Outline

TWENTY-SIX PATIENTS WITH blunt trauma of the cervical spine, producing a subluxation from a “locked” or “perched” facet, facet destruction with evidence of instability, or a fracture involving the foramen transversarium, underwent preoperative vertebral angiography to determine the incidence of vertebral artery injury. The cervical spine injury in all the patients was deemed unstable and in need of surgical stabilization. Spinal cord injury was present in one-half of the patients studied. Vertebral artery injury was identified angiographically in 12 patients (46%). Occlusion of the vertebral artery near its origin or at the level of the spinal injury was identified in nine patients. An intimal flap, arterial dissection, and a pseudoaneurysm were identified in the remaining three patients. The injury involved the left vertebral artery in all but three patients. In none of the patients did the vertebral artery injury clearly result in neurological dysfunction or other sequelae. After cervical spine fracture or dislocation, vertebral artery injury is more prevalent than commonly believed. The possibility of vertebral artery injury should be considered during the establishment of clinical management schemes for blunt trauma of the cervical spine.

The vertebral artery is particularly prone to injury from cervical spine trauma because of the intimate relationship of its second segment to the bony structures of the spine. The second segment is the portion of the artery that courses through the foramina transversaria from C6 to C1. Fractures involving the lateral masses, especially fractures into the foramen transversarium, may damage the artery within its bony confines. Likewise, subluxations of one vertebral body upon another may exert undue tension and traction on the artery.

Although numerous authors refer to this predisposition of the vertebral artery to injury and numerous isolated case reports describe its occurrence, there is but one clinical series documenting the incidence of vertebral artery injury in nonpenetrating cervical spine trauma (16). To further define the incidence of angiographically evident injury to the vertebral artery after trauma, a prospective clinical study of consecutive patients is presented.

In the 21-month period from July 1989 to March 1991, all adult patients admitted to the University of New Mexico and the New Mexico Regional Federal Medical Centers for acute fracture or dislocation of the midcervical spine were considered for angiographic evaluation as part of a prospective study to determine the incidence of vertebral artery injury.

The criteria for angiography were as follows: 1) age over 16 years; 2) admission or transfer to the participating hospitals within 48 hours of injury; 3) injury to the cervical spine with radiographically evident facet dislocation or lateral mass fracture involving the foramen transversarium; and 4) spinal injury occurring at or below the C2 vertebra or at or above the C6 vertebra. Patients were excluded if they refused angiography, were allergic to iodinated contrast agents, or had cervical spine injuries of insufficient severity to warrant surgical stabilization, such as minor ligamentous sprains or nondisplaced and simple posterior element fractures. Thirty consecutive patients met eligibility requirements during the time frame of the study. Four patients refused angiography and were excluded from the study, leaving a total of 26 eligible patients who were evaluated angiographically.

In all patients, angiography was performed preoperatively, using the traditional Seldinger technique with ioxaglatemeglumine (39.3%)-ioxaglate sodium (19.6%) (Hexabrix, Mallinckrodt Medical, St. Louis, MO), a “low-ionic” contrast agent. Five vertebral angiograms were performed in association with aortic arch angiography obtained to rule out intrathoracic aortic injury. In 20 of the 26 patients, angiography was performed within 72 hours of trauma.

Vertebral artery injury was strictly defined as angiographically proven occlusion, dissection, pseudoaneurysm, intimal flap, or arteriovenous fistula involving the first or second portion of the vertebral artery. The presence or absence of vertebral artery injury was compared with hypotension requiring resuscitation within the first 24 hours after injury, the interval from injury until arteriography, spinal cord injury, subluxation of the cervical vertebrae of more than 1 cm, a fracture involving the foramen transversarium, and a comminuted fracture into the foramen transversarium with bone fragments encroaching into the foraminal canal. Statistical significance was determined by [chi]² analysis. Patients were monitored until discharge for signs and symptoms of vertebrobasilar circulation events or for a deterioration in spinal cord function.

The patient population included 15 male and 11 female patients, with a median age of 28 years (17–76 yr). Injuries were secondary to automobile accidents in 20 patients and to assaults, sports-related injuries, and falls in 2 patients each (Table 1).

Isolated cervical spine injuries or those associated with minor injuries elsewhere occurred in 19 patients (73%). The remaining seven patients (27%) sustained multiple and severe injuries, including pelvic and extremity fractures, pneumothoraces, and intra-abdominal hemorrhage. Three patients had associated head injuries (Table 1).

Ligamentous disruption without bony fracture causing subluxation occurred in six patients. Twenty patients had bony fractures involving either the anterior body, lateral mass, or posterior elements, with or without associated subluxation. Fractures involving the foramen transversarium were observed in 17 of these patients; 6 had bone fragments displaced into the foraminal canal. The C5 or C6 vertebra was the site most often injured. This area was affected in more than 60% of the injuries.

