Showing papers on "Skull published in 1993"

The triple origin of skull in higher vertebrates: a study in quail-chick chimeras

Abstract: We have used the quail-chick chimera technique to study the origin of the bones of the skull in the avian embryo. Although the contribution of the neural crest to the facial and visceral skeleton had been established previously, the origin of the vault of the skull (i.e. frontal and parietal bones) remained uncertain. Moreover formation of the occipito-otic region from either the somitic or the cephalic paraxial mesoderm had not been experimentally investigated. The data obtained in the present and previous works now allow us to assign a precise embryonic origin from either the mesectoderm, the paraxial cephalic mesoderm or the five first somites, to all the bones forming the avian skull. We distinguish a skull located in front of the extreme tip of the notochord which reaches the sella turcica and a skull located caudally to this boundary. The former (9prechordal skull9) is derived entirely from the neural crest, the latter from the mesoderm (cephalic or somitic) in its ventromedial part (9chordal skull9) and from the crest for the parietal bone and for part of the otic region. An important point enlighten in this work concerns the double origin of the corpus of the sphenoid in which basipresphenoid is of neural crest origin and the basipostsphenoid is formed by the cephalic mesoderm. Formation of the occipito-otic region of the skeleton is particularly complex and involves the cooperation of the five first somites and the paraxial mesoderm at the hind-brain level. The morphogenetic movements leading to the initial puzzle assembly could be visualized in a reproducible way by means of small grafts of quail mesodermal areas into chick embryos. The data reported here are discussed in the evolutionary context of the ‘New Head’ hypothesis of Gans and Northcutt (1983, Science, 220, 268–274).

Bizarre parosteal osteochondromatous proliferation of bone (Nora's lesion)

Abstract: Bizarre parosteal osteochondromatous proliferation was first described in 1983, when Nora et al. reported 35 examples of a proliferative lesion involving the small bones of the hands and, less often, the feet. No examples involving the large bones were reported. We present 65 cases of this condition, five from the Mayo Clinic files and 60 from our consultation files, including 34 females and 31 males; patients' ages ranged from 8 to 73 years (average, 33.9 years). Thirty-six lesions involved the hands, 10 the feet, 17 the long bones, one the skull, and one an unknown site. The long bones involved were the radius (three lesions), ulna (six), fibula (two), femur (three), tibia (two), and humerus (one lesion). Roentgenograms typically showed a heavily calcific mass attached to the underlying cortex and having a broad base. Histologically, a large amount of hypercellular cartilage showed maturation to trabecular bone, which frequently contained spindle cells in the intertrabecular spaces, an appearance that could lead to a mistaken diagnosis of parosteal osteosarcoma. A helpful feature was the distinct blue tinctorial characteristic of the bone in the lesion. Follow-up information was available for 40 patients; approximately 55% had a recurrence. No metastasis had been reported in any of the 65 cases. Bizarre parosteal osteochondromatous proliferations are a form of heterotopic ossification and should not be mistaken for chondrosarcoma or osteosarcoma.

Thickness and resistivity variations over the upper surface of the human skull

Abstract: A study of skull thickness and resistivity variations over the upper surface was made for an adult human skull. Physical measurements of thickness and qualitative analysis of photographs and CT scans of the skull were performed to determine internal and external features of the skull. Resistivity measurements were made using the four-electrode method and ranged from 1360 to 21400 Ohm-cm with an overall mean of 7560±4130 Ohm-cm. The presence of sutures was found to decrease resistivity substantially. The absence of cancellous bone was found to increase resistivity, particularly for samples from the temporal bone. An inverse relationship between skull thickness and resistivity was determined for trilayer bone (n=12, p<0.001). The results suggest that the skull cannot be considered a uniform layer and that local resistivity variations should be incorporated into realistic geometric and resistive head models to improve resolution in EEC Influences of these variations on head models, methods for determining these variations, and incorporation into realistic head models, are discussed.

Tissue interactions with underlying dura mater inhibit osseous obliteration of developing cranial sutures.

