A case of external beveling with an entrance gunshot wound to the skull made by a small caliber rifle bullet.

The external beveling caused by an entrance gunshot wound to the skull has not been completely explained, but the mechanism is probably a combination of several factors including the angle of shot, twisting force of a rotating bullet, blow-back effect, velocity, shape and size of the bullet, outspread of the kinetic energy from the bullet, and resistance of the skull.     

The colour of the human skull

The colour of the human skull was determined from 124 fresh skull samples using the tristimulus colour measurement system "Micro Color" and listed as The Commission Internationale de l'Eclairage (CIE) L*a*b*-values. The skulls were found to be relatively light (L*=72.5), nearly colourless on the a*-axis (a*=-7.4), and slightly yellow (b*=16.4). No difference was found between the colours of the outer and the inner surfaces of the skulls. Including a small number (n=8) of skulls from diabetic patients in the study, we detected no colour difference between the samples from diabetics and non-diabetics. However, a hitherto unknown correlation between the subjects' age and the yellowness (b*-value) of the skull could be demonstrated.     

Biomechanical fragility of the infant skull

Following previous experiments on postmortem skull fractures of infants, falls from 82-cm heights onto stone (A), carpet (B) and foam-backed linoleum (C), 35 further falling tests were carried out onto softly cushioned ground. In 10 cases a 2-cm thick foam rubber mat (D) was chosen and in 25 further cases a double-folded (8-cm-thick) camel hair blanket (E). Hence the results of altogether 50 tests could be evaluated. In test groups A-C on a relatively hard surface, skull fractures of the parietale were observed in every case; in test group D this fracture was seen in one case and in test group E in four cases. Measurements along the fracture fissures showed bone thickness of 0.1-0.4 mm. The fracture injuries originated in paper-thin single-layer bone areas without diploe, which can also be considered the preferred regions for skull fractures of older infants following falls from low heights. These results indicate that it is no longer possible to assume that the skull of infants is not damaged after falls from table height.     

Destruction of the skull during compression

The article contains the results of an experimental modeling of the destruction of the head of a bio-mannequin by compressing it between two blunt objects with the hard, flat and broad surfaces and by using a mechanical press (with slow motion) and freely falling object (with fast motion). The obtained results were compared with two opposite-direction blows by a similar object. The author studied the main regularities of fractures of the skull of the main shapes, i.e. ellipsoid or ovoid as well as spheroid and rhomboid shapes, at different directions of its compression (sagittal, lateral, diagonal, vertical or moving). A comparison of local, constructional and local-and-constructional zones of the inflicted fractures made it possible to establish the succession in the formation of the destruction of the skull at the static and dynamic compression types.     

Ring fractures of the base of the skull

Besides complete ring fracture, also incomplete fractures open to the front, back, or side(s) are discussed on the basis of 61 ring fractures of the base of the skull. The fractures were found in casualties from traffic accidents (car passengers, cyclists and motorcyclists, pedestrians), after falls and other accidents. In traffic accidents, compression, traction, hyperextension, extreme lateral movements, and torsional forces can lead to ring fractures. In falls, compression and traction are the main forces. A fall in one plane is also capable of producing an incomplete ring fracture. Incomplete ring fractures may show lateral emphasis. The greater fracture length is found on the impact side (e.g., in falls). In contrast to complete ring fractures, incomplete ring fractures are compatible with longer survival times. Ring fractures are to be classified under direct fractures. This does not exclude the possibility that overall deformations of the skull with bursts can partly determine the course of the fracture.     

Stab injuries of the skull and brain

A few cases of skull and brain stab wounds are described and the clinicodiagnostic problems discussed. The injuries often remain unrecognized because the external wound often appears harmless, there are no neurological symptoms, or the clinical picture is interpreted as drunkenness, blunt injury or as another disease. The importance of a precise physical examination of the whole patient's head is pointed out. The refined methods used in modern radiodiagnostics of the skull are the most helpful in correctly recognizing these injuries; there are reports of patients with severe injuries who recovered when the correct diagnosis had been established.     