Thirteen patients (50%) suffered no spinal cord injury, although two experienced a transient radiculopathy related to the cervical spine fracture or subluxation. The remaining one-half of the patients sustained significant spinal cord injury. A complete cervical cord injury occurred in eight patients, and five patients sustained incomplete injury (Table 1).

Angiographic abnormalities were observed in 16 patients (62%). Four patients had angiographic abnormalities that did not clearly represent arterial injury. These findings included arterial stretching and/or mild vasospasm (three patients) and vascular blush in and adjacent to a fractured vertebral body (one patient).

Arterial injury, as strictly defined in this study, was observed in 12 patients (46%). Findings included occlusion of the vertebral artery (nine patients), pseudoaneurysm (one patient), intimal flap (one patient), and arterial dissection (one patient). Illustrative cases are depicted in Figures 1, 2, 3, 4. Injury to the left vertebral artery occurred in nine patients, and to the right in three patients. No cases of bilateral arterial injury were observed.

Therapy was not altered by the angiographic findings in the nine patients with vertebral artery occlusion. However, therapy was altered in the three patients with arterial injury without occlusion. The patient with the pseudoaneurysm was treated intravenously with low doses of heparin for 7 days. A second vertebral angiogram 7 days after the first revealed slight interval enlargement of the aneurysm. The heparin was discontinued, and aspirin therapy was begun (5 grains twice daily). A third angiogram 6 weeks later showed that the aneurysm had disappeared; only a small irregularity of the vessel wall persisted at the site of the previous aneurysmal defect.

The patient with vertebral artery dissection (Fig. 4A) began receiving heparin intravenously. A follow-up angiogram 2 days later revealed occlusion of the artery just above its origin (Fig. 4B and C). The heparin was discontinued, and the patient later underwent surgical fusion of his unstable cervical spine without adverse sequelae.

The patient with a nondissecting intimal disruption (Fig. 3) was similarly treated intravenously with low doses of heparin. A vertebral angiogram 10 days later revealed interval healing of the defect.

It is difficult to attribute neurological deficits in the patients sustaining brain or spinal cord injury to the vertebral artery injuries. In no patients were spinal cord deficits found higher than one spinal level above the bony injury or subluxation. In the single case of acute mortality (Patient 6), an occluded vertebral artery was found during aortic arch arteriography in a deeply comatose automobile accident victim with severe multiorgan injuries. Although the trauma was sufficient to cause severe intracranial damage, the possibility of brain stem ischemia as a result of the patient's vertebral artery injury cannot be dismissed. Because the patient was hemodynamically unstable, selective vertebral injections for intracranial examination of the vertebrobasilar system were not feasible. The patient died from cardiovascular collapse 36 hours after admission; an autopsy was not obtained.

Various factors were examined to determine their value in predicting the presence of vertebral artery injury. A spinal cord injury, hypotension requiring resuscitation within the first 24 hours of injury, an interval of more than 72 hours from injury until arteriography, anatomic malalignment at the time of arteriography, subluxation of the cervical vertebrae of more than 1 cm, and a fracture involving the foramen transversarium did not have a statistical relationship to the presence of vertebral artery injury. Only bone fragments in the foraminal canal (i.e., a comminuted fracture of the foramen transversarium) has a high predictive value (P < 0.05). Six patients had comminuted foramen transversarium fractures; all but one of these sustained vertebral artery injury.

There were no angiography-related complications. Two patients died during the study period (8%). An obese patient with severe abdominal, thoracic, brain, and spinal cord injuries died 36 hours after being injured (Patient 6; Table 1). The second death occurred in an elderly man who suffered a complete myelopathy at the C3 level. He died 1 month after injury of sepsis and pulmonary failure (Patient 11; Table 1).

The literature is replete with isolated case reports of trauma to the vertebral artery. Vertebral artery injury has been reported as the result of penetrating wounds, such as knife, shrapnel, or gunshot wounds (11,25,27), blunt injury of the head (9,17), birth trauma (38), sports (12,14), yoga (12), and various other “physiological” forceful movements or sustained rotation or hyperextension of the neck (7,14,21,32). Iatrogenic injuries to the vertebral arteries have also been reported (1,4). Vertebrobasilar ischemia after chiropractic manipulation of the cervical spine is well described (14,18,26,29).

