1.Dr. Vishal Sankpal

2. 1. Introduction, clinical considerations and imagingtechniques overview2. Plain Film Radiography and CT of the Cervical Spine:Normal Anatomy3. Plain Film Radiography and CT of the Cervical Spine:Classification and Subtypes of Spinal Injury4. Imaging of Thoracolumbar Spinal Injury5. Magnetic Resonance Imaging of Acute Spinal Trauma6. Imaging of Pediatric Spinal Injury 3. During ancient times, spinal trauma and paralysis wasuntreatable and fatal Spinal cord injury (SCI) still remains a significant cause ofdisability The majority (81%) are males and the average age isrelatively young at 32.8 years. Approximately half the spinal cord injuries occur frommotor vehicle crashes. Falls from >10 feet, gunshotwounds, motorcycle crashes, crush injuries, andmedical/surgical complications account for most of theremaining cases 4. In addition to the obvious quality-of-life implicationsof such injuries, life expectancy is also affected, beingapproximately half of that of otherwise matchedindividuals 5. Radiography Computed Tomography (CT) MRI 6. Only one third of spinal trauma patients presentinitially with a neurological deficit Moreover, important clinical features such as pain frominjury may be masked by otherinjuries, medication, and drug and alcohol intoxication Defining the group of subjects who are at risk forcervical spine fracture and therefore in whom imagingis appropriate remains challenging. 7. The NEXUS study indicates that cervical spine imaging is not necessary in trauma patientswho meet all of the following five criteria:1. No midline cervical spine tenderness2. No focal neurological deficit3. Normal level of alertness4. No intoxication5. No painful distracting injury NEXUS - National Emergency X-Ray Utilization Study, United States, publishedin 2000 Source: Hoffman J, Mower W, Wolfson A, et al. Validity of a set of clinical criteria to ruleout injury to the cervical spine in patients with blunt trauma. N Eng J Med. 2000;343:9499.sensitivity - 99.6%specificity - 12.6% 8. Imaging of the cervical spine is not necessary if patients are alert (GCS 15) and all of theconditions detailed below are met.1. No high-risk factor present, including:Age 65 or more yearsDangerous mechanism, including:Fall from >3 meters/5 stairsAxial load to head (diving)High-speed vehicular crash (60 mph, rollover )Bicycle crashMotorized recreational vehicle crashParesthesias in extremities3. Able to actively rotate neck (45 degrees left and right) Source: Stiell I, Wells G, Vandemheen K, et al. The Canadian C-spine rule for radiographyin alert and stable trauma patients. JAMA. 2001;286: 18411848.2. Any low-risk factor is present, including:Simple rear-end vehicular crash mechanism,excluding:Pushed into oncoming trafficHit by bus/large truckRolloverHit by high-speed vehicleSitting position in emergency departmentAmbulatory at any timeDelayed onset of neck painAbsence of midline cervical tenderness99.4% - sensitivity45.1% - specificity 9. The three-view radiography series antero-posterior, lateral, and open mouth odontoidis still the imaging modality of choice as initial study forsymptomatic patients( as recommended by the American College of Radiology Appropriateness Criteriaand the Advanced Trauma Life Support (ATLS) course of the American College ofSurgeons ) 10. Single detector CT scan has a sensitivity of 98% forfracture with a specificity of 93% With the new generation of 16 and up to 64 detectorscanners, it is likely that CT today is more accurate andmore cost effective In summary, despite the aforementionedrecommendations, CT is being used for screeningcervical spine in high-risk patients, particularly if CT isalso to be used to evaluate the subjects head Radiography remains appropriate in low-risksubjects, as well as in those situations where CT is notavailable. 11. Only if ligamentous injury is suspected The AANS suggests that cervical spine immobilizationmay be discontinued if normal and adequate flexion-extension radiographs are obtained in an awake patientwith normal radiographs or CT in the presence of neckpain or tenderness In summary, no reliable evidence exists regarding theappropriate role for flexion-extension radiography inthe acute evaluation of cervical spine trauma. 12. The biomechanics of injury in the elderly differ from younger adults1. Osteopenia, which is ubiquitous in this population, leads to alower energy threshold for fracture and affects fracture location2. Biomechanically, the spine in elderly patients is altered bydegenerative fusion usually in the lower cervicalsegments, which leads to marked decrease in motion in the lowercervical spine3. Finally, the mechanism of cervical spine injury in the elderly issubstantially different than in younger adults with low-velocityfalls being more common in the elderly, and high-energy motorvehicle crashes more common in younger subjects 13. Fractures of the upper cervical spine, particularly C2,are more common in subjects over 65 years of age thanin younger subjects In very elderly subjects (> 75 yrs), C2 fractures accountfor nearly 50% of all fractures Injuries to the lower cervical segments becomeincreasingly uncommon as patients age. 14. Cervical spine fractures are uncommon in children The injury patterns are different, with cranio-cervicaljunction injuries being more prevalent in this group No validated method exists to identify pediatricsubjects who are of high risk for fracture 15. Special consideration regarding radiation dose due tothe inherent radio-sensitivity of developing tissues inchildren compared to adults Antero-posterior (AP) and lateral radiographs underthe age of 4 AP, lateral and open mouth radiographs from 4 to 8years old Children at 9 years of age and older are imaged with theadult protocol. This is the approximate age at which thefracture patterns revert to the adult patterns. CT is reserved for those subjects in whom anabnormality is identified on radiography. 