Volumetric quantification of intracranial and ventricular volume following cranial vault remodeling: a preliminary report

This preliminary study documents preoperative and postoperative changes in cerebral tissue as well as intracranial and ventricular volume in patients who underwent cranial vault remodeling for craniosynostosis. The documentation and calculations were provided from CT data according to a craniofacial protocol. Three-dimensional images were then obtained of the preoperative and postoperative skulls and cerebral tissues. From these data, comparisons of preoperative and postoperative volumes of the cerebral tissue and ventricles could be examined. In one case, a frontal bone advancement combined with anterior cranial vault remodeling was associated with an increase in intracranial volume of 110 cc (8 percent) and a ventricular volume increase of 112 percent. The reported technique should allow more complete evaluation of the preoperative pathology and documentation and prediction of the projected intracranial and ventricular volume changes.     

The use of intraoperative autotransfusion during cranial vault remodeling for craniosynostosis.

Intraoperative autotransfusion salvages blood shed during surgery for use in immediate resuscitation of the patient. The purpose of this study was to determine whether such autotransfusion decreases the volume of homologous blood transfused in patients undergoing primary cranial vault remodeling for craniosynostosis. The Cobe-Bret 2 autologous blood recovery system (Hemo Concepts, Union, N.J.) was used in 11 cases, and an equal number of consecutive cases did not receive intraoperative autotransfusion. There were no significant differences between the groups with respect to age, sex, and weight. Mean estimated blood loss was 43.2 ml/kg (range, 20.3 to 65.0 ml/kg) in the intraoperative autotransfusion group and 40.2 ml/kg (range, 6.8 to 72.3 ml/kg) in the control group (not statistically significant; p < 0.05). There was no significant difference in volume of homologous blood transfusion between the two groups. The autotransfusion group received 34.1 ml/kg of homologous blood (range, 0 to 60.7 ml/kg), and the control group received a mean of 32.7 ml/kg (range, 14.5 to 60.2 ml/kg). The autotransfusion group received a mean of 10.4 ml/kg of recovered autologous blood (range, 0 to 21.4 ml/kg). In four of the 11 autotransfusion patients, insufficient autologous blood was recovered intraoperatively to warrant transfusion. Results of this study suggest little benefit for the use of intraoperative autotransfusion in primary cranial vault remodeling for craniosynostosis in the young patient. It was hypothesized that this finding was a result of the following: (1) intraoperative autotransfusion blood was usually available only toward the end of the procedure, after homologous blood had already been administered, and (2) the volume of recovered intraoperative autotransfusion blood is minimal, compared with the homologous transfusion volume requirements during an extensive cranial vault remodeling and fronto-orbital advancement procedure. In the context of unproven cost benefit and increasing similar evidence from other comparative studies, emphasis should be directed to other medical and surgical strategies to minimize the need for perioperative blood transfusion.     

Effects of fronto-occipital artificial cranial vault modification on the cranial base and face.

Artificial reshaping of the cranial vault has been practiced by many human groups and provides a natural experiment in which the relationships of neurocranial, cranial base, and facial growth can be investigated. We test the hypothesis that fronto-occipital artificial reshaping of the neurocranial vault results in specific changes in the cranial base and face. Fronto-occipital reshaping results from the application of pads or a cradle board which constrains cranial vault growth, limiting growth between the frontal and occipital and allowing compensatory growth of the parietals in a mediolateral direction. Two skeletal series including both normal and artificially modified crania are analyzed, a prehistoric Peruvian Ancon sample (47 normal, 64 modified crania) and a Songish Indian sample from British Columbia (6 normal, 4 modified). Three-dimensional coordinates of 53 landmarks were measured with a diagraph and used to form 9 finite elements as a prelude to finite element scaling analysis. Finite element scaling was used to compare average normal and modified crania and the results were evaluated for statistical significance using a bootstrap test. Fronto-occipitally reshaped Ancon crania are significantly different from normal in the vault, cranial base, and face. The vault is compressed along an anterior-superior to posterior-inferior axis and expanded along a mediolateral axis in modified individuals. The cranial base is wider and shallower in the modified crania and the face is foreshortened and wider with the anterior orbital rim moving inferior and posterior towards the cranial base. The Songish crania display a different modification of the vault and face, indicating that important differences may exist in the morphological effects of fronto-occipital reshaping from one group to another.     

