Neuroradiology

Postmortem Radiology of Head and Neck Injuries in Fatal Traffic Accidents 1 George J. Alker, Jr., M.D., Young S. Oh, M.D., Eugene V. Leslie, M.D., Judith Lehotay, M.D., Victor A. Panaro, M.D., and Edward G. Eachner, M.D. A series of 146 victims of fatal traffic accidents were subjected to postmortem radiographic examination prior to medicolegal autopsy. A total of 42% were found to have radiographically demonstrable head injuries ranging from relatively simple linear skull fractures to massive skull damage. Free intracranial or intravascular air was demonstrated in more than 60 %. A total of 21 % had demonstrable neck injuries, most of which were localized to a single level at the craniocervical junction or the upper two cervical vertebrae. Flexion and extension studies of this area are of major importance in demonstrating the injury and locating potentially occult lesions for the forensic pathologist. INDEX TERMS: Atlas and Axis, dislocations. Automobiles, accidents. Head, wounds and injuries • Neck, wounds and injuries. Pneumocephalus • Skull, wounds and injuries • Spine, wounds and injuries

Radiology 114:611-617, March 1975 OR A NUMBER of years, the Departments of Radiology and Forensic Pathology at our institution have cooperated closely in the examination of victims of fatal traffic accidents and other violent deaths. Most such individuals are subjected to the appropriate postmortem radiographic examination prior to autopsy in order to facilitate a preliminary assessment of pathology before dissection is begun. We wish to summarize our experience in a series of 146 consecutive postmortem radiographic examinations performed on victims of fatal traffic accidents. Only those who were pronounced dead at the scene of the accident or who died shortly after arrival at a hospital and thus were essentially untreated were included. Many were involved in single- or two-car accidents; most others were pedestrians struck by a motor vehicle, while a small number had been riding a bicycle or motorcycle.

F

Table I:

Incidence of Head and Neck Injuries

Craniocervical trauma Skull fractures only Skull and cervical injury Cervical injury only

82 (56.2%)

ia ~~~8~ ~ 21 (14.3%

}

64 (43.8%)

No eraniocervieal trauma TOTAL Table II:

61 (41. 7%) 31 (21.2%)

146 (100%) Localization of Cervical Spine Fractures and/or Dislocations

Atla nto-occi pita I

C1

8

7 10 1 1 2 2

C2 C3

C4

C5 C6 C7 TOTAL

o

n

METHODS AND MATERIAL

carried out when indicated. The chest, abdomen, pelvis, extremities, and the remainder of the spine are evaluated when this is deemed necessary on the basis of visible injuries. Craniocervical injuries were present in 82 individuals and represented the cause .ot death in most of them (TABLE I). Skull fractures were found in 51, and fractures and/or dislocations of the cervical spine were present in 21, while 10 persons had injuries to both regions. In the remaining 64 individuals without fractures of the skull or cervical spine, death was usually due to chest or abdominal injuries.

All postmortem radiographic examinations were carried out shortly after arrival of the body at the morgue and generally within a few hours after death. The routine examination of victims of traffic accidents with known or suspected craniocervical trauma now includes (a) anteroposterior, half-axial, and cross-table lateral views of the skull, with the head elevated from the surface of the radiographic table by means of a plastic block placed beneath the occiput in the latter case, and (b) anteroposterior and cross-table lateral views of the cervical spine, the latter taken with the head resting on the radiographic table. The lateral views of the head and neck thus comprise a flexion and extension study of the upper cervical spine, which is desirable because of the high incidence of unstable fractures and/or dislocations of the craniocervical area. Tomographic studies are

Head Injuries

The severity of skull wounds varied from linear frac-

1 From the Departments of Radiology (G. J. A., Y. S. 0., E. V. L., V. A. P., E. G. E.) and Pathology (J. L.) of the Edward J. Meyer Memorial Hospital, the State University of New York at Buffalo School of Medicine, Buffalo, N.Y., and the Erie County Medical Examiner's Office. Accepted for publication in October 1974. sjh

611

Fig. 1. A and B. This 21-year-old man was struck by a car while walking to get help after his car broke down on an expressway. There is massive head injury, including numerous linear, stellate, and depressed skull fractures. Note the free intracranial air over the frontal and ternporallobes.

