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Biomedical subjects

M D Schloss

Publications and source records attributed to M D Schloss.

At least 19 recordsLinked to original sources
PubMed2002

Overview of the radiology, histology, and bone morphogenetic protein expression during distraction osteogenesis of the mandible.

INTRODUCTION: Distraction osteogenesis (DO) is a form of in vivo tissue engineering during which an osteotomy and controlled distraction are used to lengthen bone. The molecular signals that govern distraction-induced bone formation have not been fully elucidated. Specifically, the role of bone morphogenetic proteins (BMPs) in DO of the mandible remains unclear. OBJECTIVE: To characterize the radiologic and histologic evolution of newly formed bone during DO of the mandible and to relate these changes to the expression of BMPs. METHODS: Fourteen skeletally mature male rabbits were used. A distractor device was surgically applied to one side of the mandible following osteotomy. After 1 week (latency period), distraction was started at a rate of 0.25 mm every 12 hours for 3 weeks (distraction period) and was followed by a 3-week consolidation period. Two animals were sacrificed each week after surgery (weeks 1 to 7). The mandible was resected and the new bone assessed by radiography and histology. The expression of BMPs was also analyzed using immunohistochemistry. RESULTS: There was radiographic and histologic evidence of bone formation during the distraction period. By week 6, there was mature woven bone within the distraction zone. Bone morphogenetic proteins 2 and 4 were strongly expressed in osteoblasts during distraction and in chondrocytes during consolidation. The expression of BMP-7 was relatively minor. CONCLUSION: The temporal and spatial pattern of BMP expression suggests that these proteins are important mediators of mandibular DO. Understanding the expression of BMPs may facilitate the use of recombinant proteins to enhance the rate and quality of bone generation during craniofacial DO.

Animals↗
PubMed2001

Clinical applications of a finite-element model of the human middle ear.

Computer-generated models are increasingly being used in otolaryngology for teaching purposes, preoperative planning, and clinical simulations, especially when dealing with small, complex areas such as the middle ear. One technique used to analyze the mechanics of complex models is the finite-element method, whereby the system of interest is divided into a large number of small, simple elements. The mechanical properties and applied forces are represented by functions defined over each element, and the mechanical response of the whole system can then be computed. We present a unique three-dimensional finite-element model of the human eardrum and middle ear. Our model takes advantage of phase-shift moiré shape measurements to precisely define the shape of the eardrum. The middle ear geometry is derived from histologic serial sections and from high-resolution magnetic resonance microscopy of the human ear. We discuss the importance of this model in terms of understanding and teaching the mechanics of the human middle ear, simulating various pathologic conditions, and designing ossicular prostheses.

Computer Simulation↗
PubMed1999

A new predictive modality of cranial bone thickness.

The objective of this study was to evaluate A-mode ultrasound in the assessment of cranial bone thickness utilizing an in vivo animal model. A prospective study was performed that identified four standardized calvarial points in 10 Landrace porcine skulls. The individual points were scanned with an A-mode ultrasonic transducer to obtain bone thickness measurements. The same points were measured subsequently using digital calipers for objective comparison. The accuracy of each of the measurement modalities was evaluated for inter- and intrarater reliability. The association between ultrasonic and caliper measurements was evaluated using Student's t-test, Pearson's correlation coefficient, and linear regression models to assess the effect of confounding variables. The mean difference between the ultrasonic and the caliper values was 0.31 +/- 0.22 mm (standard deviation). The statistical analyses employed strongly supported the predictive value of ultrasound as a function of the true calvarial thickness (p < 0.05, r > 0.88, R2 = 0.89). The results suggest that ultrasound is an accurate reflection of cranial bone thickness in an in vivo animal skull model. The development of a portable, noninvasive ultrasonic device can have substantial clinical implications for craniomaxillofacial surgery.

Animals↗
PubMed1999

Langerhans' cell histiocytosis: paediatric head and neck study.

OBJECTIVE: This study presents the experience of the Montreal Children's Hospital (MCH) with Langerhans' cell histiocytosis (LCH) and reviews the new advances in diagnosis and therapy of this disorder. DESIGN: Retrospective study of 20 patients seen between July 1986 and July 1997 diagnosed with LCH. METHODS: All of the 20 charts were examined for variables including age, sex, area involved, treatment modalities, and complications. RESULT: Sixty-five percent of patients presented with localized lesions and 35% with multisystem involvement. The most common involved area was the skull, and 57% of skull lesions involved frontal bone. The temporal bone was involved in 25% of cases. The most common ear symptom was otorrhea. CONCLUSION: Langerhans' cell histiocytosis is a rare paediatric disorder. Head and neck involvement occurs frequently in both localized and multisystem disease. The prognosis is highly dependent on the age and number of systems involved.

