Suresh K. Mukherji, MDArchana Wagle, MDDiane M. Armao, MDSunil Dogra, MD

Index terms:Brachial plexus, 276.126Computed tomography (CT),

guidance, 276.1211Interventional procedures, 276.126Nerves, root

Radiology 2000; 216:886–890

1 From the Departments of Radiology(S.K.M., D.M.A.), Surgery (S.K.M.), andAnesthesiology (S.K.M., A.W., S.D.),University of North Carolina School ofMedicine, 3324 Old Infirmary, CB 7510,Chapel Hill, NC 27599-7510. ReceivedSeptember 3, 1999; revision requestedOctober 14; revision received December10; accepted January 11, 2000. Addresscorrespondence to S.K.M.

© RSNA, 2000

Author contributions:Guarantors of integrity of entire study,all authors; study concepts and design,all authors; definition of intellectual con-tent, all authors; literature research, allauthors; clinical studies, all authors; dataacquisition and analysis, all authors;manuscript preparation, editing, and re-view, all authors

Brachial Plexus Nerve Blockwith CT Guidance forRegional Pain Management:Initial Results1

Brachial plexus nerve blocks are per-formed to treat patients with chronicpain referable to the brachial plexus.The needle insertion and trajectoryare based on palpation of surfacelandmarks. Occasionally, the surfacelandmarks are difficult to identify ow-ing to body habitus or anatomic al-terations secondary to surgery or ra-diation therapy. The intent of thismanuscript is to describe a techniquefor brachial plexus block guided withcomputed tomography and to re-port our initial results for regionalpain management.

The role of imaging-guided therapy fordelivery of regional anesthesia for painmanagement and treatment of patientswith brachial plexopathies is an impor-tant area that has received little atten-tion (1–7). Causes of such chronic bra-chial plexopathies include stenosis ofthe cervical neural foramina that causesa mononeuropathy, neoplastic inva-sion of the brachial plexus by Pancoasttumor or metastases, and plexopathiesthat result from prior treatment. Treat-ment for such patients often includespercutaneous nerve root block. The siteof needle insertion is based on palpa-tion of surface anatomic landmarks (8–12). At times, the normal surface land-marks may be difficult to palpate inpatients who have short thick necks orhave undergone surgery or radiationtherapy. This often results in an inabil-ity to properly localize the anatomicsite for needle insertion and may resultin incorrect needle placement. The re-sult is often inadequate pain control.

Imaging guidance may be used toguide percutaneous nerve root block by

helping to localize the optimal site ofneedle insertion and identify the extentof analgesic distribution that wouldprovide optimum pain relief. The pur-pose of this article is to describe a tech-nique for brachial plexus block guidedwith computed tomography (CT) and re-port our initial results for regional painmanagement in patients with chronicpain referable to the brachial plexus andsurface landmarks that cannot be pal-pated.

Materials and Methods

We performed six CT-guided brachialplexus block procedures in five patients(three men and two women; age range,33–72 years; mean age, 52.2 years). Allpatients had chronic neuropathic painthat was believed by members of the painmanagement center of the department ofanesthesiology at our institution to orig-inate from the brachial plexus. Brachialplexus blocks are routinely performed inour anesthesiology clinic on the basis ofsurface landmarks. Because the surfacelandmarks were difficult to palpate onclinical examination in these five pa-tients, our pain management colleaguesrequested that we perform the proce-dures with imaging guidance.

Patients 2 and 3 had cervical mono-neuropathies, and the blocks were per-formed as diagnostic procedures prior toforaminotomy to help confirm that thepain was originating from nerve rootcomponents of the brachial plexus (Fig1). One procedure was performed in pa-tient 5, who had recurrent Pancoast tu-mor (Fig 2); he underwent a secondprocedure 6 weeks after the original diag-nostic block to duplicate the pain reliefreceived from the initial procedure. Pa-tient 1 experienced chronic pain follow-ing a modified radical mastectomy forbreast carcinoma, and postmastectomy

Technical Developments

886

syndrome was diagnosed. Patient 4 un-derwent phenol neurolysis of the bra-chial plexus to treat intractable pain frommetastatic carcinoma encasing the retro-clavicular portion of the brachial plexus.

