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Iatrogenic vertebral artery injury during anterior cervical spine surgery
The Spine Journal 5 (2005) 508–514
Iatrogenic vertebral artery injury during anterior cervical spine surgery James P. Burke, MD, PhD, Peter C. Gerszten, MD, MPH, William C. Welch, MD, FACS* Department of Neurological Surgery, University of Pittsburgh, 200 Lothrop Street, Suite B-400, Pittsburgh, PA 15213, USA Received 3 March 2004; accepted 23 November 2004
Abstract
BACKGROUND CONTEXT: Iatrogenic injury to the vertebral artery during an anterior cervical decompression is a rarely mentioned but potentially catastrophic complication. PURPOSE: This study was designed to examine the incidence and management of iatrogenic vertebral artery injury (IVAI) in a large database. STUDY DESIGN/SETTING: This was a retrospective study performed at a large teaching institution over a 7-year period (1994–2001). PATIENT SAMPLE: All anterior cervical spinal procedures performed for herniated or degenerative disc disease, or cervical spondylosis were identified, as were incidences of IVAI. Anterior cervical procedures performed for trauma, neoplasia, or infection were excluded from this study. OUTCOME MEASURES: Neurological and associated morbidity as well as mortality were recorded. METHODS: Data were accessed through an institution-wide electronic medical record search through the operative reports of 10 spine surgeons. Hospital and clinical charts of IVAI cases were subsequently reviewed. Demographic data and intraoperative strategies for repair were recorded. RESULTS: A total of 1,976 patients underwent anterior cervical spinal procedures in the review period. Six cases of IVAI were identified. In three of the six patients, arterial bleeding was controlled with hemostatic agents. Of these three, two suffered complications. The initial management of controlling arterial bleeding is by hemostatic agents; however, one must also consider repair or ligation. The remaining three patients were treated with primary repair or ligation, and no complications were noted. CONCLUSIONS: IVAI is a rare complication (0.3%) of anterior cervical procedures. The arterial bleeding can usually be controlled with topical hemostatic agents, but mortality may occur in instances where it cannot be adequately addressed in a timely fashion. 쑖 2005 Elsevier Inc. All rights reserved.
Keywords:
Vertebral artery; Anterior cervical spine; Cervical corpectomy; Anterior cervical discectomy and fusion (ACDF); Iatrogenic
Introduction The anterior approach for decompression of the cervical spinal cord and nerve roots is widely used for herniated intervertebral disc, spondylosis, trauma, tumor, and infection. Although anterior approaches to the cervical spine are associated with a lower incidence of neurologic complications [1,2], injury to the many vital structures encountered in FDA device/drug status: not applicable. Nothing of value received from a commercial entity related to this research. * Corresponding author. Department of Neurological Surgery, University of Pittsburgh, 200 Lothrop Street, Suite B-400, Pittsburgh, PA 15213. Tel.: (412) 647-0958; fax: (412) 647-0989. E-mail address: [email protected] (W.C. Welch) 1529-9430/05/$ – see front matter doi:10.1016/j.spinee.2004.11.015
쑖 2005 Elsevier Inc. All rights reserved.
the anterior approach remains a risk. Potential complications include vocal cord paralysis, dysphagia, carotid artery injury, Horner’s syndrome, esophageal perforation, and respiratory obstruction resulting from acute retropharyngeal edema or hematoma [1–7]. Despite these potential complications, anterior procedures have been successful and are popular. Additionally, most of the complications of the anterior approach do not detract from the excellent long-term clinical results [8–12]. In contrast to this, iatrogenic injury to the vertebral artery during an anterior cervical decompression can be catastrophic [13–15]. Such injuries have been acknowledged in the literature, but their incidence is rarely mentioned, except to state that it is an unusual complication [3,8,15–22]. Vertebral artery laceration is particularly grave because of the
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difficulty of controlling hemorrhage, and the uncertain neurological consequences, often resulting in significant neurological injuries [13,15,23,24]. Although vertebral artery trauma is uncommon, penetrating injuries to the neck can result in life-threatening hemorrhage. In the general surgery literature, there are good accounts of the surgical exposure of the artery and of the control of bleeding caused by penetrating neck injuries [25– 29]. However, little has been published to guide the spinal surgeon in the avoidance or intraoperative management of such an injury. While prevention of the problem is the best treatment, spine surgeons who perform anterior cervical decompressions should be prepared to manage an inadvertent laceration of the vertebral artery during the lateral extent of the decompression. The present study reviews the experience at a single institution with anterior cervical spine procedures complicated by vertebral artery injuries in terms of incidence, intraoperative strategies for repair, and postoperative outcome.
ligation; one was tamponaded with thrombin-soaked Gelfoam (Pfizer, New York, NY). In each of these cases, no neurological sequelae were noted postoperatively. The duration of postoperative follow-up was approximately 3 months. Only one postoperative cerebral angiogram was performed; this demonstrated a mild defect in the arterial wall consistent with the intraoperative packing of the vertebral artery. In the final case in which bright arterial bleeding was encountered, hemodynamic instability from hypovolemia resulted in intraoperative death. In the sixth case of vertebral artery injury, no arterial or excessive bleeding was encountered; however, thrombinsoaked Gelfoam was placed laterally to tamponade epidural oozing. Postoperatively, the patient awoke with a lateral medullary infarct, and cerebral angiography demonstrated a vertebral artery dissection with posterior inferior cerebellar artery occlusion (Fig. 1). Anticoagulation with heparin was started immediately after the diagnosis of vertebral artery dissection was made.
Methods
Discussion
We present a retrospective review of six adult patients in whom an anterior cervical spinal procedure was complicated by iatrogenic vertebral artery injury (University of Pittsburgh IRB #000565). An institution-wide electronic medical record search through the operative reports of 10 spine surgeons (seven neurosurgeons, three orthopedic surgeons) over the past 7 years (1994–2001) was conducted. All procedures were performed for herniated or degenerative disc disease, or spondylosis; procedures for trauma, neoplasia, or infection were excluded from this study. Hospital and clinical charts subsequently were reviewed. Demographic data, intraoperative strategies for repair, and postoperative outcome were recorded.
