Oral and Maxillofacial Surgery in Children (eBook)

Leonard B. Kaban (Autor)

eBook Download: EPUB

2023 | 1. Auflage
463 Seiten
Quintessence Publishing Co Inc USA (Verlag)
978-1-64724-140-7 (ISBN)

Infos

Surgery is always planned in three dimensions, but for pediatric patients, the fourth dimension-growth-is instrumental in proper treatment planning. In this book, experts in the fields of pediatric oral and maxillofacial surgery describe how to perform operations with this parameter in mind. The book covers congenital and syndromic facial deformities as well as acquired conditions, benign and malignant tumors, and trauma. All ages from neonates to adolescents are included, with a special focus on appropriate timing for surgery, taking into consideration anatomical functionality and the psychosocial well-being of the patient. Intrasurgical photographs and detailed illustrations complement the text, showing procedures step by step and providing long-term follow-up for actual cases. Anatomical areas include not only the oral cavity, mandible, and midface but the ears, eyes, TMJs, and skull, and additional locations for bone and tissue graft harvesting are also discussed. This text will be an indispensable guide for anyone who performs oral and maxillofacial surgery on growing individuals.

Leonard B. Kaban MD, DMD

Inhalt

"1.Molecular Genetics and Syndrome Recognition for the Clinician
2.Psychologic Preparation for the Child Undergoing a Maxillofacial Surgical Procedure
3.Practical Considerations in Facial Growth
4.Contemporary Pediatric Outpatient Anesthesia
5.Dentoalveolar Surgery
6.Intraoral Soft Tissue Abnormalities
7.Infection of the Maxillofacial Region
8.Ancillary Surgical Procedures
9.Free Vascularized Bone and Soft Tissue Transfers for Pediatric Mandibular Reconstruction
10.Salivary Gland Inflammatory Disorders in Children
11.Salivary Gland Tumors in Children
12.Benign Maxillofacial Bone Tumors in Children
13.Head and Neck Malignancies in Children
14.Maxillofacial Vascular Anomalies
15.Congenital Temporomandibular Joint and First and Second Pharyngeal Arch Deformities
16.Acquired Abnormalities of the Temporomandibular Joint
17.Orthognathic Surgery in the Growing Child
18.Obstructive Sleep Apnea in Infants and Children: Diagnosis and Management
19.Contemporary Diagnosis and Management of Craniosynostosis
20.Microtia and Ear Construction/Reconstruction
21.Sequential Management of the Child with Cleft Lip and Palate
22.Facial Trauma I: Midfacial Fractures
23.Facial Trauma II: Dentoalveolar Injuries and Mandibular Fractures"

Textauszug

1

Molecular Genetics and Syndrome Recognition for the Clinician

Joan M. Stoler

Why is knowledge of genetics important? During the last century, physicians have made great strides in treating infectious diseases and lowering associated morbidity and mortality. Advances have also been made in the management of medical conditions such as hypertension, diabetes mellitus, and heart disease. There have been significant improvements in the surgical management of disease, such as transplantation and repair of congenital and acquired facial deformities. In some ways, the last frontier is the field of genetics. Understanding the role of genes in the pathogenesis of anatomical and physiologic abnormalities will aid in diagnosis and the development of rational treatments. Genetic disorders accounted for 5% of pediatric admissions in a general hospital and 34% of deaths in a children’s hospital series. In a neonatal intensive care unit, 28% of deaths were due to malformations or genetic disorders.1–3 Understanding the etiology of such disorders and devising new methods of prevention and treatment would be of enormous benefit.