In patients with intractable pain at ourinstitution, the majority (80%–90%) ofbrachial plexus nerve root blocks are per-formed without the use of imaging guid-ance. Indications for the use of CT guid-ance are (a) inability to palpate normalsurface landmarks owing to body habitusor anatomic alterations due to tumor in-filtration or fibrotic changes from previ-ous radiation therapy, (b) prior unsuc-cessful block, and (c) neurolysis of thebrachial plexus. Previous investigators(13) have stated that the success of a localanesthetic block may be adversely af-fected by anatomic distortion caused byradiation therapy or surgery.

Figure 3 is a schematic of our approachwith CT guidance. The patient is placedon the CT table in the supine position.An attempt is made to rotate the patientso that the side of interest is elevatedapproximately 30° above the plane of thetable, and every attempt is made to re-tract the patient’s arm inferiorly. This po-sitioning was performed to make theangle of needle insertion more perpen-dicular to the plane of the table, but itwas not always possible because the pa-

tient’s pain was exacerbated. The headwas turned away from the area of inter-est. The skin was marked with bariumpaste and contrast material was injected(100 mL, 2 mL/sec) prior to helical CT(Somatom Plus 4; Siemens Medical Sys-tems, Erlangen, Germany) (3-mm-thickcontiguous sections) from the hyoidbone to the thoracic inlet (Fig 1).

An appropriate site of entry was thenchosen by first identifying the anteriorand middle scalene muscles (Fig 1),which denote the plane of the supracla-vicular portion of the brachial plexus. Forstandard brachial plexus block, the site ofinsertion was usually located at the infe-rior half of the cricoid cartilage to placethe region of insertion between theC7-C8 nerve roots. The site of entry wasaltered in a patient with a mononeuropa-thy: The exiting neural foramen wasidentified, and the needle tip was di-rected toward the site where the nerveroot entered the plane between the ante-rior and middle scalene muscles. Thecourse of the needle was expected to belateral to the common carotid artery andinternal jugular vein and posterior to thesternocleidomastoid muscle (Fig 1).

The distance from the skin site to the

plane between the anterior and middlescalene muscles was measured. The skinsite was prepared and draped in sterilefashion. The superficial area overlyingthe insertion site was anesthetized with1% lidocaine hydrochloride via a 1⁄2-inch27-gauge needle. The deep tissues wereanesthetized by using a 3⁄4-inch 27-gaugeneedle, which was left in place and itsposition identified with CT. The needlewas then replaced with a 20-gauge Chibacutting needle (Manon Medical Products,Northbrook, Ill) and the tip advancedthrough the midportion of the anteriorscalene muscle so it lay between theplane of the anterior and middle scalenemuscles. The position of the needle wasintermittently identified with CT (Fig 1).

The amount and type of local anes-thetic to be injected depended on theclinical indication and was determinedby the anesthesiologist present duringthe procedure. The local anesthetic wascombined with iodinated contrast mate-rial (Omnipaque 300; Nycomed Amer-sham, Princeton, NJ) with a dilution of 1mL of contrast agent to 10 mL of localanesthetic. After the solution was admin-istered, CT was performed to identify thedistribution of the solution. Distributionbetween the anterior and middle scalenemuscles indicated involvement of the su-praclavicular plexus (Figs 1, 2).

