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At least 73 records · Page 4Linked to original sources
PubMed2005

Mandibular advancement by distraction osteogenesis for tracheostomy-dependent children with severe micrognathia.

PURPOSE: The purpose of this study was to evaluate mandibular lengthening by distraction osteogenesis (DO) to achieve decannulation of micrognathic children with "permanent" tracheostomies. PATIENTS AND METHODS: Using a retrospective chart review, patients were included who had 1 ) airway compromise/tracheostomy, 2 ) micrognathia, 3 ) polysomnography-documented obstructive apnea, and 4 ) mandibular advancement using DO. Excluded were 1 ) adults, 2 ) neonates without tracheostomy, and 3 ) patients with central apnea. Patient age, past medical history, age at tracheostomy, and distraction protocol were documented. Oxygen saturation, posterior airway space (in millimeters), and sella-nasion-B point (SNB) angle were recorded. The distraction protocol consisted of a latency of 48 hours and a rate of 1 mm/day. RESULTS: There were 5 children, aged 2 to 14 years, who received a tracheostomy between ages 2 and 36 months for airway obstruction. All patients underwent bilateral mandibular distraction using semiburied, unidirectional devices. The average latency was 58 hours, the rate was 1 mm/day, the duration of fixation was 40 to 60 days, and the magnitude of advancement was 23 mm. Healing was evaluated by clinical, radiologic, and ultrasound examinations. No complications were experienced. Mean follow-up was 3.2 years. Postdistraction sleep studies demonstrated no obstructive apneic events and a mean oxygen saturation of 98% (preoperative, 76%, P < .005). Cephalometric values improved: posterior airway space 4 to 14 mm; SNB 66 degrees to 72 degrees ( P < .005 for both variables). Four of the 5 patients have been successfully decannulated to date. CONCLUSIONS: The results of this preliminary study indicate that mandibular advancement by DO is a potentially viable treatment option for tracheostomy-dependent children with upper airway obstruction secondary to micrognathia.

Adolescent↗
PubMed1996

Role of posterior transverse interarch discrepancy in Class II, Division 1 malocclusion during the mixed dentition phase.

Posterior transverse interarch discrepancy (PTID), measured as the difference between the maxillary and mandibular intermolar widths, was investigated in a sample of 60 Class II, Division 1 subjects during the mixed dentition phase. Two main groups were detected: Class II group 1 (30 subjects) with PTID and Class II group 2 (30 subjects) without PTID. A sample of 30 Class I subjects in the mixed dentition phase was used as a control group. In Class II group 1, PTID was found to be due to a significantly narrower maxillary arch. The craniofacial skeletal features of both Class II groups and of the Class I group were assessed. The Class II group with PTID showed mandibular retrusion associated with a posteriorly displaced mandible of normal size (functional mandibular retrusion). The Class II group without PTID had mandibular retrusion due to a micrognathic mandible (anatomic mandibular retrusion). The relevance of these findings for treatment planning in Class II, Division 1 malocclusion in the mixed dentition was stressed.

Adolescent↗
PubMed2001

Mandibular distraction osteogenesis in very young patients to correct airway obstruction.