Vertebral artery injury is a serious complication of anterior spinal surgery. The possibility of severe hypotension and cardiac arrest is present. If control of blood loss is not obtained carefully, the spinal cord and nerved roots may be injured. Control of the hemorrhage may be adequate initially. However, recurrent hemorrhage or the chronic problems of arterial injury (eg, arteriovenous fistula, pseudoaneurysm, arterial thrombosis, and cerebrovascular emboli), are real possibilities [15,19,20,30]. The true incidence of iatrogenic injury to the vertebral artery during anterior decompressive surgery in the subaxial spine is unknown. In a questionnaire survey of 82,114 patients, Flynn [31] did not mention iatrogenic vertebral artery injury. Isolated reports include one by Cloward [17], in which he described a case of Wallenberg’s syndrome, resulting from thrombosis of the vertebral artery after the use of a vertebral spreader. Additionally, Cloward reported personal communications from three surgeons, each with a case of vertebral artery injury that required only tamponade [3]. Weinberg and Flom [30] reported injury to the vertebral artery during cervical discectomy, resulting in an arteriovenous fistula. Cosgrove and The´ron [19] reported two cases with “troublesome” and “difficult hemostasis,” in which delayed vertebral arteriovenous fistulae were treated endovascularly. De los Reyes et al. [20] reported the direct repair of a pseudoaneurysm that developed 3 days after a drill injury to the vertebral artery during an anterior cervical vertebrectomy. Schweighofer et al. [24] reported injury to the vertebral artery during vertebrectomy and reduction of a locked facet. In this case, the artery was ligated with clips, and no neurologic injury was observed. Smith et al. [15] reviewed a 5-year experience and reported an incidence of vertebral artery laceration of 0.5% (10 of 1,195 operations); most of these occurred during vertebrectomy for
Results Using an electronic search of medical records at our institution over the past 7 years, six adult patients were identified who suffered iatrogenic vertebral artery injury during anterior cervical spine procedures for herniated or degenerative disc disease or spondylosis. A total of 1,976 anterior cervical spine procedures were performed for these indications during this time (incidence of 0.3%); procedures for traumatic, neoplastic, and infectious processes were excluded from entry into this study. Of these six patients, one single-level and one three-level anterior cervical discectomy and fusion, and one reexploration and three primary cervical corpectomies and fusions were performed. Median patient age was 60 years; female to male ratio was 2:1. In five of six cases presented, an operating microscope was used. In all six patients with vertebral artery injury, the operation was performed from the patient’s right side (Table 1). In five cases, bright arterial bleeding was encountered: two were repaired primarily; one was treated with arterial
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Table 1 Summary of demographic, operative, and outcome data in six patients with iatrogenic vertebral artery injury during anterior cervical spine surgery Age (yr)
Sex
Operative procedure
Complication
Management
Outcome
66 53
Female Female
Left vertebral artery laceration Left vertebral artery laceration
Primary repair Ligation
No sequelae No sequelae
45
Male
Left vertebral artery laceration
Primary repair
No sequelae
62 58
Female Male
66
Female
C5-6 corpectomy, C4-7 fusion, right side approach C4-5, C5-6, C6-7 anterior cervical discectomy and fusion, right side approach Redo C4-5 corpectomy and C3-6 fusion, right side approach C6 corpectomy, right side approach C4-5-6 corpectomy, C3-7 fusion, right side approach C5-6 anterior cervical discectomy and fusion, right side approach
spinal cord decompression. Management consisted of hemostatic packing in three cases, with direct exposure and ligation of the artery in the remaining seven cases. In their study, three brainstem infarcts (from the ligated group) and one reversible cardiac arrest secondary to hemorrhage were noted. The causes that they identified were: drill was off midline; excessive width of bone and disc removal; or abnormal softening of the lateral bone, resulting either from tumor or infection. Pfeifer et al. [32] reported a case in which the vertebral artery was entered when a trough was made laterally during a C4-5 corpectomy. The artery was repaired primarily, with no postoperative neurologic sequelae. Golfinos et al. [21] reviewed an 8-year experience and reported an incidence of 0.3% (4 in 1,215 anterior approaches) of vertebral artery injury during anterior cervical discectomy or corpectomy. Three of the four arteries were repaired primarily at the time of injury; one artery was ligated. No vertebrobasilar symptoms were noted postoperatively (Table 2). In this retrospective study, we identified six anterior cervical spine procedures that were complicated by iatrogenic vertebral artery injury. This yielded an incidence of approximately 0.3% (6 of 1,976). Our results are similar to the incidence reported in other studies [15,21]. In these six patients, one intraoperative death and one vertebrobasilar stroke occurred. Two scenarios may account for iatrogenic vertebral artery injury during anterior cervical spine procedures. The first is tortuosity of the vertebral artery in which it has migrated into the vertebral body. Careful attention to the preoperative computed tomographic and magnetic resonance imaging studies may reveal dilated or tortuous vertebral artery anatomy, which can then be avoided intraoperatively. The second scenario involves asymmetric and excessive far lateral bone removal. This injury is more likely to occur on the left side during a right-sided approach. Vertebral artery injury can occur during lateral exploration of the neural foramen after anterior cervical discectomy and resection of uncovertebral joint osteophytes. The injury is usually minor and is readily controlled with small amounts of
Left vertebral artery laceration Tamponade Right vertebral artery compression Tamponade
Intraoperative death No sequelae
Left vertebral artery dissection
Posterior inferior cerebellar artery infarct, lateral medullary syndrome
Tamponade with postoperative anticoagulation
hemostatic packing. The segment of the extracranial vertebral artery that runs through the transverse foramen of the C16 vertebrae is surrounded by an extensive venous plexus. Excellent postmortem studies have described the anatomic relationships of the vertebral artery to the vertebral bodies, intervertebral foramina, and cervical roots [33,34]. The vertebral artery at the level of the disc space is usually found lateral to the midportion of the vertebral body and is normally protected during anterior cervical discectomy by the bone ridge of the uncovertebral joint. However, during removal of laterally placed osteophytes or difficult reoperations, the vertebral artery or its venous plexus may be damaged. More significant injuries can be created during cervical corpectomy if the decompression is taken too far laterally. The injuries are usually incurred when drilling is asymmetric or overly aggressive and can be avoided if the drill is not allowed to penetrate the deep bony cortex. The vertebra can be eggshelled out with the drill, leaving only a thin bony cortex to be avulsed with a fine curette or thin-footed Kerrison rongeur. Maintaining the midline orientation is key to adequate decompression of the neural structures, as well as to avoid injury to the vertebral artery. Marking the midline with the monopolar cautery or a marking pen before dissecting the longus colli, and then frequently confirming orientation by referring to the midline markings is often helpful. The medial uncovertebral joint should be a guide as to the lateral extent of any dissection or drilling. One must use caution with the dissection and drilling of pathologically softened bones from tumor or infection. The use of a measuring standard, eg, a standard 13-mm-wide cottonoid patty, is also useful to confirm orientation. Several anatomic clues to maintain the midline are the curvature of the vertebral body and thecal sac, the location of epidural veins and fat, visualization of the nerve roots, palpation of the pedicle, and the location of the sternomanubrial notch. Surgical adjuncts may be considered in selected cases of patients requiring anterior cervical approaches. The operating microscope does aid in visualization and may reduce the risk of vertebral artery and neurological structure injury.