Osseous expansion of the cranial vault by craniotasis.

A study of cranial vault lengthening using a custom expandable fixation-distraction (craniotatic) appliance was performed in the young-adult rabbit model. Ten 24-week-old rabbits underwent circumferential suturectomy plus expansion (expanded group), 10 underwent circumferential suturectomy without expansion (sham control group), and 10 served as normal controls. The appliance was lengthened at a rate of 2.5 mm per week for 5 weeks. Serial lateral cephalometry, comparative dry-skull anthropometric measurements, and histologic examinations were performed. The expanded group demonstrated a significantly longer skull, cranial vault, anterior cranial base, posterior face, and orbit as compared with the control groups (p less than 0.05). Callus bone filled the distracted suturectomy and united the frontofacial complex to the posterior cranium. In conclusion, skull lengthening by distraction osteogenesis is possible in the rabbit model and offers a new technique for future investigation in the treatment of coronal synostosis.     

Cranio-orbital correction for massive enlargement of the cranial vault.

A case is reported in which an immense cranial vault was reduced as part of the rehabilitation of a patient with severe hydrocephalus who had preservation of the intellect. This patient was selected carefully, and we do not advocate such procedures on every hydrocephalic. This patient was recumbent and bedridden prior to the procedure because of the size and weight of his head, but he was able to move freely in a wheelchair and attend a special school after the reduction of the skull.     

Effects of annular cranial vault modification on the cranial base and face

Artificial modification of the cranial vault was practiced by a number of prehistoric and protohistoric populations, frequently during an infant's first year of life. We test the hypothesis that, in addition to its direct effects on the cranial vault, annular cranial vault modification has a significant indirect effect on cranial base and facial morphology. Two skeletal series from the Pacific Northwest Coast, which include both nonmodified and modified crania, were used: the Kwakiutl (62 nonmodified, 45 modified) and Nootka (28 nonmodified, 20 modified). Three-dimensional coordinates of 53 landmarks were obtained using a diagraph, and 36 landmarks were used to define nine finite elements in the cranial vault, cranial base, and face. Finite element scaling was used to compare average nonmodified and average modified crania, and the significance of the results were evaluated using a bootstrap test. Annular modification of the cranial vault produces significant effects on the morphology of the cranial base and face. Annular modification in the Kwakiutl resulted in restrictions of the cranial vault in the medial-lateral and superior-inferior dimensions and an increase in anterior-posterior growth. Similar dimensional changes are observed in the cranial base. The Kwakiutl face is increased anterior-posteriorly and reduced anterior-laterally to posterior-medially. Similar effects of modification are observed in the Nootka cranial vault and cranial base, though not in the face. These results demonstrate the developmental interdependence of the cranial vault, cranial base, and face. © 1993 Wiley-Liss, Inc.     

Intentional cranial vault deformation and induced changes of the cranial base and face

Three morphologically distinct populations of Peruvian crania (n = 130) were metrically analysed to quantify changes resulting from intentional artificial vault deformation. Two of these samples are artificially deformed (anteroposterior [AP] and circumferential [C] types). Measurements taken from lateral radiographs demonstrated that alternative forms of the cranial base angle (N-S-Ba, planum angle, planum sphenoidale to plane of the clivus and PANG angle, planum sphenoidale to basion-sella plane) and the orbital and OANG angles (orbital roof to plane of the clivus and basion-sella plane, respectively) of both deformed groups increased while the angle S-Ba-O decreased significantly with respect to the undeformed (N) sample. Changes in the AP group are largely due to anteroinferior displacement of the basion-sella plane. Similar changes in group C are amplified by this group's posterosuperior frontal migration. This migration results in a relatively shallow orbit at the orbital plate/frontal squama interface. Unlike the deformation experienced by the external vault plates, the basion-sella plane orientation remains stable with respect to the Frankfort Horizontal. Additionally, nasal region measurements such as maximum nasal aperture breadth and nasal height were largely stable between each deformed group and the undeformed group. However, facial (bimaxillary and bizygomatic), basicranial, cranial, and frontal breadths decreased significantly from group AP to group N to group C. Thus, gross morphological facial changes between each undeformed group and the control group are largely accounted for by dimensional changes in peripheral structures. These results stress the importance of the dynamic interrelationship between the cranial vault and base in the development of the craniofacial complex.     

Early development of the primitive cranial vault in the chick embryo.