Abstract: Cranial sutures play a critical role in calvarial morphogenesis, serving as growth centers during skull development. Both biomechanical tensile forces originating in the cranial base and biochemical factors present in dura mater have been postulated as determinants of suture morphogenesis and patency. A rat transplant model free of the putative biomechanical influence of the dura and cranial base was used to investigate the role of the dura mater in both the initial morphogenesis and maintenance of sutures during skull growth. Day 19 fetal presumptive (F19) and day 1 neonatal differentiated (N1) coronal sutures, including associated frontal and parietal bones, were transplanted with or without underlying dura mater to the center of adult parietal bones. After 1, 2, and 3 weeks, transplanted tissues were examined histologically and histomorphometrically to determine whether sutures formed and whether they were obliterated by ossification in the absence of dura mater. Both F19 and N1 sutures remained patent for 2 weeks either in the presence or the absence of transplant dura mater. However, at 3 weeks, in the absence of transplant dura mater, sutures were obliterated by bone, while in the presence of dura mater sutures resisted ossification, demonstrating an essential requirement for interactions with the transplant dura mater in maintaining functional sutures. Both F19 and N1 transplants showed comparable bone growth (cross-sectional surface area), regardless of the presence of transplant dura mater. These experiments suggest that tissue interactions of a biochemical nature, rather than biomechanical forces generated through the cranial base, are required to maintain the suture as a non-ossified growth center. Furthermore, while the presence of dura mater was essential for maintenance of suture patency, fetal dura mater was not required for initial suture formation.

Dibothrosuchus elaphros, a crocodylomorph from the Lower Jurassic of China and the phylogeny of the Sphenosuchia

Abstract: Much of a skeleton of Dibothrosuchus elaphros from the Lower Lufeng Group (Lower Jurassic) of Yunnan, China permits a detailed review of the anatomy and relationships of sphenosuchian crocodylomorphs The skull is strongly built, akinetic, and monimostylic The quadrate shows three dorsal processes that are firmly sutured to the skull roof and the braincase The otic capsule is essentially crocodilian, and the tympanic pneumaticities are more elaborate than in extant forms The animal possessed refined hearing ability and was probably vocal The coracoid has an extremely elongated, posteriorly directed postglenoid process The humerus bears an oval depression anteriorly near the head, and the radiale and ulnare are longer than the metacarpals The limbs are long and slender, adapted for quadrupedal terrestrial gait The estimated total length was 13 m Phylogenetic analysis of 65 characters indicates the monophyly of the Sphenosuchia Within the Sphenosuchia, Saltoposuchus (=Terrestrisuchus), Ps

Augmentation of the craniofacial skeleton with porous hydroxyapatite granules.

Abstract: Augmentation of the craniofacial skeleton with porous hydroxyapatite granules (Interpore 200) has been performed in 52 sites on 43 patients. Follow-up extends to 5 years, and 26 patients have been followed for greater than 1 year with excellent results. The procedure has been used for reconstruction of congenital and posttraumatic deformities and for purely aesthetic purposes. Areas that have benefited from hydroxyapatite augmentation include the skull, zygomaticomaxillary region, lateral mandible, perialar region, periorbital area, and temporal region. There have been no cases of infection, and only two patients have required minor revisions. Resorption has not occurred.

Cranial osteogenesis in Monodelphis domestica (Didelphidae) and Macropus eugenii (Macropodidae)

Abstract: The pattern of onset and general rate of cranial ossification are compared in two marsupials, Monodelphis domestica (Didelphidae) and Macropus eugenii (Macropodidae). In both species a similar suite of bones is present at birth, specifically those surrounding the oral cavity and the exoccipital, and in both postnatal events follow a similar course. The facial skeleton matures more rapidly than the neurocranium, which is characterized by an extended period of ossification. Most dermal bones begin ossification before most endochondral bones. Endochondral bones of the neurocranium are particularly extended in both the period of onset of ossification and the rate of ossification. These data confirm suggestions that morphology at birth is conservative in marsupials and we hypothesize that the pattern of cranial osteogenesis is related to two distinct demands. Bones that are accelerated in marsupials are correlated with a number of functional adaptations including head movements during migration, attachment to the teat, and suckling. However, the very slow osteogenesis of the neurocranium is probably correlated with the very extended period of neurogenesis. Marsupials appear to be derived relative to both monotreme and placental mammals in the precocious ossification of the bones surrounding the oral cavity, but share with monotremes an extended period of neurocranial osteogenesis.