The visual analog scale was used to as-sess pain relief following the CT-guidedbrachial plexus block. The visual analogscale is a linear scale that represents therange of pain a patient experiences. Thescale usually is divided into centimetersand is 10 cm long. At each end of thescale, the descriptors often read “nopain” at the zero end and “the worst painimaginable” at the 10 end. Patients canthen draw a line through the scale at thelevel of pain they experience. To illus-trate the results of therapy, a visual ana-log scale is commonly obtained beforeand after an intervention. The advantageof this type of measurement is simplicityand worldwide usage since it is not lan-guage dependent (9). In all five patientsin our study, the visual analog scale wasobtained both before and after treat-ment.

Results

A summary of our results appears inthe Table. Four of the five patients expe-rienced 75% or greater relief of pain fol-lowing CT-guided nerve block. In the twopatients with diagnostic block, 100%pain relief was experienced for the dura-tion of the local anesthetic. Patient 4 ex-

Figure 1. Patient 2. Brachial plexus block totreat a left C7 mononeuropathy. (a) Transversecontrast-enhanced CT scan, obtained after theskin over the brachial plexus was marked withbarium paste (arrows), was acquired to helpidentify the locations of the common carotidartery (C), internal jugular vein ( J), and verte-bral artery (V). A 5 anterior scalene muscle,M 5 middle scalene muscle. (b) Transverse CTscan demonstrates the tip of the needle in-serted within the plane separating the anterior( A) and middle (M) scalene muscles. (c) Trans-verse CT scan helps confirm that the solution(2 mL) (arrow), which contains lidocaine andwater-soluble contrast material and is injectedthrough the needle, is located between theplanes of the anterior and middle scalene mus-cles and thereby must involve the supraclavic-ular brachial plexus. The patient experiencedcomplete pain relief immediately after the in-jection.

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perienced 50% pain reduction with theneurolytic brachial plexus block; in hiscase, other pain generators from diffusemetastatic disease could not be alleviatedwith the single procedure.

Two transient complications occurred.Patient 3 developed an ipsilateral Hornersyndrome that resolved within 8 hours.Patient 5, with an extensive recurrentPancoast tumor, developed a phrenicnerve palsy that necessitated overnighthospitalization due to oxygen saturationof less than 90% with 2 L of oxygen via anasal cannula. The palsy resolved over-night, and the patient was discharged thenext day without any further pulmonarycompromise. The patient underwent re-peat CT-guided brachial plexus block andexperienced no complications.

Discussion

Brachial plexus nerve blocks are oftenused as regional anesthesia techniquesthat allow surgical procedures to be per-formed in the upper extremity. Periph-eral nerve blocks obviate general anesthe-sia and are typically performed in patientswho choose to be awake during the proce-dure or in outpatient surgeries (10);therefore, the potential complications as-sociated with general anesthesia areavoided and earlier discharge from therecovery room and hospital are possible.

Four main approaches are used for per-cutaneous brachial plexus nerve blocks:interscalene, supraclavicular, infraclavic-ular, and axillary (8,10–16). The inter-scalene block is performed to anesthetizethe brachial plexus as it courses betweenthe anterior and middle scalene musclesand is used for surgical procedures in-volving the shoulder. The approach isbased on palpation of the interscalenegroove, which is situated posterior to thesternocleidomastoid muscle (11). It ishoped that the trajectory of insertion willintroduce the needle into the brachialplexus along the plane between the an-terior and middle scalene muscles(11,16–21) (Fig 4).

The approach of our imaging-guidedtechnique is similar to that in the inter-scalene approach. The insertion site inboth techniques is posterior to the ster-nocleidomastoid muscle (11). Our CT-guided approach, however, differs fromthat used for the standard interscaleneblock (11) (Figs 3, 4). In our technique,the needle enters the brachial plexus af-ter it courses through the anterior scalenemuscle. In the interscalene approach,however, the needle enters the brachialplexus along the plane between the an-

terior and middle scalene muscles with-out piercing the anterior scalene muscle(11) (Figs 3, 4). We chose our anteriorapproach over the standard interscaleneapproach as it provides a more directroute that permitted the needle to be in-serted in a trajectory perpendicular to theplane of the patient. In the interscaleneapproach, the trajectory of the needle ismore parallel to the plane of the patient.We chose the anterior approach becauseit allows much easier control of needleplacement during biopsies of the ex-tracranial head and neck, in which thetrajectory of the needle is perpendicularto the patient.

