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DOI:10.2214/AJR.04.1541
AJR 2007; 188:1218-1221
© American Roentgen Ray Society

Case Report

Complications of Cervical Selective Nerve Root Blocks Performed with Fluoroscopic Guidance

Marc A. Wallace1, Melanie B. Fukui1, Robert L. Williams1, Andrew Ku1 and Parviz Baghai2

1 Department of Radiology, Allegheny General Hospital, 320 E North Ave., Pittsburgh, PA 15212.
2 Department of Neurosurgery, Allegheny General Hospital, Pittsburgh, PA.

Received September 30, 2004; accepted after revision July 7, 2005.

 
Address correspondence to M. A. Wallace (marcawallace{at}comcast.net).

Keywords: CT • fluoroscopy • head and neck imaging • neonatal imaging • spine


Introduction
Top
 Introduction
Case Reports
 Discussion
 References
 
Cervical nerve root blocks have been performed since the late 19th century [1], and the use of the procedure has been increasing over the past decade [2]. Cervical nerve root blocks are used to manage or treat spinal pain, radiculopathy, and complex regional pain syndromes. Many such blocks are performed in outpatient clinics with and without imaging guidance such as fluoroscopy or CT. If imaging guidance is not used, palpable anatomic landmarks are generally used to direct needle placement.

Various complications associated with the nerve block procedure have previously been described [3-7]. The most serious reported complications include death, stroke, arrhythmias, sensory or motor loss, meningitis, bleeding, and seizures. To our knowledge, arterial dissection has not previously been reported after a cervical selective nerve root block (SNRB). Our purpose is to present two cases that show potentially devastating outcomes when a cervical SNRB is performed using fluoroscopic guidance and to evaluate possible alternative methods currently available.


Case Reports
Top
 Introduction
 Case Reports
Discussion
 References
 
Case 1
A 44-year-old woman with a history of migraine headaches, chronic neck pain, hypertension, and chronic hepatitis C suddenly became unresponsive and required cardiopulmonary resuscitation (CPR) during a fluoroscopically guided C7 right-sided SNRB performed under local anesthesia at an outpatient pain clinic. The procedure was completed using a 25-gauge, 3.5-inch spinal needle inserted from an oblique lateral approach with no misplacement of the needle tip reported on intermittent fluoroscopic examinations.

The patient was intubated at the clinic and taken immediately to a nearby hospital. She continued to be unresponsive and without spontaneous respiration and subsequently was transferred to our institution for further management and treatment. On presentation, she was hemodynamically stable and intubated and had a Glasgow Coma Scale (GCS) of 3. She reportedly had allergies to sulfonamides, erythromycin, and Darvocet (propoxyphene napsylate and acetaminophen, Eli Lily and Company). Her medications included atenolol, sumatriptan, loratadine, and celecoxib.

A neurologic examination revealed dilated (8 mm) and nonreactive pupils bilaterally. She had no corneal or gag reflexes and did not respond to painful stimuli. CT of the head performed on arrival showed marked edema of the pons and mid brain. Furthermore, the scan showed a large hemorrhagic infarction within the pons, mid brain, cerebellum, and thalami with intraventricular extension, subarachnoid hemorrhage, and hydrocephalus (Fig. 1A, 1B).


Figure 1
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  		Fig. 1A —44-year-old woman who underwent complicated cervical selective nerve root block (SNRB) performed under fluoroscopic guidance. CT scan of brain obtained after SNRB procedure shows marked edema of brainstem, pons, and mid brain (A). Furthermore, additional scan (B) shows large hemorrhagic infarction within brainstem, mid brain, cerebellum, and thalami with intraventricular extension, subarachnoid hemorrhage, and hydrocephalus.

 

Figure 2
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  		Fig. 1B —44-year-old woman who underwent complicated cervical selective nerve root block (SNRB) performed under fluoroscopic guidance. CT scan of brain obtained after SNRB procedure shows marked edema of brainstem, pons, and mid brain (A). Furthermore, additional scan (B) shows large hemorrhagic infarction within brainstem, mid brain, cerebellum, and thalami with intraventricular extension, subarachnoid hemorrhage, and hydrocephalus.

 
She was pronounced brain-dead within 24 hours after admission to our hospital. A coroner's autopsy described the cause and manner of death as massive cerebral edema with perforation of the right vertebral artery and dissection that extended into the basilar artery. In addition, there was an intraluminal thrombus within the dissected vertebral artery.

