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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6022_Библиотеки_им_академика_М_И_Перельмана
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variousimagingmodalitiesisespeciallyimportantinimagingspinetrauma.
Plainradiographsarepartoftheroutineevaluationofpatientsinwhomthere
is a strong suspicion of spine injury. Radiographic evaluation of the cervical
spineisrecommendedforallpatientswithevidenceofsignificantinjuryabove
the clavicles. There is no consensus on which views should be obtained, and
numerousdifferentopinionsandprotocolshavebeenoffered.Alateralviewto
include the cervicothoracic junction should always be obtained, and a typical
radiographicseriesforcervicalspinetraumaincludesAPandodontoidviewsas
well. A “swimmer’s” view is often helpful if the cervicothoracic junction is
obscuredbytheshoulders.Additionalprojectionssuchasobliqueviewsorthe
“pillar” view may be obtained but are often reserved for special cases. These
viewsofferadditionalinformationabouttheposteriorelements,butobtaininga
technicallyadequateviewwithoutmovingthepatientischallenging.Theadded
time,effort,andradiationaredetractingfactors.
FIGURE6.17(A)Upright lateralview of anormal spineshowsthe
smooth alignment along, from left to right, the anterior vertebral
bodies, posterior vertebral bodies, spinolaminar line, and posterior
margin of the spinous processes. Artifact from a cervical collar is
faintly visible. (B) Same patient, magnified view shows the normal
thinsofttissuesanteriortothebodyofC3(arrowandline).
Radiographic evaluation of the thoracic and lumbarspine includes at least
lateral,andoftenalsoAP,views.Obliqueviewsofthethoracolumbarspineare
rarelyindicatedintheevaluationofacutetrauma.
Inassessingspineradiographs,theinterpretershouldlookatalignment,the
bonesthemselvesforpresenceoffractures,andadjacentsofttissueoutlines(50).
Focalkyphosisorsubluxationshouldsuggestthepossibilityoffractureormajor
ligamentous injury, although chronic degenerative change can cause minor
abnormalitiesofalignment.Inthecervicalspine,anteriorandposteriormargins
ofthevertebralbodies,thespinolaminarline(alongtheposteriormarginofthe
spinal canal and anterior margin of the spinous processes), and the posterior
margin of the spinous processes should all demonstrate a regular, relatively
smooth change (Figure 6.17A). The prevertebral soft tissues in the cervical
regioncanprovideimportantcluestoinjury,especiallyintheupperhalfofthe
cervical spine. The presence of the esophagus adjacent to the lower cervical
spinenormallywidensthesofttissuesinthisregionandmakesitmoredifficult
to identify swelling. At the C3 vertebral body,the prevertebral tissues should
normallynotexceed4mminthicknessonaroutinelateralview(183-cm[72-in]
distance); a portable technique using a shorter focal distance can cause
magnificationand slightly largerapparentthickness (see Figure6.17B). In the
thoracicspine, a paraspinoushematomafrom a fractureisoften visible onthe
AP view. Fractures may be visualized directly or inferred from the loss of
vertebral body height or from increased density in the region of compressed
bone. Fractures of the posterior elements are particularly difficult to identify
withplainfilms,andasmanyashalfofallposteriorelementfracturesidentified
on CT are missed on plain film. The odontoid process should be inspected
carefullyforfractures(Figure6.18).
CT is more sensitive than plain radiographs for the detection of fractures
(51,52).FracturesorientedintheaxialplanemaybedifficulttoidentifyonCT.
Suchinjuries includefractures throughthebase ofthe odontoidprocess,some
compression fractures, and Chance fractures (whicharediscussed later in this
chapter under thoracic and lumbar injury patterns). Sagittal and coronal
reformatted views can be particularly helpful in such cases (Figure 6.19). 3D
reconstructionsaresometimeshelpful inassessing alignmentand displacement
of fragments. Such reconstructions, as well as routine CT scanning of longer
segments of the spine, are more readily performed with spiral or helical
techniques. Modern multislice CT machines can quickly scan through the
anatomyof interestwithin afewseconds,andthey enablemultiplanar and3D
reconstructions of excellent quality (Figure 6.20). CT of the spine should be
performedwithaslicethicknesssmallenoughtopermitreformattedviewsand
to identify fractures. In the authors’experience, slice thickness should not be
more than 3 mm; in areas such as the cervicocranial junction and odontoid
process,thinneroroverlappingslicesmaybenecessary.
FIGURE6.18Odontoidfracture.Lateralradiograph (A)shows mild
posterior displacement (arrow). Odontoid view (B) shows a jagged
lucency(arrow).
