Volume 21, Issue 1, Pages 1-121 (February 2005) Brachial Plexus Injuries in Adults Edited by Allen T. Bishop, Robert J. Spinner, Alexander Y. Shin articles 1 - 13 1 Brachial plexus injuries in adults Pages ix-x Allen T. Bishop, Robert J. Spinner and Alexander Y. Shin 2 Clinically relevant surgical anatomy and exposures of the brachial plexus Pages 1-11 Alexander Y. Shin and Robert J. Spinner 3 Adult brachial plexus injuries: mechanism, patterns of injury, and physical diagnosis Pages 13-24 Steven L. Moran, Scott P. Steinmann and Alexander Y. Shin 4 Imaging the brachial plexus Pages 25-37 Kimberly K. Amrami and John D. Port 5 Preoperative and intraoperative electrophysiologic assessment of brachial plexus injuries Pages 39-46 C. Michel Harper 6 Planning brachial plexus surgery: treatment options and priorities Pages 47-54 Robert H. Brophy and Scott W. Wolfe 7 Direct plexus repair by grafts supplemented by nerve transfers Pages 55-69 David G. Kline and Robert L. Tiel 8 Nerve transfers in adult brachial plexus injuries: my methods Pages 71-82 David Chwei-Chin Chuang 9 Brachial plexus injuries in the adult. nerve transfers: the Siriraj Hospital experience Pages 83-89 Panupan Songcharoen, Saichol Wongtrakul and Robert J. Spinner 10 Functioning free-muscle transfer for brachial plexus injury Pages 91-102 Allen T. Bishop 11 Pre-/postoperative therapy for adult plexus injury Pages 103-108 Denise Kinlaw 12 Repair of avulsed ventral nerve roots by direct ventral intraspinal implantation after brachial plexus injury Pages 109-118 Henri D. Fournier, Philippe Mercier and Philippe Menei 13 Index Pages 119-121 HandClin21(2005)ix–x Preface Brachial Plexus Injuries in Adults AllenT.Bishop,MD RobertJ.Spinner,MD AlexanderY.Shin,MD GuestEditors Thelossofupperextremityfunctionfollowing the reconstructive team and patient are substan- a traumatic brachial plexus injury causes devas- tial.Successfuloutcomesrequirenotonlyconsid- tating functional deficits that require complex eration of the nature of the plexus injury surgical reconstruction. Because of advances and (includinglocation, mechanism,andelapsedtime innovations in surgical techniques, it is now from injury) and presence of associated injuries possible to reliably restore elbow flexion and but also surgical expertise, practical operative- shoulder stability, provided intervention is timeconstraints,andabilitytoprovideandattend prompt. Recently, innovations have provided prolongedpostoperative rehabilitation. additional surgical reconstructive options that In this monograph, an international group of can be expected to improve functional outcomes. experts has distilled the current state-of-the-art For example, methods are available that may, at inevaluationandmanagementofbrachialplexus times,restorebasicgraspfunctioninpatientswith injury. The concept for the monograph arose lower plexus rupture or avulsion. Surgeons from during a recent skills course held at the Mayo all disciplines must be cognizant of these new Clinic under the sponsorship of the American possibilities and seek out additional training or SocietyforSurgeryoftheHandandendorsement partnerships across specialty boundaries to pro- of the Congress of Neurological Surgeons. The vide the best possible care in these devastating contributors are derived from that faculty and injuries. In many such reconstructive schemes, were selected based on their experience, knowl- nervetransferfrommultipleintra-andextraplexal edge, and innovative approach to the evaluation donornerves and microvascular transfer of func- and managementof this difficult problem. tioning free muscles to the paralyzed limb are It is our hope that these efforts will help integralpartsofthetotalreconstructiveplan.The clinicians caring for these unfortunate patients complexityandrigoroftheseproceduresforboth and, perhaps most important, to enable 0749-0712/05/$-seefrontmatter(cid:1)2005ElsevierInc.Allrightsreserved. doi:10.1016/j.hcl.2004.10.001 hand.theclinics.com x PREFACE appropriateevaluationandtimelyreferraltocen- Robert J. Spinner, MD terswithexpertiseinbrachialplexuscare.Further, Departments ofNeurologic Surgery, the experience of the authors should provide a Orthopedics,andAnatomy means to allow surgeons to improve patient out- Mayo Clinic Schoolof Medicine comes, and allow clinical investigators to further 200First Street,SW refineandimprovethecurrentstateoftheart. Rochester,MN 