accurate placement 4 ultrasound-guided peripheral nerve ... · continuous popliteal sciatic nerve...

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Accurate Placementof Ultrasound-GuidedLateral Popliteal-SciaticPerineural Catheters

Accepted for Publication: 8 October 2010

To the Editor:

I read with interest the article by Marianoet al1 describing the placement of

ultrasound-guided perineural catheters forcontinuous lateral popliteal-sciatic nerveblock. Catheters were initially advanced5 cm beyond the needle tip and graduallywithdrawn to a position inferred by the in-jection of air boluses. However, the positiveor negative predictive values of this testremain unknown. A suboptimal locationof the ultrasound-guided catheters in thisstudy may be suggested by mean postop-erative pain scores of 4.5 (range, 0Y7.1),which are significantly higher than thosein other studies using neurostimulation toplace continuous popliteal-sciatic cathetersfor pain control.2 Their relatively super-ficial location and transverse trajectoryensures that long-axis ultrasound images ofperineural catheters are readily obtainedduring the lateral approach to the popliteal-sciatic nerve (Fig. 1). Catheters can becontinually visualized, and the spread oflocal anesthetic around the sciatic nerve canalso be confirmed.3 Sonographic placementof perineural catheters may offer a numberof advantages compared to landmark-based

neurostimulation techniques alone.4 How-ever, significant improvement in postoper-ative pain scores may be difficult to confirmif, as in the study by Mariano et al,1 ultra-sonography is used to simply infer catheterposition rather than to view the catheter inreal time and to confirm precise placementof the catheter tip and spread of local an-esthetic within the perineural sheath.

John Dolan, BSc, MSc, PhD, MB, ChBFFARCSI

Department of AnaesthesiaGlasgow Royal InfirmaryGlasgow, Scotland, UK

REFERENCES

1. Mariano ER, Cheng GS, Choy LP, et al.Electrical stimulation versus ultrasoundguidance for popliteal catheter perineuralcatheter insertion. Reg Anesth Pain Med.2009;34:480Y485.

2. Ilfeld BM, Morey TE, Wang RD, EnnekingFK. Continuous popliteal sciatic nerveblock for postoperative pain control athome. A randomised double-blinded,placebo-controlled study. Anesthesiology.2002;97:959Y965.

3. McCartney CJL, Brauner I, Chan VWS.Ultrasound guidance for a lateral approachto the sciatic nerve in the popliteal fossa.Anaesthesia. 2004;59:1023Y1025.

4. Walker A, Roberts S. Stimulating catheters:a thing of the past? Anesth Analg. 2007;104:1001.

Ultrasound-GuidedPeripheral Nerve Block

in a Patient WithNeurofibromatosis

Accepted for Publication: 16 June 2010

To the Editor:

W e would like to congratulate Dr.Sites and his team for a thorough

and interesting discussion of clinicalsonopathology.1,2 Although they includeneurofibromas in their discussion of neu-ral tumors, a sonographic example islacking. We would like to contribute ourspecific sonographic experience adminis-tering a peripheral nerve block to a patientwith neurofibromatosis (NF).

Neurofibromatosis is an autosomaldominant neurologic disorder character-ized by neurofibromas and hyperpig-mented (cafe au lait) spots of the skin.Type 1 NF, von Recklinghausen disease,is the most common form and is charac-terized by cutaneous, nodular (peripheralnerve), and paraspinal neurofibromas.3

The presence of nodular neurofibromasposes a unique challenge to the perfor-mance of peripheral nerve blockade.4

Our patient was a 47-year-old womanwith Type 1 NF who had a history signifi-cant for postoperative nausea and vomitingafter previous general anesthetics. Shepresented for excision of a painful lesion inher left lateral foot and ankle and requestedto have a regional anesthetic. Ultrasoundallowed the placement of a sciatic nerveblock in the popliteal fossa without con-cerns of an intraneural injection. Thenerve was identified and appeared to havehypoechoic structures resembling vesselswithin it. Neither were these structurescompressible nor did they have evidence ofblood flowing through them when Dopplerwas applied. In the absence of direct visu-alization or pathologic section, we couldonly presume that the hypoechoic areasmay represent neurofibromas (Fig. 1). Ourobservations are consistent with those ofReynolds et al5 who sought to describe thesonographic characteristics of peripheralnerve sheath tumors. They note that suchtumors are often hypoechoic, with posterioracoustic enhancement and thus may simu-late a ganglion cyst. Beggs, too, describesneurofibromas as well-defined solid hypo-echoic masses that have faint distal acous-tic enhancement. Occasionally, a coarseechotexture or discrete focal area may be

FIGURE 1. Ultrasound-guided lateral popliteal-sciatic catheter. The 3 arrows indicatethe perineural catheter. LA indicates local anesthetic; LAT, lateral; MED, medial;SN, sciatic nerve.

LETTERS TO THE EDITOR

88 Regional Anesthesia and Pain Medicine & Volume 36, Number 1, January-February 2011


appreciated within the lesion, which is sec-ondary to collagen deposits.6 Thirty milli-liters ofmepivacaine 1.5%was injected, andthe patient underwent an uneventful proce-durewithminimal intravenous sedation andno narcotics. She did not experience post-operative neurologic complications.

The case highlights the utility of ul-trasound in placement of peripheral nerveblocks in NF patients and presents theassociated sonographic findings.

Melissa L. Rocco, MD

Meg A. Rosenblatt, MDMount Sinai School of Medicine

New York, NY

REFERENCES

1. Sites BD, Macfarlane AJR, Sites VR, et al.Clinical sonopathology for the regionalanesthesiologist. Part 1: Vascular and neural.Reg Anesth Pain Med. 2010;35:272Y280.

2. Sites BD, Macfarlane AJR, Sites VR, et al.Clinical sonopathology for the regionalanesthesiologist. Part 2: Bone, viscera,subcutaneous tissue and foreign bodies.Reg Anesth Pain Med. 2010;35:281Y289.

3. Hirsch NP, Murphy A, Radcliffe JJ.Neurofibromatosis: clinical presentationsand anaesthetic implications. Br J Anaesth.2001;86:555Y564.

4. Manickam BP, Perlas A, Chan VW, Brull R.The role of preprocedure systematicsonographic survey in ultrasound-guidedregional anesthesia. Reg Anesth Pain Med.2008;33:566Y570.

5. Reynolds DL, Jacobson JA, Inampudi P, et al.Sonographic characteristics of peripheralnerve sheath tumors. AJR. 2004;182:741Y744.

6. Beggs I. Sonographic appearances of nervetumors. J Clin Ultrasound. 1999;27:363Y368.

Continuous FemoralNerve Block Under

Ultrasound Guidance:Perineural Opening Before

Catheter Placement IsPerhapsNo LongerNecessaryAccepted for Publication: 24 September 2010

To the Editor:

D r. Ficarrotta et al1 have made anextraordinary effort in clarifying the

need for perineural space before expansionbefore catheter placement for continuousfemoral nerve block (CFNB).2 We applaudtheir complex achievement in eliminat-ing bias, which could have influenced ourpreviously reported data.2 We accept theirevidence-based conclusion that dilating theperineural space is not necessary to place acatheter around the femoral nerve.