FIGURE6.19Chanceinjury.Youngadultwomaninamotorvehicle
accident had anterior loss of height seen on plain x-rays at the T12
level.AxialCTscan(A)showslucencyandirregularityattheanterior
margin of T12 and subtle lucency through the right lamina
representing fractures. Sagittal 2D reconstruction image (B) clarifies
theanteriorcompressionandposteriorwideningbetweenthelaminain
thisChance-typeinjury.
MRI is particularly helpful for visualization of the spinal cord and for
identificationofsofttissueinjury.Hematomas,diskherniation,andspinalcord
contusion,hemorrhage,orcompressioncanbedirectlydemonstratedbyMRI,as
is patency of the vertebral arteries (53). Indications for MRI in the setting of
acute spine trauma include neurologic injury; evaluation of suspected
complicatingfactors,suchasdiskherniationwhensurgeryisbeingconsidered;
and evaluation of soft tissue injury, especially in patients in whom clinical
assessment is limited. Sagittal T1- and T2-weighted images can be used to
screenthespinalcord,withaxialimagesbeingusedthroughareasofparticular
concern.BecausenormalparaspinalfathashighsignalintensityonT2-weighted
FSE, which could mask T2-bright edema from injury to the soft tissues, it is
importanttouseafat-suppressiontechniquewithFSE–T2-weightedimaging.As
discussed earlier in the section on fat saturation, inversion-recovery (IR)
techniques(i.e.,STIR)orchemicalfatsaturationcanbeusedwithFSEimaging.
Numeroustypesofcervicalspinefracturescanoccur,andacomprehensive
review is beyond the scope of this chapter (see Chapter 14). More extensive
reviewsareavailable, including entire books (54–56). However,itisuseful to
consider cervical spine fractures in terms of the major mechanisms of injury.
Flexion injuries resulting primarily from excessive force in flexion include
compressionorwedgefracture,bilateralfacetdislocation(Figure6.21),spinous
process fracture (clay-shoveler’s), hyperflexion sprain, and flexion-teardrop
fracture.Injuriesresulting primarily from excessive force in extension include
hyperextensiondislocation,C1anteriorarchavulsionfracture,C1posteriorarch
fracture, laminar fracture, extension-teardrop fracture, hangman’s fracture
(traumatic spondylolistheis) (Figure 6.22), and hyperextension fracturedislocation. A combination of rotation and flexion causes unilateral facet
dislocation(Figure6.23). Rotation incombinationwith extensioncausespillar
or lateral mass fractures, which can be especially difficult to demonstrate on
plainfilms.WehavefoundthatMRIcanbehelpfulwiththeseposterior-element
fracturestodemonstratetheextentofaccompanyingligamentousinjury,which
may be an important factor in determining instability (57). More extensive
ligamentousinjuryprobablyindicatesagreaterriskofinstabilityintheselateral
mass fractures. Combined fractures of the pedicle and lamina result in a
separationofthelateralmassandriskofrotationalinstability(Figure6.24).
FIGURE 6.20 Multislice, high-resolution CT in trauma. CT of the
cervicalspineofanelderlywomaninamotorvehicleaccident.Axial
images (A, B) showfractures of the C1 ring and of the base of the
dens.Reconstructedsagittalimage (C)demonstratesmoreclearlythe
horizontalfracturethroughthebaseofthedens,as wellasoldlower
cervical spine fusion (C5 through C7) and extensive, multilevel
degenerative changes. Scan was performed on a 16-slice helical
scannerusing0.75-mmslicethickness.
FIGURE6.21 Bilateral facetdislocationina middle-aged man with
tetraplegia after motor vehicle accident. Axial CT (A) shows
dislocation and small fracture fragments. Parasagittal 2D
reconstruction view (B) demonstrates more directly the facet
dislocationatC6–C7.SagittalT2-weighted(IR)MRimage(C)shows
subluxation at C6–C7, spinal cord compression and edema, marrow
edema in the upper thoracic spine, severe anterior and posterior
longitudinal ligament injury, and extensive posterior paraspinal soft
tissueedema.
FIGURE 6.22 Hangman’s fracture (traumatic spondylolisthesis).
Axial CT at C2 shows bilateral fractures through the pars
interarticularis.
Injuries resulting primarily from axial loading mechanisms include the
JeffersonburstfractureofC1,burstfracturesofC3throughC7,burstfractures
involvingthethoracicorlumbarspine,andobliquesagittalfractures(type2)of
the C2 body. The Jefferson fracture pattern includes two or more fractures
throughtheringofC1.CTisthebestmethodforidentifyingthisfracture(Figure
6.25).PlainfilmfindingsincludelateraldisplacementofthelateralmassesofC1
ontheAPodontoidview,lucencythroughtheposteriorarchofC1onthelateral
view,anduppercervicalprevertebralsofttissueswelling.