Fig. 2. This 32-year-old man was killed instantly when struck by a car as he walked along the highway at night. There were no witnesses, and the driver of the car, who was not charged, stated that he did not see the victim until the impact. A. The lateral view shows a fracture of the clivus with upward displacement of the occipital condyles. B. Midline and right and left parasagittal polytomograms demonstrate the clivus fracture and the upward displacement of both occipital condyles, i.e., traumatic basilar invagination. There were no other skull fractures, and the entire spine was intact. ~ C. At postmortem examination, a large subgaleal hematoma was found across the vertex of the skull and traumatic basilar invagination was confirmed. There was an epidural hematoma around the foramen magnum, and the medulla oblongata was compressed. The only other findings were bruises on the posterior aspect of both thighs. On the basis of the radiographic and postmortem pathological findings. it was felt that the victim was struck from behind on the thighs and flipped up into the air, landing on the vertex of the skull and thus sustaining the fatal injury in the region of the foramen magnum. Note the circumferential fracture around the foramen magnum.

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Fig. 3. This 5·year-old boy was struck and killed instantly when he ran into the path of an automobile from between parked cars. A. Although the bilateral linear parietal skull fractures appear to be relatively insignificant, there is a large amount of air in the superior sagittal sinus (upper arrow) and the left transverse sinus (lower arrow ). B. The chest film shows a massive air embolus in the right atrium (arrows).

tures of the cranial vault or base to the type of devastat ing injuries which one might encounter in military combat (Fig. 1). In one case, a tremendous force on the vertex of the skull resulted in essentially a circumferential fracture around the foramen magnum with a consequent traumatic basilar invagination (Fig. 2), analogous to the bursting fracture of C1 which is produced in a similar manner. An indication of the severity of the skull fractures was the large number of persons (41/61) with air in the cranial cavity. Of these, 18 had subdural and/or subarachnoid air, while 23 had air in an extracerebral site as well as in the dural venous sinuses, most commonly the superior sagittal sinus (Fig. 3, A). A number of victims also had air In one or more ventricles or in the cervical spinal canal. Of those with air in a dural sinus, many had relatively simple linear fractures, most frequently involving the mastoids or the base of the skull; presumably a dural venous sinus was lacerated during the accident (Fig. 4). Victims of head injury who exhibit subdural, subarachnoid, or intraventricular air have been known to recover; however, individuals with significant intravascular air generally do not survive. Many of them also had air in the jugular veins (Fig. 5) or right heart (Fig. 3, 8), indicating that a massive air embolus was either the cause of death or a significant contributing factor. Sutural diastasis and air-fluid levels in the paranasal sinuses, most frequently the sphenoidal sinus, were also common radiological findings in head injuries. Neck Injuries

Seventeen of the 31 cervical spine injuries resulted

from flexion ; these included all of the atlanto-occipital dislocations and some of the odontoid fractures. Seven were extension injuries, most commonly " hangman's fractures" (so named because of their similarity to the hyperextension injury encountered in persons executed by hanging); this type of injury results in fracture of the pedicles of C2 and dislocation or subluxation at C2-C3. The exact mechanism of injury could not be determined in the remaining 7 cervical spine fractures, but some were thought to be caused by lateral forces . TABLE II shows the distribution of fatal fractures and dislocations of the cervical area. The overwhelming majority involved the craniocervical junction or the first or second cervical vertebra. Atlanto-occipital dislocation (Fig. 6) was encountered in 8 patients; almost all were pedestrians struck by a motor vehicle, apparently causing sudden posterior acceleration of the body in relation to the head and resulting in hyperflexion of the head on the neck. In one such case. dislocation of C2-C3 occurred as a result (Fig. 7). Rupture of the transverse and alar ligaments resulted in atlanto-axial dislocation in some cases (Fig. 8); odontoid fractures were also seen . Fractures of the second cervical vertebra were usually of the " hangman" type (Fig. 9). Injuries to the mid- and lower cervical area were very uncommon and consisted largely of dislocation of one vertebra in relation to another in either the anteroposterior or lateral direction. In almost all cases of cervical spine trauma, injuries occurred at a single level while the rest of the cervical spine remained intact. Cervical spine fractures were invariably accompanied by marked retropharyngeal soft-tissue swelling, often with associated soft-tissue emphysema (Figs. 2,

Fig. 4. This 35-year old man was killed instantly when the car he was driving collided head-on with another which was headed in the wrong direction on the New York State Thruway . A. Note the intracranial air over the frontal and temporal lobes in the supine posttion. B. The anteroposterior view also shows intravascular air in the superior sagittal sinus (upper arrow) . The linear fracture responsible for entry of the air into the head is seen in the region of the right mastoid process (arrows) .