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Fig. 1. Case 6. (A) Cerebral angiogram demonstrating dissection of the left vertebral artery (arrow). (B) Cerebral angiogram demonstrating tapered occlusion of the left vertebral artery (arrow), with no flow in left posterior inferior cerebellar artery. (C) T2-weighted magnetic resonance imaging study showing infarction and edema in the left cerebellar hemisphere and medulla (Wallenberg infarct).
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Table 2 Summary of treatment options and associated complications of study site compared with observations from other institutions
Primary author and reference number Our study site Cloward [3] Smith [15] Cosgrove [19] de los Reyes [20] Golfinos [21] Weinberg [30] Pfeifer [32]
Treatment option and incidence of complications (Number of complications/Number of subjects treated) Tamponade
Ligation
Primary repair
2/3 0/3 0/3
0/1
0/2
3/7 0/2 0/1 0/2
0/1 0/3 0/1
Interestingly, the microscope was used in five of the six cases described above. One potential shortcoming of the microscope is that surgeons tend to become highly focused on a small area and may lose their larger surgical perspective. Should the operating surgeon choose to use the microscope, we would recommend lowering the magnification on an intermittent basis and reestablishing surgical orientation. Fluoroscopy may also be used to aid in maintaining midline orientation. This adjunct is readily available in most operating rooms and might enable the surgeon to confirm or regain midline orientation in difficult cases. Intraoperative computed tomographic scans were not used in any of the six cases presented here. Intraoperative computed tomographic scanning has been used to assess the adequacy of surgical decompression during anterior cervical procedures, and it would be a logical step to use this adjunct should the surgeon have concerns about orientation [35]. Computed tomographic scanning or the use of image guidance techniques could be especially helpful in cases with severe patho-anatomic anomalies or reoperations, and this would seem to be a reasonable surgical adjunct if it is readily available. Intraoperative angiography may be an appropriate adjunct to help identify and potentially treat the bleeding source should vertebral artery injury occur. The endovascular team may be able to place a stent into the vertebral artery across the injury. Alternatively, they may be able to temporarily occlude the artery with close observation of intraoperative neurophysiological monitoring. Should temporary occlusion be tolerated, either the surgeon or the endovascular team can directly occlude the vessel. Prevention of iatrogenic vertebral artery injury remains the best treatment. However, when laceration of a vertebral artery has occurred, generous use of thrombostatic agents, along with direct pressure and suction over cotton patties should be used initially to control the bleeding. The anesthesia team should be immediately informed of the event, and blood products should be made readily available. The patient should be fluid-resuscitated and, if possible, appropriate surgical assistance should be gathered, including vascular surgery. Basic vascular principles, including proximal and distal control of the bleeding vessel, should be employed if
possible. Management options at this time include continued tamponade, microvascular repair of the injured artery, and ligation of the vertebral artery. Endovascular embolization has also been described as a postoperative adjunct [19]. When tamponade does not control the hemorrhage, a small, high-speed bone cutting tool then should be used to expose the vertebral artery proximal and distal to the injury. The artery can then be temporarily occluded and carefully repaired. For this reason, the head must be returned to the midline position to avoid kinking the contralateral artery and producing vertebrobasilar insufficiency. The therapeutic goal is the elimination of the injury with preservation of the normal flow in the patent vertebral artery, and the management of vertebral artery lacerations needs to be based on 1) controlling the hemorrhage locally, 2) preventing immediate vertebrobasilar ischemia, and 3) preventing cerebrovascular complications. Without angiography, one cannot predict in advance the risks of ischemic deficits from vertebral artery sacrifice. Therefore, one must weigh the options of vertebral artery ligation versus repair. The majority of patients tolerate unilateral vertebral ligation well [25,36–38]. A small number of patients, however, will have an isolated vertebral artery terminating in the posterior inferior cerebellar artery, an atretic, stenotic, or previously occluded vertebral artery, or inadequate collateralization of the circle of Willis. Ligation of the vertebral artery in these circumstances can result in cerebellar or brainstem infarction. Shintani and Zervas [14] found a 12% mortality rate after acute vertebral artery ligation. The anatomy of the vertebral artery in the general public should also be considered. The left vertebral artery is hypoplastic in 5.7%, and absent entirely in 1.8% of cases. On the right side, the artery is hypoplastic in 8.8%, and absent in 3.1% [39]. In an older population, the adequacy of collateral circulation is further compromised by atherosclerosis in the circle