16. More common than fractures of the cervical spine The majority of these fractures, however, arepathologic fractures that occur in the elderly as aconsequence of minor trauma and due to underlyingosteoporosis Non-pathological traumatic fractures of thethoracolumbar spine do occur in approximately 2% to6% of admitted trauma patients The most common sites of injury are the T12 to L4 17. CT reconstructions from an abdominal CT data set can beconsidered an adequate substitute for thoracolumbar spineradiographs for trauma patients ADV obviate the need for dedicated thoracolumbar spine imagingwith radiography, more sensitive than radiography can be performed at minimal additional cost avoid additional radiation exposure The current rapid evolution of multidetector CT scannerswith increased numbers of detectors and higher spatialresolution is expected to increase accuracy of suchreconstructions 18. 1. Introduction, clinical considerations and imagingtechniques overview2. Plain Film Radiography and CT of the Cervical Spine:Normal Anatomy3. Plain Film Radiography and CT of the Cervical Spine:Classification and Subtypes of Spinal Injury4. Imaging of Thoracolumbar Spinal Injury5. Magnetic Resonance Imaging of Acute Spinal Trauma6. Imaging of Pediatric Spinal Injury 19. ADV readily available in all emergency centers can be performed with portable and fixed equipment the standard initial screening examination Cross-table lateral radiographs - inadequate to excludecervical spine injury, incomplete visualization of thecervicothoracic and cranio-cervical junctions Oblique views - although useful in patients with unilaterallocked facet, are most valuable in adding two more views ofthe cervico-thoracic junction in patients with equivocallateral that are not undergoing CT examination (lowrisk, obese short-necked patients) 20. Flexion-extension radiographs are not very helpful inthe acute setting because muscle spasm in acutelyinjured patients precludes an adequate examination Flexion-extension radiographs are helpful for ensuringthat minor degrees of anterolisthesis or retrolisthesisin patients with cervical spondylosis are fixeddeformities 21. ADV over single slice CT faster acquisition of a volumetric data set Motion and mis-registration artifacts are minimized high-quality reconstructed images can be obtained Horizontal fractures that are oriented in the plane of thescan, such as transverse odontoid fractures, may not alwaysbe demonstrated by single CT without MPR (Sag and Cor) CT may reveal more fractures than plain films and mayallow evaluation of the cervicothoracic and cranio-cervicaljunctions, areas traditionally poorly visualized on plainfilms 22. Three-dimensional (3D) CT software programstransform existing axial CT data into a 3D rendering ofthe portion of the spinal skeleton being examined 3D CT reformations do not reveal a significant numberof unsuspected traumatic lesions but they do provideimproved definition and comprehension of the extentand nature of detected injuries 23. Advantages of 3D CT imaging includes: (a) ability to synthesize multiple 2D imageinformation, especially in areas with complex anatomy, (b) visualization of complex injuries presentingvertebral rotation or dislocation and loss of alignment, (c) a more comprehensive assessment of cases requiringsurgical planning, and (d) better demonstration of displaced fractures. 24. Surface rendering Maximum Intensity Projection (MIP) Volume rendering 25. Surface rendering 26. Volume rendering 27. Maximum Intensity Projection (MIP) 28. 1 Anterior spinal line2 Posterior spinal line3 Spino-laminar line 29. Laminar Space Distance fromposterior aspect ofarticular pillars (1)to the spino-laminar line (2) Used to indicaterotational injuriesof the cervical spine Injury is suggestedwhen there is abruptalteration of thespace betweenadjacent levelsLaminar Space 30. Yellow line pre-vertebral space (C2 12 mm Basion Dental distance Separated occipital condyle and superiorsurface of C1Atlanto-occipital Distraction 53. Generally related to axial loading Neurologic compromise is relatively infrequent withfractures of the C1 ring, presumably because the axialcompression mechanism results in a burstconfiguration with expansion of the spinal canal Jefferson Fracture Lateral Mass (C1) Fracture Isolated Fractures of C1 54. Classically, a four-point injury with fractures occurring at thejunctions of the anterior and posterior arches with the lateralmasses, the weakest structural portions of the atlas Most commonly there are two fractures in the posterior arch(one on each