Adolescent↗
PubMed1999

Surgical treatment of cholesteatoma in children.

We retrospectively reviewed patients surgically treated for cholesteatoma to determine the impact of surgical procedures on preoperative hearing status and whether there was preservation, improvement, or deterioration. We reviewed 173 patients treated over a 15-year period. One hundred eighteen (68%) patients had acquired cholesteatoma and 55 (32%) patients had congenital cholesteatoma. One hundred (58%) patients had extensive disease on presentation that required canal wall-down mastoidectomy. Patients with attic cholesteatoma underwent canal wall-up mastoidectomy, and those with cholesteatoma localized to the middle-ear space were adequately treated with tympanotomy. Hearing was preserved in 101 cases (59%), improved in 30 (17%), became worse in 23 (13%), and could not be accurately assessed in 19 (11%) due to lack of documentation. A second surgical procedure for recidivistic (recurrent or residual) disease was required in 53 (30%). Ipsilateral facial paralysis was noted in 3 (1.7%) patients immediately after recovery from anaesthesia, and 1 (0.5%) patient had a sensorineural hearing loss. This study confirmed the aggressiveness of cholesteatoma in children and demonstrated the need for careful preoperative evaluation, meticulous surgical technique, and prudent postoperative follow-up.

Adolescent↗
PubMed1998

Acute airway obstruction in Hunter syndrome.

Hunter syndrome is one of the mucopolysaccharidoses, characterized by a deficiency of the lysosomal enzyme iduronate sulfatase. Among its physical manifestations, there are numerous head and neck signs, including characteristic facial features, macroglossia and short neck. The accumulation of glycosaminoglycans in the soft tissues of the head and neck can be associated with acute airway obstruction. We report a 7 year old boy with Hunter syndrome who developed acute airway compromise requiring an emergency tracheotomy. A review of the literature of airway management in patients with this disease is also presented.

Airway Obstruction↗
PubMed1998

Children who can't smell the coffee: isolated congenital anosmia.

Two children with isolated congenital anosmia, a rare syndrome of deficient restricted neuronal migration, are presented with early diagnosis confirmed by standardized smell testing and detailed neuroimaging studies. Recognition of this disorder and its spectrum of presentations provides important insights into the molecular mechanisms underlying the development of the olfactory system.

Adolescent↗
PubMed1995

Home testing for pediatric obstructive sleep apnea syndrome secondary to adenotonsillar hypertrophy.

The objective of this study was to determine the accuracy and practicality of home testing for pediatric obstructive sleep apnea syndrome (OSAS) secondary to adenotonsillar hypertrophy. Twenty-one children aged 2-12 years and referred for possible OSAS were studied twice, once at home and once in the sleep laboratory. The home test consisted of two parts: 1) a cardiorespiratory recording of saturation (SaO2), pulse rate, pulse waveform, electrocardiogram, and respiratory inductive plethysmography; and 2) an 8-hour videotape recording of the sleeping child. In the laboratory, standard nocturnal polysomnography including electroencephalography was performed. Experiences with another 62 children who underwent home testing alone were also reviewed and are reported. At home, saturation, respiratory, and video data were obtained 96.4 +/- 13.3% (mean +/- SD) 99.4 +/- 1.6%, and 90.0 +/- 78% of the time, respectively. The sleep efficiency was greater at home than in the laboratory, 91.1 +/- 3.9% vs. 86.1 +/- 7.2%, with a mean difference of 5.0% (P < 0.01). The median environmentally induced movement/arousal index was lower in the home than in the laboratory, 0.0 (inter-quartile range, 0.0-0.3 vs. 2.4/hr (inter-quartile range 1.2-4.2), with a median difference of 2.4/h (P < 0.001). Study duration, apnea/hypopnea index, desaturation index, respiratory and spontaneous movement/arousal indices, and oxygen saturation during sleep were similar for home and laboratory studies. Although neither sleep state nor PCO2 (transcutaneous or end-tidal) was measured in the home, this information would have modified patient management in, at most, one case. In the second group of 62 children, exclusively studied at home, all studies were successfully recorded despite a wide range of sleep efficiencies, apnea/hypopnea indices, and desaturation indices. We conclude that home testing, using a simplified cardiorespiratory montage plus video recording, is accurate and of practical use in the routine evaluation of OSAS in patients with adenotonsillar hypertrophy.