We wish to add 2 important points.Their results were obtained under ultra-sound guidance, which itself constitutes abias. Also, they used a different materialfor CFNB (Stimucath is more rigid thanStimulong). This makes it more difficultto compare our work with theirs. Further-more, ultrasound imaging shows that in-jectates deposited around the femoral nerveexpand the perineural space between thenerve and the fascia iliaca, a condition ofsuccess either for a single-shot block orfor a catheter placement. Ultrasound imag-ing also shows that, in an out-of-plane ap-proach (did Dr. Ficarrotta et al use this intheir study?), the Tuohy needle can beplaced nearer the nerve, beneath the fasciailiaca, which leads to similar success. Thus,ultrasound imaging is a visual alternativeaccurate enough to partly replace dextrose5% in water, which we used in our blind

anatomic techniques for anatomic expan-sion and for maintaining accurate electro-location of the nerve.2,3 We further suggestthat the conclusion that perineural open-ing is unnecessary has to be viewed alsofrom the perspective of anesthesiologiststo whom an ultrasound machine is not yetavailable. In summary, opening the peri-neural space may be necessary in blindtechniques as shown in our study2 but isunnecessary when ultrasound guidance isused.1 The coming questions posed by ul-trasound imaging for CFNB should bewhat types of motor responses would weaccept from the stimulating catheter? Onlyquadriceps contraction as the authors sug-gested1? Is electrostimulation of the nervefrom the catheter the sole end point orshould it be combined with other end points,such as (to cite only one) image of perineuralexpansion after injection via the catheter?Such a combination of several end pointscould perhaps help us understand the failedblocks encountered by the authors.1

Charles Pham Dang, MD

Cecile Langlois, MD

Chantal Lambert, MDPole Anesthesie-Reanimations

Hotel-Dieu, CHU NantesNantes Cedex, France

REFERENCES

1. Ficarrotta MR, Morey TE, Boezart AP.Does Bopening the perineural space[before stimulating catheter placementfor continuous nerve block add value inclinical practice? Reg Anesth Pain Med.2010;35:245Y248.

2. Pham Dang C, Guilley J, Dernis L, et al.Is there any need to expand the perineuralspace before catheter placement forcontinuous femoral nerve block? Reg AnesthPain Med. 2006;31:393Y400.

3. Tsui BC, Wagner A, Finucane B. Dextrose 5%in water: fluid medium maintaining electricalstimulation of peripheral nerve duringstimulating catheter placement. ActaAnaesthesiol Scand. 2005;49:1562Y1565.

Injection of Injectates IsMore Than Just for ‘‘Opening

the Perineural Space’’Accepted for Publication: 6 October 2010

To the Editor:

W e read with interest the recent articleby Ficarrotta et al,1 in which they

conclude that the concept of Bopeningthe space[ surrounding the femoral nervewith 5% dextrose (D5W) before the peri-neural placement of stimulating femoralcatheters does not add value, in particularto the catheter threading time and number

FIGURE 1. Sciatic nerve in popliteal fossa. Arrows highlight the intraneural fibromas.

Regional Anesthesia and Pain Medicine & Volume 36, Number 1, January-February 2011 Letters to the Editor

* 2011 Lippincott Williams & Wilkins 89


of passes. This is in contrast to the findingsof Pham et al,2 in which a similar method-ology was used. Moreover, this report byFicarrotta et al1 may mislead readers byfailing to show full appreciation of the util-ity of injectates during block procedures.Apart from opening the perineural space,injectates (especially D5W) help confirma-tion of the proper location of the needle3

and the catheter by real-time observation ofthe solution spread under ultrasound imag-ing, while maintaining threshold stimulatingcurrent when applying electrolocalization.

The conclusion of the study isequivocal. The authors recognized thatthe difficulty in blinding and efforts weremade to blind the anesthesiologist whothreaded the catheter. However, havingcatheter placement performed by 1 of8 anesthesiologists may have further in-troduced confounders of variable experi-ence and technique. Furthermore, therewas no mention of how many catheterseach anesthesiologist placed in the studyor whether the same anesthesiologistsperformed both methods (catheter inser-tion in the presence or absence of D5W).It was also unclear whether the secondanesthesiologist who inserted the stimu-lating catheter was selected at random.Another interesting observation is themean threshold stimulating currents forthe needle, and catheter placements wereexactly the same in both the control andthe D5W groupsVwe wonder if this isperhaps a typographical error?

More importantly, we ask the funda-mental question of whether Bopening theperineural space[ as set out by Ficarrottaet al1 in their objective has been achieved.The blind injection of D5W in the studycould not guarantee whether the injectatewas indeed opening the perineural spaceby separating the fascial layers. The suc-cessful separation of fascial layers de-pends on the angling of the needleVwhenangled too steeply, the injected D5W mayaccumulate as a localized pool rather thanserving its purpose as opening up thespace. This phenomenon can be con-firmed with the tissue and fascial move-ments only by using imaging techniquessuch as ultrasound. Therefore, a moreappropriate conclusion of the study byFicarrotta et al1 is Bthe findings do notsupport the concept that blind injectionof D5W before femoral catheter place-ment adds value to perineural catheterplacement.[ We strongly believe the abil-ity to visualize the spread of injectates andthe surrounding milieu in a dynamic man-ner using ultrasound is useful. It allows theinjectates to indeed Bopen the perineuralspace[ in a purposeful and demonstratedmanner for perineural catheter placement.

Vivian Hui Yun Ip, MBChB, MRCP,FRCA

Ban C. H. Tsui, BSc(Pharm), MD,MSc, FRCP(C)

Department of Anesthesiaand Pain Medicine

University of Alberta HospitalEdmonton, Alberta

Canada

REFERENCES

1. Ficarrotta MR, Morey TE, Boezaart AP.Does Bopening the perineural space[ beforestimulating catheter placement for continuousnerve block add value in clinical practice?Reg Anesth Pain Med. 2010;35:245Y248.

2. Pham DC, Guilley J, Dernis L, et al. Is thereany need for expanding the perineural spacebefore catheter placement in continuousfemoral nerve blocks? Reg Anesth Pain Med.2006;31:393Y400.

3. Tsui BC, Kropelin B. The electrophysiologicaleffect of dextrose 5% in water on single-shotperipheral nerve stimulation. Anesth Analg.2005;100:1837Y1839.

Ultrasound RefractionArtifact Is Unlikely

A Response to Duplicationof Brachial Plexus


To the Editor:

W e read with interest the letter bySaranteas and colleagues1 reporting

2 brachial plexus duplication artifactsvisualized using ultrasound. Two qualityimages were published to illustrate animage duplication of the divisions of theplexus and the C5 nerve root. The authors

attributed these duplications to refractionof ultrasound beams similar to previouslypublished reports of deep structures(aorta, kidney) duplicated within the ab-domen using ultrasound visualization.2,3

On initial evaluation of the published im-ages, we agree that the structures high-lighted appear quite similar. However,upon further inspection, we disagree withthe authors’ explanation that these structureswere duplications resulting from ultrasoundbeam refraction within the human body.

To analyze these images, we first usedSnell’s law of refraction, which describesthe relationship between the angle of in-cidence and refraction when referring toacoustic waves passing through an interfacebetween 2 different media. We calculatedthe expected refraction of the ultrasoundbeam based on the speed of sound valuesprovided by the authors, that is, 1540 m/sec(assumed speed of sound in soft tissue) and1450 m/sec (speed of sound in adiposetissue). If we assume a generous angle ofincidence of 30 degrees, then the maxi-mum angle between the refracted and inci-dent beam to be approximately 2 degrees(Fig. 1). This small angle would result inthe duplicated neural structures beingmuchcloser to the actual neural structures thandepicted in the authors’ images. In fact,Figures 2A and B demonstrate that thesmallest angle of refraction that justifiesthat the lateral displacement for each im-age is 30 and 60 degrees, respectively.Furthermore, even if we use higher ul-trasound velocities in biologic media(1620 m/sec), the amount of refractiondoes not increase significantly.

Therefore, we conclude that theauthors’ explanation regarding refractionartifacts needs to be reconsidered. A

FIGURE 1. Visual diagramof Snell’s law (left) and ultrasound beam refraction (right) showinglarge incident angles (V) are necessary to produce large angles of refractions (V j 5). Plotof ultrasound beam refraction on right with incident angle (V) on x axis and amount ofrefraction indegrees (Vj5) with respect to incident beamon y axis. For example, an incidentangle of 30 degrees (x axis) results in a refraction of 2 degrees (y axis). Figure courtesy ofNiko Pagoulatos.