Cranial Morphology of the Therian Common Ancestor, as Suggested by the Adaptations of Neonate Marsupials

Abstract: Skull structures are properly understood only if their ontogenetic development is considered. It has been argued by a number of authors that the reproductive biology of marsupials may be reminiscent of a primitive ovo-viviparous phase of therian evolution. Therefore, it seemed rewarding to test the hypothesis that the skull structures of neonatal didelphids may be adapted to such a primitive mode of development as well. It is assumed that the head skeleton of the altricially born didelphid is constructed mainly to sustain mechanical strain caused by sucking at the teat, where it is also suspended. It is investigated which structures of the skull may be functionally correlated with the “lactation-complex.” It is mainly the strong chondrocranium that has to provide sufficient stability at first, because exocranial bone development is retarded. It is further argued that the ala temporalis, which ossifies as the alisphenoid, lends support to the side wall of the braincase; the alisphenoid is considered to be fully homologous to the reptilian epipterygoid. The ontogenetic development of the didelphid middle ear is also reminiscent of a primitive evolutionary state. The postdentary elements lie at first close to the medial side of the dentary; in a complicated process of growth they become fixed to the basicranium and then detached from the mandible. The “horizontal anlage” of the tympanic in monotremes and eutherians is not considered to be primitive (postulate of Van Kampen) but secondarily derived two times independently. The nasal capsule of all extant mammals shows a common “bauplan,” which is presented schematically; the importance of macrosmatic adaptations in mammals is pointed out. Most of the derived features of the eutherian skull seem to be linked with its prolonged intrauterine development, which sets different functional conditions on the growing structures; therefore, phenomena of heterochrony play an important role for understanding the eutherian conditions. Whereas early skull development in marsupials is characterized by a number of narrow functional and biological constraints resulting in a certain structural uniformity, the eutherian mode of development seems to provide more freedom for fetal differentiation

Surgery for hindbrain related syringomyelia.

Abstract: Syringomyelia is a condition with many possible causes, the commonest of which seems to be an abnormality at the foramen magnum. Such cases may be grouped under the heading of “Hindbrain related syringomyelia” and the principles of treatment for all such cases are largely similar. The commonest of these foramen magnum region abnormalities is hindbrain herniation which may be associated with a history of birth difficulties, a small posterior fossa, segmentation abnormalities of the cervical vertebrae or the base of the skull, arachnoiditis of the subarachnoid spaces, subarachnoid pouches, hydrocephalus and intracranial tumours or tumours partly blocking the foramen magnum.

Free tissue transfer for skull base reconstruction analysis of complications and a classification scheme for defining skull base defects.

Abstract: Objective: The role of free flaps in skull base reconstruction is discussed in detail. Twenty-six microvascular free tissue transfers performed in 22 patients are reviewed in detail. A classification scheme for skull base defects is presented. Setting: Tertiary referral center. Patients: Twenty-two patients with neoplasms that involve the skull base underwent a combined craniotomy and facial approach for resection. The resultant defects were reconstructed with a variety of microvascular free flaps. Results: All 22 patients were ultimately successfully reconstructed with a free flap. One patient required a second free flap following ablative surgery for a recurrent tumor. The initial free flaps in three patients were unsuccessful and a second flap was required. The classification scheme was applied to all defects. Conclusions: The creation of a functional separation of the intracranial and extracranial cavities can be extremely difficult to accomplish, especially when multiple cavities (nasal, oral, pharyngeal) are violated. Free flaps provide a solution to this problem in select cases. Skull base defects can and should be classified for the purpose of communication, treatment planning, prognosis of reconstruction, and judging therapeutic outcome. (Arch Otolaryngol Head Neck Surg. 1993;119:1318-1325)

Cranial Anatomy and Functional Morphology of Pliosaurus brachyspondylus (Reptilia: Plesiosauria) from the Upper Jurassic of Westbury, Wiltshire