The “New Genetics”

There has been an explosion in genetic knowledge with the ability to examine almost all human genetic information by exome or genome analysis. The identification of specific genes responsible for many diseases has become a reality. In some cases, such identification has led to a better understanding of the pathophysiology of a disorder, and hopefully, in the future, genetic diagnosis will result in targeted treatment. The identity and the roles of genes responsible for various disorders inherited in the classical Mendelian patterns (eg, autosomal recessive, autosomal dominant, X-linked) have been documented. Similarly, genes responsible for multifactorial or complex inherited disorders have also been discovered. Congenital diseases that have traditionally been labeled as multifactorial, such as cleft lip and palate, may represent abnormalities in genes which confer susceptibility to exogenous influences, thereby leading to development of the disorder.4 Acquired conditions such as cancer have been found to have a specific genetic basis with accumulation of somatic (non-germline) mutations over time. Advances have been made in understanding the underlying pathogenesis of nontraditional types of inheritance, such as imprinting (in which the expression of a gene depends upon the parent of origin) and anticipation (in which the disorder becomes more severe in subsequent generations due to expansion of a series of nucleotide repeats in a gene).

Next-generation sequencing

Many of the recent advances in genetics have resulted from the development of next-generation sequencing. This is a high-throughput technique, making use of massive parallel sequencing, which has made multigene panels, exome, and whole genome testing possible.5

A short primer on molecular genetics

Genes are the basic unit of heredity and are composed of molecules of deoxyribonucleic acid (DNA). They are located on chromosomes, which are the physical structures transmitted in the sperm and ovum. Most of the DNA on chromosomes does not code for specific genes. The genes themselves are composed of various compartments and regulatory elements needed for the machinery of transcription. Exons and introns are two examples of such elements. Exons contain the exact sequence needed to make a protein. A gene is transcribed into messenger RNA (mRNA) in the nucleus of the cell. The mRNA then leaves the nucleus and enters the cytoplasm. It contains the exact sequence for making the protein but lacks the intron component of the gene. The introns are removed after transcription of the RNA through a precise process called splicing. The mRNA is then translated into the respective protein.6 Mistakes affecting the production, composition, and activity of the protein may occur at various levels, from a single base pair change to duplication or deletion of whole genes, parts of chromosomes, and whole chromosomes.

Birth Defects

Birth defects are a common cause of morbidity and mortality, with an incidence in the newborn period ranging from 1% to 4% depending on the population analyzed.7 The method and time period of ascertainment and the definition of a malformation also affect the reported incidence.8 With age, the rate of diagnosis rises, doubling by 1 year of age, and tripling by school age.7 It is known that low birth weight, twinning, and consanguinity are all associated with an increased frequency of birth defects.9–11 In addition, male sex is associated with an increased frequency of many, but not all, malformations.12 The etiologies of birth defects are classified as chromosomal disorders, single-gene disorders, genetic disorders resulting from teratogens, and multifactorial conditions (combinations of genes and environmental factors).

Chromosomal disorders

Abnormalities in chromosome number and structure result in significant pathology. A normal karyotype consists of 46 chromosomes, divided into 23 pairs: 22 autosomal and 1 sex chromosome pair (either XX or XY). Normally, an individual receives one copy of each chromosome from each parent. Abnormal division of a chromosome pair (nondisjunction) can occur during meiosis or during mitosis (after fertilization). Mosaicism, ie, some cells with a normal chromosome number and others with an extra chromosome, occurs as a result of abnormal division during mitosis. Theoretically, an extra copy of any chromosome pair (trisomies) can occur, but most of these affected embryos abort spontaneously. Only a few trisomies are compatible with a liveborn infant, as follows:

• Trisomy 21 (Down syndrome; Fig 1-1a)

• Trisomy 13

• Trisomy 18 (Fig 1-1b)

• 47, XXY (Klinefelter syndrome)

• 47, XXX

• 47, XYY

Fig 1-1 (a) Female karyotype with trisomy 21. The arrow indicates the extra chromosome 21. Note the presence of 2 X chromosomes and no Y chromosome, indicating it is a female. (b) Female karyotype with trisomy 18. The arrow shows the presence of three copies of chromosome 18.

These are usually associated with advanced maternal age, and the features differ according to the chromosome involved.