Letters to the Editor Regional Anesthesia and Pain Medicine & Volume 36, Number 1, January-February 2011

90 * 2011 Lippincott Williams & Wilkins


thorough investigation similar to the invivo or in vitro studies referenced by theauthors2 should be undertaken when po-tential artifacts are discovered. In this case,we would first encourage the evaluation ofthe ultrasound by the manufacturer orother appropriate servicing department.Also, other anechoic structures can appearsimilar to the C5 nerve root in this area in-cluding other nerve roots (eg, C4 or C6) andblood vessels (eg, transverse cervical artery).In addition, the apparent duplication in Fig-ure 2C could result from the presence of ananatomic anomaly of C5. These otherstructures should be included in thedifferential.

David B. Auyong, MD

Lucy S. Hostetter, MDDepartment of Anesthesiology

Virginia Mason Medical CenterSeattle, WA

Stuart A. Grant, MB, ChB, FRCADepartment of Anesthesiology

Duke University Medical CenterDurham, NC

REFERENCES

1. Saranteas T, Matsota P, Stachtos G,Kostopanagiotou G. Duplication of thebrachial plexus: an ultrasound refractionartifact? Reg Anesth Pain Med.2010;35:405Y406.

2. Middleton WD, Melson GL. Renalduplication artifact in US imaging.Radiology. 1989;173:427Y429.

3. Heyne JP. The double aortaVrarityor artifact of ultrasound [in German].Ultraschall Med. 2000;21:145Y147.

Practical Considerationsin Preparing the Pig

Carcass Spine PhantomAccepted for Publication: 1 October 2010

To the Editor:

W e congratulate Kwok et al1 on theirinnovative porcine carcass model.

FIGURE 2. Images from Saranteas et al1 with overlay of minimum angles of refraction. Note that the top of the ultrasound images wasused as an interface for refraction to measure the smallest angle possible between the original and last refracted beam. BP indicatesbrachial plexus; SA, subclavian artery; C-5, nerve root of C5.

FIGURE 1. The first step in preparation of the phantom is to dissect outand disarticulate the uppermost cervical vertebrae (A) to expose a 3- to 4-cmlength of spinal cord with intact meninges (B).

FIGURE 2. The spinal cord is tightly ligated with a 2-0 silk suture to create a watertightseal. A piece of latex from a disposable glove is placed under the ligature to preventit from cutting through the spinal cord. A 22-gauge cannula is inserted through thedura to lie in the intrathecal space, through which saline may subsequently be injected.




We too have found it to be an excellenteducational tool for ultrasound-guidedneuraxial blockade.

In our experience, the greatest dif-ficulty in preparing the carcass relates toinstillation and retention of fluid in theintrathecal space. This, as the authors havepointed out, is essential if good images areto be obtained.

We have found the following stepshelpful in this regard. First, a 3- to 4-cmlength of spinal cord must be exposed withits covering meninges intact (Fig. 1B). Thisrequires disarticulation and removal ofthe uppermost cervical vertebra. This canbe difficult, especially at the facet joints;we find a chisel and a stout pair of bonecutters or similar instrument to be helpfulhere. At the same time, it must be donecarefully to avoid tearing the dural sleevearound the spinal nerve roots, whichwould lead to subsequent leakage of fluidfrom the thecal sac.

Next, the proximal end of the spinalcord is ligated with a 2-0 silk suture tocreate a watertight seal. A small piece oflatex (cut from a disposable glove) is

placed under the ligature to prevent it fromcutting through the meninges as it ispulled tightly (Fig. 2).

Finally, a 22-gauge intravenous can-nula is inserted carefully through thedura to lie in the intrathecal space (Fig. 2).A colored saline solution may then beinjected or infused through the cannula.Placing the carcass in a slight, reverseTrendelenburg position facilitates fillingof the lumbar intrathecal space. We havefound that 10 to 15 mL of fluid is adequateto fill the thecal sac and provide good ul-trasonographic images (Figs. 3 and 4).

Owing to the thickness of porcineskin, a 20-gauge or larger needle with aQuincke or Tuohy tip is recommendedwhen practicing ultrasound-guided spi-nal and epidural needling techniqueson the phantom. Needle tip placementin the epidural or intrathecal spacecan be readily visualized (Fig. 4 B; seeVideo, Supplemental Digital Content 1,http://links.lww.com/AAP/A25); however,we have found that aspiration of fluidfrom the lumbar intrathecal space is usu-ally possible only if an additional 5 mL

is simultaneously injected through thecannula at the cephalad end of thethecal sac.

Ki Jinn Chin, FRCPC

Cyrus C.H. Tse, BSc

Vincent Chan, FRCPCDepartment of AnesthesiaToronto Western Hospital

University of TorontoOntario, Canada

REFERENCES

1. Kwok WH, Chui PT, Karmakar MK. Pigcarcass spine phantomVa model to learnultrasound-guided neuraxial interventions.Reg Anesth Pain Med. 2010;35:472Y473.

Investigation of PunctureAngles Needs ClinicallyDefined Insertion Points

Accepted for Publication: 10 August 2010

To the Editor:

W ith great interest, we read the articleby Grasu et al1 investigating 289

magnetic resonance images (MRIs) of thethigh to give biometric data for the distallateral approach to the sciatic nerve.

The results of the study confirm ourown results published in 2005,2 in whichwe investigated similar biometric data forlateral sciatic approaches at different sites.In this study, we already defined some ofthe present parameters on 246 MRIs ofthe thigh.

In contrast to Grasu et al, we markedour potential needle insertion point involunteers before the magnetic resonanceimaging to get a realistic view of clinicalpractice. The reference for the puncturepoint was the border of the vastus lateralismuscle of the thigh.

Approximately 12 cm proximal of thejoint line of the knee, we found a Bsciaticnerve-to-femur[ distance of 2.5 T 0.4 cmand a Bskin-to-nerve[ distance of 5.2 T0.6 cm in 82 MRIs. The depth of the nervewas 39% of the diameter of the thigh.

A puncture angle of 10.9 T 7.4 degreeswas determined in our study, which was incontrast to the results of Grasu et al, whodetermined an angle of 30 T 8 degrees.According to Grasu et al, we found a widerange of insertion anglesVin our study, 5to 29 degrees.

The explanation of the differentangles determined in the 2 studies couldbe that Grasu et al measured the anglefrom a retrospectively assessed virtualneedle insertion point defined by a hori-zontal, image-marked femur-to-skin line

FIGURE 4. Paramedian sagittal oblique view of the porcine lumbar spine (A). In this view,a spinal needle may be guided in real time into the epidural or intrathecal space (B).

FIGURE 3. Transverse midline view of the porcine lumbar spine.




crossing the skin surface. Our prospec-tively determined and clinically used in-sertion point of the puncture needle isregularly more dorsal, so that the angle tothe nerve gets smaller.

Also, our needle insertion point is3 cm proximal compared with that ofGrasu et al. Three cm to proximal, thevastus lateralis muscle proceeds to dorsalbecause of its anatomical configurationwhereas the sciatic nerve holds its positionin the depth (we found a similar sciatic tonerve distance over the whole femur dis-tance). In confirmation of this, we foundthe smallest angle of 8 degrees in themiddle of the thigh where the muscleborder is at its most dorsal point. In con-clusion, at the distal lateral approach to thesciatic nerve, the puncture angle increaseswith approximating the puncture point tothe joint line of the knee, using the borderof the vastus lateralis muscle of the thighas reference.

One must define a clinically usedneedle insertion point to get exact infor-mation about the needed insertion angle inclinical practice.

Michael Neuburger, MDDepartment of Anesthesiology

Ortenau Klinikum AchernGermany

Alexander Brinkmann, PhDDepartment of Anesthesiology

Klinikum HeidenheimGermany

Johannes Buttner, MDDepartment of Anesthesiology

BG Unfallklinik MurnauGermany

REFERENCES

1. Grasu RM, Costelloe CM, Boddu K.Revisiting anatomic landmarks: lateralpopliteal approach for sciatic nerve blockbased on magnetic resonance imaging.Reg Anesth Pain Med. 2010;35:227Y230.

2. Neuburger M, Hendrich E, Lang D, et al.Lateral approach to blockade of thesciatic nerve. Biometric data usingmagnetic resonance imaging [in German].Anaesthesist. 2005;54:877Y883.