of Willis and in the posterior circulation. In an autopsy study and review of the literature, Thomas et al. [40] indicated that the predictable incidence of brainstem infarction is 3.1% of cases when the left vertebral artery is ligated, and 1.8% when the right vertebral artery is ligated. Because the status of the vertebral artery anatomy is unlikely to be known preoperatively and because the long-term consequences of even a successful vertebral artery ligation are unclear, every effort should be made to preserve arterial patency whenever possible. Prior studies also conclude that direct repair is the preferred management, when possible, with clean ligation as a second choice [15,20,21,32,41,42]. Several cases in the literature have reported delayed complications from packing the injured vessels rather than directly repairing or cleanly ligating the vessels [15,19,20]. When not possible to perform microvascular repair, exposure of the artery with ligation proximally and distally is recommended [21], because experience in the trauma population reveals a risk of delayed embolic complications, hemorrhagic complications, and a risk of fistula formation in
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those patients treated with packing or proximal ligation alone [36,43]. In patients in whom hemorrhage can only be controlled by packing, this may have to suffice, although there remains a risk of delayed hemorrhage and fistula formation [19,20]. Smith’s 3 patients treated with packing alone had no neurologic complications. However, the mean estimated blood loss was 2370 cc in these three patients [15]. Once the decision has been made to proceed with microvascular repair or ligation, the anterior bony foramen transversarium immediately beneath the laceration, as well as regions above and below, needs to be unroofed. Once proximal and distal control are obtained, the laceration can often be reapproximated. If ligation is to be performed, both proximal and distal ends of the artery are to be ligated to reduce the risk of delayed complications. The patient should be admitted to an intensive care unit postoperatively for close monitoring of neurologic function. Additionally, a confirmatory radiographic study should be performed (either magnetic resonance angiogram or conventional angiogram) to rule out arterial pathology. Further management would be based upon the etiology of the abnormality detected by these studies (consider reoperation, embolization, or anticoagulation). Anticoagulation is generally indicated when neurological deficits occur due to thromboembolic phenomena. Heparin is immediately started and then an antiplatelet agent is used for 3 months postoperatively. Anticoagulation carries some risk of local rebleeding or conversion of a recent brain infarct to a hemorrhagic infarct requiring evacuation. Consultation by a stroke neurologist would be appropriate in this setting. We would recommend postoperative angiography when feasible so as to identify the extent of the injury, and to identify any evidence of vertebral artery dissection. The collateral circulation to the brain should also be confirmed. This study may influence the extent and duration of postoperative anticoagulation.
Conclusions Iatrogenic vertebral artery injury during anterior cervical spine procedures is an infrequent, yet potentially catastrophic complication. Initial management of vertebral artery injury is immediate tamponade; either primary repair or arterial ligation may be required if this maneuver is unsuccessful. Appreciation for the local, “hidden” anatomic structures may limit the incidence of vertebral artery injury during lateral exploration of the neural foramen after discectomy and uncovertebral joint osteophytes or during the lateral decompression of a cervical corpectomy. Injuries need to be readily identified and controlled with either direct tamponade, microsurgical repair, or vessel occlusion.
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[35] Freidberg SR, Pfeifer BA, Dempsey PK, et al. Intraoperative computerized tomography scanning to assess the adequacy of decompression in anterior cervical spine surgery. J Neurosurg (Spine 1) 2001;94:8–11. [36] Golueke P, Sclafani S, Phillips T, et al. Vertebral artery injury: diagnosis and management. J Trauma 1987;27:856–65. [37] McCormick WF. Trauma. In: Resenber RN, ed. The clinical neurosciences. Vol. III. New York: Churchill Livingstone, 1983:241–4. [38] Perry MO. Injuries to the brachiocephalic vessels. In: Rutherford RB, ed. Vascular surgery, Vol. 2, 3rd ed. Philadelphia: W.B. Saunders, 1989:604–12. [39] George B, Laurian C. The vertebral artery: pathology and surgery. New York: Springer-Verlag, 1987. p. 6–17. [40] Thomas GI, Anderson KN, Hain RF, Merendino KA. The significance of anomalous vertebral-basilar artery communications in operations on the heart and great vessels: an illustrative case with review of the literature. Surgery 1959;46:747–59. [41] Stambaugh JL, Simeone FA. Vascular complications. In: Garfin SR, ed. Spine surgery and complications of spine surgery. Baltimore: Williams & Wilkins, 1989:110–26. [42] Tew JM, Mayfield FH. Complications of surgery of the anterior cervical spine: clinical neurosurgery. Baltimore: Williams & Wilkins, 1976:424–34. [43] Reid JDS, Weigelt JA. Forty-three cases of vertebral artery trauma. J Trauma 1988;28:1007–12.
