Diagnóstico da Craniossinostose

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Diagnóstico da Craniossinostose

Mensagem  Convidad em Qui Jul 11, 2013 10:33 am

The newborn infant's skull is composed of bony plates separated by sutures. This arrangement accommodates transient skull distortion during birth and permits future growth of the brain, the volume of which quadruples during the first two years of life. There are four major sutures: the metopic, coronal, sagittal, and lambdoid. Three additional sutures that contribute to calvarial development are considered minor: the frontonasal, temporosquamosal, and frontosphenoidal. The sagittal, coronal, and metopic sutures meet at the anterior of the skull to form the anterior fontanelle, palpable just behind the forehead at the midline. The posterior fontanelle is formed by the intersection of the sagittal and lambdoid sutures.
 The osseous cranial base is embryologically derived from a cartilaginous framework (endochondral bone) that undergoes a proliferative growth pattern. In contrast, the calvarium consists of membranous bone, which has no cartilaginous phase. The calvarium grows by depositing new bone along suture lines in response to the distending forces of the rapidly growing brain. During the first two years after birth, the brain increases in size to 75 percent of its adult volume. The remaining 25 percent of growth occurs during the next 18 years.
 Fontanelle and suture closure occurs in a specific pattern. At two months of age, the posterior fontanelle closes, followed by anterior fontanelle closure at approximately two years. The anterolateral and posterolateral fontanelles close at three months and one year, respectively. While the metopic suture typically closes at two years of age, all remaining patent sutures close in adulthood following completion of craniofacial growth.
 The diagnosis of craniofacial deformity is primarily based upon physical examination. Radiographic studies, such as plain radiographs and computed tomography (CT), may further characterize the structural abnormality. However, making a specific diagnosis can be complicated when features overlap two known syndromes or otherwise fail to fit into a defined clinical category. Radiographic studies are best performed at a center with a craniofacial team. On occasion, molecular diagnosis is available.

Computed tomography — Computed tomography (CT) can identify the sutures more accurately than can plain radiographs and can be used to assess the extent of fusion and its effect on adjacent bones. The brain can be examined for abnormalities, including hydrocephalus. Asymmetry and deformities of the cranial base can be seen. CT also is used to evaluate the spatial and geometric relationships between the bony orbit and its soft tissue contents (the globe and extraocular muscles).
 Three-dimensional surface reconstructions using CT can assist in the classification of craniofacial disorders. These images, together with cephalometric and anthropometric data, can be used to quantitate the skeletal deformity and plan surgical treatment of complex craniofacial reconstructions.
 Changes in intracranial volume can be calculated in children with craniosynostosis using CT, although these measurements typically are within normal limits .

Cephalometrics — Cephalometry is the precise measurement of the dimensions of the head. Cephalometric radiography is a standardized technique that enables accurate longitudinal studies of head growth. Standardization is achieved by a constant orientation of the X-ray axis, the patient's head, and the film. The orienting device, called a cephalometer, stabilizes the patient's head with a pair of ear rods that enter the external auditory meatus, and a third rod, which rests on the nasofrontal suture, thereby preventing sagittal rotation of the head. The radiographic film is held at a constant distance from the midline of the head and the X-ray source. Lateral and frontal views are obtained. Skeletal landmarks are identified in order to compare lengths and angles to normal values or in the same patient over time.

Genetics — Early screening for mutations that affect genes encoding for members of the fibroblast growth factor receptor family (FGFR) can be performed in affected newborns . Causative mutations are more commonly identified in children with unicoronal or bicoronal, rather than sagittal or metopic, nonsyndromic craniosynostosis.



Fonte: http://www.uptodate.com/contents/overview-of-craniosynostosis?detectedLanguage=en&source=search_result&translation=craniosynostosis&search=craniossinostose&selectedTitle=1%7E42&provider=google

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