Specialist’s Knowledgeof Local AnestheticSystemic Toxicity

Accepted for Publication: 23 July 2010

To the Editor:

W e read with great interest the excel-lent series of articles on local anes-

thetic systemic toxicity (LAST) that were

featured in the March-April issue.1Y3

Awareness of this much feared complica-tion is high among anesthetists, particu-larly those who regularly perform regionalanesthesia. However, there are physiciansin other specialties who regularly use localanesthetic in clinical practice such asplastic surgeons and dermatologists. Allpractitioners using local anesthetic areresponsible for knowing the maximumdosage, recognizing the signs and symp-toms of toxicity, and being able to man-age toxicity should it arise. Because manycases of local anesthetic toxicity arise notfrom excessive doses but from inadvertentintravascular injection, it is conceivablethat even practitioners using lower volumesof local anesthetic solution may provoketoxicity. With many dermatologists work-ing in a predominantly nonacute setting,more specialist assistance may not be im-mediately available from anesthetic oracute physician colleagues; the need forrecognition of the early signs of toxicityand the prompt institution of early man-agement is essential.

We recently conducted a survey ofdermatologists in the United Kingdomand Ireland to determine the knowledge ofLAST with some interesting results. Intotal, 92 dermatologists (66% of whomwere consultants) responded to our onlinesurvey. We found that 61% of respondentsknew the maximum safe dose of lig-nocaine in milligrams per kilogram. Wepresented 2 clinical vignettes of patientsof different age and weight presentingfor excision of skin lesions and askedrespondents to choose the maximum vol-ume of lignocaine that could be safelyused to anesthetize the area. Just morethan half (53%) chose the correct answer.Significantly, 47% chose volumes of lig-nocaine that exceeded the maximum safedose of local anesthetic. Knowledge ofsymptoms of local anesthetic toxicity washigh among dermatologists in our survey,but just 19 (21%) of 92 were aware ofthe place of lipid emulsion in the man-agement of LAST.

Our results show that dermatologistsare cognizant of the signs and symptomsof LAST, but a worrying percentage arenot sure of the correct maximum safedoses of lignocaine that can be used forskin infiltration. We applaud the authorson a most informative review series, whichwill be of use to a wide audience as dem-onstrated by the results of our survey.

Abigail M. Walsh, MB,FCARCSI, MRCP

Department of AnaesthesiaSt Vincent’s University Hospital

Dublin, Ireland

Benvon Moran, MB, MRCPIDepartment of DermatologyWaterford Regional Hospital

Waterford, Ireland

Sarah A. Walsh, MB, MRCPDepartment of Dermatology

King’s College HospitalLondon, UK

REFERENCES

1. Di Gregorio G, Neal JM, Rosenquist RW,Weinberg GL. Clinical presentation of localanaesthetic systemic toxicity. Reg AnesthPain Med. 2010;35:181Y187.

2. Mulroy MF, Hejtmanek MR. Preventionof local anaesthetic systemic toxicity.Reg Anesth Pain Med. 2010;35:177Y180.

3. Weinberg GL. Treatment of local anaestheticsystemic toxicity. Reg Anesth Pain Med.2010;35:188Y193.

Reply to Drs. Walsh,Moran and Walsh

Accepted for Publication: 26 July 2010

To the Editor:

O n behalf of the American Society ofRegional Anesthesia and Pain Medi-

cine’s (ASRA) practice advisory panel onlocal anesthetic systemic toxicity (LAST),1

I wish to thank Drs. Walsh and Walsh2

for sharing their insights and the resultsof their survey of United Kingdom andIrish dermatologists’ knowledge regard-ing LAST. Their correspondence makesseveral important points that are worthyof reemphasis. First, as the survey con-firms, local anesthetics are widely usedby a variety of medical specialists who donot always possess complete knowledgeof potential complications or contemporarytherapeutic options. Like some membersof the anesthesiology community itself,nonanesthesiologists can be unaware thatweight and body mass index are not reli-able metrics from which to calculate localanesthetic maximum dose3 or that pro-pensity for LAST varies by age and med-ical comorbidity.4

When the ASRA panel began thisproject, it solicited input from a numberof US organizations that represent physi-cians who routinely use local anestheticsin potentially toxic doses.1 Although theAmerican Society of Plastic Surgeons wason that list, we unfortunately neglected tosolicit input from the American Academyof Dermatology. The summary article fromthe Practice Advisory1 has been sharedsubsequently with all of these professional




societies, with permission given to distrib-ute the 2-page summary checklist to theirmembership. Both the summary articleand the checklist are available for freedownload at www.asra.com/publications.Anesthesiologists worldwide are encour-aged to share this information (or similarguidelines from the Association of Anaes-thetists of Great Britain and Ireland) withtheir nonanesthesiologist colleagues.

Joseph M. Neal, MDDepartment of Anesthesiology


REFERENCES

1. Neal JM, Bernards CM, Butterworth JF, et al.ASRA practice advisory on local anestheticsystemic toxicity. Reg Anesth Pain Med.2010;35:152Y161.

2. Walsh AM, Walsh SA. Specialists’ knowledgeof local anesthetic toxicity. Reg Anesth PainMed. 2011;36:93.

3. Mulroy MF, Hejtmanek MR. Prevention oflocal anesthetic systemic toxicity. Reg AnesthPain Med. 2010;35:177Y180.

4. Di Gregorio G, Neal JM, Rosenquist RW,Weinberg GL. Clinical presentation of localanesthetic systemic toxicity: a review ofpublished cases, 1979Y2009. Reg AnesthPain Med. 2010;35:181Y187.

An UnsubstantiatedCondemnation of

Intraneural InjectionAccepted for Publication: August 6, 2010.

To the Editor:

W e have read the editorial by Drs.Neal and Wedel in the JulyYAugust

2010 edition of Regional Anesthesia andPain Medicine.1 We disagree with someof Drs. Neal’s and Wedel’s interpretationof the case reports and their final recom-mendations. In the case report of Reiset al, the injection was most likely extra-neural.2 We propose this because the nerveblock took 15 mins to set up after the in-jection of 30 mL of ropivacaine, 0.6%.In our experience (91000 intraneural su-praclavicular injections), the injection of30 mL of 0.6% ropivacaine in the supra-clavicular fossa results in a very rapid onsetof sensory and motor block. In this setting,most patients will have a surgical block bythe time the needle is removed from thepatient’s skin and the block will be com-pletely set in 98% of patients after 5 mins.

The results in the report of Cohen and Grayare not surprising.3 Virtually all texts (oursincluded) advise practitioners of the seri-ous risks and sequelae of intraneural in-jection at the level of the nerve root orduring interscalene block.4 Moreover, theneedle used in this case (Cook EchoTip,Bloomington, Ind) is not designed for nerveblocks and has a bevel that is designed forvascular access or the biopsy/puncture ofcysts. In the video of Cohen and Gray, thenerve plexus does not move as the needleenters the plexus. This is distinctly differentfrom our experience and is likely related tothe type of bevel on the needle. In morethan 1000 supraclavicular intraneural injec-tions, we cannot recall being able to punc-ture the plexus with a blunt needle designedfor nerve block without indenting or mov-ing the nerve/plexus. Our experience usingultrasound guidance and needles that arenot designed for nerve block is similar toCohen and Gray’s. Sharp beveled needlescan penetrate the nerve without indentingor moving the nerve and in this settinglead to a high incidence of transient nervepraxias.4 In this scenario, it may be thechoice of needle bevel (lack of a tactile popor visualization of nerve movement) thatdid not alert the users to intraneural needleplacement. Finally, Cohen and Gray inter-pret their patient’s outcome as injury to theplexus and subsequent recovery. Althoughthis interpretation may be accurate, it isalso possible that the injection of a largedose of local anesthetic around or into afascicle may provide a long-acting reservoirof local anesthetic, which takes weeks tobe metabolized or reabsorbed from aroundor within the perineurium.5

The analogy between neuraxial an-esthesia and peripheral nerve block isgermane here. Despite case reports of per-manent nerve injury after spinal anesthesia,no one has called for its extermination, eventhough epidural anesthesia (which is per-formed outside the protective barrier ofthe axons) accomplishes most of the tasksof spinal anesthesia. Most practitionerswould agree that spinal anesthesia is morereliable at producing a surgical block thanepidural anesthesia; so too, intraneural in-jection is more reliable at producing surgi-cal anesthesia than extraneural injection inour hands.