COMMENTARY Gregory J. Przybylski, MD, Edison, New Jersey The authors describe the management of six patients with vertebral artery injuries sustained during anterior cervical surgery in the largest retrospective series of patients examined for this complication. There is limited publication about this complication secondary to the infrequency of this iatrogenic injury. Consequently, the authors’ analysis of the management options available can prove exceedingly helpful for the surgeon who encounters this rare intraoperative problem. Several useful recommendations for avoidance of vertebral artery injury during anterior cervical surgery were given. Review of preoperative imaging to identify anomalous or tortuous vertebral arteries, careful identification of the midline, and recognition of the lateral extent of decompression are important ways to prevent vertebral injury. Although one might assume that the illumination and magnification of an operating microscope would be a useful adjunct, the microscope was actually used in five of their six patients. In managing a patient once a vertebral artery injury occurs, the authors observed no neurological consequences in the three patients treated with direct repair or ligation, whereas two of three treated with tamponade had serious complications. Although the reader might conclude that direct repair is the preferred treatment, one of the two patients died from intraoperative hemorrhage with inadequate tamponade. Others have observed successful treatment with tamponade. Given the limited data available, it becomes difficult to recommend a particular treatment among the options of tamponade, ligation, or repair at the time of surgery. While obtaining control of bleeding with tamponade, the authors recognize the importance of communicating with
the anesthesiologist the potential need for fluid resuscitation including blood products. In addition, one should also emphasize to the anesthesia team the importance of maintaining perfusion pressure to reduce the risk of posterior circulation ischemia. Postoperative monitoring of neurological status is likewise important as delayed symptoms may arise. Postoperative imaging with magnetic resonance, computed tomographic, or conventional angiography may help guide subsequent additional treatment if a fistula or pseudoaneurysm is present. However, the management of cerebral ischemia or infarction after control of bleeding with either tamponade, ligation, or repair remains unclear. In examining the publications concerning traumatic nonpenetrating vertebral artery injury in acute cervical spine injury, anticoagulation with heparin was recommended in patients sustaining a stroke [1]. However, patients with only symptoms of ischemia could be alternatively managed with observation. Because hemorrhagic complications from heparin anticoagulation were observed, observation alone was recommended in asymptomatic patients. Although patients with iatrogenic penetrating vertebral artery injuries may respond differently, the published data remain inadequate to offer evidencebased recommendations. Reference [1] Hadley MN, Walters BC, Grabb PA, et al. Management of vertebral artery injuries after nonpenetrating cervical trauma. Neurosurgery 2002;50:S173–8. doi:10.1016/j.spinee.2005.01.001
Iatrogenic vertebral artery injury during anterior cervical spine surgery James P. Burke, MD, PhD, Peter C. Gerszten, MD, MPH, William C. Welch, MD, FACS* Department of Neurological Surgery, University of Pittsburgh, 200 Lothrop Street, Suite B-400, Pittsburgh, PA 15213, USA Received 3 March 2004; accepted 23 November 2004
Abstract
BACKGROUND CONTEXT: Iatrogenic injury to the vertebral artery during an anterior cervical decompression is a rarely mentioned but potentially catastrophic complication. PURPOSE: This study was designed to examine the incidence and management of iatrogenic vertebral artery injury (IVAI) in a large database. STUDY DESIGN/SETTING: This was a retrospective study performed at a large teaching institution over a 7-year period (1994–2001). PATIENT SAMPLE: All anterior cervical spinal procedures performed for herniated or degenerative disc disease, or cervical spondylosis were identified, as were incidences of IVAI. Anterior cervical procedures performed for trauma, neoplasia, or infection were excluded from this study. OUTCOME MEASURES: Neurological and associated morbidity as well as mortality were recorded. METHODS: Data were accessed through an institution-wide electronic medical record search through the operative reports of 10 spine surgeons. Hospital and clinical charts of IVAI cases were subsequently reviewed. Demographic data and intraoperative strategies for repair were recorded. RESULTS: A total of 1,976 patients underwent anterior cervical spinal procedures in the review period. Six cases of IVAI were identified. In three of the six patients, arterial bleeding was controlled with hemostatic agents. Of these three, two suffered complications. The initial management of controlling arterial bleeding is by hemostatic agents; however, one must also consider repair or ligation. The remaining three patients were treated with primary repair or ligation, and no complications were noted. CONCLUSIONS: IVAI is a rare complication (0.3%) of anterior cervical procedures. The arterial bleeding can usually be controlled with topical hemostatic agents, but mortality may occur in instances where it cannot be adequately addressed in a timely fashion. 쑖 2005 Elsevier Inc. All rights reserved.
Keywords:
Vertebral artery; Anterior cervical spine; Cervical corpectomy; Anterior cervical discectomy and fusion (ACDF); Iatrogenic
Introduction The anterior approach for decompression of the cervical spinal cord and nerve roots is widely used for herniated intervertebral disc, spondylosis, trauma, tumor, and infection. Although anterior approaches to the cervical spine are associated with a lower incidence of neurologic complications [1,2], injury to the many vital structures encountered in FDA device/drug status: not applicable. Nothing of value received from a commercial entity related to this research. * Corresponding author. Department of Neurological Surgery, University of Pittsburgh, 200 Lothrop Street, Suite B-400, Pittsburgh, PA 15213. Tel.: (412) 647-0958; fax: (412) 647-0989. E-mail address: [email protected] (W.C. Welch) 1529-9430/05/$ – see front matter doi:10.1016/j.spinee.2004.11.015
쑖 2005 Elsevier Inc. All rights reserved.
the anterior approach remains a risk. Potential complications include vocal cord paralysis, dysphagia, carotid artery injury, Horner’s syndrome, esophageal perforation, and respiratory obstruction resulting from acute retropharyngeal edema or hematoma [1–7]. Despite these potential complications, anterior procedures have been successful and are popular. Additionally, most of the complications of the anterior approach do not detract from the excellent long-term clinical results [8–12]. In contrast to this, iatrogenic injury to the vertebral artery during an anterior cervical decompression can be catastrophic [13–15]. Such injuries have been acknowledged in the literature, but their incidence is rarely mentioned, except to state that it is an unusual complication [3,8,15–22]. Vertebral artery laceration is particularly grave because of the
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difficulty of controlling hemorrhage, and the uncertain neurological consequences, often resulting in significant neurological injuries [13,15,23,24]. Although vertebral artery trauma is uncommon, penetrating injuries to the neck can result in life-threatening hemorrhage. In the general surgery literature, there are good accounts of the surgical exposure of the artery and of the control of bleeding caused by penetrating neck injuries [25– 29]. However, little has been published to guide the spinal surgeon in the avoidance or intraoperative management of such an injury. While prevention of the problem is the best treatment, spine surgeons who perform anterior cervical decompressions should be prepared to manage an inadvertent laceration of the vertebral artery during the lateral extent of the decompression. The present study reviews the experience at a single institution with anterior cervical spine procedures complicated by vertebral artery injuries in terms of incidence, intraoperative strategies for repair, and postoperative outcome.
ligation; one was tamponaded with thrombin-soaked Gelfoam (Pfizer, New York, NY). In each of these cases, no neurological sequelae were noted postoperatively. The duration of postoperative follow-up was approximately 3 months. Only one postoperative cerebral angiogram was performed; this demonstrated a mild defect in the arterial wall consistent with the intraoperative packing of the vertebral artery. In the final case in which bright arterial bleeding was encountered, hemodynamic instability from hypovolemia resulted in intraoperative death. In the sixth case of vertebral artery injury, no arterial or excessive bleeding was encountered; however, thrombinsoaked Gelfoam was placed laterally to tamponade epidural oozing. Postoperatively, the patient awoke with a lateral medullary infarct, and cerebral angiography demonstrated a vertebral artery dissection with posterior inferior cerebellar artery occlusion (Fig. 1). Anticoagulation with heparin was started immediately after the diagnosis of vertebral artery dissection was made.