Abstract: An exceptionally complete skull, mandible and other bones of Pliosaurus brachyspondylus were collected from the Kimmeridge Clay of Westbury, Wiltshire, in 1980. The recovery and preparation of this large specimen required special techniques. The specimen is apparently part of a more complete skeleton, mostly destroyed before discovery. The decayed carcass was apparently disrupted so that the skull finally lay upside down over many of the teeth, which had fallen out, while the mandible lay several metres away. The reasons for this are unclear. The skull does not differ markedly from the usual pliosauroid pattern, being long and low, with a wide gape, narrow snout, and high temporal region. There are no nasals. The mandible cannot be satisfactorily reconstructed due to crushing but does not appear to deviate from the usual pliosauroid pattern. The dentition is robust and caniniform anteriorly, presumably to penetrate, hold and kill large prey. The posterior teeth are hook-shaped posteriorly to act as ratchets, helping to move large prey items back into the gullet. The jaw musculature is reconstructed as a dual-function system, the pterygoideus musculature being specialized to close the open jaws rapidly against inertia and drag, and the main adductor mass being specialized to clamp the jaws tightly onto prey. The cranial skeleton is well adapted to resist bending stresses induced when the animal bit onto prey. However, there is no evidence for any adaptation to torsional resistance, such as a pterygoid flange-mandible contact, as would be useful in twist-feeding to dismember large prey. Pliosaurus, at about 10 m overall length, may have been large enough to swallow most potential prey without being particularly specialized to dismember it. Its wide gape would help it swallow large prey. However, the comparatively narrow anterior snout, and evidence from gut contents in other specimens, suggest that it was an opportunistic feeder on a wide variety of prey of different sizes, including cephalopods and presumably fish and other reptiles. Large orbits and the lack of acoustically isolated ears indicate that it was primarily a visual hunter. The nares seem too small to be used in respiration, and may instead have been used in underwater olfaction.

Reconstruction of skull defects in children and adolescents by the use of fixed cranial bone grafts: long-term results.

Abstract: This article presents the long-term results of skull defect reconstruction in a series of 27 children studied between 1986 and 1990 (mean age, 8.4 yr; range, 1-17 yr). Causes of their defects were encephalocele (six patients), trauma (seven patients), tumor (eight patients), fibrous dysplasia (two patients), postsynostectomy defects (two patients), osteomyelitis (one patient), and Reye's syndrome with bone flap loss (one patient). All patients underwent clinical and computed tomographic scan documentation of their skull defects before and immediately after surgery and at least 1 year later. The average preoperative defect surface area measured 33 cm2 (range, 2.5-114 cm2). Skull defects were reconstructed in all patients with fixed autogenous cranial bone grafts. In the initial five patients, the grafts were fixed with interosseous wires, and in the remainder, they were fixed with a combination of miniplates and microplates and screws. Follow-up ranged from 12 to 66 months (mean, 31.4 mo). Complications were minimal, with no infection, plate or graft exposure, or intracranial injuries. In 24 of 27 patients, clinical examination and computed tomographic scans showed no evidence of skull defect or appreciable irregularity of donor or recipient sites. Two patients had documented small regions of graft resorption. One skull had palpable contour irregularities but without a bony defect. All patients have resumed routine activities and sports without special head protection. Repair of skull defects in children with fixed autogenous cranial grafts is a reliable method of reconstruction with minimal morbidity. Although we prefer miniplates and microplates and screws for fixation, the grafts fixed in place with interosseous wires did equally well.

Non-Hodgkin lymphoma of the central skull base: MR manifestations.

Abstract: Objective The aim of this study was to demonstrate the MR characteristics of non-Hodgkin lymphoma of the skull base to help in the differential diagnosis of this neoplasm from other conditions. Materials and methods MR of five patients, 7-64 years old, with pathologically proved lymphomas of the skull base were reviewed. Three cases had primary skull base lesions involving the sphenoid bone and the cavernous sinus. One case with a nasal cavity lesion involving the skull base and one with a relapsing skull base lesion of previously treated tonsillar lymphoma were included. Results The lesions had signal intensities that were similar to that of gray matter of brain on both T1- and T2-weighted imaging. Bilateral cavernous sinuses were involved with encasement of internal carotid arteries in every case. Postcontrast MR showed homogeneous enhancement of the tumor with dural infiltration along the planum sphenoidale, clivus, or tentorium. The clivus was destroyed or replaced by tumors in adult cases but in two children the clivus was preserved with intact sphenooccipital synchondrosis. In one case the tumor extended to the extracranial portion through the jugular foramen. Conclusion The MR findings of a permeative lesion of the skull base, invasion of the cavernous sinus without arterial narrowing, infiltration along the dural surface, and an iso- or hypointensity with brain on T2-weighted imaging should suggest lymphoma.

Calvarial deformity regeneration following subtotal craniectomy for craniosynostosis: a case report and theoretical implications.

Abstract: We describe an infant with combined sagittal and unilateral coronal synostosis who underwent "total vault" craniectomy for skull reshaping. The operative procedure was interrupted without replacement of the calvarial bone grafts. Follow-up over the ensuing 2 months revealed regeneration of the entire cranium and supraorbital rims, as well as (in contrast to earlier reports) redevelopment of fusion within the suture at the same site noted in the initial operation, associated with similar skull deformity. These observations are reviewed with special emphasis on the theoretical implications for the etiology of craniosynostosis and skull deformity.

