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DOI:10.2214/AJR.07.2331
AJR 2007; 189:563-565
© American Roentgen Ray Society


Technical Innovation

A Cervical Nerve Block Approach to Improve Safety

Louis A. Gilula1 and Daniel Ma2

1 Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110.
2 Department of Medicine, Tufts/New England Medical Center, Boston, MA.

Received September 14, 2006; accepted after revision April 19, 2007.

 
Address correspondence to L. A. Gilula (gilulal{at}mir.wustl.edu).

FOR YOUR INFORMATION

A data supplement for this article can be viewed in the online version of the article at: www.ajronline.org.


Abstract
Top
Abstract
Introduction
Materials and Methods
Discussion
References
 
OBJECTIVE. The objective of this report is to describe a previously unreported technique of selective cervical nerve block, performed from January 1, 2004, to May 19, 2006, in 560 injections, that was designed to allow continual monitoring of injectate passage and verification of needle tip position. We also illustrate faulty needle placement in a cadaveric neck.

CONCLUSION. Using a short connecting tube, contrast material mixed with the final injectate, and fluoroscopy when performing a selective cervical nerve block allows continual monitoring of injectate including where washout of the original testing contrast material actually flows. A true lateral view shows a more dangerous anterior needle tip placement. In addition, performing a test with anesthetic and contrast material, waiting 1.5 minutes before administering the final injectate, and using a water-soluble steroid may provide further safety with selective cervical nerve block.

Keywords: anesthesia • anesthetic • cervical nerve block • CNS • injection technique • spinal injection


Introduction
Top
Abstract
Introduction
Materials and Methods
Discussion
References
 
Fluoroscopically guided extraforaminal selective cervical nerve blocks require precise needle tip positioning. Improper placement diminishes the procedure's therapeutic and diagnostic potential while increasing probability for complications [1]. Death, spinal cord infarction, injection into an anterior radicular artery, epidural sac puncture, and vertebral artery injury have been reported during selective cervical nerve blocks [1]. These complications are thought to be related to medication passage [2]. Currently, standard imaging protocols involve frontal and oblique views for accurate visualization of the needle tip [3]. However, adding a lateral view shows needle tip displacement anterior to the articular pillars, which is associated with an increased incidence of complications [1]. This study is designed to describe the inadequacy of using only frontal and oblique views; to stress the need for the lateral view to verify the adequacy of needle tip placement; and to present an injection technique, which we could not find previously reported, that provides potential marked improvement in safety with medication injection.


Materials and Methods
Top
Abstract
Introduction
Materials and Methods
Discussion
References
 
To illustrate the inadequacy of only frontal and oblique fluoroscopic views in determining needle tip position, we used a cadaveric neck as performed with live patients, omitting only sterility and anesthetic procedures, to show the importance of a true lateral view. In our standard procedural protocol, patients are in a lateral decubitus position with the side of interest elevated and the head and neck bent slightly toward the table (Appendix S1, available online at www.ajronline.org). In this cadaveric neck, the needle tip is more than 3 needle-tip widths anterior to the articular pillar on the lateral view (Fig. 1A), whereas it projects over the posterior aspect of the foramen on the oblique (Fig. 1B) and along the midportion of the pillar on the frontal (Fig. 1C) views.


Figure 1
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Fig. 1A —Radiographs show needle positions in cadaver. Lateral view shows that needle tip is displaced more than 3 needle-tip widths anterior to articular pillar.

 

Figure 2
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Fig. 1B —Radiographs show needle positions in cadaver. Oblique view shows that same anteriorly displaced needle appears adequately positioned as needle tip projects over anterior surface of articular pillar.

 

Figure 3
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Fig. 1C —Radiographs show needle positions in cadaver. Frontal view shows that same displaced needle tip appears adequately placed over midportion of articular pillar.

 
Injection Technique
To ascertain that the needle tip is not intravascular, dense myelographic contrast material (iohexol [Omnipaque 300, Amersham Health]) is injected before injecting the final injectate (Appendix S2 and Figs. S1A-S1D).