The calcified tissues involved in the early morphogenesis of the cranial vault were studied by microradiographic analysis and histological techniques in 12 chick embryos on the 9th, 12th, and 14th days of incubation. On the 9th day, the frontal, parietal, and squamosal bones are comprised of a thin lamina of chondroid tissue deposited at a short distance from the fibers of the dura mater. Woven bone formation takes place in the calvarial mesenchyme only after the 12th day of incubation and occurs mainly on the external side of the chondroid primordium. The present data obviously indicate that the primitive desmocranium of the chick embryo, which is usually known to be formed by intramembranous ossification, consists first of chondroid tissue. This tissue represents thus the initial modality of skeletogenic differentiation within the cephalic mesenchyme of the cranial vault.     

Enlargement of the temporalis muscle and alterations in the lateral cranial vault

The purpose of this study was to test the hypothesis that increasedmasticatory muscle accompanied morphologic changes in the temporalbone and squamosal suture. Ten mice deficient for the proteinmyostatin (Mstn –/–) had significantly increasedskeletal muscle mass and were compared with nine controls (Mstn+/+). Variables measured include linear and areal metrics describingtemporal size and temporal bone shape as well as the extentof the area of the squamosal suture that overlaps, or bevels,with parietal bones. Mstn–/– mice showed significantlylarger temporalis muscles. Their temporal bones showed significantlydecreased size as well as decreased beveling of the squamosalsuture. These decreases were absolute as well as relative andwere not restricted to either vertical or horizontal axes. Theincreased masticatory musculature of Myostatin-null mice hada shrinking effect on the temporal aspect of the cranium. Theseresults are inconsistent with the interpretation that increasedtemporalis mass induces morphologic changes in temporal bonethat compensate for putative increases in compressive forcestransduced at this region. Rather than increase in the areaof overlap between two calvarial bones, potential increase inbiomechanical loading along the temporal squama led to a smallerbevel which would presumably weaken this joint. It is unclearwhy this is so. Either compressive forces are not anabolic tosuture beveling or they do upregulate growth of the suture bevel,with compression not being the primary loading regime at thissuture.     

A factor analysis of cranial base and vault dimensions in children

Lengths within the cranial base and vault were measured in cephalometric radiographs of 220 boys and 177 girls ranging in age from 0 to 15 years; all these children are participants in The Fels Longitudinal Growth Study. The present study is based on mixed longitudinal data derived from 1640 radiographs for boys and 1260 radiographs for girls. Factor analysis was applied separately for boys and girls for each age group; i.e., 0–3, 4–6, 7–9, 10–12, and 13–15 years. For the 0–3 year age group, two factors were extracted in each sex, whereas four factors were extracted in the rest of the age groups. The factor structures are similar in the three older age groups of boys (7–9, 10–12, and 13–15 years). The first four factors for these groups are labelled, respectively: cranial vault size, posterior cranial base length, presphenoid length, and basisphenoid length. The order of the third and fourth factors is reversed in the 7–9 year olds. For girls, the factors extracted were also the same in both the 7–9 and 10–12 year age groups, even though the order of factors was different between age groups; i.e., anterior cranial base length, cranial vault size, basisphenoid length, and basioccipital length. Differential growth rates among cranial base dimensions probably cause changes in factor patterns. Obliteration of the spheno-occipital synchondrosis is suggested as the mechanism responsible for the change of factor pattern in the girls. Closure of this synchondrosis would have occurred too late to affect the patterns in boys.     

Frontal cranioplasty: risk factors and choice of cranial vault reconstructive material

A study of patients with large cranial defects involving the frontal bone, frontal sinus, nose, and orbit does not support the contention that there is a clear superiority of reconstructive material despite a history of previous bone infection. No patient with an isolated cranial reconstruction experienced an infection despite location in the area of the frontal sinus or the use of acrylic material. All patients experiencing infection underwent simultaneous reconstruction of the frontal cranium and nose and three- or four-wall reconstruction of the orbit, where the frontal sinus had previously been eliminated and where a previous bone infection had been present. Risk factors associated with cranioplasty were timing (p = 0.001) and cranial vault reconstruction in communication with previously infected ethmoid sinuses and the nose (p = 0.03). A history of previous bone infection suggests increased risk (p = 0.15). The choice of reconstructive material was not significant, although acrylic cranioplasties did not experience the complications expected from a review of the literature.