Developmental studies on the interparietal part of the human occipital squama.

Abstract: The development of ossification centres in the membranous occipital squama is described, based on observations on human fetal skulls. The interparietal part develops basically from 3 pairs, 1 primary pair and 2 secondary pairs; an additional 4th pair is occasionally observed. The so-called separated interparietal bones (Inca bones) are formed by a failure of fusion between the primary and secondary centres, not between the supraoccipital and interparietal parts. The preinterparietal bones, which are developed from the additional 4th pair of interparietal ossification centres, are clearly differentiated from other anomalies in the lambda region by the shape of their territory and by their location. The issue still remains as to how to establish their identity in skulls from individuals of advanced age.

Transsphenoid basilar skull fracture: CT patterns.

Abstract: The authors studied computed tomographic (CT) scans obtained in 40 patients with transsphenoid basilar skull fractures to establish if there were reproducible patterns of fracture along lines of weakness. Medical records were reviewed. Four major fracture patterns were identified: anterior transverse (n = 22), lateral frontal diagonal (n = 7), posterior transverse (n = 16), and mastoid diagonal (n = 3). Eight patients had two fracture patterns. Eleven of 40 patients (28%) died as a result of their head injury. The diagonal patterns were statistically significantly more frequently associated with in-hospital mortality than were the transverse fractures (P = .014). Complications included blindness, cranial nerve injury, cerebrospinal fluid leak, and hearing loss. These results indicate that transsphenoid basilar skull fractures occur along reproducible lines of weakness, including a coronal plane through the anterior sphenoid body and pterygoid plates, a coronal plane through the posterior sphenoid body and clivus, and the sphenopetrosal synchondrosis.

Extended Osteoplastic Maxillotomy: A Versatile New Procedure for Wide Access to the Central Skull Base and Infratemporal Fossa

Abstract: Extended osteoplastic maxillotomy provides wide, direct exposure of the lateral and/or central skull base. This procedure, developed in cadavers, has been used successfully in six patients. Briefly, the maxillofacial skeleton is partially exposed via a Weber-Fergusson incision. Osteotomies in the maxilla and zygoma completely disengage the maxilla from the facial skeleton. The maxilla is mobilized on the skin and soft tissues of the ipsilateral cheek, maintaining its vascularity. Medial positioning of the anterior osteotomy through the face of the maxilla determines the extent of exposure to the nasopharynx. The lateral osteotomy can be placed anteriorly at the malar eminence or posteriorly to include the glenoid fossa, thus determining the extent of exposure to the infratemporal fossa. Concurrent use of a pterional or temporal craniotomy provides corresponding access to the cranial cavity. Miniplate fixation of the maxilla and zygoma reestablishes skeletal contour. This new, versatile procedure can be used for benign and malignant lesions of the nasopharynx and infratemporal fossa, particularly in those patients requiring preoperative or postoperative adjuvant therapy.

Scintimetric Evaluation of Remodeling after Bone Fractures in Man

Abstract: In a review of bone scans of 2000 post-trauma patients, the following rules of bone remodeling after fracture were found: different bones behave differently; lesions in the vicinity of joints show an early and high accumulation of the tracer within the first days after the trauma, whereas fractures of the axial skeleton and shafts of long bones sometimes need up to 12 days to appear on scan; all except skull fractures demonstrate a steady rise of accumulation intensity compared to normal bone for 2-5 wk; the steepness of increase and time of maximum differ significantly for different fracture sites. Calculating a ratio 24:4 hours after injection helps differentiate fractures from soft tissue lesions since fresh fractures show a ratio > 1:1. We found no clinically relevant dependence on sex and age. The scintigraphic/scintimetric behavior of fractures is reproducible and predictable, adding specificity to the well-known high sensitivity of bone scans.

Craniofacial abnormalities in 52 school-age and adult patients with cleidocranial dysplasia.