A slight needle tip movement can move a needle intravascularly, thereby misleading the operator about the location of medication delivery. In January 2004, we began using a short lymphangiographic tube (MX453, Medex) (Palmer W, personal communication) attached to a 10-mL syringe with dense contrast material (Omnipaque 300) (Appendix S3 and Figs. S2 and S3). The tube is tightly attached, "press fit," to the 25-gauge needle hub with one of the operator's hands holding the connecting tube hub at its attachment to the syringe containing contrast material. That same operator's hand rests on the patient's head to keep the tube and needle from moving (Fig. S3B). A small amount of contrast material (Omnipaque 300) is injected with frontal fluoroscopy to verify that the contrast material does not pass intravascularly. If it does, the operator repositions the needle tip slightly with minimal turning or advancement while checking contrast flow. When contrast material is not intravascular, a frontal fluoroscopic spot view is taken while observing injection (Fig. 2A). The fluoroscopic tube is rotated to precisely overlap bilateral articular pillars in the lateral view (Fig. S1D) for a second spot view and then to an oblique view maximally profiling the foramen (Fig. 2B). The tube is rotated back to the frontal position, and the syringe with contrast material is exchanged with a 3-mL syringe containing 0.5 mL of methylprednisolone acetate (80 mg/mL; Depo-Medrol, Pharmacia Upjohn), 0.5 mL of preservative-free lidocaine 2%, and 0.5 mL of Omnipaque 300. Intermittent fluoroscopy during placement ensures absence of intravascular filling. The 3-mL syringe is removed, and the tubing, which holds 0.2 mL of injectate, is cleared with the contrast syringe to deliver the entire injectate. A final frontal spot view shows the extent of injectate flow (Fig. 2C).


Figure 4
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Fig. 2A —Nerve block and focal foraminal epidural at left C5-C6 level in 33-year-old man undergoing selective cervical nerve block for right CT radiculopathy. Frontal view shows injectate with contrast flow, dispersion of contrast material, and no vascular filling.

 

Figure 5
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Fig. 2B —Nerve block and focal foraminal epidural at left C5-C6 level in 33-year-old man undergoing selective cervical nerve block for right CT radiculopathy. Oblique view shows contrast material outlining anterior margin of pillar and posterior surface of exiting nerve.

 

Figure 6
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Fig. 2C —Nerve block and focal foraminal epidural at left C5-C6 level in 33-year-old man undergoing selective cervical nerve block for right CT radiculopathy. Final frontal view shows 1.5 mL of injectate at end of injection. No contrast-filled vascular structures showed during or at end of injection. Injectate passed from C4 to C7 in epidural space.

 

This latter technique with connecting tube and injectate-containing contrast material mixed with steroid and anesthetic has been used in 560 injections from January 1, 2004, to May 19, 2006. No deaths or severe neurologic complications have been encountered with this newer technique. We have seen no problems mixing contrast material with injectate in several thousand nerve blocks of various types performed over several years. For additional safety, this technique has been recently further modified since February 28, 2007, by using a test dose of anesthetic (4% lidocaine) and contrast material with digital subtraction, waiting 90 seconds and replacement of deposteroid with water-soluble steroid suitable for intravascular injection (dexamethasone [Decadron, Merck & Co.]); see Appendix S3 for details.


Discussion
Top
Abstract
Introduction
Materials and Methods
Discussion
References
 
Selective cervical nerve blocks and transforaminal cervical spine epidurals have been associated with death and severe neurologic complications [1]. Because of potential complications, some physicians have anecdotally stopped performing such blocks. However, large retrospective studies have documented that complications associated with selective cervical nerve blocks or foraminal epidural blocks can be infrequent and minor given careful technique [1, 4].

During fluoroscopically guided selective cervical nerve blocks, true lateral views can display anterior needle tip displacement, which sometimes may be considered as otherwise adequate using only oblique and frontal views as illustrated by the cadaveric example. Prevention of anterior needle tip displacement is notable for two reasons. First, vertebral artery closeness to the articular pillars has been reported as a potential problem by Vallée et al. [5]. Therefore, an anteriorly displaced needle tip threatens vertebral artery integrity. Second, anterior needle tip displacement can still significantly increase the probability of minor complications [1]. During analysis of 1,036 fluoroscopically guided selective cervical nerve blocks, Ma et al. [1] found that a needle tip displaced more than 2 needle-tip widths anterior to the articular pillar significantly increased the probability of dizziness, numbness, transient weakness, and radicular pain. This is important because the published literature does not generally stress the importance of obtaining a lateral view to establish safe needle tip positioning. Indeed, in the selective cervical nerve block guidelines established by the International Spine Intervention Society, only frontal and oblique views are recommended to determine whether the position of the needle tip is adequate [3]. Many publications concerning selective cervical nerve blocks repeat these guidelines [5, 6].