BurstfracturesoccurfromC3throughthelowercervicalandentirethoracic
andlumbarspine.Theyresultwhenaxiallydirectedforcetransmittedthrougha
disk is transmitted to the centrum or body below, which then fractures. A
prominent sagittal component nearly always occurs; more extensive
comminution of the vertebral body isvariable. It is common forfragments to
displaceposteriorlyintothespinalcanal,possiblycompromisingthespinalcord
(Figure6.26).
Thecervicocranialjunctioniscomplex,consistingofthearticulationsofC1
andC2andtheocciput,aswellasmultipleligamentsthatcontributetostability
andmotioninmultipledirections.InadditiontothefracturesofC1andC2,the
occipital condyles can fracture. Such fractures are difficult to identify except
withCT(58,59)(Figure6.27).Ligamentousinjurycanbeinferredbysofttissue
swelling and can be more directly demonstrated by MRI. The transverse
ligament responsible for maintaining the relationship between C1 and the
odontoid process is very strong and is damaged only by major injuries. The
ligamentcanbevisualizeddirectlybyMRI,butinjuryisoftenidentifiedonthe
lateralx-raybyabnormalwideningoftheanterioratlantodentalinterval(Figure
6.28).Thisspaceshouldmeasurenomorethan3mminadults.Wideningofthis
spacecanoccurfromtraumaticinjurytotheligament,eitherruptureoravulsion
fromthetuberclesonthelateralmassesofC1,orfromdamagefromrheumatoid
arthritis(RA)orotherinflammatoryconditions,andsomecongenitalconditions
(Figure6.29).
FIGURE 6.23 Unilateral facet dislocation. Axial CT (A) shows
reversal of the usual relationship of the facets on the patient’sright
(arrow).NotethatunlikeFigure3.17,bilateralfacetdislocation,only
one side is dislocated, and there is less subluxation. Sagittal T2weighted(IR)MRimage(B)showssubluxationatC5–C6,spinalcord
compressionandedema,anddorsalsofttissueedema.
Atlanto-occipital dissociation (AOD) requires severe forces to tear the
ligamentsattachingtheocciputtotheatlas,especiallythestrongsuperiorportion
ofthecruciateligament.Suchinjuriesareoftenfatal(60).Severeuppercervical
prevertebral soft tissue swelling is present. Some patients with less severe
displacement can survive, and plain film findings of AOD can be subtle. A
varietyofmeasurementshavebeenproposedtoidentifytheabnormalitiesofthe
relationship of C1, C2, and the occiput. The most reliable appear to be those
describedbyHarrisetal.(61).Twomeasurementsaremadefromthebasionor
inferiortipoftheclivus.Thedistancefrombasiontothetipofthedens(basion–
dentalintervalor [BDI])should notexceed12mmin adultsas measuredona
lateralradiographobtainedat102-cm(40-in)target-filmdistance.Thedistance
from basion perpendicularly to a line extended rostrally from the posterior
corticalmarginofthebodyofC2(basion–axialintervalor[BAI])measuredona
lateral radiograph should not exceed 12 mm in children or adults. Normative
valuesforthesamemeasurementsbasedonCT(62)arereportedtobelowerfor
BDI (95% of adults less than 9 mm) and difficult to measure for BAI (i.e.,
poorly reproducible) (Figure 6.30). MRI can more directly demonstrate
ligamentousdisruption(Figure6.31).
FIGURE6.24Pedicolaminarfracturepattern.CTshows fracturesof
theboththerightpedicleandtherightlamina.
FIGURE6.25JeffersonburstfractureofC1.CTshowsfourfractures
intheanteriorandposteriorarchesofC1.
FIGURE 6.26 Lateral radiograph of a C5 burst fracture shows
displacement of both anterior and posterior margins of the vertebral
bodyinferiorly.
FIGURE 6.27 Occipital condyle fracture. Axial CT (A) shows
lucencythroughtheleftoccipitalcondyle.Coronal2Dreconstruction
(B)demonstratesthefracturemoreclearly.
FIGURE 6.28 Lateral radiograph shows widening of the anterior
atlantodental interval (line). Normally this should measure no more
than3mmfromtheposteriormarginoftheanteriorarchofC1tothe
anterior aspect of the odontoid process. The distance in this patient
was7mm,andthelikelyunderlyingetiologywasRA.
RA,rheumatoidarthritis.
Injury patterns in the thoracic and lumbar spine in which motion is more
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