55905,USA E-mail address:[email protected] Allen T. Bishop,MD Division of HandSurgery AlexanderY. Shin,MD Department ofOrthopedic Surgery OrthopedicHandandMicrovascular Surgery MayoClinic MayoMedical School 200First Street, SW 200First Street,SW Rochester, MN55905,USA Rochester,MN 55905,USA E-mail address:[email protected] E-mailaddress: [email protected] HandClin21(2005)1–11 Clinically Relevant Surgical Anatomy and Exposures of the Brachial Plexus Alexander Y. Shin, MDa,*, Robert J. Spinner, MDb aDivisionofHandSurgery,DepartmentofOrthopedicSurgery,MayoClinic,Rochester,MN55905,USA bDepartmentofNeurosurgery,MayoClinic,200FirstStreetSW,Rochester,MN55905,USA Qu’ilsn’oublientjamaisquesansanatomieiln’y C8) and that of the first thoracic nerve (T1; apointde physiologie,pointdechirurgie, point Fig. 1). Although a frequent percentage of bra- demedicine. chial plexuses have contributions from C4 (pre- —J.CruveilhierTraited’Anatomie fixed) [1–3] or T2 (postfixed) [2,4,5], these Descriptive(1834) contributions havelittle clinical significance. Thecomplexanatomyofthebrachialplexusis The true form of the brachial plexus has been probably one of the most anxiety-provoking best described by Kerr [2], who performed de- subjectsofmedicalschoolandresidencycurricula. tailedanatomicdissectionson175specimens(see Surgical exploration of this area, however, de- Fig.1).Inthe‘‘trueform,’’thecomponentsofthe mands a clear and concise understanding of the brachial plexus include the following: roots, normal anatomy and its variations, including the trunks, divisions, cords, and terminal branches. pathoanatomy. This article summarizes several Five roots form three trunks, which form six hundredyearsofliteratureontheanatomyofthe divisions.Thesedivisionsformthreecords,which brachial plexus and then describes common sur- ultimatelyformfiveterminalbranches.Rootsand gicalexposurestohighlighttheclinicallyrelevant trunks are found supraclavicularly; divisions are features. located retroclavicularly; and cords and terminal branches comprise the infraclavicularportion. C5 and C6, and C8 and T1 roots merge to Generaloverview of thebrachial plexus formtheupperandlowertrunks.C7becomesthe Thebrachialplexusrunswithintheinterscalene middle trunk. The point at which C5 and C6 triangle(formedbytheanteriorscaleneanteriorly, merge is known as Erb’s point. The upper trunk the middle scalene posteriorly, and the superior trifurcates;thesuprascapularnerveemergesfrom border of the first rib inferiorly). The brachial theuppertrunkandthetwodivisionsareformed. plexusisalsolocatedwithintheposteriortriangle Eachtrunkdividesintoananteriorandposterior of the neck (formed by the sternocleidomastoid division, and passes beneath the clavicle. The (SCM) medially, the trapezius laterally, and the posterior divisions from the trunks merge to clavicleinferiorly). become the posterior cord, and the anterior The brachial plexus is the network of nerves divisions of the upper and middle trunk merge thatprovidessensationandfunctiontotheupper to form the lateral cord. The anterior division extremity. It is formed from the ventral primary from the lower trunkforms the medial cord.The rami of the lowest four cervical nerve roots (C5– lateralcordsplitsintotwoterminalbranches:the musculocutaneous nerve and the lateral cord contribution to the median nerve (the so-called * Correspondingauthor. ‘‘sensory’’ part). The posterior cord forms the E-mailaddress:[email protected] axillarynerveandtheradialnerve,andthemedial (A.Y.Shin). cordgivesoffthemedialcordcontributiontothe 0749-0712/05/$-seefrontmatter(cid:1)2005ElsevierInc.Allrightsreserved. doi:10.1016/j.hcl.2004.09.006 hand.theclinics.com 2 SHIN&SPINNER Fig. 1. The fiveportionsofthe brachialplexus are drawnout and separatedinto roots,trunks,division,cords, and terminalbranches.LSS,lowersubscapularnerve;MABC,medialantebrachialcutaneousnerve;MBC,medialbrachial cutaneous nerve; TD, thoracodorsal nerve; USS, upper subscapular nerve. (Courtesy of the Mayo Foundation, Rochester,MN;withpermission.) mediannerve(theso-called‘‘motor’’part)andthe Common variationsof thebrachial plexus ulnarnerve. Overall variations to the brachial plexus have There are a few terminal branches that come beenreportedinmorethan50%ofcases[6].The off the roots, trunks, and cords. The branches most common variations of the brachial plexus fromtheC5rootincludethedorsalscapularnerve arerelatedtothecontributionsofC4andT2—the (rhomboidmuscles),abranchtothephrenicnerve prefixedandpostfixedbrachialplexus.Ithasbeen (with C3 and C4), and a branch to the long estimated that C4 will be contributory in 28%to thoracic nerve (serratus anterior muscle). 