Although lateral views may show anterior needle tip displacement, this view alone may be insufficient to monitor potential severe complications. Cadaveric studies show that anatomic variation may occasionally place aberrant deep cervical artery and thyrocervical trunk branches along the ideal needle path placement during selective cervical nerve blocks, especially from the C5 to C7 nerves [1]. Many serious complications of selective cervical nerve blocks are thought to be related to placing injectate into vital arteries [1]. A major problem with current injection techniques is inadequate flow monitoring during injection. Once contrast material is injected to verify that needle tip position is satisfactory, injectate washout is all that has been checked. However, contrast material can washout into soft tissues around nerves or blood vessels, into the epidural space, or even into blood vessels.

The addition of a high-density contrast agent to the injectate allows monitoring of injectate flow to see even tiny blood vessels filling during injectate placement. Although various procedures use intravascular contrast material, we could find no articles in the literature about adding contrast material to the final selective cervical nerve block injectate to monitor all injectate flow. Because the needle tip may move easily during needle positioning, syringe attachment, or minimal patient motion, adding dense contrast material to the injectate and using a short lymphangiographic connecting tube (Palmer W, personal communication) allow early recognition of vascular filling while minimizing needle movement. The use of digital subtraction during fluoroscopy can help show tiny blood vessels (Appendix S3).

Several authors recommend CT guidance for selective cervical nerve blocks, stating that CT "is the safest and most effective method of localizing the neural foramen, thereby ensuring steroid deposition at this exact location" [7]. CT can be valuable to place a needle in a desired position. However, neither CT nor CT fluoroscopy can be used to monitor vascular filling during injection, especially fast-moving arterial flow that may not be confined within a CT section plane. Also because it is necessary to observe the vertebral body above and below the injected level to detect vascular filling, the CT beam may inadequately display such a spine length. CT also presents more procedural cost than fluoroscopy. Therefore, because of potential serious risks associated with selective cervical nerve blocks, we strongly encourage radiologists to stop using CT or CT fluoroscopy for selective cervical nerve block in recognition of the fact that rapid filling of critical vascular structures can be missed with CT (Appendix S4).

In conclusion, we strongly believe that using a true lateral view to confirm needle tip placement within 3 needle-tip widths anterior to the articular pillar surface, using a short lymphangiographic connecting tube, adding dense contrast material to the injectate, testing with anesthetic mixed with contrast material before steroid injection, using digital subtraction, using a water-soluble steroid, and monitoring the entire injectate placement with intermittent fluoroscopy in the frontal position can provide a method to markedly improve the safety of selective cervical nerve blocks.


References
Top
Abstract
Introduction
Materials and Methods
Discussion
References
 

  1. Ma D, Gilula LA, Riew KD. Complications of fluoroscopically guided extraforaminal cervical nerve blocks: an analysis of 1036 injections. J Bone Joint Surg Am 2005;87 : 1025-1030[Abstract/Free Full Text]
  2. Furman MB, Giovanniello MT, O'Brien E. Incidence of intravascular penetration in transforaminal cervical epidural steroid injections. Spine 2003; 28:21 -25[CrossRef][Medline]
  3. Bogduk N. Practice guidelines for spinal diagnostic and treatment procedures: cervical transforaminal injection of corticosteroids. Kentfield, CA: International Spine Intervention Society, 2004: 237-248
  4. Derby R, Lee SH, Kim BJ, Chen Y, Seo KS. Complications following cervical epidural steroid injections by expert interventionalists in 2003. Pain Physician 2004;7 : 445-449[Medline]
  5. Vallée JN, Feydy A, Carlier RY, Mutschler C, Mompoint D, Vallée CA. Chronic cervical radiculopathy: lateral-approach periradicular corticosteroid injection. Radiology2001; 218:886 -892[Abstract/Free Full Text]
  6. Windsor RE, Storm S, Sugar R, Nagula D. Cervical transforaminal injection: review of the literature, complications, and a suggested technique. Pain Physician 2003;6 : 457-465[Medline]
  7. Silbergleit R, Mehta BA, Sanders WP, Talati SJ. Imaging-guided injection techniques with fluoroscopy and CT for spinal pain management. RadioGraphics 2001;21 : 927-939; discussion 940-942[Abstract/Free Full Text]
  8. Zinreid SJ, Murphy K. Invited commentary regarding article: Silbergeit R, Bharat M, et al. Imaging-guided injection techniques with fluoroscopy and CT for spinal pain management. RadioGraphics 2000;21 : 941-942

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This Article
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