The purpose of this study was to measure changes in the airway cross-sectional area of pediatric patients with micrognathia and obstructive airway symptoms after treatment by mandibular distraction. The measurements obtained were correlated with the clinical outcomes.Ten patients, ranging in age from 3 months to 8 years, underwent measurement and distraction. Eight patients were under 30 months of age. Six were diagnosed with Pierre Robin sequence, two with Treacher Collins syndrome, and two with Nager syndrome. All patients had retrognathia of greater than 8 mm and obstructive airway symptoms while awake that had resulted in tracheostomy (3), repeated apnea monitor triggering (5), or abnormal sleep study (2). Cephalometric analysis was performed pretreatment and posttreatment by distraction. The effective airway space was defined with the following boundaries: a horizontal line from the tip of the odontoid to the velum, the uvula tip to the tongue base along the shortest line, the tongue base down to the base of the epiglottis, and the horizontal line to the posterior pharynx. These lines were traced for each cephalogram, the outline was digitized, and the area was calculated by computer. An analysis of the square area change was done by paired t test. The range of distraction was 8 to 22 mm; the mean effective airway increase was 67.5 percent, with a range of 26 to 120 percent. Measurable airway increase occurred in all patients who underwent distraction, and all patients showed clinical improvement. Six patients with Pierre Robin sequence became asymptomatic, with normal sleep, feeding, and weight gain. Two patients with Nager syndrome and tracheostomies were decannulated and were asymptomatic postdistraction. One patient with Treacher Collins syndrome without tracheostomy became asymptomatic after mandibular distraction; one patient failed to distract because of premature consolidation and continued to require a cannula. Mandibular distraction seems to provide a consistent change in tongue base position that improves obstructive airway symptoms by increasing measured effective airway space. The potential for mandibular distraction exceeds the simple correction of malocclusion also by eliminating soft-tissue obstruction of the micrognathic airway. Airway improvement is independent of the syndrome diagnosed. Mandibular distraction osteogenesis may be useful to avoid or decannulate existing tracheostomy in infants with micrognathia.

Airway Obstruction↗
PubMed2004

The dentofacial features of Sanjad-Sakati syndrome: a case report.

Sanjad-Sakati syndrome is an autosomal recessive disorder that was first reported by Sanjad et al. in 1988. It is characterized by congenital hypoparathyroidism, severe growth failure and dysmorphic features. The clinical features include deep set eyes, microcephaly, thin lips, depressed nasal bridge with beaked nose, external ear anomalies and learning difficulties. This report presents the case of a 4-year-old patient who was referred to our dental clinic because of pain in her mouth and poor dental health. Oral findings included micrognathic mandible and maxilla, microdontia, enamel hypoplasia as well as severely decayed teeth. Treatment was carried out under general anaesthesia to extract the most severely affected teeth and restore those which could be conserved. It was concluded that these patients have special dental needs; early diagnosis of the affected children is therefore important in order to commence preventive dental therapy and carry out appropriate dental treatment at the optimum time.

Child, Preschool↗
PubMed2005

The upper airway in Weaver syndrome.

Weaver syndrome is a rare disorder of unknown etiology characterized by skeletal overgrowth, distinctive craniofacial and digital abnormalities, and advanced bone age. The prime anesthetic problem reported in children with Weaver syndrome is difficulty with tracheal intubation, resulting in part from relative micrognathia, short neck, and an anterior and cephalad position of the larynx. In this report, the authors describe their experience with two children diagnosed with Weaver syndrome who presented for dental surgery. Contrary to previous reports, tracheal intubation was accomplished with relative ease, suggesting that difficulty in intubation in Weaver syndrome may be age-related, diminishing with advancing age and growth of the mandible, as has been reported for other micrognathic syndromes such as Pierre Robin sequence.

Anesthesia, General↗
PubMed1975

The Weissenbacher-Zweymuller syndrome of micrognathia and rhizomelic chondrodysplasia at birth with subsequent normal growth.

Two patients are reported with the clinical and roentgenographic findings of the Weissenbacher-Zweymuller syndrome. The features are neonatal micrognathia (Pierre Robin syndrome), rhizomelic chondrodysplasia with dumbbell shaped femur and humeri. The bone changes tend to regress and there is normal growth on serial studies. A third case seemed at birth to show similar roentgenographic changes but was dwarfed; serial observations revealed him to be a case of the Kniest syndrome with micrognathia as an added feature. The term "micrognathic dwarfism" suggested by Maroteaux is probably best aboided since it will inevitably include a variety of conditions, only some of which are associated with dwarfism.

Diagnosis, Differential↗
PubMed2000

[Distraction osteogenesis of the mandible in 2 children with obstruction of the upper respiratory tract due to micrognathia].