Brachial plexus block can be ac-complished with as little as 4 mL of localanesthetic.6 Is it possible that 30 to 40 mLof local anesthetic deposited outside anerve or plexus is as dangerous or moredangerous than 3 to 4 mL of local anes-thetic deposited within the nerve or plexusbut outside the perineurium? No onewouldcriticize the use of 20 to 30 mL of localanesthetic for an epidural block, but cer-

tainly this dose would be inappropriate fora subarachnoid block and possibly toxic tothe nerve tissue.

At this time, it is difficult to deter-mine if intraneural injection of peripheralnerves is more or less dangerous than ex-traneural injection. The use of multiplemethods to prevent intraneural injectionis speculative, and in a study, it seemedto contribute to additional intraneural in-jections.7 To improve safety, it seemsmore prudent to recommend limiting thetype and dose of local anesthetic (as wellas additives) used and to recommend theuse of needles designed for nerve block.We believe that a scholarly debate at ournational meeting with both sides of theissue presented would help to enlighten ourreaders.

Paul E. Bigeleisen, MDDepartment of Anesthesiology

University of PittsburghPresbyterian University Hospital

Pittsburgh, PA

Jacques Chelly, MDDepartment of Anesthesiology

University of PittsburghShady Side Hospital

Pittsburgh, PA

REFERENCES

1. Neal JM, Wedel DJ. Ultrasound guidanceand peripheral nerve injury, is our vision assharp as we think it is? Reg Anesth Pain Med.2010;35:335Y337.

2. Reis W, Kurapati S, Shariat A,Hadzic A. Nerve injury complicatingultrasound/electrostimulation guidedsupraclavicular brachial plexus block.Reg Anesth Pain Med. 2010;35:400Y401.

3. Cohen JM, Gray AT. Functional deficitsafter intraneural injection during interscaleneblock. Reg Anesth Pain Med. 2010;35:397Y399.

4. Bigeleisen PE, Orebaugh SL, Moayeri N,Groen GJ, Breneman SM, Chelly J.Ultrasound-Guided Regional Anesthesia andPain Medicine. Baltimore, MD: LippincottWilliams and Wilkins; 2010:26Y38.

5. French JD, Strain WH, Jones GF. Mode ofextension of constrast substances injectedinto peripheral nerves. J Neuropathol ExpNeurol. 1948;7:47Y58.

6. O’Donnell B, Iohom G. An estimation ofthe minimum effective anesthetic volume of2% lidocaine in ultrasound-guided axillarybrachial plexus block. Anesthesiology.2009;111:25Y29.

7. Robards C, Hadzic A, Somasundaram L,et al. Intraneural injection with low currentstimulation during popliteal sciatic nerveblock. Anesth Analg. 2009;109:673Y677.




Neurologic Deficit inConjunction with

Intraneural Injection:More Questions than

AnswersAccepted for Publication: 1 September 2010

To the Editor:

I n the July-August issue of the journal,Cohen and Gray1 present an interesting

case of transient neurologic deficit in con-junction with a sonographically observedand recorded intraneural injection. Theauthors present a set of impeccable high-quality images as well as a video docu-menting the involved anatomical structuresbefore and after injection. Then they pro-ceed at discussing the possible causes forthe observed neurological deficit, alludingto the observed intraneural injection as thecausative event.1

I would like to present the readerswith an intriguing fact. On careful reviewof the excellent quality digital data pro-vided, it is clear to me that Bthe injectedbrachial plexus component[1 is indeed themiddle trunk/distal part of the C7 root ofthe brachial plexus. The clinical deficitsreported by Cohen and Gray, however,are consistent with a C5 and C6 or uppertrunk brachial plexopathy.

This discrepancy raises more ques-tions than I can discuss in this limitedspace. Is the plexus postfixed? Are thereother reasons for the axons to the mus-culocutaneous nerve to be carried by themiddle trunk? Could the neuropraxia besecondary to surgical causes? It is unfor-tunate that the authors have not obtainedan electrophysiologic study, which is stan-dard practice after nerve injury. That couldhave helped elucidate the causative eventof this case. Hence, unlike the authors, it isdifficult for me to conjure a cause-effectrelationship between a middle trunk intra-neural injection and upper trunk clinicalplexopathy. Although intraneural injectionis controversial and not standard practice,Cohen and Gray’s case report, otherwiseexquisitely well written and illustrated, isfar from providing strong evidence thatintraneural injection can result in neuro-logical injury.2

If anything, it could be used as evi-dence of the contrary.

Patrick Filip, MDAllegheny General Hospital

Pittsburgh, PA

REFERENCES

1. Cohen JM, Gray AT. Functional deficitsafter intraneural injection duringinterscalene block. Reg Anesthe Pain Med.2010;35:397Y399.

2. Neal JM, Wedel DJ. Ultrasound guidanceand peripheral nerve injury, is our visionas sharp as we think it is? Reg Anesth PainMed. 2010;35:335Y337.

Reply to Drs. Bigeleisen,Chelly, and Filip

Accepted for Publication: 9 September 2010

To the Editor:

T he authors thank Drs. Bigeleisenand Chelly for their detailed com-

ments1 on the recent set of publica-tions in Regional Anesthesia and Pain

Medicine, which address adverse clini-cal outcomes after intraneural injectionsas visualized with ultrasound imaging(Video, Supplemental Digital Content 1,http://links.lww.com/AAP/A24).2Y4 Indeed,previous reports written by these authorshave contributed significantly to our un-derstanding of intraneural injections.

We practice extraneural injections forregional anesthesia because of the overallefficacy and safety of these procedures.5

In the broad scope of this practice, wecontinue to recognize small incidentalintraneural injections on rare occasions(in the range of 1%Y2% of peripheralnerve blocks). The incidence of neu-rologic complaints and injury after re-gional blocks depends on the method offollow-up and timing.6 However, our pres-ent case clearly stands out as an adverseneurologic outcome. All discussion of thiscase must be placed in the context of morethan 10 thousand unremarkable blocks we

FIGURE 1. Tentative assignments of the sixth (A) and seventh (B) cervical transverseprocesses (T) based on bony morphology. The sixth cervical transverse process typicallyhas a ‘‘U’’ shape because of the relatively equal size of its anterior and posterior tubercles.The anterior tubercle of the seventh cervical transverse process is characteristically poorlydeveloped. The C5 and C6 ventral rami are identified in panel A (arrows), and in panel B,the C5, C6, and C7 ventral rami are identified (arrows) in short-axis view. Note that theseventh ventral ramus is bifascicular in echotexture as it exits the transverse process, as isthe sixth ventral ramus (B). The intraneural injection occurred within neural elementsderived from the identified seventh ventral ramus. The skin surface is at the top of theimages, L = posterolateral, with images 3 cm in depth.




have performed with ultrasound imagingduring the last decade.

Regarding the clinical management,an interscalene block was chosen becausethe patient was highly satisfied with theprevious block performed a week beforehis second shoulder surgery. His onlyreservation was that pain relief only lasted4 hrs after surgery, and now chronicshoulder pain symptoms had developed.The pharmacologic adjuncts (tetracaineand buprenorphine added to bupivacaine)were specifically chosen because of theneed for prolonged pain relief when anindwelling catheter was considered con-traindicated because of the proximity ofshoulder infection. Particularly impressivewas the absence of reported paresthesiaby the unsedated patient.

