PMC6925784_01
(a) Physical examination of the scaphocephalic cadaver head. Superior view shows the demarcation of the displaced sagittal strip (black arrows). (b) Computed Tomography (CT) images of the cadaver head. Left: The axial view reveals a thickened skull and spaces of bone towards the posterior aspect of the skull. The long, narrow skull yielded a cranial vault index of 0.56. The brain appears to have undergone significant atrophy. Right: The coronal view shows an abnormal thinning of the skull on each side of the sagittal suture near the superior aspect of the skull. These areas likely coincide with the areas lacking bone in the axial view. (c) Increased bone thickness in the scaphocephalic skull of the individual with CS. The thickness of the frontal, parietal, occipital and temporal bones was measured in five male mesocephalic skulls (normal, dark grey) at the bony points described in using Neiko digital calipers. The measurements of the frontal bones were conducted approximately 15 mm above the supraorbital ridges at three points: center point (FC) and 2 cm away from the center point on the left (FL) and right (FR). The occipital bones were measured approximately 4 cm above the external occipital protuberance at three points: center point (OC) and 2 cm away from the center point on the left (OL) and right (OR). Thickness of the temporal bones were measured at the level of the zygomaticofrontal suture on the left (TL) and right (TR) sides. The parietal bones were measured approximately 1 cm above the most superior point of the squamosal suture on the left (PL) and right (PR) side. The same measurements were conducted on the scaphocephalic cadaveric head (CS, pattern) at the bony points described above using Syngo Fast-View software. Data shown are mean of three measurements for a single scaphocephalic skull and 15 measurements for five mesocephalic skulls (three measurements per skull).
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The initial visual examination of the embalmed patient's head revealed its abnormal, scaphocephalic, shape as well as a presence of bulging sagittal bone strip (Figure 1(a)). The subsequent CT image analysis confirmed the scaphocephaly (CI = 56) and demonstrated clearly a significant bone thickening in the scaphocephalic skull as compared to mesocephalic skulls (Figure 1(b)). The respective fold change varied from 1.34 for occipital bone to 2.76 for parietal bone with the rest of the scaphocephalic skull bone thickening falling into the ~1.6-2.3 fold range (Figure 1(c)). It should be noted, that the bone thickness values derived in the current report from five mesocephalic skulls (Figure 1(c)) could be viewed as a representative snapshot of a large respective sampling because they were very similar to those reported for the group of 66 male mesocephalic skulls.
Examination of the exposed calvarium. (a) The exposed calvarium shows the presence of the coronal and lambdoid sutures. The vertical displacement of the sagittal strip is apparent at bregma. At the sagittal strip:parietal bone junction (dashed lines), there are areas of bridging bone and fibrous bridging tissue. (b) Internal view of the calvarium. Black arrowheads:large arachnoid granulations. (c) Torus palatinus is evident in the midline (arrow) with the epithelium reflected.
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One of the most interesting features of the present case is an abnormal re-growth of the surgically removed bone strip and the resultant elevated vertical displacement of the skull (Figure 2(a)). Examination of the calvarial region revealed an oval segment of calvarial bone that included remnants of frontal and parietal bone with all suture lines obliterated (Figure 2(b)). At a few locations there was a confluence of healed bone between the original, surgically created margins and the oval bone segment removed and replaced at the time of craniotomy (Figure 2(b)). This procedure revealed an exostotic hard palate (torus palatinus) and complete edentulism (Figure 2(c)).
Histological analysis of the scaphocephalic calvarium. (a) The sagittal strip displays cancellous bone with variably sized osteons (white stars). Intervening medullary spaces (black star) contain typical myeloid cellular elements, but without the presence of osteoclasts. (b) The bridging bone demonstrates scattered immature Haversian systems. Areas suggestive of osteon remnants are indicated by the arrowheads. (c) An additional image through the bridging bone shows dense, confluent areas of well-formed Haversian systems characteristic of typically formed compact or cortical bone. (d) Enlarged boxed area in C shows variably sized Haversian systems of similar orientation (arrows). Portions of the image indicated by arrowheads suggest immature (woven bone) that has been replaced by newer Haversian systems resulting in the formation of compact bone.
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Sections of bony tissue from the sagittal strip revealed areas of immature compact bone with incomplete or developing Haversian systems, whose orientation was predominately perpendicular to the section orientation (Figure 3(a)). More importantly, sections of bony tissue from surgically created margins revealed an extremely high number of osteons, with some, well-formed and others, formed incompletely (Figures 3(b)-3(d)).