A girl approximately 2 years old with Pierre Robin sequence had periods of nocturnal respiratory insufficiency as a consequence of micrognathia and a boy nearly 4 years old with Nager syndrome and tracheostomy was retarded in his speech development, had problems swallowing and often had respiratory tract infections. The obstruction of the upper respiratory tract was resolved by performing a distraction osteogenesis of the lower jaw. A tracheostomy was avoided or else removed. The girl became more active and there was an improvement in the boy's speech development. Distraction osteogenesis is a good alternative to the current practice of mandibular reconstruction in micrognathic patients, which involves extensive bone grafts.

Child, Preschool↗
PubMed1989

Teratogenicity of 3,3-dimethyl-1-phenyltriazene in the rat: histopathologic and ultrastructural alterations.

3,3-Dimethyl-1-phenyltriazene (DMPT) is a methylating agent which is teratogenic, carcinogenic, and mutagenic. A single intraperitoneal injection of 30 mg DMPT/kg given to pregnant rats on day 12 of gestation produces malformations with minimal maternal toxicity. Malformations include skeletal deformities such as micrognathism, cleft palate, and digital malformations, as well as central nervous system hypoplasia. The purpose of the present study was to characterize the light and electron microscopic alterations produced by DMPT. Electron microscopy (EM) revealed that at 4 hr postinjection of DMPT, rare cells of the neural tube contained few membrane-bound aggregations of organelles and condensed chromatin; this change was consistent with apoptosis, a type of cell death characterized by morphologic and biochemical alterations distinct from necrosis. At 8 hr postinjection, apoptosis was more prominent in the neural tube and also observed in the mandibular process. At 16 hr postinjection, numerous apoptotic cells were interspersed with unaffected cells that contained phagocytized apoptotic bodies. Light microscopic examination of DMPT-exposed conceptuses showed apoptosis in the neural tube at 24 hr postinjection. Forty-eight hours postinjection, apoptosis, in decreasing order of severity, was observed in the neural tube, craniofacial processes, limb buds, and somites and liver. Apoptosis was absent in all tissues by 72 hr postinjection. Nervous tissues failed to achieve proper histologic organization, but all other tissues appeared microscopically normal from 72 hr postinjection until the end of gestation. There appeared to be some degree of tissue specificity to the effects of DMPT.

Abnormalities, Drug-Induced↗
PubMed1997

Mevalonic acidemia: first case of Japan.

Mevalonic acidemia is a rare metabolic disorder due to mevalonate kinase deficiency which affects the biosynthesis of cholesterol and nonsterol isoprenes. We report the first case of Japan. The clinical course is characterized by intrauterine growth retardation, postnatal growth failure, intractable diarrhea, liver dysfunctions and death at three months of age. Dysmorphic features including triangular face, protrusion of forehead, hypertelorism, low set ears and micrognathism were noted. High mevalonic acid level was found by GC/MS.

Fatal Outcome↗
PubMed1996

Retrograde fibreoptic intubation in a child with Nager's syndrome.

PURPOSE: The authors describe a retrograde fibreoptic technique for tracheal intubation in a micrognathic child with a tracheo-cutaneous fistula. CLINICAL FEATURES: A four-year-old child with Nager's syndrome presented for surgical closure of a tracheocutaneous fistula. A tracheostomy tube had been placed in the neonatal period for management of upper airway obstruction due to severe micrognathia. At 2 1/2 yr of age, after a successful mandibular advancement procedure, the tracheostomy was removed and the child allowed to breathe through the natural airway. Preoperative physical examination revealed an uncooperative child, unable to open her mouth due to limited temporo-mandibular motion. The child was first anaesthetized with ketamine, 70 mg im, then halothane by mask. The authors were unable to open the child's mouth sufficiently to allow rigid laryngoscopy. Attempts at oral and nasal fibreoptic intubation were unsuccessful. Ultimately, the authors were able to intubate nasally by passing an ultrathin Olympus LF-P laryngoscope under direct vision through the tracheocutaneous fistula in a cephalad direction, through the larynx and nasopharynx, then out the nares. An endotracheal tube was then advanced over the fibreoptic scope and positioned distal to the tracheocutaneous fistula. The surgical procedure was successfully accomplished and the trachea was extubated postoperatively without difficulty. CONCLUSION: Retrograde fibreoptic intubation may be an option for airway management of a select group of children who cannot be intubated by traditional techniques.