Methods
Discussion
We present a retrospective review of six adult patients in whom an anterior cervical spinal procedure was complicated by iatrogenic vertebral artery injury (University of Pittsburgh IRB #000565). An institution-wide electronic medical record search through the operative reports of 10 spine surgeons (seven neurosurgeons, three orthopedic surgeons) over the past 7 years (1994–2001) was conducted. All procedures were performed for herniated or degenerative disc disease, or spondylosis; procedures for trauma, neoplasia, or infection were excluded from this study. Hospital and clinical charts subsequently were reviewed. Demographic data, intraoperative strategies for repair, and postoperative outcome were recorded.
Vertebral artery injury is a serious complication of anterior spinal surgery. The possibility of severe hypotension and cardiac arrest is present. If control of blood loss is not obtained carefully, the spinal cord and nerved roots may be injured. Control of the hemorrhage may be adequate initially. However, recurrent hemorrhage or the chronic problems of arterial injury (eg, arteriovenous fistula, pseudoaneurysm, arterial thrombosis, and cerebrovascular emboli), are real possibilities [15,19,20,30]. The true incidence of iatrogenic injury to the vertebral artery during anterior decompressive surgery in the subaxial spine is unknown. In a questionnaire survey of 82,114 patients, Flynn [31] did not mention iatrogenic vertebral artery injury. Isolated reports include one by Cloward [17], in which he described a case of Wallenberg’s syndrome, resulting from thrombosis of the vertebral artery after the use of a vertebral spreader. Additionally, Cloward reported personal communications from three surgeons, each with a case of vertebral artery injury that required only tamponade [3]. Weinberg and Flom [30] reported injury to the vertebral artery during cervical discectomy, resulting in an arteriovenous fistula. Cosgrove and The´ron [19] reported two cases with “troublesome” and “difficult hemostasis,” in which delayed vertebral arteriovenous fistulae were treated endovascularly. De los Reyes et al. [20] reported the direct repair of a pseudoaneurysm that developed 3 days after a drill injury to the vertebral artery during an anterior cervical vertebrectomy. Schweighofer et al. [24] reported injury to the vertebral artery during vertebrectomy and reduction of a locked facet. In this case, the artery was ligated with clips, and no neurologic injury was observed. Smith et al. [15] reviewed a 5-year experience and reported an incidence of vertebral artery laceration of 0.5% (10 of 1,195 operations); most of these occurred during vertebrectomy for
Results Using an electronic search of medical records at our institution over the past 7 years, six adult patients were identified who suffered iatrogenic vertebral artery injury during anterior cervical spine procedures for herniated or degenerative disc disease or spondylosis. A total of 1,976 anterior cervical spine procedures were performed for these indications during this time (incidence of 0.3%); procedures for traumatic, neoplastic, and infectious processes were excluded from entry into this study. Of these six patients, one single-level and one three-level anterior cervical discectomy and fusion, and one reexploration and three primary cervical corpectomies and fusions were performed. Median patient age was 60 years; female to male ratio was 2:1. In five of six cases presented, an operating microscope was used. In all six patients with vertebral artery injury, the operation was performed from the patient’s right side (Table 1). In five cases, bright arterial bleeding was encountered: two were repaired primarily; one was treated with arterial
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Table 1 Summary of demographic, operative, and outcome data in six patients with iatrogenic vertebral artery injury during anterior cervical spine surgery Age (yr)
Sex
Operative procedure
Complication
Management
Outcome
66 53
Female Female
Left vertebral artery laceration Left vertebral artery laceration
Primary repair Ligation
No sequelae No sequelae
45
Male
Left vertebral artery laceration
Primary repair
No sequelae
62 58
Female Male
66
Female
C5-6 corpectomy, C4-7 fusion, right side approach C4-5, C5-6, C6-7 anterior cervical discectomy and fusion, right side approach Redo C4-5 corpectomy and C3-6 fusion, right side approach C6 corpectomy, right side approach C4-5-6 corpectomy, C3-7 fusion, right side approach C5-6 anterior cervical discectomy and fusion, right side approach
spinal cord decompression. Management consisted of hemostatic packing in three cases, with direct exposure and ligation of the artery in the remaining seven cases. In their study, three brainstem infarcts (from the ligated group) and one reversible cardiac arrest secondary to hemorrhage were noted. The causes that they identified were: drill was off midline; excessive width of bone and disc removal; or abnormal softening of the lateral bone, resulting either from tumor or infection. Pfeifer et al. [32] reported a case in which the vertebral artery was entered when a trough was made laterally during a C4-5 corpectomy. The artery was repaired primarily, with no postoperative neurologic sequelae. Golfinos et al. [21] reviewed an 8-year experience and reported an incidence of 0.3% (4 in 1,215 anterior approaches) of vertebral artery injury during anterior cervical discectomy or corpectomy. Three of the four arteries were repaired primarily at the time of injury; one artery was ligated. No vertebrobasilar symptoms were noted postoperatively (Table 2). In this retrospective study, we identified six anterior cervical spine procedures that were complicated by iatrogenic vertebral artery injury. This yielded an incidence of approximately 0.3% (6 of 1,976). Our results are similar to the incidence reported in other studies [15,21]. In these six patients, one intraoperative death and one vertebrobasilar stroke occurred. Two scenarios may account for iatrogenic vertebral artery injury during anterior cervical spine procedures. The first is tortuosity of the vertebral artery in which it has migrated into the vertebral body. Careful attention to the preoperative computed tomographic and magnetic resonance imaging studies may reveal dilated or tortuous vertebral artery anatomy, which can then be avoided intraoperatively. The second scenario involves asymmetric and excessive far lateral bone removal. This injury is more likely to occur on the left side during a right-sided approach. Vertebral artery injury can occur during lateral exploration of the neural foramen after anterior cervical discectomy and resection of uncovertebral joint osteophytes. The injury is usually minor and is readily controlled with small amounts of
Left vertebral artery laceration Tamponade Right vertebral artery compression Tamponade
Intraoperative death No sequelae
Left vertebral artery dissection
Posterior inferior cerebellar artery infarct, lateral medullary syndrome
Tamponade with postoperative anticoagulation