Monosomy (one missing chromosome) has only been reported for the sex chromosomes, as fetuses with other monosomies are nonviable. Turner syndrome (45, X) has a high in-utero mortality rate, but some fetuses do survive (Fig 1-2). In general, 45, X is not associated with advanced maternal age. The X chromosome is of maternal origin in the majority of cases (70%), indicating that the paternal copy was lost.13

Fig 1-2 Turner syndrome. (a) Infant with Turner syndrome with widespread nipples and mild pectus excavatum. (b) Right eyelid ptosis and epicanthal folds. (c) Low posterior hairline and redundant skin of neck. (d) Low-set ears and lymphedema in upper extremity and hand. (Photographs courtesy of Dr Angela Lin, Massachusetts General Hospital for Children.)

Structural chromosomal abnormalities, such as deletions, duplications, and rearrangements (eg, translocations, inversions) also occur. Deletions and duplications may be visible microscopically (seen with the usual method of performing a karyotype) or at a submicroscopic level using a chromosomal microarray.

A very common deletion is located on the long arm of chromosome 22 (22q11). This results in velocardiofacial syndrome (VCFS) and DiGeorge sequence (absent thymus and parathyroids, micrognathia, and heart abnormalities). The features are varied and include cleft palate, Pierre Robin sequence or velopharyngeal insufficiency in the absence of a cleft, conotruncal heart defects, learning disabilities, psychiatric problems, DiGeorge sequence, and a characteristic facial appearance (Fig 1-3).

Fig 1-3 A 3-year-old girl with velocardiofacial/DiGeorge syndrome. The characteristic features of this syndrome include rectangular-shaped nose, low-set ears, micrognathia (mild in this child), and long tapered fingers (left hand here). Patients also have cleft palate, velopharyngeal insufficiency, thymic aplasia, and cardiac anomalies.

Duplications of parts or regions of chromosomes result in different phenotypes. Cat eye syndrome is caused by tetrasomy (four copies) of chromosome 22 material with two copies present as an additional small chromosome pair. The clinical features include coloboma of the iris, anal atresia with fistula, down-slanting palpebral fissures, ear abnormalities including tags and pits, heart and kidney malformations, and mild intellectual impairment (Figs 1-4 and 1-5).

Fig 1-4 Child with cateye syndrome exhibiting iris colobomas bilaterally.

Fig 1-5 (a to e) Photographs of a 4-year-old girl with cateye syndrome and bilateral craniofacial microsomia. Her problems include 22q11 tetrasomy, anal atresia and fistula, single kidney, total anomalous pulmonary venous return, submucous cleft palate, low-set ears, multiple ear tags, abnormal external ear morphology, epibulbar dermoids (OD at 7 o’clock at iris and OS at 6 o’clock), hearing loss, micrognathia, syndromic Pierre Robin sequence, severe mandibular asymmetry with bilateral craniofacial microsomia with type III mandible on left and type II mandible on right, VII...

Produkt-Details

• Erscheint lt. Verlag: 13.9.2023
• Verlagsort: Batavia
• Sprache: englisch
• Themenwelt: Medizin / Pharmazie ► Zahnmedizin
• Schlagworte: Ancillary Surgical Procedures • Cleft lip and palate • congenital deformities • Contemporary Pediatric Outpatient Anesthesia • dentoalveolar surgery • Facial Growth • facial growth deformities • facial trauma • Head and neck malignancies • Infection of the Maxillofacial Region • Intraoral Soft Tissue Abnormalities • managing facial trauma in children • maxillofacial bone tumors • Maxillofacial Surgical • Microtia • molecular genetics • oral and maxillofacial surgery • orthognathic surgery • orthognathic surgery in children • pediatric anesthesia • pediatric mandibular reconstruction • pediatric OMS • pediatric oral and maxillofacial surgery • Psychologic Preparation • salivary gland tumors • Syndrome Recognition
• ISBN-10: 1-64724-140-5 / 1647241405
• ISBN-13: 978-1-64724-140-7 / 9781647241407