Fig. 5. A and B. This 16-year-old boy was killed instantly when he lost control of his car on the New York State Thruway and ran off the road. Note the large amount of air in the right jugular vein (arrows) and the massive retropharyngeal hematoma. Although no fractures of the cervical spine are seen, the tip of the odontoid process is separated from the anterior lip of the foramen magnum, indicating damage to the alar ligaments .

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5, and 10). At times the origin of the retropharyngeal air was uncertain, and it was postulated that laceration of the posterior pharyngeal wall was responsible. Air was frequently seen in the cervical spinal canal; this was quite likely related to coexisting skull fracture in most instances, but in some cases neither the radiologist nor the pathologist could pinpoint the area of entry. DISCUSSION

Fig. 6. According to eyewitnesses , this 22-year-old woman wandered onto the center of an expressway and was struck by a car traveling toward her at approximately 81 km (50 miles) per hour. Note the complete anterior dislocation of the head in relation to the CI vertebra. caused by sudden posterior acceleration of the body while the head snapped forward. The medulla oblongata was transected, causing death instantaneously. Retropharyngeal air and pneumocephalus are seen.

Fig. 7. This 20-year-old woman was a passenger involved in a two-car accident. Note the complete anterior dislocation and overriding of the body of C2 in relation to C3 as the result of hyperf/exion. The upper cervical spinal cord was severed. and pneumocephaIus is present.

A search of the literature has revealed no previous report of postmortem radiographic investigation of victims of traffic accidents. Several autopsy series have been reported, with some including only vehicular occupants (1-3) and others including occupants, pedestrians, and cyclists (4-7), but none of these papers discuss the radiological findings. About 50 % of deaths occur within the first two hours after the accident (7), including those cases which conform most closely to our material. Multiple injuries are common; Sevitt (5) reports 1.44 fatal injuries per person, while Tonge et al. (7) report 5.8 injuries per person . Although severe chest injuries and multiple traumata were statistically significant, serious brain damage was the dominant factor in all series (2, 4. 7), accounting for mortality in 58 % of Sevitt's cases. These figures varied somewhat depending upon the elapsed time since the accident and whether the individual was the driver of the vehicle, an occupant, or a pedestrian. Tonge et al. (7) compared two groups studied from 1935 to 1963 and from 1963 to 1968 and noted a decrease in the number of head wounds rela-

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Fig. 8. This 23-year-old man was driving at a high rate of speed when the car went out of control and struck a lamp post. No fractures are demonstrated. but there is complete anterior dislocation of the atlas in relation to the axis, with the posterior arch of the atlas coming to rest against the odontoid process. The upper cervical spi· nal cord was severed as it ran between them.

March 1975

tive to all other injuries; however, 81 % had superficial but serious scalp, face, or ear injuries and 48% had skull fractures involving the base alone in 23.8%, the vault alone in 4.8 % , and both the vault and the base in 20.5%. Hossack (3) reported a 40% incidence of skull fractures with more than half occurring at the base, especially adjacent to and in the petrous bones. Intracranial hemorrhage was present in 61.8% of Tonge's cases, with subdural predominating over epidural hemorrhage by a ratio of 15 to 1. Alcohol was an important factor in many reported series. Loh and Williams noted that 64 % of those tested showed a significant level of blood alcohol (4). Asphyxia was of some importance in Hossack's series, in which 7 % of the victims died of aspiration (3); in Tonge's series the incidence was 4% (7). While most authorities consider ejection from the vehicle extremely important in terms of morbidity and mortality, Tonge indicated that 81 % of the victims had sustained the fatal trauma before ejection. None of these authors mention intracranial or intravascular air, a common finding in our series; perhaps this phenomenon can be documented further at the autopsy table once the pathologist is made aware of the possibility. Our figure of 21.2 % cervical spine injuries is significantly higher than those reported previously, which vary from a low of 3% in Hossack's report (3) to 15.3% in Tonge's series (7). Detection of fractures and/or dislo-

Fig. 9. A and B. This 23-year-old man was struck by a car while walking on the side of the road with a companion. He died shortly after arrival at the hospital. Note the fractures through the pedicles of the C2 vertebra and the separation of the bodies of C2 and C3. The flexion and extens ion views demonstrate the instability of the fracture very well. This type of injury, caused by sudden hyperextension of the neck, is referred to as a "hangman's fracture."