We have not performed the traditionalinterscalene approach with CT guidance,but it is an alternative. CT guidancecould also be used for needle localizationduring supraclavicular and infraclavicu-lar brachial plexus nerve blocks. In theseapproaches, however, the course of theneedle is close to the lung apex. As aresult, these approaches are associatedwith a higher frequency of pneumotho-rax than is the interscalene approach(8,18,21). Both the infraclavicular andaxillary approaches are performed with90° abduction of the arm. As a result,these procedures are difficult to performin the CT gantry (8,18,21–24).

It is possible that interventional mag-netic resonance units may be used forimaging guidance of supraclavicular, in-fraclavicular, and axillary approaches.The open gantry and multiplanar imag-ing capabilities may allow better visual-ization than that with CT for the variouspatient positions and oblique needle tra-jectories that are used routinely in theseapproaches. Ultrasonography (US) hasalso recently been described for imagingguidance of surgical anesthesia of thebrachial plexus (25). In our study, weevaluated patients with chronic pain. USappears to be a viable alternative to CTfor brachial plexus blocks in such pa-tients, although Yang et al (25) state thatthe spread of solution should be docu-mented with conventional radiographyand the catheter position with CT. USguidance appears to be a reliable alterna-tive in patients with normal muscularand fascial planes, but CT guidance maybe preferred to US in patients with dis-torted anatomy due to neoplastic inva-sion or prior treatment. CT is also able tohelp localize therapy in patients withchronic mononeuropathies. It is notclear if US can be used to guide therapy in

Figure 2. Patient 5. Brachial plexus block forpain relief for recurrent Pancoast tumor.(a) Coronal nonenhanced T1-weighted image(repetition time, 600 msec; echo time, 14msec) depicts a mass (M) situated in the apexof the left lung, as well as obliteration of theapical fat and encasement of the left brachialplexus. On the contralateral side, note the nor-mal appearance of the apical fat (arrowhead)and brachial plexus (arrows). (b) Transverse CTscan obtained after injection of the solution oflocal anesthetic and contrast material showsthe majority of the solution to be distributedbetween the anterior ( A) and middle (M)scalene muscles. (c) Transverse CT scan at thethoracic inlet depicts contrast material (smallarrows) extending along the neurovascularbundle (large arrow) of the subclavian arteryand vein, which indicates that the solution isin contact with the brachial plexus. The pa-tient experienced approximately 50% reduc-tion in pain immediately after the injection.

888 z Radiology z September 2000 Mukherji et al

patients with mononeuropathies or islimited to use in only the brachial plexus.

We found no evidence that needle in-sertion directly into the brachial plexuscan result in nerve injury. In fact, elicita-tion of paresthesia helps confirm properneedle location prior to the administra-tion of analgesic when these techniquesare performed without imaging guidance(8,18,19). Three of the five patients in ourseries experienced paresthesia duringneedle placement.

Our results suggest that the use of im-

aging guidance may reduce the risk ofcomplications associated with brachialplexus nerve blocks performed with useof surface landmarks. The risk of compli-cations is even higher in patients withlandmarks that are not easily palpable(8,18). Complications commonly re-ported with percutaneous interscaleneblocks with use of surface anatomic land-marks are Horner syndrome (70%–90%)and phrenic nerve palsy (40%–60%)(8,18,19). Complications in our serieswere phrenic nerve palsy (17%) and Hor-

ner syndrome (17%) in one patient each.Pneumothorax is reported in as many as4% of patients (16). Malposition of theneedle in the vascular structures of theneck may result in injection of local an-esthetic into the jugular vein, carotid ar-tery, or vertebral artery (15), which mayresult in laceration, dissection, hema-toma, air embolism, seizures, apnea, orblindness. The addition of colloidal ma-terials to local anesthetics for pain man-agement may result in infarcts in the dis-tribution of the vessel that has beeninadvertently injected (15,17–20,22). Acontrast material–enhanced CT studyperformed prior to needle insertion helpsidentification of the pertinent vascularstructures that must be avoided.