Study on the microstructures of skull fracture

The authors observed the edges of skull fractures under the scanning electron microscope. Many microfractures can be found along the main fracture lines. The width of the microfractures varies from 5 to 100 microns. They may be located either in the external compact bone or between the outer compact bone and dipl?e, or in the dipl?e. Those within the dipl?e form transverse, longitudinal or spiral fractures of bony trabeculae. Collagenous fibre bunches in the bony matrix may be divided or broken and the different layers of collagenous fibre may be separated. The blood vessels inside the skull may be crosscut or longitudinally torn by the fracture lines. Sometimes the torn blood vessels may be drawn out of the Haversian canals. In antemortem fractures, the fibrin networks and red blood cells can be easily found in the depths of those cracks. The possible mechanism of formation of the microfractures and the possibility of differentiation between ante- and post-mortem fractures are discussed.     

Postmortem roentgen diagnosis of the skull]

In this prospective study, skulls of 164 dead bodies were x-rayed in two different planes. The findings were assessed independent to the results of the subsequent autopsy, however afterwards compared with the autopsy findings. In 86 cases (53.4%) x-ray findings were significant. Dislocated calvarium fractures were clearly visible on the x-rays, however non-dislocated calvarium fractures as well as fractures of the visceral cranium and skull base were difficult to detect. Gas and foreign bodies could easily be observed. Similar to the clinical assessment the indication for a post-mortem x-ray of the skull must consider the case history and the respective condition of the corpse (for example putrefaction, charred body).     

External beveling of cranial gunshot entrance wounds

Entrance gunshot wounds of the skull generally have internal beveling. External beveling has been previously described in association with internal beveling (keyhole defect) and with wounds from handgun projectiles. An accidental shooting is described in which a 22-year-old male sustained a perforating gunshot wound of the head at distant range from a 5.56-mm (.223-caliber) fully jacketed rifle round. Although the entrance wound had symmetrical external beveling, misinterpretation of this particular entrance wound as an exit wound would have been difficult.     

Priority of multiple gunshot injuries of the skull

In accordance with Puppe's rule, the analysis of skull fractures may provide evidence on the sequence in which multiple blunt injuries of the skull occurred. In cases of multiple gunshot wounds of the skull determination of the sequence in which the gunshot wounds took place is much more difficult. In some cases, however, analysis of the skull fractures here can also allow the order in which gunshot wounds occurred to be established.     

Classification of fractures of the skull vault bones

The proposed classification of fractures of the skull vault bones is based on fracture morphogenesis. Russian and foreign published data on skull vault fractures and the authors' own observations allowed some analogies and helped develop a new classification.     

Characteristics of gunshot wounds in the skull.

The analysis of trauma to the skeleton is an important aspect of forensic case work, but most pathology references devote limited attention to this topic. This paper describes various aspects of gunshot wounds, including entrance and exit patterns, angle and path, range of fire and velocity, and caliber of the bullet, based on observations of a series of known cases. Skeletal remains of 21 victims of gunshot wounds were studied. In most cases, there was documentation of the investigation, autopsy, and victim's identity. Each case was analyzed in terms of wound location, shape, size and exit/entry surface area ratio, beveling, and direction of shooting Skull entry wounds were most often round or oval. Unusual shapes were observed in bones like the mandible and mastoid process, but were also found to be triangular, nearly rectangular or irregular. Tunneling was observed in the mastoid process. The expected internal beveling was obvious in all but one skull. External beveling of an entry wound was only observed in one case (parietal bone). Exit wounds were roughly round, oval, square, and rectangular and were always more irregular than entry wounds. External beveling of exit wounds was observed in most vault bones, but there was none in the orbit, maxilla, greater wing of the sphenoid, temporal, or left occipital bone. Tangential gunshot wounds were seen in a mastoid process, zygomatic process, mandibular ramus and condyle, and occipital condyle. Most of the exit to entry surface area ratios (cm2) varied from 1.4 to 2.0. In four cases the ratio indicated that entrances were larger than exists. In conclusion, understanding of gunshot wound characteristics is an important matter to interpret distance, velocity, direction and sometimes caliber size. Assessment of this nature of gunshot wounds helps reconstruct events surrounding the death.     

Peculiarities of destruction in the facial area of the skull

Injuries observed in the facial skull area (FSA) in trauma made by hard blunt objects are registered within the forensic medical examinations of cadavers by far more rare than they are actually encountered in life. At the same time, a statement made to the effect that it was FSA that was affected in injuries of the cerebral skull area (CSA) is of an important forensic medical value. According to our research, the "strength beams" present in FSA and CSA are ovals and semi-ovals positioned above one another in 3 layers (top, medium and low ones). The anterior sections of all layers of FSA "strength beams" and of adjoining CSA regions, i.e. the squama of frontal bone (low one third of it) as well as anterior and middle cranial fossas, are a single deformative strength system. Specific features of each impact-zone region affect greatly a character of injuries in FSA at traumas in the medium facial third. Bones in the anterior and middle cranial fossas are damaged, apart from cranial injuries, in certain variations of impacts to FSA.     

