The interfrontal bone and mutant genes in the mouse. (1/162)

The relationship between corrected skull width and the presence and size of an interfrontal bone is discussed with regard to the effect of certain mutant genes in the mouse known to affect the development of the neural tube. All genes reviewed which increase the incidence of the interfrontal bone and affect the neural tube also change the proportions of the adult skull.  (+info)

Frontal bone windows for transcranial color-coded duplex sonography. (2/162)

BACKGROUND AND PURPOSE: The use of the conventional temporal bone window for transcranial color-coded duplex sonography (TCCS) often results in difficulties in obtaining angle-corrected flow velocity measurements of the A2 segment of the anterior cerebral artery, the posterior communicating artery, and the midline venous vasculature because of the unfavorable insonation angle. The same applies to B-mode imaging of the frontal parenchyma. However, transorbital TCCS raises problems with the insonation of the orbital lens. To overcome these drawbacks, we studied the feasibility of frontal bone windows for TCCS examinations. METHODS: In 75 healthy volunteers (mean age, 45.3+/-17.0 years; age range, 17 to 77 years), the circle of Willis and the venous midline vasculature were insonated through a lateral and paramedian frontal bone window. Insonation quality of parenchymal structures (B-mode) was graded on a 3-point scale depending on the visibility of typical parenchymal landmarks. In a similar manner, the quality of the color-/Doppler-mode imaging of the arteries of the circle of Willis and the internal cerebral veins was assessed. In 15 patients (mean age, 62.7+/-13.7 years; age range, 33 to 83 years), the color-/Doppler-mode imaging quality of the intracranial vessels before and after application of an ultrasound contrast-enhancing agent was compared. RESULTS: B-mode insonation quality was optimal to fair in 73.3% of cases using the lateral and in 52.0% of cases using the paramedian frontal bone window, with defined parenchymal structures used as reference. Insonation quality decreased in those older than 60 years. In those younger than 60 years, angle-corrected flow velocity measurements of the A2 segment of the anterior cerebral artery and the internal cerebral vein were possible in 73.6% and 60.0%, respectively. Contrast enhancement resulted in a highly significant improvement in the imaging quality of the intracranial vessels. CONCLUSIONS: The transfrontal bone windows offer new possibilities for TCCS examinations, although the insonation quality is inferior to the conventional temporal bone window in terms of failure of an acoustic window. This can be compensated for by application of an ultrasound contrast-enhancing agent.  (+info)

Comparing frontal cranial profiles in archaic and modern homo by morphometric analysis. (3/162)

Archaic and modern human frontal bones are known to be quite distinct externally, by both conventional visual and metric evaluation. Internally this area of the skull has been considerably less well-studied. Here we present results from a comparison of interior, as well as exterior, frontal bone profiles from CT scans of five mid-Pleistocene and Neanderthal crania and 16 modern humans. Analysis was by a new morphometric method, Procrustes analysis of semi-landmarks, that permits the statistical comparison of curves between landmarks. As expected, we found substantial external differences between archaic and modern samples, differences that are mainly confined to the region around the brow ridge. However, in the inner median-sagittal profile, the shape remained remarkably stable over all 21 specimens. This implies that no significant alteration in this region has taken place over a period of a half-million years or more of evolution, even as considerable external change occurred within the hominid clade spanning several species. This confirms that the forms of the inner and outer aspects of the human frontal bone are determined by entirely independent factors, and further indicates unexpected stability in anterior brain morphology over the period during which modern human cognitive capacities emerged. Anat Rec (New Anat): 257:217-224, 1999.  (+info)

Fetal acalvaria with amniotic band syndrome. (4/162)

A case of amniotic band syndrome (ABS) presenting with acalvaria is reported. ABS includes a spectrum of non-genetic anomalies, varying from simple digital band constriction to major craniofacial and visceral defects, and even fetal death. Acalvaria is a rare congenital malformation characterised by the absence of the dome-like superior portion of the cranium comprising the frontal, parietal, and occipital bones and dura mater, in the presence of a normal skull base and facial bones with complete cranial contents. No two cases are the same. Acrania or absence of the flat skull bones with disorganised cerebral hemispheres have been reported in the presence of amniotic bands. ABS is an aetiological factor in acalvaria. Appropriate counselling for affected families needs to be given after prenatal diagnosis.  (+info)

Location of the glenoid fossa after a period of unilateral masticatory function in young rabbits. (5/162)