Vertebral artery injury after cervical spine fracture or dislocation is not thought to be commonplace, although its occurrence has been described in several anecdotal case reports (5,15,31–34). Parent et al. (22) recently reported an association between vertebral artery injury and lateral cervical spine dislocation. Of their retrospective review of 640 patients with cervical spine fractures, they reported 5 patients with lateral dislocation of the cervical spine who had injuries of the vertebral arteries. Three of these patients presented with or developed symptoms of vertebrobasilar ischemia, which led to the diagnosis of vertebral artery injury based on angiographic or postmortem findings.

In our 26 patients with cervical spine trauma studied prospectively with preoperative vertebral arteriography, significant vertebral artery injury was found in almost one-half of the patients. Vessel occlusion was our most common finding. Other findings included intimal disruption, arterial dissection, and pseudoaneurysm formation.

Only Louw and colleagues (16) have previously studied prospective, consecutive patients to assess the incidence of vertebral artery injury. Using digital subtraction angiography, they documented vertebral artery occlusion in 9 of 12 consecutive patients with cervical spine facet dislocation. In their study, vertebral artery injury after blunt trauma to the cervical spine was the rule rather than the exception.

Two recent necropsy series support our results as well as those of Louw et al. Using postmortem angiography and pathoanatomic examination, Saternus and Burtscheidt (28) investigated the vertebral arteries of 63 patients with fatal cervical spine injuries, 27 dying from falls or automobile accidents and 36 from suicidal hanging. They documented vessel rupture, intimal disruption, or subintimal bleeding in 37% of their cases (28). Hinz and Tamaska (13) in a similar postmortem angiographic study of fatal motor vehicle accidents found 5 cases of traumatic vertebral artery lesions among 31 cervical spine “whiplash” injuries.

The initial injury to the artery most likely involves intimal disruption, either through excessive distraction and stretching of the artery between two adjacent foramina transversaria (as observed in facet dislocation) or through direct trauma to the vessel wall (as observed in fractures involving the articulating facets or the foramen transversarium). The primary intimal disruption may then lead to a number of secondary events. Thrombus formation at the site of intimal disruption may precipitate thrombotic occlusion of the artery or, worse, may shower the vertebrobasilar circulation with emboli. Subintimal dissection may result from intimal injury, which in turn may lead to thromboembolism or vessel occlusion. Similarly, pseudoaneurysm formation may occur, which presents a risk of rupture and hemorrhage (especially intraoperatively) or of cerebral embolism.

Intramural hematoma may also play a role in the evolution of thrombosis. Two of our patients without clear evidence of vertebral artery injury but with angiographic abnormalities described as “vasospasm” near the site of injury may have had such a hematoma in the vessel wall. Because of the questionable clinical significance of this finding, these patients were not defined in this study as having vertebral artery injuries.

Although none of our patients suffered neurological insults that were clearly the result of their vertebral artery injuries, numerous reports in the literature describe vertebrobasilar circulation ischemia after blunt trauma to the cervical spine (3,15,24,32). Perhaps the first description of this phenomenon was by Suechting and French in 1955 (34). In this report, a 29-year-old man developed a posterior inferior cerebellar artery syndrome several days after a C5 vertebra fracture subluxation. Carpenter (5) was the first to confirm by autopsy the presence of vertebral artery thrombosis and cerebellar infarction after cervical spine trauma. Similar to Patient 1 in our series, the left vertebral artery in his patient was occluded beginning at its second segment, although the bony fracture involved the right lateral masses of C6 and C7. Schwarz et al. (31) and Parent et al. (22) have documented four and three cases, respectively, of vertebrobasilar insufficiency caused by blunt trauma of the cervical spine.

It is emphasized that the neurological deficit associated with “severe, closed-head injury,” with accompanying cervical spine fracture or dislocation, may, in part, be related to vertebrobasilar ischemia from an unrecognized vertebral artery injury (30,31). Similarly, the possibility that many cases of spinal cord injury without significant or radiographically apparent vertebral column injury are attributable to unrecognized vertebral artery injury cannot be dismissed. Spinal cord ischemia from the loss of small but vital segmental spinal arteries or the anterior spinal artery may accompany vertebral artery occlusion.

Vertebral artery occlusion does not appear to pose undue risk, providing the opposite vertebral artery fills the intracranial portion of the occluded vessel. Propagation of the thrombus into the distal segment of the vertebral artery or basilar artery apparently is rare. However, should a congenital variant exist, such as one vertebral artery ending in the posterior inferior cerebellar artery, occlusion of either vertebral artery may result in posterior circulation ischemia. Hence, if collateral flow is adequate, an occlusion will most likely be asymptomatic and intervention is rarely required. But if the collateral flow is inadequate, an occlusion may present itself as an acute brain stem or cerebellar infarction.