Once a block needle tip is intra-neural, a myriad of factors can potentiallyinfluence neurologic outcome after injec-tion including (1) bevel angle (sharp orblunt, with evidence supporting either oneas more safe), (2) bevel orientation (longi-tudinal or transverse to nerve fibers), (3)injection pressure and volume, (4) thespecific drugs injected, (5) whether nerveblood supply is damaged, (6) the anatomiclocation and regenerative capacity of thenerves, and (7) the exact needle tip loca-tion (extrafascicular versus intrafascicular,with the difference probably beyond theresolution of current ultrasound tech-nology).7Y12 The relative importance ofthese factors will be difficult to sort out inexperimental models let alone the clinicalarena. We are hard pressed to find similarcompelling evidence that these factorsinfluence neurologic outcome after extra-neural injections. Also germane to thisdiscussion are the potential advantagesof intraneural injections in block onsetkinetics and reduced volume of localanesthetic. For the reasons listed above,we agree that this debate will continue buthope that progress and resolution can bemade for patient safety and efficacy of ourinterventions.

The distinction between true nerveinjury and prolonged conduction blockfrom residual drug effect is presumablymade on the basis of intraneural drugconcentrations.13 Although certain radio-opaque dyes (since discontinued fromclinical use due to lack of resorption) canpersist after injection into peripheralnerves,14 we know of no evidence that thesame is true for any local anesthetic. Re-gardless of this formal distinction, ourpatient did not have full motor function ofhis upper extremity for 6 weeks, therebycompromising rehabilitation. The overallbevel angle of the block needle in question(20.3 [0.4] degrees, mean [SD]; n = 3

block needle samples, measured withphotomicroscopy) is within the range ofthose specifically designed and marketedfor regional anesthesia purposes.15 Thereare many determinants of nerve mobilitythat may influence the incidence of nerveimpalement in clinical practice, includingthe free-running course of the nerve,16

whether unyielding surfaces such as bonelie nearby,17 nerve stretching from patientpositioning,18 and the amount of trans-ducer compression.19 Whereas some ana-tomic locations may be more predisposedthan others to nerve injury, it is wellestablished that peripheral nerve connec-tive tissue content and fascicular archi-tecture varies considerably.20,21 Whetherultrasound imaging can accurately detectthose fascicular echotextures at higher riskfor needle injection injury remains anopen question (the present case argues thatit can not).

The authors thank Dr. Filip for hisinsights and comments22 on our report.He raises the central question of whetherthe neurologic findings were anatomicallyconsistent with recorded sonography. As

Dr. Filip himself has recently commented,there are inherent limitations to assigningcervical contributions to the brachialplexus.23 The criterion standard is to usefluoroscopy to establish cervical levelsrelative to the occiput, atlas, and axis.24

Ultrasound imaging can also be used toexamine cervical transverse process mor-phology and trace their respective ventralrami to the peripheral plexus for tentativeassignments.25 Neither of these were fullydone in the present case. However, therecorded sliding scans suggest the intra-neural injection occurred at the middletrunk (derived from a continuation of theventral ramus of C7; Fig. 1). Even withcorrect assignment, an additional layer ofcomplexity is to consider that the levels,functions, and peripheral nerve derivationare all subject to anatomic variation andthat collateral damage of adjacent nervesmay occur from needle injection injury(either within or outside the plane ofimaging).26

A prominent physical finding wasour patient’s near-complete loss of flex-ion at the elbow. The musculocutaneous

FIGURE 2. An artery (a) was identified within the posterior cervical triangle of the neckthat crosses the brachial plexus (A, sonogram; B, corresponding duplex power Dopplerimage). In this patient, the artery appears to separate the superior and middle trunks ofthe brachial plexus. These scans were obtained to avoid arterial puncture during brachialplexus block. The skin surface is at the top of the images, L = posterolateral, with images3 cm in depth.




nerve usually provides motor branches toall 3 flexor muscles (brachialis, coraco-brachialis, and biceps brachii). This nervecontains contributions from the fifth,sixth, and seventh cervical rami.27 Thefunction of flexion at the elbow is alsopartially served by the radial nerve (whichreceives contributions from all ventralrami of the brachial plexus) because itfrequently provides a small motor branchto the brachialis. Sensory and motorfunction of the axillary nerve seemed in-tact on postoperative day 1, suggestingthat at least part of the superior trunk wasspared from injury.

One anatomic variation was clearlyidentified on preprocedural scans (Fig. 2).An artery passed through the brachialplexus, with the intraneural injectionoccurring inferior to this crossing point.The dorsal scapular artery consistentlydivides the middle and inferior trunks ofthe brachial plexus.28,29 However, wesuspect that the identified artery in ourcase separates the superior and middletrunks of the plexus, in agreement with thedesignation of middle trunk injection.Electrodiagnostic studies were not donebecause of the gradual improvement insymptoms. Whereas these studies arecommonly performed for evaluation andmay have helped elucidate our patient’sneurologic deficits, we are not aware offormal standards in this setting.

Ultrasound and other imaging tech-nologies have limited ability to ascertainthe needle tip, nerve borders, and injectiondistribution (as does nerve stimulation).We reported the illustrations and accom-panying video footage of the present caseto help expedite this detection for readersand hopefully further improve the safetyof peripheral nerve blocks guided byultrasound.

Joshua M. Cohen, MD

Andrew T. Gray, MD, PhDDepartment of Anesthesia and

Perioperative CareSan Francisco General Hospital

University of CaliforniaSan Francisco

San Francisco, CA

REFERENCES

1. Bigeleisen PE, Chelly J. An unsubstantiatedcondemnation of intraneural injection. RegAnesth Pain Med. 2011;36:94.

2. Neal JM, Wedel DJ. Ultrasound guidanceand peripheral nerve injury: is our vision assharp as we think it is? Reg Anesth Pain Med.2010;35:335Y337.


4. Reiss W, Kurapati S, Shariat A,Hadzic A. Nerve injury complicatingultrasound/electrostimulationYguidedsupraclavicular brachial plexus block.Reg Anesth Pain Med. 2010;35:400Y401.

5. Gray AT. Atlas of Ultrasound-GuidedRegional Anesthesia. Philadelphia, PA:Saunders Elsevier, Inc; 2010:263Y273.

6. Liguori GA. Complications of regionalanesthesia: nerve injury and peripheralneural blockade. J Neurosurg Anesthesiol.2004;16:84Y86.

7. Selander D, Dhuner KG, Lundborg G.Peripheral nerve injury due to injectionneedles used for regional anesthesia. Anexperimental study of the acute effects ofneedle point trauma. Acta AnaesthesiolScand. 1977;21:182Y188.

8. Rice AS, McMahon SB. Peripheral nerveinjury caused by injection needles used inregional anaesthesia: influence of bevelconfiguration, studied in a rat model.Br J Anaesth. 1992;69:433Y438.

9. Gentili F, Hudson A, Kline DG, Hunter D.Peripheral nerve injection injury: anexperimental study. Neurosurgery.1979;4:244Y253.

10. Gentili F, Hudson AR, Hunter D. Clinicaland experimental aspects of injection injuriesof peripheral nerves. Can J Neurol Sci.1980;7:143Y151.

11. Hadzic A, Dilberovic F, Shah S, et al.Combination of intraneural injection andhigh injection pressure leads to fascicularinjury and neurologic deficits in dogs.Reg Anesth Pain Med. 2004;29:417Y423.

12. Sunderland S. The relative susceptibilityto injury of the medial and lateral poplitealdivisions of the sciatic nerve. Br J Surg.1953;41:300Y302.

13. Popitz-Bergez FA, Leeson S, Strichartz GR,Thalhammer JG. Relation between functionaldeficit and intraneural local anestheticduring peripheral nerve block. A study inthe rat sciatic nerve. Anesthesiology.1995;83:583Y592.

14. French JD, Strain WH, Jones GE. Modeof extension of contrast substances injectedinto peripheral nerves. J Neuropathol ExpNeurol. 1948;7:47Y58.

15. Maecken T, Zenz M, Grau T. Ultrasoundcharacteristics of needles for regionalanesthesia. Reg Anesth Pain Med.2007;32:440Y447.