62% of patients based on the dissection of BranchesfromtheC6andC7nervealsocontrib- brachial plexuses in cadavers (Fig. 2) [1–3]. The ute to the long thoracic nerve. The branches off incidence of postfixed brachial plexuses ranges the upper trunk include the nerve to the subcla- from16%to73%(Fig.3)[2,4,5].Thesebranches vius muscle (clinically unimportant) and the range from verysmallto significantsize. suprascapular nerve. The lateral cord gives off Variations in the trunk level are relatively the lateral pectoral nerve, whereas the posterior uncommon.Approximately 90%ofuppertrunks and medial cords each have three branches. The are formed by the confluence of C5 and C6, posterior cord typically gives off branches (prox- whereas in 8%, the upper trunk does not ex- imaltodistal)thatincludetheuppersubscapular ist—C5 and C6 immediately split into divisions nerve, the thoracodorsal nerve, and the lower [2]. In the remaining 2% of upper trunks, C7 subscapular nerve. The medial cord gives off the joined C5 and C6, and then divided into two medial pectoral nerve, the medial brachial cuta- parts.Themiddletrunk,whichisthecontinuation neous nerve, and the medial antebrachial cutane- of C7, was the normal finding in 93.7% of ousnerve. SURGICALANATOMY&EXPOSURES 3 Fig.2. ThemostcommonvariationinthebrachialplexusisvariabilityofcontributionsofC4tothebrachialplexus. ThiscontributionofC4nervefiberstothebrachialplexusisalsoknownasaprefixedplexus.(CourtesyoftheMayo Foundation,Rochester,MN;withpermission.) specimens, whereas 3% of specimens had the hasbeenfoundtocomefromtheuppertrunkorits middle trunk divide into two anterior divisions anterior or posterior divisions in more than 82% and one posterior division. The lower trunk was ofspecimens[2].Occasionally,C4maycontribute formedbytheconfluenceofC8andT1in95.4% directlytothesuprascapularnerve.Italsomaybe ofspecimens [2]. aterminalbranchoffofC5withasmallcontribu- Acommonvariationofthelateralcordisforit tion to C6 [7]. The musculocutaneous nerve is tocontributetotheulnarnerve,andthisvariation commonlyassociatedwithvariations.Kaplanand hasbeenreportedtooccurasfrequentlyas42.9% Spinner[8]notedthatthisnervemayseemabsent [2]. Another common variation is the size of the becauseofa‘‘doublemusculocutaneousnerve’’or lateral cord contribution to the median nerve: a combined median/musculocutaneous nerve. In whenthisissmall,thereisoftenacommunication 24%ofspecimens,therewereC7fiberspresentin of the musculocutaneous nerve to the median the musculocutaneous nerve, and these fibers nerveinthearm.Theanatomyofthemedialcord passed through a communication from the mus- isrelativelyconstant;ithasbeenfoundtoreceive culocutaneousnervetothemediannerve[8].Alow contributionsfromC8andT1in94.6%ofspeci- take-off of the musculocutaneous nerve from the mensandhasfewreportedvariations.Theposte- lateralcordmayconfusethesurgeon,especiallyif riorcordhasbeenreportedtobeabsentin20.8% he or she is using a small infraclavicular incision of cadavers. In these specimens, the radial and anddoesnotidentifythisnervebranchwithinthe axillary nerves arose independently from the surgicalfield.Theposteriorcord,withitsterminal brachialplexus. branches, the axillary and radial nerve, is also Variations in the terminal branches are com- frequentlyvariant.Theradialnervecomesoffthe mon. A discussion of every reported variation is posterior cord in its classic position in 79% of beyond the scope of this article; only the most specimens [2]. The variations include the radial commonlyencounteredvariationsintheterminal nerve coming off the posterior division of the branches are discussed. The suprascapular nerve upperandmiddletrunk.Theaxillarynervearises 4 SHIN&SPINNER Fig.3. ThepostfixedbrachialplexushasavariablecontributionofT2tothebrachialplexus.