hemostatic packing. The segment of the extracranial vertebral artery that runs through the transverse foramen of the C16 vertebrae is surrounded by an extensive venous plexus. Excellent postmortem studies have described the anatomic relationships of the vertebral artery to the vertebral bodies, intervertebral foramina, and cervical roots [33,34]. The vertebral artery at the level of the disc space is usually found lateral to the midportion of the vertebral body and is normally protected during anterior cervical discectomy by the bone ridge of the uncovertebral joint. However, during removal of laterally placed osteophytes or difficult reoperations, the vertebral artery or its venous plexus may be damaged. More significant injuries can be created during cervical corpectomy if the decompression is taken too far laterally. The injuries are usually incurred when drilling is asymmetric or overly aggressive and can be avoided if the drill is not allowed to penetrate the deep bony cortex. The vertebra can be eggshelled out with the drill, leaving only a thin bony cortex to be avulsed with a fine curette or thin-footed Kerrison rongeur. Maintaining the midline orientation is key to adequate decompression of the neural structures, as well as to avoid injury to the vertebral artery. Marking the midline with the monopolar cautery or a marking pen before dissecting the longus colli, and then frequently confirming orientation by referring to the midline markings is often helpful. The medial uncovertebral joint should be a guide as to the lateral extent of any dissection or drilling. One must use caution with the dissection and drilling of pathologically softened bones from tumor or infection. The use of a measuring standard, eg, a standard 13-mm-wide cottonoid patty, is also useful to confirm orientation. Several anatomic clues to maintain the midline are the curvature of the vertebral body and thecal sac, the location of epidural veins and fat, visualization of the nerve roots, palpation of the pedicle, and the location of the sternomanubrial notch. Surgical adjuncts may be considered in selected cases of patients requiring anterior cervical approaches. The operating microscope does aid in visualization and may reduce the risk of vertebral artery and neurological structure injury.
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Fig. 1. Case 6. (A) Cerebral angiogram demonstrating dissection of the left vertebral artery (arrow). (B) Cerebral angiogram demonstrating tapered occlusion of the left vertebral artery (arrow), with no flow in left posterior inferior cerebellar artery. (C) T2-weighted magnetic resonance imaging study showing infarction and edema in the left cerebellar hemisphere and medulla (Wallenberg infarct).
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Table 2 Summary of treatment options and associated complications of study site compared with observations from other institutions
Primary author and reference number Our study site Cloward [3] Smith [15] Cosgrove [19] de los Reyes [20] Golfinos [21] Weinberg [30] Pfeifer [32]
Treatment option and incidence of complications (Number of complications/Number of subjects treated) Tamponade
Ligation
Primary repair
2/3 0/3 0/3
0/1
0/2
3/7 0/2 0/1 0/2
0/1 0/3 0/1
Interestingly, the microscope was used in five of the six cases described above. One potential shortcoming of the microscope is that surgeons tend to become highly focused on a small area and may lose their larger surgical perspective. Should the operating surgeon choose to use the microscope, we would recommend lowering the magnification on an intermittent basis and reestablishing surgical orientation. Fluoroscopy may also be used to aid in maintaining midline orientation. This adjunct is readily available in most operating rooms and might enable the surgeon to confirm or regain midline orientation in difficult cases. Intraoperative computed tomographic scans were not used in any of the six cases presented here. Intraoperative computed tomographic scanning has been used to assess the adequacy of surgical decompression during anterior cervical procedures, and it would be a logical step to use this adjunct should the surgeon have concerns about orientation [35]. Computed tomographic scanning or the use of image guidance techniques could be especially helpful in cases with severe patho-anatomic anomalies or reoperations, and this would seem to be a reasonable surgical adjunct if it is readily available. Intraoperative angiography may be an appropriate adjunct to help identify and potentially treat the bleeding source should vertebral artery injury occur. The endovascular team may be able to place a stent into the vertebral artery across the injury. Alternatively, they may be able to temporarily occlude the artery with close observation of intraoperative neurophysiological monitoring. Should temporary occlusion be tolerated, either the surgeon or the endovascular team can directly occlude the vessel. Prevention of iatrogenic vertebral artery injury remains the best treatment. However, when laceration of a vertebral artery has occurred, generous use of thrombostatic agents, along with direct pressure and suction over cotton patties should be used initially to control the bleeding. The anesthesia team should be immediately informed of the event, and blood products should be made readily available. The patient should be fluid-resuscitated and, if possible, appropriate surgical assistance should be gathered, including vascular surgery. Basic vascular principles, including proximal and distal control of the bleeding vessel, should be employed if
possible. Management options at this time include continued tamponade, microvascular repair of the injured artery, and ligation of the vertebral artery. Endovascular embolization has also been described as a postoperative adjunct [19]. When tamponade does not control the hemorrhage, a small, high-speed bone cutting tool then should be used to expose the vertebral artery proximal and distal to the injury. The artery can then be temporarily occluded and carefully repaired. For this reason, the head must be returned to the midline position to avoid kinking the contralateral artery and producing vertebrobasilar insufficiency. The therapeutic goal is the elimination of the injury with preservation of the normal flow in the patent vertebral artery, and the management of vertebral artery lacerations needs to be based on 1) controlling the hemorrhage locally, 2) preventing immediate vertebrobasilar ischemia, and 3) preventing cerebrovascular complications. Without angiography, one cannot predict in advance the risks of ischemic deficits from vertebral artery sacrifice. Therefore, one must weigh the options of vertebral artery ligation versus repair. The majority of patients tolerate unilateral vertebral ligation well [25,36–38]. A small number of patients, however, will have an isolated vertebral artery terminating in the posterior inferior cerebellar artery, an atretic, stenotic, or previously occluded vertebral artery, or inadequate collateralization of the circle of Willis. Ligation of the vertebral artery in these circumstances can result in cerebellar or brainstem infarction. Shintani and Zervas [14] found a 12% mortality rate after acute vertebral artery ligation. The anatomy of the vertebral artery in the general public should also be considered. The left vertebral artery is hypoplastic in 5.7%, and absent entirely in 1.8% of cases. On the right side, the artery is hypoplastic in 8.8%, and absent in 3.1% [39]. In an older population, the adequacy of collateral