early palatal development with emphasis on muscle and bone development is blended with the effects of environmental insults and known genetic mutations that impact human palatal development. An extensive table of known genes in syndromic and non-syndromic CP, with or without cleft lip (CL), is provided. We have also included some genes that have been identified in environmental risk factors for CP/L. We include primary and review references on this topic.

Congenital anterior glottic webs with subglottic stenosis: surgery using perichondrial keels

Four children with severe congenital anterior glottic webs required surgical reconstruction of their laryngeal airway to either avoid a tracheotomy or allow tracheotomy decannulation. The technique of re-establishing a glottic inlet allows both normal respiration, good cough and a satisfactory voice outcome. It utilizes an autogenous graft with perichondrium acting as an overlay keel to minimize glottic web reformation. All children were found to have Shprintzen syndrome.

OBJECTIVE

The objective of this case series was to document the method of surgically using this perichondrial keel for airway reconstruction. It also examined the subsequent outcome and associated complications that were encountered.

METHODS

A prospective analysis of four cases from 2001 to 2008 created a database of information. All cases were classified using the Cohen staging system. They were treated with the same surgical technique using auricular or costal cartilage graft with attached perichondrium, but the postoperative course was tailored to each individual case.

RESULTS

All four children were successfully treated with removal or avoidance of a tracheostomy. All had an associated subglottic stenosis treated, and had no major complication requiring revision tracheotomy. They did not have any respiratory complications, and they produce a satisfactory voice albeit still slightly husky.

CONCLUSION

All four cases had Shprintzen syndrome, and confirms the need to screen for VCFS in children with an anterior glottic web. Tracheotomy is still the gold standard of treatment in severe congenital anterior glottic webs. The described technique offers another good option to the paediatric airway surgeon in managing this condition.

Focus on the physical assessment of the infant with Stickler syndrome

Stickler syndrome is an autosomal dominant, genetic connective tissue disorder characterized by ocular, orofacial, auditory, and skeletal anomalies. The diagnosis of Stickler syndrome is often missed in the newborn period and diagnosed as simply Pierre Robin sequence. For these patients, complications and disabilities could be lessened by further analysis of the family history.Neonatal caregivers are responsible for the immediate care of the newborn with Pierre Robin sequence. The prudent healthcare profession will explore the origin of the condition to provide optimal comprehensive care to the infant and family. This article reviews the physical findings of Stickler syndrome including differentiation between similar syndromes. A systematic review of physical findings is included along with treatment options.

Rescue of an in vitro palate nonfusion model using interposed embryonic mesenchyme

The authors previously established an in vitro palate nonfusion model on the basis of a spatial separation between prefusion embryonic day 13.5 mouse palates (term gestation, 19.5 days). They found that an interpalatal separation distance of 0.48 mm or greater would consistently result in nonfusion after 4 days in organ culture. In the present study, they interposed embryonic palatal mesenchymal tissue between embryonic day 13.5 mouse palatal shelves with interpalatal separation distances greater than 0.48 mm in an attempt to "rescue" this in vitro palate nonfusion phenotype. Because no medial epithelial bilayer (i.e., medial epithelial seam) could potentially form, palatal fusion in vitro was defined as intershelf mesenchymal continuity with resolution of the medial edge epithelia bilaterally. Forty-two (n = 42) palatal shelf pairs from embryonic day 13.5 CD-1 mouse embryos were isolated and placed on cell culture inserts at precisely graded distances (0, 0.67, and 0.95 mm). Positive controls consisted of shelves placed in contact (n = 6). Negative controls consisted of shelves placed at interpalatal separation distances of 0.67 mm (n = 6) and 0.95 mm (n = 7) with no interposed mesenchyme. Experimental groups consisted of embryonic day 13.5 palatal shelves separated by 0.67 mm (n = 11) and 0.95 mm (n = 12) with interposed lateral palatal mesenchyme isolated at the time of palatal shelf harvest. Specimens were cultured for 4 days (n = 19) or 10 days (n = 23), harvested, and evaluated histologically. All positive controls at 4 and 10 days in culture showed complete histologic palatal fusion. All negative controls at 4 days and 10 days in culture remained unfused. Five of six palatal shelves separated at 0.67 mm interpalatal separation distance with interposed mesenchyme were fused at 4 days, and all five were fused at 10 days. At an interpalatal separation distance of 0.95 mm with interposed mesenchyme (n = 12), no palates (zero of four) were fused at 4 days, but seven of eight were fused at 10 days. These data suggest that nonfused palatal shelves can be "rescued" with an interposed graft of endogenous embryonic mesenchyme to induce fusion in vitro.