Case 2
A 41-year-old man with a similar complication from a fluoroscopically guided cervical SNRB presented to our institution within the same month as the patient in case 1. The patient became acutely and profoundly confused and showed left-sided upper extremity weakness while undergoing a left C5 SNRB under fluoroscopic guidance at an outpatient pain clinic. This case also was completed without conscious sedation and using the same protocol as the patient in case 1. Subsequent CT at an outside institution revealed subintimal contrast material within the left vertebral artery extending from C3 to C6 (Fig. 2A).


Figure 3
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  		Fig. 2A —41-year-old man who underwent complicated cervical selective nerve root block performed under fluoroscopic guidance. Axial unenhanced CT scan of neck shows contrast material (arrow) within wall of left vertebral artery, which extended from C3 to C6.

 
The patient was then transferred to our institution for further management and treatment of a suspected left vertebral artery injury. A left vertebral arteriogram was obtained at our hospital, which showed dissection of the left vertebral artery (Fig. 2B) consistent with the previous CT findings. He was heparinized and admitted to our neuro intensive care unit (NICU) for close observation and further management. CT of the head after admission to the NICU revealed normal findings. His presenting symptoms at our hospital of confusion, visual deficits, upper extremity paresis, and facial weaknesses completely resolved within 24 hours of continuous heparin infusion. The patient's medication was converted to Coumadin (warfarin sodium, Bristol-Myers Squibb), and he was discharged from the hospital 6 days after the initial event. Findings from a follow-up head CT 1 month after discharge were also normal.


Figure 4
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  		Fig. 2B —41-year-old man who underwent complicated cervical selective nerve root block performed under fluoroscopic guidance. Left vertebral arteriogram shows irregularity of left vertebral artery (arrows), consistent with dissection.

 


Discussion
Top
 Introduction
 Case Reports
 Discussion
References
 
There is debate among physicians as to which technique—fluoroscopy or CT—is preferred when performing cervical SNRB. Whether imaging guidance should be used and, if so, whether fluoroscopy or CT should be the technique of choice have been the basis for most discussions regarding this controversy. There have been no large studies reporting complication rates with or without imaging guidance specifically during cervical SNRB procedures in an outpatient setting. Most of the reported data regarding cervical anesthesia have been obtained during carotid endarterectomy procedures [8-13] using the cervical plexus block technique described by Moore [14].

The studies that have reported complications during imaging-guided cervical nerve blocks have been relatively small prospective studies or case reports. No significant complications were reported in any of the prospective studies [15-20]. There have been, however, case reports of cerebellar infarct, spinal cord infarct, epidural hematomas, transient quadriplegia, and death [5-7]. The reported cerebellar infarct was speculated to be secondary to a corticosteroid particulate embolus [6], and the reported death [7] occurred secondary to a perforated stomach, which the patient sustained during a lengthy hospitalization after a complicated (spinal infarct) SNRB procedure.


Figure 5
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  		Fig. 3 —47-year-old woman with left arm paresthesia and pain. Axial CT scan obtained during cervical selective nerve root block clearly shows adjacent vertebral artery (V), carotid artery (C), and internal jugular vein (IJ). Needle tip is well visualized and only millimeters from vertebral artery.

 


Figure 6
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  		Fig. 4A —Fluoroscopic images obtained during C7 selective nerve root block. No vascular structures are visualized using this technique. Furthermore, exact position of needle tip is difficult to ascertain when only one projection is used. (Reprinted with permission from Silbergleit R, Mehta BA, Sanders WP, Talati SF. Imaging-guided injection techniques with fluoroscopy and CT for spinal pain management. RadioGraphics 2001; 21:927-942 [22])

 


Figure 7
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  		Fig. 4B —Fluoroscopic images obtained during C7 selective nerve root block. No vascular structures are visualized using this technique. Furthermore, exact position of needle tip is difficult to ascertain when only one projection is used. (Reprinted with permission from Silbergleit R, Mehta BA, Sanders WP, Talati SF. Imaging-guided injection techniques with fluoroscopy and CT for spinal pain management. RadioGraphics 2001; 21:927-942 [22])

 
The two cases that we report show the possible consequences after an incurred complication of vascular penetration during an SNRB procedure. Furman et al. [21] reported intravascular needle placement in 19.4% of 504 fluoroscopically guided cervical SNRB procedures confirmed by contrast injection. The incidence of vascular penetration and injury during cervical block procedures using the blind cervical plexus block technique is approximately 30% as reported by Davies et al. [8]. Intravascular needle tip placement during a blind technique is determined by aspiration or visualization of blood into the needle hub. However, Furman et al. showed during the performance of their reported 504 procedures that visualization of blood is not a sensitive sign of intravascular tip placement (45.9%) [21]. In our opinion, the incidence of vascular penetration and injury during the blind technique is unacceptably high, and this technique should be avoided when performing cervical SNRB procedures whenever possible.