Changes in glenoid fossa position and skull morphology after a period of unilateral masticatory function were studied. The right-side maxillary and mandibular molars in twenty-seven 10-day-old rabbits were ground down under general anaesthesia. The procedure was repeated twice a week, until the rabbits were 50 days old. Fourteen rabbits were then killed and 13 left to grow to age 100 days. Nine 50-day-old and sixteen 100-day-old rabbits with unmodified occlusions served as controls. Three-dimensional measurements were made using a machine-vision technique and a video-imaging camera. The glenoid fossa position become more anterior in both groups of animals subjected to molar grinding as compared with controls (P < 0.01 in the 50-day-old group and P < 0.05 in 100-day-old group). In the 100-day-old group the right-side fossa was also in a more inferior position (P < 0.01). The glenoid fossa was more anteriorly located on the right than on the left side of individual animals in the group in which the right-side molars had been ground down (P < 0.001).  (+info)

Trigonocephaly in rabbits with familial interfrontal suture synostosis: the multiple effects of premature single-suture fusion. (6/162)

Previous studies from our laboratory have characterized the craniofacial morphology and growth patterns of an inbred strain of rabbits with autosomal dominant coronal suture synostosis. A number of rabbit perinates from this colony have been collected sporadically over a 5-year period with premature interfrontal suture synostosis. The present study describes the very early onset of craniofacial dysmorphology of these rabbits and compares them to similar-aged normal control rabbits. A total of 40 perinatal New Zealand White rabbits were used in the present study. Twenty-one comprised the sample with interfrontal suture synostosis and ranged in age from 27 to 38 days postconception (term = 31 days) with a mean age of 33.53 days (+/-2.84 days). Nineteen rabbits served as age-matched, normal controls (mean age = 33.05 days +/-2.79 days). Lateral and dorsoventral radiographs were collected from each rabbit. The radiographs were traced, computer digitized, and 12 craniofacial measurements, angles, and indices were obtained. Mean measures were compared using an unpaired Student's t-test. All synostosed rabbits were stillborn or died shortly after birth. Grossly, these rabbits exhibited extreme frontal bossing, trigonocephaly with sagittal keeling, and midfacial shortening. No somatic anomalies were noted. Radiographically, rabbits with interfrontal suture synostosis had significantly (P < 0.05) narrower bifrontal widths, shorter cranial vault lengths, kyphotic cranial base angles, and different cranial vault indices (shapes) compared to controls. Results reveal severe and early pathological and compensatory cranial vault changes associated with premature interfrontal suture synostosis in this rabbit model. The 100% mortality rate noted in this condition may be related to the inheritance of a lethal genetic mutation or to neural compression from reduced intracranial volume. Results are discussed in light of current pathogenic hypotheses for human infants with premature metopic suture synostosis.  (+info)

Bilateral fronto-orbito-zygomatic craniotomy--a combined extended frontal and orbitozygomatic approach. (7/162)

In extensive skull base lesions involving the spheno-ethmoido-clival region and extending into both the cavernous sinuses and infratemporal regions, a combination of approaches is usually required, either in the same operation or at a second stage. The bilateral fronto-orbito-zygomatic craniotomy described in this report is a combination of an extended frontal approach and fronto-orbito-zygomatic craniotomy. This gives a wide exposure of the spheno-ethmoido-clival regions of both the cavernous sinuses and both the infratemporal regions. The exposure is thus greatly improved with minimal frontal lobe retraction. The single bone piece can be speedily replaced obviating the need for a complicated reconstruction technique and gives a superior cosmetic result. The operative technique is described in detail.  (+info)

Bone defect associated with middle meningeal arteriovenous fistula treated by embolization--case report. (8/162)

A 57-year-old male presented with a frontal bone defect associated with a middle meningeal arteriovenous fistula (AVF) manifesting as headache. The patient had a history of head injury 19 years previously. Skull radiography and computed tomography demonstrated a left frontal bone defect. Left external carotid angiography demonstrated a middle meningeal AVF at the frontal region, at the same location as the bone defect. The AVF was fed by the bilateral middle meningeal and left deep temporal arteries, and drained by the superior sagittal and ipsilateral cavernous sinuses. The minor feeding artery, the left deep temporal artery, was embolized with polyvinyl alcohol particles, then 0.4 ml of a 1:3 mixture of n-butyl cyanoacrylate and lipiodol was injected from the left middle meningeal artery. Follow-up angiography 3 months after the embolization revealed complete obliteration of the fistula. The bone defect may have been caused by erosion of the frontal bone by the pulsating effect of the feeding and draining vessels of the fistula, or by inadequate nutrition to the bone tissue because of the arteriovenous shunt.  (+info)