De novo interstitial direct duplication 1(q23.1q31.1) in a fetus with Pierre Robin sequence and camptodactyly

Interstitial duplications of chromosomal region 1q are rarely seen. We report the first prenatal diagnosis of pure partial trisomy 1q. The fetus was karyotyped for polyhydramnios, micrognathia, and flexion of fingers of both hands. Conventional and molecular cytogenetics showed a de novo direct duplication of the chromosomal region 1q23.1q31.1 leading to a partial trisomy 1q. At autopsy, the fetus showed Pierre Robin sequence (PRS) and camptodactyly. The main histological finding was a decreased number of motoneurons with apoptotic features in the anterior horn of the spinal cord. A literature review and our observations suggest that genetic material mapping to chromosome 1q25 could be responsible for PRS with distal arthrogryposis when this is in triple dose.

Altered mandibular development precedes the time of palate closure in mice homozygous for disproportionate micromelia: an oral clefting model supporting the Pierre-Robin sequence

BACKGROUND

Development of the human craniofacial anatomy involves a number of interrelated, genetically controlled components. The complexity of the interactions between these components suggests that interference with the spaciotemporal interaction of the expanding tongue and elongating Meckel's cartilage correlates with the appearance of cleft palate. Mice homozygous for the semi-dominant Col2a1 mutation Disproportionate micromelia (Dmm), presenting at birth with both cleft palate and micrognathia, provide the opportunity to test the hypothesis that mandibular growth retardation coincides with formation of the secondary palate as predicted from our understanding of the Pierre Robin sequence. The present study was conducted in embryonic day 14 (E14) mice, 1 day before palate closure, to describe the relationship between growth of the lower jaw/tongue complex versus genotype of the embryo.

METHODS

Whole heads, isolated from E14.25, E14.5 and E14.75 wild-type and homozygous mutant embryos, were fixed in Bouin's solution, embedded in paraffin, and serially sectioned. Mid-sagittal sections, stained with toluidine blue, were used to estimate growth of both tongue and lower jaw (Meckel's cartilage length) during a 12-hr period preceding palate closure.

RESULTS

In control embryos, the largest increase in Meckel's cartilage length occurred between E14.5 and E14.75. Compared to control, the mean Meckel's cartilage length in the mutant was similar at E14.25, but was significantly less at E14.5 and E14.75. Absolute tongue size in control embryos increased linearly during this period of E14.25 to E14.75. Relative to the rapidly growing Meckel's cartilage, however, relative tongue size in control embryos actually decreased over time. Absolute tongue size in the mutant was not significantly different from that of control at any of the embryonic stages examined, however, relative tongue size in the mutant was significantly greater at E14.75 compared to control.

CONCLUSION

Mandibular growth retardation, coupled with relative macroglossia in E14 Dmm/Dmm mice, suggests that the concerted development of the palate and lower jaw complex in the mutant is aberrant. Detection of micrognathia and pseudomacroglossia in homozygotes, before the time of palate closure, supports the hypothesis that a relationship exists between growth retardation of Meckel's cartilage and malformation of the secondary palate, as predicted by the Pierre-Robin sequence.

The infant with Pierre Robin sequence: review and implications for nursing practice

Pierre Robin sequence (PRS) is associated with long-term respiratory, nutritional, and developmental difficulties. Hypoxic complications, including cerebral impairment, cor pulmonale, and failure to thrive may be prevented or minimized with early detection and comprehensive care. This article reviews the embryological development of PRS and outlines the medical and nursing implications for treatment. Partnership with parents and a coordinated community care team are essential for successful management of infants and children with PRS.