Abstract: The purpose of the present investigation is to describe and discuss the craniofacial abnormalities in young and adult patients with cleidocranial dysplasia (CCD). Skull radiographs of 52 CCD patients were examined. Thirty-six patients were adult, 16 were between 7 and 16 years old. Facial photographs were available in 30 cases, and in one adult case with cranial CT scans, 3-D reconstructions were carried out. High quality photographs of six CCD skulls were also described. The paranasal sinuses were absent or diminished in all children and most adult patients. An inverted pear-shape of the calvaria and an open anterior fontanelle were present in more than 60% of the cases. In the cranial base an upward distortion of the clivus, an anteverted foramen magnum, and extremely narrow choanae were frequent traits, together with small sella and bulbous dorsum sellae. Nearly all patients and dry skulls showed hypoplasia or absence of nasal bones. The zygomatic arches were diminished or incomplete in all cases. Mandibular morphology was judged to be syndrome specific with the slender, upward-backward-pointing coronoid process. We have concluded that a great part of the abnormal qualitative traits are present to a lesser degree in CCD children, indicating a progressive abnormal development with advancing age. From the present and previous studies on CCD we have hypothesized that on top of their generalized reduction of growth potential, these patients suffer from a combination of skeletal immaturity resulting in deformations and a defective bone remodeling. We have acknowledged the importance of longitudinal investigations in order to ameliorate the understanding of the pathogenesis of CCD and thereby to improve total patient care. Correction of the craniofacial abnormalities may be advocated in the most severe cases of hypertelorism and midfrontal groove, if psychosocial problems occur. Also, patients with major midface underdevelopment might benefit from combined orthodontic/surgical correction.

The Subarachnoid Spaces in Craniosynostosis

Abstract: A review of 85 patients with various forms of craniosynostosis showed predictable patterns of dilatation of the subarachnoid spaces in regions of compensatory skull growth. The characteristic pattern in sagittal synostosis (43 patients) included dilatation of the frontal and occipital subarachnoid spaces associated with the elongation of the anteroposterior dimension of the skull and widening of the interhemispheric fissure. In 11 patients with unilateral coronal synostosis, dilatations of the subarachnoid spaces over the contralateral frontal lobe, the sylvian regions, and the ipsilateral temporal lobe tip were consistent with the skull changes of contralateral frontal bossing, increased bitemporal dimension, and elevation of the sphenoid wing, respectively. Four patients with bilateral coronal synostosis also had enlarged subarachnoid spaces high over the convexities of the brain consistent with the towering configuration of the skull. Four patients with true lambdoid synostosis had dilatation of the subarachnoid space only over the ipsilateral frontal lobe associated with compensatory bossing of the frontal bone. Ten of 14 patients with lambdoid deformities had bilateral enlargement of the subarachnoid spaces suggesting brain atrophy and an underlying motor delay accounting for the position-induced skull changes. The findings suggest that focal hydrodynamic mechanisms are involved in the compensatory skull changes seen in craniosynostosis.

Cryptococcal skull infection: a case report with review of the literature.

Abstract: A case of cryptococcal osteomyelitis of the skull is presented. The patient was an immunocompetent host with skull and skin involvement without central nervous system or pulmonary extension. The radiographic findings are reviewed to include skull films, bone scan, and computed tomographic and magnetic resonance imaging scans. The patient underwent surgical debridement of the lesion as well as systemic medical therapy with amphotericin B and flucytosine. The medical and surgical therapy for such lesions is reviewed. Surgical intervention is emphasized for the removal of bony sequestrum and nonviable bone while maintaining an intact dura.

Development of the skull in infants with cleidocranial dysplasia

Abstract: The purpose of the present paper is to clarify some of the questions regarding pathogenesis in cleidocranial dysplasia (CCD) in order to improve the understanding of the mechanisms leading to the craniofacial abnormalities characteristic for young and adult patients with the syndrome. The neonatal skull is described and craniofacial development from birth to 7 years analyzed. Skull radiographs of 11 CCD patients ages 0-7 years were examined. Study methods included plain radiographs of the skull and roentgencephalometric films in the lateral, frontal, and axial projections. In one patient, CT scans of the skull with 3-D reconstructions were available. Common to the four patients examined within the first 6 months postnatally was a marked delay of skeletal maturity. In the calvaria a severe reduction of calcification in all bones was found. Corresponding to the expected sutural areas, gaping defects were recorded, indicating that calcification of calvarial bones in the newborn CCD individual had only reached a stage corresponding to around 20 weeks gestational age. Calvarial size corresponded to that of normal newborns and the morphology was relatively normal, taking into account the pronounced deformation that took place during parturition due to the soft, undermineralized skull. At birth bony islands could be observed in the periphery of the occipital, parietal, and frontal bones. Ossification of the maxilla and the mandible seemed to be within normal limits. Posteriorly to the foramen magnum, the chondral part of the supraoccipital bone remained unossified. In the cranial base an increased width of the spheno-occipital synchondrosis was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of cranial bone mobility in cranial compliance.