Child, Preschool↗
PubMed2005

Tight skin and limited joint movements as early presentation of Hutchinson-Gilford progeria in a 7-week-old infant.

UNLABELLED: We present a 7-week-old male infant with pseudoscleroderma as a primary manifestation of the Hutchinson-Gilford syndrome of premature aging. He had suffered intra-uterine growth retardation; micrognathism and a cleft palate were evident at birth. He presented with feeding difficulties and severe, diffuse scleroderma-like lesions, a faint peri-oral cyanosis and prominent scalp veins. With time, special facial features became more and more apparent: frontal bossing, prominent eyes, thin and fine nose and lips, microstomia, low-set ears and occipito-parietal alopecia. Histopathology of the skin showed an increased density and thickness of collagen in the dermis and hypodermis. Within the 1st year of life, typical skeletal characteristics were observed. The diagnosis of Hutchinson-Gilford syndrome was confirmed by analysis of the lamin A gene, revealing a heterozygous c.1824C > T (G608G) mutation. CONCLUSION: Hutchinson-Gilford syndrome is an extremely rare disorder of which the full clinical spectrum becomes evident with time. Sclerodermatous changes in the infant can be the first manifestation.

Alopecia↗
PubMed2005

Anesthetic and airway management of general anesthesia in a patient with Meckel-Gruber syndrome.

Meckel-Gruber syndrome, characterized by occipital encephalocele, microcephaly, polydactyly, cleft lip or palate, mandibular micrognathism, and anatomical abnormality of the larynx and tongue, along with other associated malformations, is in the list of diseases associated with difficult airway. However, there has been no report on the management of general anesthesia and airway management for such patients. A 2-year-old girl with Meckel-Gruber syndrome was scheduled for cardioplasty and gastrostomy for gastroesophageal reflux under general anesthesia. Preoperative examination revealed obesity, microgenia, dysspondylism, proteinuria, hypoplastic kidneys, and stenosis of the anal canal. Although we anticipated some difficulty with the intubation and prepared several alternative methods for intubation, such as a bronchofiberscope and a laryngeal mask airway, tracheal intubation was completed without difficulty using conventional laryngoscopy after inhalational induction with sevoflurane. Because most patients with this syndrome die before and shortly after delivery, those who survive to some age might have less severe deformities.

Abnormalities, Multiple↗
PubMed1991

Teratogenicity of 3,3-dimethyl-1-phenyltriazene: distribution in rats and rat embryos.

3,3-Dimethyl-1-phenyltriazene (DMPT) is a methylating agent which is carcinogenic, teratogenic and mutagenic which, in the rat, provides a reproducible animal model with which to study the basis of chemically-induced micrognathism. The basis of teratogenic organotropism of DMPT and other methylating teratogens is unknown. The present study was undertaken to determine if limited chemical distribution within the embryo was responsible for the organotropism of DMPT. Whole-embryo autoradiographs and liquid scintillation analysis indicated that although DMPT may have some limitations of chemical distribution within the embryo, these limitations are not sufficient to explain its teratogenic organotropism.

Animals↗
PubMed2005

Rehabilitation of a hemophiliac with implants: a medical perspective and case report.