Perhaps more problematic is the injured vertebral artery that has not occluded. Intimal flap formation, arterial dissection, and pseudoaneurysm formation are the injuries that place the patient at further risk for delayed neurological deterioration and, as such, are the injuries for which intervention may be necessary. The treatment of “nonocclusion” arterial injuries is clinically unproven and controversial. Most information comes from studies of carotid artery trauma. For intimal disruption, some form of antiplatelet or anticoagulation therapy is generally recommended (8,36). However, anticoagulation in the trauma patient poses significant risks. Surgical ligation and endovascular balloon occlusion of the patent but injured artery are alternative therapies, especially in patients with severe, vertebral arterial injuries or symptoms of vertebrobasilar embolism (2,19,27,37). Direct surgical repair, although rarely necessary in the vertebral artery, has also been described (6,26). Thromboembolectomy, either by direct surgical or endovascular techniques, is fraught with hazards and is generally not advised. Newer thrombolytic therapies, such as intra-arterial recombinant tissue plasminogen activator, remain highly experimental and, as yet, clinically unproven (10).

Because angiography remains the “gold standard” mode of investigation, we elected to study the patients in this series with angiography exclusively to define carefully the incidence of vertebral artery injury. Because of the small but finite risk in vertebral angiography, other diagnostic modalities should be investigated, such as magnetic resonance imaging (23,35) and duplex sonography (20). Although these modalities may suffice to document the presence or absence of vessel occlusion or severe injury, they do not have the resolution to identify small but potentially harmful intimal tears.

In this prospectively studied series of 26 consecutive patients with traumatic midcervical spine subluxation or fracture into the foramen transversarium, almost one-half sustained an injury to the vertebral artery. In three patients, knowledge of the injury altered the planned therapy, thus avoiding a potential catastrophic event. Because of the potential for injury to the vertebral artery in the setting of cervical spine trauma, vertebral angiography should be considered before surgical reduction and stabilization in patients sustaining significant subluxation (more than 1 cm) or fracture involving the lateral masses or foramen transversarium. More compelling indications for angiography exist when a comminuted fracture of the foramen transversarium is present.

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This article shows the value of a defined prospective study of an important clinical problem. The authors have determined the incidence of vertebral artery injury in cervical spine injury from C2 to C6. Of the 26 patients included in the study, the vertebral artery was injured in 12 patients (46%). This is a much higher incidence than was previously suspected, although it is in keeping with the results of another recent prospective study referred to by the authors. Willis et al. show that carefully designed and well-documented prospective studies can provide new insights into clinical problems.

Of the 12 vertebral artery lesions documented, 9 were complete occlusions, and there was one each of an intimal flap, arterial dissection, and pseudoaneurysm. The authors have provided useful information about the management of these lesions.

Surprisingly, in their cases, there was no documented deterioration in neurological function resulting from vertebral artery injury, neither intracranially nor with respect to spinal cord injury. In other cases in other articles, injury to the vertebral artery was often accompanied by neurological deterioration, presumably the result mainly of thromboembolic events.

Greater awareness of the very high frequency of vertebral artery injury accompanying cervical spine injury should lead to improvement in the management of these cases.

Charles H. Tator

Toronto, Ontario, Canada

Willis et al. report a 46% incidence of vertebral artery injury in patients with cervical spine injuries, primarily in patients with subluxation from locked (perched) facets or fractures of the foramen transversarium. Once the diagnosis was made, therapy consisting of low or routine doses of heparin was instituted in three patients, depending on the circumstances. How much this treatment affected the ultimate outcome, of course, is conjectural. It is of interest to note that the left vertebral artery was involved three times as frequently as the right. Is there, perhaps, an anatomical predisposition to injury on the left side?

I have some concerns about the authors stating that the cervical spine injury in all their patients was unstable and needed surgical stabilization. I am unaware of any documentation supporting that all unilateral facets without subluxation are unstable (Patients 3 and 17) or that all patients with a lateral mass fracture without subluxation are unstable (Patients 9, 21, and 25).

In summary, this report emphasizes, as we also have found (1), that the vertebral artery is at high risk in cervical spine injuries, specifically with facet injury and subluxation or fractures of the foramen transversarium. It is hoped, as more clinical material such as that presented here is collected, that more definitive treatment modalities, if clinically indicated, will also be reported.

Volker K. H. Sonntag

Phoenix, Arizona

1. Marano S, Sonntag VKH: Vertebral artery trauma secondary to fractures and fractured dislocation of the cervical spine. Presented at the 12th Annual meeting of the Cervical Spine Research Society, December, 1984. [Context Link]

KEY WORDS: Arterial dissection; Arteriography; Spinal injury; Stroke; Vertebral artery