(CourtesyoftheMayo Foundation,Rochester,MN;withpermission.) in its classic position in 79.9% of specimens but every level, each of the roots is formed by the can also arise from the upper and middle trunk joining of dorsal (sensory) rootlets and ventral divisionsdirectly[2]. (motor) rootlets off the spinal cord as they pass The axillary artery and its relationship to the through the spinal foramen (Fig. 5A). The cell brachial plexus elements may also be variant. bodies of the sensory nerves lie within ganglia Typically, at the level of the coracoid, the three outsidethespinalcord(ie,thedorsalrootganglia cordsarenamedfortheiranatomicrelationshipto [DRG]).Therootletsthatformthecervicalroots the axillary artery: lateral, medial, and posterior are intraspinal and lack connective tissue or cords (Fig. 4). Occasionally, a large superficial a meningeal envelope. This anatomic feature branch of the axillary artery will emerge between makesthemvulnerabletotractionandsusceptible the medial and lateral cord contribution to the to avulsion at the level of the spinal cord. The mediannervetocourseintothearmasasuperfi- meningeal layers are continuous as roots are cial radial, ulnar, brachial, or median artery. In formed. For example, the dura changes to epi- addition to this variation, Miller [9] reported neurium within the foramen and is continuous several vascular anomalous relationships (occur- with it.The extraspinal nervewithinthe foramen ring in 8 of 480 specimens) where the median has a protective covering formed by the coales- nerve below the convergence of the medial and cence of the dura. lateral contributions was penetrated and divided The spinal nerve is able to move freely within by a branch of the axillary artery. Overall, the the foramina because it is not attached to it. The author reported 8% arterial and 4% venous nerverootsrundownchutesastheyemergefrom variationsassociated withthe brachialplexus. their respective foramina. There is a fibrous at- tachment of the spinal nerves to the transverse processthatisseeninthefourththroughseventh cervical root, which firmly attaches the nerves to Pathoanatomy the transverse process by an epineural sheath, The anatomy of the rootlets, roots, and the prevertebral fascia, and fibrous slips. C8 and T1 vertebralforamencontributestothetypeofinjury do not have these connective tissue attachments. (avulsion versus rupture) that is observed. At This anatomic arrangement explains the higher SURGICALANATOMY&EXPOSURES 5 the anatomic considerations of a preganglionic injury. Physical examination may provide clues thattheinjuryoccurredatleastclosetothelevelof DRG(orforaminallevel).Thesecluesmayinclude weaknessoftherhomboidsortheserratusanterior orthefindingofaHorner’ssyndrome—theresul- tant loss of sympathetic outflow to the head and neck results, producing meiosis (small pupil), enophthalmos (sinking of the eyeball), ptosis (lid droop),andanhydrosis(dryeyes)oftheipsilateral face.ThesympatheticganglionforT1liesinclose proximitytotheT1rootandprovidessympathetic outflowtotheheadandneck.Becauseofthisclose association, avulsion of the T1 root typically causesinterruptionoftheT1sympatheticganglion (Fig.7).Fibrillationsinparaspinalmuscles(which areinnervatedbythedorsalprimaryrami,which ariseattheexitoftheintervertebralforamen)also wouldsuggestapreganglionicinjury.Inaddition, Fig. 4. The relationship of the axillary artery to the cords is an important anatomic relationship. The inpreganglionicinjury,sensorynerveconduction cords surround the axillary artery and are named for studieswilloftenbepreservedwhen,clinically,the their position with respect to the axillary artery. LC, patientisinsensate,becausethesensorynervecell lateral cord; MC, medial cord; PC, posterior cord. bodyisintactwithintheDRG.Chestradiographs (Courtesy of the Mayo Foundation, Rochester, MN; may show an elevated hemidiaphragm (from withpermission.) phrenic nerve dysfunction) or cervical films may show transverse process fractures. A CT-myelo- incidence of root avulsion in the lower two roots gram may show pseudomeningoceles or an MRI comparedwiththe upperthreeroots. mayrevealabsentnerverootlets. When an injury causes the tearing of the rootlets from the spinal cord proximal to the DRG, the injury is classified as preganglionic or Anatomic considerations of postganglionicinjuries a rootavulsion. Preganglionic injuries may occur The anatomic configuration of the brachial centrally, where the nerve is torn directly from plexus predisposes it to injury at sites where it is the spinal cord, or peripherally (an intradural relatively fixed to the surrounding tissues. These rupture), where the injury is proximal to the points can occur when branches take off from DRG but remnants of the rootlets are still larger nerve