Abstract: Increases in intracranial pressure are normally buffered by the displacement of blood and cerebrospinal fluid from the cranium when there is an increase in intracranial volume (ICV). How much pressure increases with an increase in ICV is expressed in the calculation of cranial compliance (delta ICV/delta P, where delta P is change in pressure) and elastance (delta P/delta ICV). Data reported here indicate that the movement of the cranial bones at their sutures is an additional factor defining total cranial compliance. Using controlled bolus injections of artificial cerebrospinal fluid into a lateral cerebral ventricle in anesthetized cats and a newly developed instrument to quantify cranial bone movement at the midline sagittal suture where the bilateral parietal bones meet, we show that these cranial bones move in association with increases in ICV along with corresponding peak intracranial pressures and changes in intracranial pressure. External restraints to the head restrict these movements and reduce the compliance characteristics of the cranium. We propose that total cranial compliance depends on the mobility of intracranial fluid volumes of blood and cerebrospinal fluid when there is an increase in ICV, but it also varies as a function of cranial compliance attributable to the movement of the cranial bones at their sutures. Our data indicate that although the cranial bones move apart even with small (nominally 0.2 ml) increases in ICV, total cranial compliance depends more on fluid migration from the cranium when ICV increases are less than approximately 3% of total cranial volume. Cranial bone mobility plays a progressively larger role in total cranial compliance with larger ICV increases.

The epigenetic influence of growth hormone on skeletal development

Abstract: We studied the epigenetic effect of growth hormone using mice that were transgenic for a sheep metallothionein 1a-sheep growth hormone, which was expressed beginning at 21 days postnatal age. The impact of exogenous growth hormone (GH) on various skeletal traits with special emphasis on the mandible was examined by conventional statistical analysis and finite element scaling analysis. In long bones, growth hormone enhances the proliferation rate of cartilage cells in the growth plate and should thus lead to increased lengths. Further, growth hormone is known to increase muscle mass. Our results are consistent with these developmental considerations. We found that the lengths of long bones increased in the transgenic mice compared to the control mice, while the differences in long bone width were less pronounced. In the mandible and skull, the impact of GH is most pronounced in areas of major muscle attachment, i.e., the proximal part of the mandible and the occipital and malar bones in the skull.

Acalvaria: a unique congenital anomaly.

Abstract: Acalvaria is a rare malformation usually regarded as a postneurulation defect. It consists of absense of the calvarial bones, dura mater and associated muscles in the presence of a normal skull base and normal facial bones. The condition is frequenctly confused by prenatal ultrasonography with anencephaly or an encephalocele. Whereas the cerebral hemispheres are absent in anencephaly, the cranial contents in acalvaria are generally complete, though some neuropathological abnormality is often present. The presumed pathogenesis of acalvaria is faulty migration of the membranous neurocranium with normal placement of the embryonic ectoderm, resulting in absence of the calvaria but an intact layer of skin over the brain parenchyma. We describe 2 cases of acalvaria, one misdiagnosed ultrasonographically as an occipital encephalocele prenatally. The brain in one fetus demonstrated semilobar holoprosencephaly and micropolygyria, but in the other, was structurally and histologically normal with the exception of hydrocephalus. © 1993 Wiley-Liss, Inc.

Craniofacial morphology of children with Williams syndrome.

Abstract: Facial dysmorphology is considered to be a major diagnostic feature in patients with Williams syndrome (WS). The dysmorphology is composed of soft tissue and skeletal components. In this study the skeletal component of the facial dysmorphology was examined by analyzing the lateral cephalometric radiographs of 8 children with WS. Seven anatomic areas were judged by means of the analysis of 48 cephalometric variables. Four skeletal features contributed to the facial appearance of children with WS: (1) the anterior cranial base was short, although the cranial base angle (N-S-Ba) was normal; (2) the angle of the mandibular plane was steep, although total facial height was normal; (3) despite the normal facial height, there was an unusual proportion of upper to lower anterior facial height and posterior to anterior facial height; and (4) the chin button (pogonion to N-B line) was deficient, although the mandible could not be classified as retrognathic. The common skeletal components were not dominant enough to characterize the facial dysmorphology completely.