Insertion of the needle into a subarach-noid, subdural, or epidural space has alsobeen reported (8,10,17,18,20,22–24).Unintentional injection of local anes-thetic in these areas may result in partialor complete spinal anesthesia (8,10,17,18,20,22–24). CT guidance during theprocedure helps avoid needle insertioninto the spinal canal and reduces the like-lihood of intraspinal injection. Othercomplications reported are injury to therecurrent laryngeal and vagus nerves(15). The two complications in our serieswere likely due to spread of the analgesicto the adjacent nerves (sympatheticchain and phrenic nerve), because theywere transient and resolved within thetime expected in nerve blocks performedwith use of surface landmarks.

Patient Data Summary

Patient No./Age (y)/Sex History Reason for CT Guidance

Type ofProcedure

Type of Analgesicand Volume

Reduction in Pain Basedon Visual Analog Score

Pretreatment Posttreatment

1/43/F Left-sidedpostmastectomysyndrome

Distorted surface anatomydue to prior surgeryand radiation therapyand possible neurolysis

Therapeutic brachialplexus block

20 mL 2% lidocainehydrochloride, 4 mL0.5% bupivacainehydrochloride,40 mg triamcinoloneacetonide

9 2

2/33/M Left C7 radiculopathy Unsuccessful previousattempt withflouroscopy

Diagnostic C7nerve block

2 mL 2% lidocainehydrochloride

4 0

3/50/F Left C7 radiculopathy Unsuccessful previousattempt withflouroscopy

Diagnostic C7nerve block

2 mL 2% lidocainehydrochloride

7 0

4/63/M Metastatic squamous cellcarcinoma to leftbrachial plexus

Possible neurolysis Neurolysis ofbrachial plexus

5 mL 12% phenol,20 mL 0.25%bupivacainehydrochloride

8 4

5/72/M* Recurrent left-sidedPancoast tumor

Distorted surface anatomydue to prior radiationtherapy

Therapeutic brachialplexus block

30 mL 0.25%bupivacainehydrochloride,40 mg triamcinoloneacetonide

8 2

* Patient underwent two therapeutic brachial plexus blocks on two separate occasions.

Figure 3. Schematic illustrates the approachused in the CT-guided procedure. The needle isinserted through the anterior scalene muscle.The tip is located in the plane between the an-terior and middle scalene muscles, which de-notes the location of the supraclavicular brachialplexus.

Figure 4. Schematic illustrates the traditionalinterscalene approach. The needle is insertedinto the interscalene groove within the planeseparating the anterior and middle scalenemuscles. Compare this with the approach il-lustrated in Figure 3.

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Another potential advantage of CT guid-ance is a reduction in the amount of anal-gesic injected to achieve adequate pain re-lief. As much as 40 mL of local anesthetic isoften recommended to achieve adequatepain relief for blocks that are performedwithout imaging guidance (8). With CTguidance, adequate pain relief was ob-tained with less than 20 mL of local anes-thetic in most cases. The ability to visualizespread following administration allowedidentification of the structures that cameinto contact with the analgesic (Figs 1, 2).Visualization of adequate distribution al-lowed use of a lower volume of analgesicand may have contributed to the low rateof Horner syndrome and phrenic nervepalsy in our series.

In summary, our initial results suggestthat CT-guided brachial plexus block is apromising technique for the treatment ofpatients with intractable pain in whomnormal surface landmarks cannot be pal-pated. Larger series must be studied be-fore the benefits of performing these pro-cedures with CT guidance as opposed touse of standard surface landmarks can beadequately determined.

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