structures, or when nerves are teth- attached to the spinal cord (Fig. 5B). When an ered by soft tissue (eg, muscles, ligaments, ten- injury is distal to the DRG, it is called post- dons)orosseousstructures.Oneofthemorewell ganglionic. This type of stretch lesion may cause know points of tethering is that of Erb’s point, a disruption of the cervical root, or a rupture wherethesuprascapularnervecomesofftheupper (Figs. 5C, D, and 6). trunk. Because the upper trunk is relatively The implications that pre- versus postgangli- tethered, and the suprascapular nerve and the onic injuries have in surgical reconstruction are divisionoftheuppertrunkarerelativelyfree,itis enormous. For practical purposes, the nerve a common site of a rupture. The suprascapular connections in preganglionic injuries cannot be nerve is also bound at the suprascapular notch, restored, and thus alternative nerves (eg, nerve and with displacement of the scapula from trau- transfers) must be used to reanimate the injured ma,thesuprascapularnervecansustainarupture extremity. In postganglionic injuries, the nerve at this location as well. The clavicle can also connections can be restored with interpositional contributetobrachialplexusinjuriesatthelevelof nervegraftingto restore function. the divisions. The axillary nerve, as it passes posteriorly after its take-off from the posterior Anatomic considerationsof preganglionic injuries cord, istetheredby the softtissue,which isoften Clinical examination and electrodiagnostic or asiteforitsrupture.Inaddition,theaxillarynerve imaging studies can provide evidence to support canbeinjuredwithinthequadrangularspace. 6 SHIN&SPINNER Fig.5. (A)Therootismadefromcontributionsfromdorsal(sensory)rootletsandventral(motor)rootletsthatemerge from the spinal cord and coalesce into the cervical root and emerges from the vertebral foramen. It is important to understand that the cell bodies of the dorsal (sensory) portion lie within the DRG. When an injury occurs and the rootletsaretornoutofthespinalcord,theinjuryisclassifiedaspreganglionic,becauseitoccursproximaltotheDRG. (B)Thistypeofinjuryisalsoknownasanavulsion.(C,D)Whenthecervicalrootisinjuredorbecomesdiscontinuous distaltotheDRG,theinjuryisclassifiedasapostganglionicinjury.(CourtesyoftheMayoFoundation,Rochester,MN; withpermission.) Operative approachesto thebrachial plexus subplatysmal flaps are raised, which enhance the exposure. The external jugular vein is retracted. Supraclavicularbrachial plexus TheborderoftheSCMmuscleisidentifiedandits The patient is placed supine, occasionally clavicular head is either retracted medially or placedinamodifiedbeachchairpositiontofacil- released (and later repaired). The supraclavicular itateaposteriorapproachtotheshoulderorarm. fat pad is dissected and mobilized laterally. The Afoldedsheetisplacedbeneaththescapula.The omohyoid muscle is either retracted, or tagged neckisextendedgentlyandturnedtotheopposite and divided for later reapproximation. Nerves of side.Abumpisalsoplacedbeneaththebuttockto the cervical plexus may be seen during the externally rotate one leg (should a sural nerve superficial exposure, and they can be traced to graft be desirable). The neck, shoulder, entire C3 and C4 origins. These branches should be limb, chest, and both legs are prepared and preservedifatallpossibletopreventthepotential draped. formationofpainfulneuroma,iftransected.Ifthe The supraclavicular brachial plexus can be carotidarteryorinternaljugularveinisidentified, approached through an incision paralleling the then the dissection istoomedial. lateralborderoftheSCM.Thisapproachmaybe The phenic nerve should be identified on the combined with an incision along the clavicle by surface of the anterior scalene muscle and care- itself and one inferiorly in the deltopectoral fully mobilized proximally. The phrenic nerve grooveforexposureoftheinfraclavicularbrachial runsinferiorlyandmedially(theonlymajornerve plexus.Forcosmeticreasons,thecurrentauthors to take this course). This nerve is usually func- prefer displaying the supraclavicular brachial tional, and it can be stimulated intraoperatively. plexus through a transverse incision placed in Thephrenicnerveistracedproximally,andatthe a skin crease several fingers above the clavicle lateral edge of the anterior scalene, its C5 contri- (Fig. 8). The platysma is divided, and generous bution is identified. Once C5 is identified and