circulation is further compromised by atherosclerosis in the circle of Willis and in the posterior circulation. In an autopsy study and review of the literature, Thomas et al. [40] indicated that the predictable incidence of brainstem infarction is 3.1% of cases when the left vertebral artery is ligated, and 1.8% when the right vertebral artery is ligated. Because the status of the vertebral artery anatomy is unlikely to be known preoperatively and because the long-term consequences of even a successful vertebral artery ligation are unclear, every effort should be made to preserve arterial patency whenever possible. Prior studies also conclude that direct repair is the preferred management, when possible, with clean ligation as a second choice [15,20,21,32,41,42]. Several cases in the literature have reported delayed complications from packing the injured vessels rather than directly repairing or cleanly ligating the vessels [15,19,20]. When not possible to perform microvascular repair, exposure of the artery with ligation proximally and distally is recommended [21], because experience in the trauma population reveals a risk of delayed embolic complications, hemorrhagic complications, and a risk of fistula formation in
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those patients treated with packing or proximal ligation alone [36,43]. In patients in whom hemorrhage can only be controlled by packing, this may have to suffice, although there remains a risk of delayed hemorrhage and fistula formation [19,20]. Smith’s 3 patients treated with packing alone had no neurologic complications. However, the mean estimated blood loss was 2370 cc in these three patients [15]. Once the decision has been made to proceed with microvascular repair or ligation, the anterior bony foramen transversarium immediately beneath the laceration, as well as regions above and below, needs to be unroofed. Once proximal and distal control are obtained, the laceration can often be reapproximated. If ligation is to be performed, both proximal and distal ends of the artery are to be ligated to reduce the risk of delayed complications. The patient should be admitted to an intensive care unit postoperatively for close monitoring of neurologic function. Additionally, a confirmatory radiographic study should be performed (either magnetic resonance angiogram or conventional angiogram) to rule out arterial pathology. Further management would be based upon the etiology of the abnormality detected by these studies (consider reoperation, embolization, or anticoagulation). Anticoagulation is generally indicated when neurological deficits occur due to thromboembolic phenomena. Heparin is immediately started and then an antiplatelet agent is used for 3 months postoperatively. Anticoagulation carries some risk of local rebleeding or conversion of a recent brain infarct to a hemorrhagic infarct requiring evacuation. Consultation by a stroke neurologist would be appropriate in this setting. We would recommend postoperative angiography when feasible so as to identify the extent of the injury, and to identify any evidence of vertebral artery dissection. The collateral circulation to the brain should also be confirmed. This study may influence the extent and duration of postoperative anticoagulation.
Conclusions Iatrogenic vertebral artery injury during anterior cervical spine procedures is an infrequent, yet potentially catastrophic complication. Initial management of vertebral artery injury is immediate tamponade; either primary repair or arterial ligation may be required if this maneuver is unsuccessful. Appreciation for the local, “hidden” anatomic structures may limit the incidence of vertebral artery injury during lateral exploration of the neural foramen after discectomy and uncovertebral joint osteophytes or during the lateral decompression of a cervical corpectomy. Injuries need to be readily identified and controlled with either direct tamponade, microsurgical repair, or vessel occlusion.
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COMMENTARY Gregory J. Przybylski, MD, Edison, New Jersey The authors describe the management of six patients with vertebral artery injuries sustained during anterior cervical surgery in the largest retrospective series of patients examined for this complication. There is limited publication about this complication secondary to the infrequency of this iatrogenic injury. Consequently, the authors’ analysis of the management options available can prove exceedingly helpful for the surgeon who encounters this rare intraoperative problem. Several useful recommendations for avoidance of vertebral artery injury during anterior cervical surgery were given. Review of preoperative imaging to identify anomalous or tortuous vertebral arteries, careful identification of the midline, and recognition of the lateral extent of decompression are important ways to prevent vertebral injury. Although one might assume that the illumination and magnification of an operating microscope would be a useful adjunct, the microscope was actually used in five of their six patients. In managing a patient once a vertebral artery injury occurs, the authors observed no neurological consequences in the three patients treated with direct repair or ligation, whereas two of three treated with tamponade had serious complications. Although the reader might conclude that direct repair is the preferred treatment, one of the two patients died from intraoperative hemorrhage with inadequate tamponade. Others have observed successful treatment with tamponade. Given the limited data available, it becomes difficult to recommend a particular treatment among the options of tamponade, ligation, or repair at the time of surgery. While obtaining control of bleeding with tamponade, the authors recognize the importance of communicating with
the anesthesiologist the potential need for fluid resuscitation including blood products. In addition, one should also emphasize to the anesthesia team the importance of maintaining perfusion pressure to reduce the risk of posterior circulation ischemia. Postoperative monitoring of neurological status is likewise important as delayed symptoms may arise. Postoperative imaging with magnetic resonance, computed tomographic, or conventional angiography may help guide subsequent additional treatment if a fistula or pseudoaneurysm is present. However, the management of cerebral ischemia or infarction after control of bleeding with either tamponade, ligation, or repair remains unclear. In examining the publications concerning traumatic nonpenetrating vertebral artery injury in acute cervical spine injury, anticoagulation with heparin was recommended in patients sustaining a stroke [1]. However, patients with only symptoms of ischemia could be alternatively managed with observation. Because hemorrhagic complications from heparin anticoagulation were observed, observation alone was recommended in asymptomatic patients. Although patients with iatrogenic penetrating vertebral artery injuries may respond differently, the published data remain inadequate to offer evidencebased recommendations. Reference [1] Hadley MN, Walters BC, Grabb PA, et al. Management of vertebral artery injuries after nonpenetrating cervical trauma. Neurosurgery 2002;50:S173–8. doi:10.1016/j.spinee.2005.01.001