A patient suffering from classical hemophilia had previous surgery for ankylosis of the right temporomandibular joint. This was replaced by a costochondral graft and an overlay of temporalis muscle. A bilateral sagittal split was performed for a micrognathic mandible and a sleep apnea problem. That procedure solved the sleep apnea; however, it resulted in a prognathic mandible and an anterior open bite. The lower anterior teeth were periodontally involved with impaired alveolar support. The restricted opening of the oral cavity of 18 mm between maxillary and mandibular centrals and the potential danger of bleeding complicated the surgical and restorative procedures. The patient was prepared medically on each of 4 occasions with factor VIII replacement concentrate, and oral antifibrinolytic therapy (tranexamic acid). The treatment of choice was the extraction of the remaining lower incisors and their replacement with an implant-supported temporarily cemented retrievable fixed prosthesis. Serial extractions and chairside temporization provided the surgeon with precise guides for implant placement, and enabled the patient to enjoy unimpaired function through periods of healing and osseointegration.

Dental Implantation, Endosseous↗
PubMed2002

Effect of distraction osteogenesis of the mandible on upper airway volume and resistance in children with micrognathia.

Children with craniofacial anomalies often have compromise of the upper airway, a condition with potential for morbidity and mortality. In children with microretrognathia, the diminutive size and retruded position of the mandible reduces the size of the oropharynx, thereby predisposing to glossoptosis and airway obstruction. Although several authors have reported successful use of mandibular distraction osteogenesis to alleviate this type of upper airway obstruction, the physiologic relationship between changes in mandibular shape, size, and position and upper airway dynamics remains undefined. The purpose of this study was to develop methodologies to quantitatively evaluate upper airway dynamics in children with micrognathia both before and after mandibular distraction osteogenesis. The patient population consisted of four children with micrognathia who had successfully undergone upper airway stabilization by bilateral mandibular distraction osteogenesis. The data used were digitally archived computed tomographic scan data from high-resolution, thin-slice head computed tomographic scans obtained before and after mandibular distraction. Upper airway evaluation was performed in two ways: static and dynamic. Static analysis consisted of computer quantification of predistraction and postdistraction mandibular and upper airway volumes using Analyze imaging software. Dynamic analysis consisted of fabrication of rigid stereolithographic hollow cast models of the upper airway produced from computed tomographic scan data. Models were used for characterization of upper airway resistance and flow patterns as related to respiration. After distraction osteogenesis, mandibular total volume increased 32, 32, 18, and 25 percent (mean, 27 percent) and upper airway volume increased by 20, 31, 23, and 71 percent (mean, 37 percent). A significant decrease in flow resistance, both inspiratory and expiratory, was observed in the patient with the greatest upper airway volume increase (71 percent) after distraction. After distraction, the inspiratory resistance was diminished by 51 percent and the expiratory resistance diminished by 85 percent. However, the three patients with more modest upper airway volume increases of 20 to 31 percent demonstrated no statistically significant change in flow resistance after distraction. Results of this study support the conclusion that distraction osteogenesis of the micrognathic mandible increases the volume of the upper airway, roughly paralleling the increase in mandibular volume. In the biomechanical airway model studied, upper airway volume expansion has been shown to be able to decrease the flow resistance over the length of the airway, presumably secondary to an increase in the average cross-sectional area. The artificial rigidity of the stereolithographic "airway" compared with the elasticity of the human upper airway may account for the insensitivity of this model to smaller but clinically significant airway changes.

Airway Resistance↗
PubMed2004

Distraction osteogenesis of the mandible.

