Brachial Plexus Injuries in Adults [an issue of Hand Clinics] - A. Bishop, et al., (Saunders, 2005) WW

2005·4.99 MB·English

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
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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