The difficulty in performing a cervical SNRB using a blind or a fluoroscopically guided approach is not merely related to the increased incidence of vascular injury compared with similar procedures in other spinal regions and the underestimation of vascular injuries. The difficulty of the procedure is also exacerbated by the fact that a fatal injury may have already occurred before any sign of the complication is present. Many physicians will use contrast injection to help identify an intravascular needle tip. However, this technique will not assist in avoiding dissection. If the needle tip enters an artery during a cervical SNRB procedure, dissection is possible, and visualization of blood or injection of contrast material to determine vascular placement would not prevent this possibly fatal complication. We recognize that not all vascular injuries—that is, venous penetrations—would result in the complications that occurred in the cases we have described, and that blood aspiration or "flash" during the procedure cannot definitively determine the extent of vascular injury.

The cases we report show the potentially devastating outcomes that can result from what many consider a relatively simple procedure. The complexity of the cervical anatomy dictates that there is rarely a simple invasive procedure of the neck. Fluoroscopic guidance during cervical SNRB procedures has been used to minimize the complications occurring with blind cervical SNRB. Fluoroscopy is limited, however, because it does not show the soft-tissue structures of the neck. Figure 3 shows that CT guidance not only permits clear visualization of the needle but also depicts the surrounding soft tissues and vascular structures well in comparison with fluoroscopic images obtained during cervical SNRB [22] (Fig. 4A, 4B). Note that the fluoroscopic images fail to show the noncalcified vessels, and the depth of the needle tip, in the sagittal plane, is not shown without obtaining a lateral projection image. Physicians performing cervical SNRB procedures should be aware that inadvertent needle placement into a vertebral or carotid artery can result in vascular injury with its associated complications of arterial dissection and death.

We think that imaging guidance is essential for accurate needle placement during cervical SNRB. CT guidance is superior to fluoroscopy in its ability to delineate soft-tissue structures, especially the carotid and vertebral arteries. There are no studies that systematically compare the complication rates of fluoroscopy- and CT-guided SNRB procedures; studies dedicated to this comparison are recommended because both techniques are routinely used in practice.

It has been argued that fluoroscopy is preferred because it provides real-time examination and permits the operator to ascertain quickly any required changes in needle position. Fluoroscopy also permits real-time evaluation of injected contrast material used to confirm proper placement. However, with the development of fluoroscopic CT this argument is weakened. Furthermore, as Murtagh [23] argues, the advent of faster CT scanners minimizes delays in confirming needle position after manipulation. CT can easily be used in conjunction with contrast material to confirm proper placement [23], although we would argue that injecting contrast material is not necessary when using CT guidance and does not prevent the arterial injury that CT is aiding to avoid.

A surprising advantage of CT guidance may be in lower patient and operator radiation doses because fewer images are generally obtained at our institution during low-dose (120kVp, 40mA) intermittent fluoroscopic CT-guided cervical SNRB procedures than with other techniques. Radiation dose differences between fluoroscopy and fluoroscopic CT or CT guidance during SNRB procedures has yet to be evaluated, and further study in this area is recommended. However, Wagner [24] recently reported that intermittent fluoroscopic CT guidance significantly lowered patient and operator radiation doses compared with continuous fluoroscopic CT- and general CT-guided lumbar nerve root block procedures. Therefore, a study should be designed to compare fluoroscopy and intermittent fluoroscopic CT doses.

In summary, we believe that both the technical complexity and the potential complications of performing cervical nerve root blocks are underappreciated. The combination of not recognizing the potential of lethal complications with a belief that a procedure is simple can easily lead to the precipice of failure and disaster. As we have reported, inadvertent penetration of the vertebral artery during the procedure can lead to a fatal outcome from dissection, thrombosis, and brainstem hemorrhagic infarction. Therefore, imaging guidance should be used in cervical SNRB procedures to minimize complications. Fluoroscopic guidance does not permit visualization of cervical vascular structures. CT is, in our opinion, the imaging technique of choice for guiding cervical SNRB procedures because CT minimizes potentially fatal complications by providing optimal visualization of the soft-tissue structures.


Acknowledgments
 
We thank Richard Silbergleit for permitting the use of his previously published fluoroscopic images (Fig. 4A, 4B). Accordingly, we wish to recognize that none of the complications described in this article occurred during the procedure illustrated in Figure 4A, 4B. Furthermore, we do not attribute any of the described complications to Richard Silbergleit, his associates, or the Henry Ford Hospital.


References
Top
 Introduction
 Case Reports
 Discussion
 References
 

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