16. Peer S, Bodner G, eds. High-ResolutionSonography of the Peripheral NervousSystem. Berlin: Springer Verlag; 2003.

17. Lofstrom B, Wennberg A, Wien L. Latedisturbances in nerve function afterblock with local anaesthetic agents. An

electroneurographic study. Acta AnaesthesiolScand. 1966;10:111Y122.

18. Boyd BS, Wanek L, Gray AT, Topp KS.Mechanosensitivity of the lower extremitynervous system during straight-leg raiseneurodynamic testing in healthy individuals.J Orthop Sports Phys Ther. 2009;39:780Y790.

19. Perlas A, Chan VW, Simons M. Brachialplexus examination and localization usingultrasound and electrical stimulation: avolunteer study. Anesthesiology. 2003;99:429Y435.

20. Sunderland S, Bradley KC. Thecross-sectional area of peripheral nervetrunks devoted to nerve fibers. Brain.1949;72:428Y449.

21. Sunderland S. The connective tissues ofperipheral nerves. Brain. 1965;88:841Y854.

22. Filip P. Neurologic deficit in conjunctionwith intraneural injection: more questionsthan answers. Reg Anesth Pain Med.2011;36:95.

23. Filip P. Complex arithmetic at the brachialplexus roots. Reg Anesth Pain Med.2009;34:79Y80.

24. Narouze SN, Vydyanathan A, Kapural L,Sessler DI, Mekhail N. Ultrasound-guidedcervical selective nerve root block: afluoroscopy-controlled feasibility study.Reg Anesth Pain Med. 2009;34:343Y348.

25. Martinoli C, Bianchi S, Santacroce E,Pugliese F, Graif M, Derchi LE. Brachialplexus sonography: a technique for assessingthe root level. AJR Am J Roentgenol.2002;179:699Y702.

26. Selander D, Sjostrand J. Longitudinal spreadof intraneurally injected local anesthetics.An experimental study of the initial neuraldistribution following intraneural injections.Acta Anaesthesiol Scand. 1978;22:622Y634.

27. Hu SN, ZhouWJ,WangH, et al. Origination ofthe brachialis branch of the musculocutaneousnerve: an electrophysiological study.Neurosurgery. 2008;62:908Y911.

28. Demondion X, Boutry N, Drizenko A,Paul C, Francke JP, Cotten A. Thoracic outlet:anatomic correlation with MR imaging. AJRAm J Roentgenol. 2000;175:417Y422.

29. Weiglein AH, Moriggl B, Schalk C,Kunzel KH, Muller U. Arteries in theposterior cervical triangle in man.Clin Anat. 2005;18:553Y557.

Intraneural InjectionsAccepted for Publication: 13 September 2010

To the Editor:

W e respectfully disagree with Drs.Bigeleisen and Chelly’s boldly as-

sertive stance on benefits and apparentsafety of intraneural injections. The dis-missal of the dangers of intraneural




injections is at odds with the plethora ofliterature on the potential risk for devas-tating neurologic complications of in-traneural, intrafascicular injections1 andcannot be supported by nonYpeer-reviewedpublications, such as book chapters.2 Theanalogy between spinal anesthesia and in-traneural injection with peripheral nerveblocks is not germane as the former com-prises an injection into the subarachnoidspace that is filled with cerebrospinalfluid, whereas the latter is a violation ofthe densely packed peripheral nerves.Intraneural needle placement is alwaysaccompanied by an adverse nerve re-sponse, such as intraneural inflamma-tion.3 Fapojuwo et al4 have recently starklyrefreshed our memory of the potential forsevere nerve injury with intraneural in-jection with their report of 160 cases ofdebilitating sciatic neuropathy after glu-teal intramuscular injections.

Drs. Bigeleisen and Chelly argue thatin the case by Reiss et al, an intraneuralinjection did not occur because the blocktook 15 mins to reach full onset. We dis-agree; injection into 1 trunk does not nec-essarily lead to an unusually rapid onsetof the block in the entire plexus.

O’Donnell and Iohom,5 Latzke et al,6

and Eichenberger et al7 have all reportedthat miniscule volumes of local anes-thetics (e1 mL/nerve) result in rapid onsetof nerve blockade when deposited underultrasound guidance outside the peripheralnerves. If so, what can be gained with anintentional intraneural injection, except anunnecessary risk?

We agree with Drs. Bigeleisen andChelly that the discussion on this andother emerging anecdotal observationswith ultrasound-guided blocks shouldregularly take place at a national leader-ship level. Until a consensus on safety ofintraneural injections is reached, our po-sition is that such should not be recom-mended as standard practice.

Wojciech Reiss, MD

Ali Nima Shariat, MD

Sushmitha Kurapati, MD

Admir Hadzic, MD, PhDDepartment of Anesthesiology

St Luke’sYRoosevelt Hospital CenterNew York, NY

REFERENCES

1. Mackinnon SE, Hudson AR, Llamas F,Dellon AL, Kline DG, Hunter DA.Peripheral nerve injury by chymopapaininjection. J Neurosurg. 1984;61:1Y8.

2. Bigeleisen PE, Orebaugh S, Moayeri N,Groen G, Breneman S, Chelly J.Ultrasound-Guided Regional Anaesthesiaand Pain Medicine. 1st ed. Philadelphia, PA:Lippincott Williams and Wilkins; 2010.

3. Lupu CM, Kiehl TR, Chan VW, El-BeheiryH, Madden M, Brull R. Nerve expansionseen on ultrasound predicts histologic butnot functional nerve injury after intraneuralinjection in pigs. Reg Anesth Pain Med.2010;35:132Y139.

4. Fapojuwo OA, Akinlade TS, Gbiri CA.A three year review of sciatic nerve injectionpalsy in the Physiotherapy Department of aNigerian Specialist Hospital. Afr J Med MedSci. 2008;37:389Y393.

5. O’Donnell BD, Iohom G. An estimation of theminimum effective anesthetic volume of 2%lidocaine in ultrasound-guided axillary brachialplexus block. Anesthesiology. 2009;111:25Y29.

6. Latzke D, Marhofer P, Zeitlinger M, et al.Minimal local anaesthetic volumes forsciatic nerve block: evaluation of ED 99 involunteers. Br J Anaesth. 2010;104:239Y244.

7. Eichenberger U, Stockli S, Marhofer P, et al.Minimal local anesthetic volume for peripheralnerve block: a new ultrasound-guided nervedimensionYbased model. Reg Anesth PainMed. 2009;34:242Y246.

Reply to Drs. Bigeleisen,Chelly, and Filip

Accepted for Publication: September 21, 2010

To the Editor:

W e thank Drs. Bigeleisen and Chelly1

and Dr. Filip2 for their criticismsregarding our editorial,3 which was writ-ten as a commentary on case reports byCohen and Gray4 and Reiss et al5 thatdescribed peripheral nerve injury in thesetting of ultrasound-guided regional an-esthesia. The central theme of both lettersto the editor is that the case reports andeditorial represent Ban unsubstantiated con-demnation of intraneural injection.[1 Webelieve this debate to be an important oneand appreciate the unique perspectives of-fered by Dr. Bigeleisen and his colleagues.

