The morphogenesis of wormian bones: a study of craniosynostosis and purposeful cranial deformation.

Wormian bones are accessory bones that occur within cranial suture and fontanelles, most commonly within the posterior sutures. They occur more frequently in disorders that have reduced cranial ossification, hypotonia or decreased movement, thereby resulting in deformational brachycephaly. The frequency and location of wormian bones varies with the type and severity of cranial deformation practiced by ancient cultures. We considered the hypothesis that the pathogenesis of wormian bones may be due to environmental variations in dural strain within open sutures and fontanelles. In order to explore this further, we measured the cephalic index (CI) in 20 purposefully deformed pre-Columbian skulls: 10 from Chichen Itza, Mexico, and 10 from Ancon, Peru, as well as 20 anatomically normal skulls used for medical school anatomy classes. We tested for a direct correlation between the CI and the number of wormian bones in skulls with varying degrees of brachycephalic cranial deformation and found no significant correlation. When the CI was grouped into three categories (normal (CI < 81), brachycephalic (CI 81-93), and severely brachycephalic (CI > 93)) there was a trend toward increasing number of wormian bones as the skull became more brachycephalic (P = 0.039). A second part or our study tabulated the frequency and location of large wormian bones (greater than 1 cm) in 3-dimentional computerized tomography (3D-CT) scans from 207 cases of craniosynostosis and compared these data with published data on 485 normal dry skulls from a manuscript on wormian bones by Parker in 1905. Among cases of craniosynostosis, large wormian bones were significantly more frequent (117 out of 207 3D-CT scans) than in dry skulls (131 out of 485). There was a 3.5 greater odds of developing a wormian bone with premature suture closure (P < 0.001). Midline synostosis, specifically metopic or sagittal synostosis, has more wormian bones in the midline, whereas unilateral lambdoidal or coronal synostosis more often had wormian bones on the contralateral side. Taken together, these data suggest that wormian bones may arise as a consequence of mechanical factors that spread sutures apart and affect dural strain within sutures and fontanelles.

New clinical findings in the Richieri-Costa/Pereira type of acrofacial dysostosis.

The Richieri-Costa/Pereira form of acrofacial dysostosis is an autosomal-recessive condition characterized by short stature, Pierre-Robin sequence, preaxial and postaxial abnormalities in hands, congenital talipes, cleft mandible and malformations of the larynx. We report female infant presenting with severe micrognathia, a hypoplasic clavicle, median mandible cleft, bilateral hand abnormalities and talipes, laryngeal malformations, hip subluxation with acetabular dysplasia and mesomelic shortening of limbs. A few reported patients have clavicular hyploplasia but hip subluxation with acetabular dysplasia and mesomelic shortening of limbs have not been described.

Acrocallosal syndrome: report of a Brazilian girl.

We report on a Brazilian girl born to nonconsanguineous parents and presenting with frontonasal dysostosis, callosal agenesis, abnormal upper lids, cleft lip/palate, redundant skin in the neck, grooved chin, and bifid thumbs. Major diagnostic criteria present in this patient are related to the acrocallosal syndrome. The clinical and major nosologic aspects of this condition are discussed.

A distinctive triad of malformations of the central nervous system in the Meckel-Gruber syndrome.

A distinct triad of central nervous system (CNS) malformations (prosencephalic dysgenesis, occipital exencephalocele and rhombic roof dysgenesis) was present in seven cases of the Meckel-Gruber syndrome examined at autopsy. We compared our findings with those previously described. Microcephaly, sloping forehead, posterior occipital exencephalocele, cerebellar hypoplasia, Chiari malformation, hydrocephalus, polymicrogyria, arhinencephaly, holoprosencephaly and anencephaly constituted a broad spectrum of the reported CNS anomalies. Few reports contained a comprehensive description of the observed CNS malformations. In those reports, and in our cases, features of prosencephalic dysgenesis included agenesis of olfactory bulbs and tracts (arhinencephaly), hypoplasia of optic nerves and chiasm, agenesis of corpus callosum, fused thalami or complete holoprosencephaly. The occipital encephalocele has consisted of a displacement of rhombic roof elements, including caudal third ventricle, cerebellar vermis and fourth ventricle, extruded through an enlarged posterior fontanelle rather than through an occipital cranium bifidum and is thus more precisely labeled an exencephalocele. Different degrees of dysgenesis of posterior fossa structures, described by some as a variant of Dandy-Walker cyst with features of a Chiari malformation, were often associated with this occipital exencephalocele. This pattern of CNS anomalies represents a triad of malformations probably associated with defective ventral induction of the developing CNS by the prechordal mesoderm.