PURPOSE OF REVIEW: Airway obstruction and craniofacial deformities resulting from mandibular deficiency are challenging and complex clinical problems. Mandibular distraction osteogenesis is playing a rapidly expanding role in the treatment of these children and has supplanted traditional management techniques in many centers. Several recent studies have reviewed clinical experience, described technical refinements, and addressed issues in patient selection and preoperative workup. RECENT FINDINGS: The extension of mandibular distraction osteogenesis to newborns with Pierre Robin sequence or craniofacial syndromes associated with micrognathia and airway obstruction has radically altered treatment protocols at several institutions. Early bilateral mandibular distraction has obviated tracheostomy in most newborns, with low operative morbidity. In addition, early decannulation and resolution of obstruction has occurred when mandibular distraction osteogenesis was applied to selected micrognathic children. Some of these patients were tracheotomized and others presented with severe obstructive symptoms. Studies have described success with external and internal distraction techniques. Recent publications have also demonstrated the surgeon's ability to mold the regenerate safely, the dynamic characteristics of the consolidation phase, and success with secondary and tertiary distraction. SUMMARY: After 15 years of clinical use in children for craniofacial deformities, recent advances in distraction osteogenesis have obviated tracheostomy in most newborns with micrognathia and severe airway obstruction. Applications of this technique to children with airway issues related to micrognathia or retrognathia have been rapidly expanding. In addition, refinements in distraction technique have advanced treatment of nonairway-related mandibular deformities.

Airway Obstruction↗
PubMed2004

Acrogeria with decreased gene expression of alpha1 (I) and alpha1 (III) collagen in cultured dermal fibroblasts.

We report a case of acrogeria. A 47-year-old Japanese man presented with micrognathism, thin lips, radial wrinkles around his month, atrophy of skin and subcutaneous tissue, and mottled hyperpigmentation on his extremities. A biopsy of the lesional skin showed flat epidermis and atrophy of the dermal layer. The in vitro life span of the patient's fibroblasts (18+/-2.2 PDL) was significantly shorter than that of control fibroblasts (42+/-3.5 PDL). The early-passage fibroblasts from the patient showed abnormal morphology which was also seen in the late-passage (in vitro aging) of normal fibroblasts. In northern blotting analysis of cultured dermal fibroblasts, mRNA levels of alpha1 (I) collagen and alpha1 (III) collagen were markedly reduced. These results revealed that patient fibroblasts might be in severe senescence in vitro and contribute to the phenotypes of this premature aging syndrome.

Biopsy, Needle↗
PubMed1992

Renal transplacental carcinogenicity of 3,3-dimethyl-1-phenyltriazene in rats: relationship of renal mesenchymal tumor to congenital mesoblastic nephroma and intralobar nephrogenic rests.

Exposure of rat embryos to 3,3-dimethyl-1-phenyltriazene (DMPT) results in numerous malformations, but the urogenital system is not affected. In contrast, exposure of rat fetuses to DMPT has been reported to result in renal neoplasms, which were not further classified. To better understand this discrepancy in organotropism of the teratogenic and transplacental carcinogenic processes, the present study was undertaken to characterize the neoplasms induced in rat fetuses exposed to DMPT in utero. Renal neoplasms and persistent mesenchyme were observed in 19.2 and 11.5%, respectively, of the offspring of rats treated with 1 mg DMPT/kg body weight intraperitoneally on gestation days 16, 18, and 20. The majority of these renal lesions were observed in females. The renal neoplasms were mixtures of various types of mesenchymal tissue derivatives including smooth muscle and fibrous connective tissue. These neoplasms would be classified as renal mesenchymal tumors in rats. Brain neoplasms (numerous types), compound odontomas, and micrognathism were observed predominantly in male offspring from the same group. This treatment also resulted in decreased body weights, increased incidence of sudden loss of body weight, tremors and ataxia, and hypoplastic testes. Exposure to single intraperitoneal doses of DMPT on gestation day 20 did not produce a classic dose-response pattern: Minimal effects were observed with 10 mg DMPT/kg (occasional renal mesenchymal tumors and brain neoplasms), marked effects were observed with 30 mg DMPT/kg (lower incidence rate of most of the alterations observed with 1 mg/kg on gestation days 16, 18, and 20), and no effects were observed with 60 mg DMPT/kg. DMPT administered intraperitoneally at 1 mg/kg body weight on gestation days 16, 18, and 20 is an animal model of transplacental chemically induced renal neoplasms, which provide lesions with similarities to both intralobar nephrogenic rests and congenital mesoblastic nephroma of humans. Why the kidney is a carcinogenic target and not a teratogenic target remains unknown.

Animals↗