The primary purpose of our editorialwas to highlight the reports of peripheralnerve injury occurring despite the useof ultrasound-guided regional anesthesia,which together with an evidence-basedreview6 challenges the hope of some anes-thesiologists that ultrasound guidance willprevent nerve injury. Nevertheless, the ed-itorial did agree with the basic assertions ofCohen and Gray4 and Reiss et al5 that in-tentional intraneural injection is a practicewith an unknown, but potentially high,

risk-to-benefit ratio. The accompanyingresponses in this issue of Regional Anes-thesia and Pain Medicine by Cohen andGray7 and by Reiss et al8 defend theirpatient management and conclusions re-garding causation. One issue not directlyaddressed by these respondents is the as-sertion by Bigeleisen and Chelly1 that lim-iting the type and dose of local anestheticmay be more prudent than avoiding in-traneural needle placement when the goalis improved safety. Based on animal datathat clearly link nerve injury severity tolocal anesthetic concentration,9 we partiallyagree their recommendation regardinglocal anesthetic. However, the landmarkanimal studies of Selander et al10,11 suggestthat even miniscule volumes of local anes-thetic (0.01Y0.5 mL) are capable of causingnerve injury in the setting of increasedintraneural pressure or mechanically dam-aged nerves; thus, we remain unconvincedthat limiting local anesthetic volume is re-levant once a nerve has sustained needleinjury. We have little to add to our editorialstance other than to emphasize that our in-terpretation of the existing peer-reviewedliterature of anesthesia-related peripheralnerve injury is that intraneural injectionis probably best avoided,12 even while ac-knowledging that recent ultrasound-basedstudies demonstrate unintentional intraneu-ral injection (most presumably are extra-fascicular) occurs much more frequentlyduring peripheral nerve stimulation, andperhaps ultrasound guidance, than suspectedpreviously.3,13

We agree with our critics that the fullrisks and benefits of intentional intra-neural injection are currently unknown.We applaud and support Drs. Bigeleisenand Chelly’s call for open scholarly debateon this topic. In closing, we have chosento interpret the existing literature conser-vatively while awaiting definitive answersto these important questions. Ultimately,only future peer-reviewed research willallow us to confidently understand thisissue.

Joseph M. Neal, MDDepartment of Anesthesiology


Denise J. Wedel, MDDepartment of Anesthesiology

Mayo Clinic College of MedicineRochester, MN

REFERENCES

1. Bigeleisen PE, Chelly J. An unsubstantiatedcondemnation of intra-neural injection.Reg Anesth Pain Med. 2011;36:94.




2. Filip P. Neurologic deficit in conjunctionwith intraneural injection: more questionsthan answers. Reg Anesth Pain Med. 2011;36:95.

3. Neal JM, Wedel DJ. Ultrasound guidanceand peripheral nerve injury. Is our vision assharp as we think it is? Reg Anesth Pain Med.2010;35:335Y337.


5. Reiss W, Kurapati S, Shariat A, Hadzic A.Nerve injury complicating ultrasound/electrostimulation-guided supraclavicularbrachial plexus block. Reg Anesth Pain Med.2010;35:400Y401.

6. Neal JM, Brull R, Chan VWS, et al. TheASRA evidence-based medicineassessment of ultrasound-guided regionalanesthesia and pain medicine: executivesummary. Reg Anesth Pain Med.2010;35:S1YS9.

7. Cohen JM, Gray AT. Reply to Dr. Bigeleisen.Reg Anesth Pain Med. 2011;36:95Y97.

8. Reiss W, Kurapati S, Shariat A, Hadzic A.Intraneural injections. Reg Anesth Pain Med.2011;36:97Y98.

9. Bainton CR, Strichartz GR. Concentrationdependence of lidocaine-inducedirreversible conduction loss in frognerve. Anesthesiology. 1994;81:657Y667.

10. Selander D, Sjostrand J. Longitudinalspread of intraneurally injected localanesthestics. An experimental study ofthe initial neural distribution followingintraneural injections. Acta AnaesthesiolScand. 1978;22:622Y634.

11. Selander D, Brattsand R, Lundborg G,Nordborg C, Olsson Y. Local anesthetics:importance of mode of application,concentration and adrenaline for theappearance of nerve lesions. ActaAnaesthesiol Scand. 1979;23:127Y136.

12. Neal JM, Gerancher JC, Hebl JR, et al.Upper extremity regional anesthesia.Essentials of our current understanding,2008. Reg Anesth Pain Med. 2009;34:134Y170.

13. Orebaugh SL, McFadden K, Skorupan H,Bigeleisen PE. Subepineurial injection inultrasound-guided interscalene needletip placement. Reg Anesth Pain Med.2010;35:450Y454.

Recognizing DangerousIntraneural Injection:Is It the Musician orthe Instrument?


To the Editor:

W e read with interest the enlighteningeditorial by Neal and Wedel1 regard-

ing the challenges of real-time ultrasound(US) in detecting inadvertent intraneural in-jection and preventing nerve injury. Theselimitations are echoed in the AmericanSociety of Regional Anesthesia and PainMedicineYsponsored evidence-based reviewof US-guided regional anesthesia recentlypublished in this journal, which concludedthat a superior safety profile with respectto nerve injury cannotVand likely willneverVbe demonstrated for US comparedwith traditional nerve localization tech-niques. One explanation offered to supportthis conclusion was that the Bcharacteristicsof US machines vary [and], acoustic reso-lution is limited.[2 Indeed, there have nowbeen various reports3Y5 of unintentional in-traneural injection despite the vigilant useof US guidance, some of which resulted invarying degrees of nerve damage.However,what is common to each of these reports isthe retrospective recognition of intraneuralinjection following subsequent review ofthe stored images. Although the authorsof each of these 3 reports are experts inUS-guided regional anesthesia, they none-theless apparently failed to recognize intra-neural needle tip placement and intraneuralinjection during US-guided block perfor-mance. It thus begs the question: Is it themusician or the instrument? We proposethat the limitation lies with the former, inthat we as providers still do not reliablyknow what changes in nerve sonoanatomyconstitute an intraneural injection and,morespecifically and importantly, a dangerousintraneural injection. It seems probable thatthe sonocharacteristics of an intraneuralinjection are quite different depending onthe type and location of the nerve6,7; muchlike the motor responses to nerve stimula-tion,8,9 and arguably the propensity fornerve injury,10 vary depending on nervetype. Inevitably, pathognomonic sono-graphic features of intraneural injectionsand hazardous patterns of local anesthetic

spread will declare themselves as we con-tinue to gain experience with US technol-ogy, but at present, we may be shortsightedto blame our own limitations on the qualityof our instrument.

Shane McGeary, MB, FCARCSI

Vincent Chan, MD, FRCPC

Richard Brull, MD, FRCPCDepartment of Anesthesia and Pain Management

Toronto Western HospitalToronto, Ontario, Canada

REFERENCES

1. Neal JM, Wedel DJ. Ultrasound guidance andperipheral nerve injury: is our vision as sharpas we think it is? Reg Anesth Pain Med.2010;35:335Y337.

2. Neal JM. Ultrasound-guided regionalanesthesia and patient safety. Reg AnesthPain Med. 2010;35:S59YS67.

3. Cohen JM, Gray AT. Functional deficits afterintraneural injection during interscalene block.Reg Anesth Pain Med. 2010;35:397Y399.

4. Russon K, Blanco R. Accidental intraneuralinjection into the musculocutaneous nervevisualised with ultrasound. Anesth Analg.2007;105:1504Y1505.

5. Schafhalter-Zoppoth I, Zeitz ID, Gray AT.Inadvertent femoral nerve impalement andintraneural injection visualised by ultrasound.Anesth Analg. 2004;99:627Y628.

6. Bigeleisen PE, Groen G, Moayeri N.Ultrasound-guided supraclavicular block:what is intraneural? Anesthesiology. 2010;112:251Y252.

7. Morfey D, Brull R. Ultrasound-guidedsupraclavicular block: what is intraneural?Anesthesiology. 2010;112:250Y251.

8. Sauter AR, Dodgson MS, Stubhaug A,Cvancarova M, Klaastad O. Ultrasoundcontrolled nerve stimulation in the elbowregion: high currents and short distancesneeded to obtain motor responses. ActaAnaesthesiol Scand. 2007;51:942Y948.

9. Moayeri N, Bigeleisen PE, Groen G.Quantitative architecture of the brachialplexus and surrounding compartments, andtheir possible significance for brachialblocks. Anesthesiology. 2008:108:299Y304.

10. Moayeri N, Groen GJ. Differences inquantitative architecture of sciatic nerve mayexplain differences in potential vulnerabilityto nerve injury, onset time, and minimumeffective anesthetic volume. Anesthesiology.2009;111:1128Y1134.



accurate placement 4 ultrasound-guided peripheral nerve ... · continuous popliteal sciatic nerve...

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