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POSTMORTEM RADIOLOGY OF HEAD AND NECK INJURIES IN FATAL TRAFFIC ACCIDENTS

cations of the upper cervical spine requires tedious and time-consuming dissection by the pathologist, which is often not feasible; however, such injuries are demonstrated with relative ease by postmortem radiographic examination, especially if flexion and extension views are routinely taken. This probably accounts for the higher incidence of neck injuries in our series, compared to those based on autopsy material alone. Among passengers and drivers, the head rests do prevent a considerable number of whiplash injuries; however, fracture dislocations are still a possibility, most notably at C5-C6. Spitz (6) noted that fracture dislocations of the cervical spine secondary to sudden and unexpected hyperextension are common in pedestrians. Our series included a significant number of hyperflexion injuries in pedestrians, most notably at the atlanta-occipital junction. Although Spitz gave no statistics, he did find a number of injuries in the atlanta-occipital joint at autopsy, often with laceration of tendons and joint capsules and separation of the cartilaginous linings. While some of these soft-tissue injuries were minor, they occurred in a vital area. Neck injuries are supposedly more common when a diagonal strap is used, whereas injuries to the head and neck of those in the front seat are more common in deceleration accidents involving impact with the dashboard and windshield. Seat belts alone would presumably reduce this group of injuries considerably. In Tonge's series, only 9 (1.9 %) of the 210 occupants for whom data were available were wearing seat belts, and all 9 died as the result of either a high-speed collision or compression of the driving compartment. Our series exhibited a remarkable incidence of atlanto-occipital and high cervical injuries, not noted by previous authors; it is very likely that the use of flexion and extension radiographs contributed to this finding. Previous authors reported an amazing preponderance of deaths among male drivers and pedestrians; Tonge et al. reported 90 % and 68 %, respectively (7), while Loh and Williams (4) gave a mortality rate of 92% among drivers. A remarkable percentage of men die of coronary artery disease while at the wheel, including 95 of 98 individuals in Bowen's series (1); however, little or no property or personal damage has been reported as the result of coronary deaths while driving.

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SUMMARY A series of 146 victims of fatal traffic accidents were subjected to postmortem radiographic examination prior to medicolegal autopsy. The radiographically demonstrable head and neck injuries were analyzed to determine the type, frequency, and probable mechanism of injury. A total of 42 % were found to have radiographically demonstrable head injuries ranging from relatively simple linear skull fractures to massive skull damage. Free intracranial or intravascular air was demonstrated in more than 60 %, a point not emphasized previously. A total of 21 % had demonstrable neck injuries. The vast majority were localized to a single level at the craniocervical junction or the upper two cervical vertebrae. Flexion and extension studies of this area are of major importance in demonstrating the injury and locating potentially occult lesions for the forensic pathologist, thus helping to establish the cause of death and the precise nature of the trauma. It is hoped that further examinations of this type will suggest areas which are particularly susceptible to injury in a given type of accident. Such investigations may well contribute to improved safety devices and awareness of appropriate safe-driving practices which will ultimately result in the reduction of traffic fatalities. Department of Radiology Edward J. Meyer Memorial Hospital 462 Grider St. Buffalo, N.Y. 14215

REFERENCES 1. Bowen DA: Deaths of drivers of automobiles due to trauma and ischaemic heart disease: a survey and assessment. Forensic Sci 2: 285-290, Aug 1973 2. Gikas PW: Mechanisms of injury in automobile crashes. Clin Neurosurg 19: 175-190, 1972 3. Hossack DW: The pattern of injuries received by 500 drivers and passengers killed in road accidents. Mad J Aust 2: 193-195, 22 Jul 1972 4. Loh WP, WiII~ms AS: Traffic deaths in Lake County Indiana: a two-year study. Med Times 96: 982-987, Oct 1968 5. Sevitt S: Fatal road accidents in Birmingham: times to death and their causes. Injury 4: 281-293, May 1973 6. Spitz WU: Essential postmortem findings in the traffic accident victim. Arch Pathol90: 451-457, Nov 1970 7. Tonge JI, O'Reilly MJJ, Davison A, et al: Traffic crash fatalities. Injury patterns and other factors. Mad J Aust 2: 5- 17, 1 Jul 1972

Postmortem radiology of head neck injuries in fatal traffic accidents.

A series of 146 victims of fatal traffic accidents were subjected to postmortem radiographic examination prior to medicolegal autopsy. A total of 42% ...
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