Restoration of the fragmented skull in expert human identification

Restoration of fragmented skull in expert personality identification is attained by assembly of bone fragments, modeling of bone defects by means of special plastic, and mathematical prediction of the lacking craniometric parameters. The authors suggest 111 equations of multiple linear regression which can be used in restoration of fragmented cerebral and facial parts of the skull. Prediction of craniometric parameters is useful for control and correction of plastic restoration of the skull. Regression equations are the most efficient in cases when the mandible is absent or in defects of symmetrical right- and left-side fragments of the skull. All stages of restoration are illustrated with examples from expert practice.     

Posttraumatic periosteal reaction in the skull arch bones

The mechanisms of genesis, morphological features of posttraumatic periosteal reaction in skull cap bones were considered. The forensic-medical assessment of this reaction was given.     

Categories of variability in the thickness of human skull bones

Problems in standardization of the thickness of skull vault bones at certain strictly determined points are discussed. Race, ethnic, regional, and sex-associated variability of this criterion was studied on extensive material for many peoples of the world (1261 men, 549 women, and 570 men + women). The most significant differences are characteristic only for the male and female totalities. A table of categories of the skull bone thickness has been created, covering 5 intervals with the following incidence: 33% medium, 22% low and high (each), and 11% very low and very high (each). An expert example is offered.     

The specificity of healing of fractures in the skull base

On the basis of actual observations we elucidated the main processes occurring in the reparation of fractures in the skull base. The specificity of reparation was shown to be conditioned by the structure of base bones and of surrounding tissues as well as by the nature of blood supply to them. Criteria are suggested for the determination if the lesions were inflicted in life time and when.     

Reverse engineering--rapid prototyping of the skull in forensic trauma analysis

Rapid prototyping (RP) comprises a variety of automated manufacturing techniques such as selective laser sintering (SLS), stereolithography, and three-dimensional printing (3DP), which use virtual 3D data sets to fabricate solid forms in a layer-by-layer technique. Despite a growing demand for (virtual) reconstruction models in daily forensic casework, maceration of the skull is frequently assigned to ensure haptic evidence presentation in the courtroom. Owing to the progress in the field of forensic radiology, 3D data sets of relevant cases are usually available to the forensic expert. Here, we present a first application of RP in forensic medicine using computed tomography scans for the fabrication of an SLS skull model in a case of fatal hammer impacts to the head. The report is intended to show that this method fully respects the dignity of the deceased and is consistent with medical ethics but nevertheless provides an excellent 3D impression of anatomical structures and injuries.     

Evaluation of pediatric skull fracture imaging techniques

Radiologic imaging is crucial in the diagnosis of skull fracture, but there is some doubt as to whether different imaging modalities can accurately identify fractures present on a human skull. While studies have been performed to evaluate the efficacy of radiologic imaging at other anatomical locations, there have been no systematic studies comparing various CT techniques, including high resolution imaging with and without 3D reconstructions to conventional radiologic imaging in children, we investigated which imaging modalities: high-resolution CT scan with 3D projections, clinical-resolution CT scans or X-rays, best showed fracture occurrence in a pediatric human cadaver skull by having an expert pediatric radiologist examine radiologic images from fractured skulls. The skulls used were taken from pediatric cadavers ranging in age from 5 months to 16 years. We evaluated the sensitivity and specificity for the imaging modalities using dissection findings as the gold standard. We found that high-resolution CT scans with 3D projections and conventional CT provided the most accurate fracture diagnosis (single-fracture sensitivity of 71%) followed by X-rays (single-fracture sensitivity of 63%). Linear fractures outsider the region of the sutures were more identifiable than diastatic fractures, though the incidence of false positives was greater for linear fractures. In the two cases where multiple fractures were present on the same anatomical skull location, the radiologist was less likely to identify the presence of additional fractures than a single fracture. Overall, the high-resolution and clinical-resolution CT scans had the similar accuracy for detecting skull fractures while the use of the X-ray was both less accurate and had a lower specificity.