Adenoids↗
PubMed1995

Usher syndrome in four siblings from a consanguineous family of Pakistani origin.

Usher syndrome is a heterogeneous group of disorders of autosomal recessive inheritance characterized by retinitis pigmentosa and congenital sensorineural hearing loss. Two types are accepted clinically: type I is associated with profound congenital deafness with progressive pigmentary retinopathy and total loss of vestibular function. Type II is a milder form, with moderate-to-profound hearing loss and a milder form of retinitis pigmentosa. Vestibular function is preserved. A total of five loci have been identified as accounting for the two distinct phenotypic presentations. We describe a consanguineous family of Pakistani origin whose four children all are affected with Usher syndrome type I. DNA analysis showed non-linkage to any of the loci already identified as tightly linked to the Usher syndrome type I.

Canada↗
PubMed1994

Outpatient tonsillectomy and adenoidectomy: complications and recommendations.

An example of cost-effective alternatives in medical care is the increasing use of out-patient surgery for those children requiring tonsillectomy, or tonsillectomy with adenoidectomy rather than an in-patient procedure. Two studies were carried out to answer questions about the complications, in addition to post-operative hemorrhage, and also the questions about the parental views and concerns relating to providing at-home care for their children following surgery. A triad, including recent history of upper airway infection, knife dissection technique, and increased intra-operative blood loss of 100 ml or more should be used to help identify the risk of post-operative hemorrhage.

Adenoidectomy↗
PubMed1993

Introduction of a Canadian dollar coin has created a new health hazard for children.

Coins have remained at the top of the incidence list of published series of endoscopic removal of pediatric foreign bodies. The introduction of the Canadian dollar coin in 1987 has presented another hazard for children. A total of 228 consecutive pediatric patients that underwent esophagoscopy for removal of foreign body from 1979 to 1989 are reviewed. Esophagoscopy under general anesthesia is the safest technique for the removal of impacted foreign bodies in the esophagus.

Adolescent↗
PubMed1992

Otitis media and CNS complications.

Intracranial complications from otitis media can be quite devastating to the patient if an early diagnosis is not made. Patients may develop meningitis, venous sinus thrombosis or cranial nerve palsies, as well as intracranial abscess. The presenting features in such cases may be subtle and include headache, nausea, vomiting, personality changes and signs of increased intracranial pressure as well as focal neurological deficits. A case of intracranial brain abscess is presented in a patient with a history of chronic otitis media with cholesteatoma. Delay in the diagnosis of intracranial complications of otitis media can lead to improper treatment with increased morbidity and mortality. The etiology and treatment of complications affecting the CNS is discussed.

Brain Abscess↗
PubMed1991

Extensive upper aerodigestive tract anomalies in 'VACTERL' Association.

Extensive upper aerodigestive tract anomalies are rare in newborns. When they occur, they are often accompanied by other congenital malformations. We present a case of a newborn who presented to the Montreal (Quebec) Children's Hospital with severe tracheoesophageal abnormalities, as part of vertebral, anal, cardiac, tracheal, esophageal, renal, and limb anomalies (VACTERL) association. In spite of surgical intervention, the patient finally succumbed to other congenital abnormalities. Management of infants with such conditions usually involve complex reconstructive efforts, while prognoses remain poor due to other congenital defects and cardiopulmonary complications.

Abnormalities, Multiple↗
PubMed1991

Cholesteatoma in children.

This is a retrospective review of 71 patients charts, over a 10-year period, with the diagnosis of cholesteatoma. An analysis included the demographic data, audiological data and surgical results. The selection of the surgical technique depended on the extent of the disease. In the majority of cases the primary procedure was of the canal wall down technique, which is contrary to most recently published reports. Most of the cholesteatomas were extensive, thereby requiring a more aggressive surgical approach. It was our opinion that the extent of the disease in a child was greater than in an adult. Another feature found in children is the occurrence of the disease behind an intact tympanic membrane. In this review, 35% of the cases presented in this manner. Hearing was maintained or improved in the majority of cases. It is concluded that cholesteatoma in children may differ from that in the adult and that even with canal wall down procedures, maintenance or improvement of hearing is achieved in most patients.

Adolescent↗