side) and a single fracture in the anterior arch,off the midline Mechanism - A JF is created by sudden and direct axialloading on the vertex.The lateral articular masses of the atlas become compressedbetween the occipital condyles and the superior articular facetsof the axis. By its nature, this is a decompressive injury becausethe bony fragments are displaced radially away from the neuralstructures 55. Most common 56. Plain film findings:Open-mouth odontoid view - Bilateral offset or spreading of the lateral articular masses of C1 inrelation to the apposing articular surfaces of C2 It is often difficult to visualize the lines of fracture per seLateral view: (difficult diagnosis on the lateral view) Occasionally, the fractures are demonstrated on the lateralprojection (usually the posterior arch fracture) Increase in the atlanto-axial distance (>3 mm) Anterior or posterior displacement of the C1 spino-laminar line The retropharyngeal soft tissue may be abnormal in both contourand thicknessAP view: Usually not visible on AP cervical spine radiograph 57. UNSTABLE (on radiography ): It has been suggested that the degree of offsetdistinguishes between stable and unstable Jeffersonsfractures. An unstable JF is one in which the transverseligament is disrupted. Total C1 lateral masses offset of both sides > 7 mm(adding the amount of lateral displacement of each C1lateral mass) Increase in the atlantoaxial distance (>3 mm) 58. NormalJefferson fracture 59. Axial images: Identify and establish the sites and number of C1 ringfractures Establish separation between fracture fragments of theatlas, if >7 mm the lesion is considered unstable Coronal reconstruction: Assess offset or spreading of the lateral articular masses of C1in relation to the apposing articular surfaces of C2 Sagittal reconstruction: Assess increase in the atlanto-axial distance (>3 mm) andanterior or posterior displacement of the C1 spino-laminar line 60. An unstable JF is one in which the transverse ligament is disrupted. Coronal reconstructions: Total C1 lateral masses offset of the two sides in excess of 7 mm(adding the amount of lateral displacement of each C1 lateral mass) Sagittal reconstructions: Increase in the atlantoaxial distance (>3mm) Axial views: >7 mm separation between fracture fragments of theatlas Because multilevel fractures (C1 and C2) are considered unstable, acautious search for contiguous fractures is critical 61. Atypical Jefferson fracture Axial CT images show a displaced (>> 7mm suggesting instability) single fractureof the left anterior arch of C1 (whitearrows) and left lateral comminutedfracture of the posterior atlas ring (blackarrows). Avulsed fragments from the medialsurface of the left lateral mass of C1 arenoted (open arrowhead). 62. Usually occur as a result of a lateral tilt May be limited to the lateral mass of C1, or morecommonly, occurs in association with occipital condylefractures and/or fracture of the articular process of C2 Usually visible on the open-mouth view However, sometimes the abnormal cervico-cranialprevertebral soft tissue contour is the only sign of injury inplain films A fracture of the lateral mass of C1 is considered unstable 63. usually stable should be distinguished from the Jefferson bursting fractureand its variants The most common isolated fracture of C1 is a bilateral verticalfracture through the posterior neural arch Carries no risk of neurologic deficit This fracture must be distinguished from developmentaldefects 64. Isolated fracture of posterior arch smooth margins of a partiallynon-ossified posterior atlasring 65. Approximately 25% are hangman fractures, over half(58%) are odontoid fractures, and the remainder aremiscellaneous fractures involving the body, lateralmass, or spinous process Hangman Fracture (Traumatic Spondylolisthesis ofC2) Odontoid Fractures C2 Lateral Body Fractures 66. Injury is identical to that created by judicial hanging and thus thedesignation of the hangman fracture Mechanism most common form of this injury results from extension combined withaxial loading The full force of acute hyperextension of the head on the neck istransmitted through the pedicles of C2 onto the apophyseal joints. Theweakest points in this chain are the interarticular segments of thepedicle. Thus, the arch of C2 is fractured anterior to the inferior facet Hangman fracture is a bilateral fracture through the pars interarticularisof C2 The pars interarticularis is found between the superior and inferiorarticular processes of C2 Spinal cord damage is uncommon, despite frequent significant fracturedisplacement, due to the wide spinal canal at this level 67. Lateral view: The fracture usually is diagnosed readily on the lateral radiograph in>90% of cases unless non-displaced. Prevertebral soft tissue swelling or hematoma, often absent Fractures are often anterior to the inferior facets. They are oblique, extending fromsuperior/posterior to inferior/anterior Positive axis ring sign, which will show posterior ring disruption from atypicalfractures extending into the posterior C2 vertebral body cortex Fat C2 sign Posterior displacement of the C2 spino-laminar line of >2 mm, An avulsion fracture of the anterior margin of the axis or anterior superior margin atC3 is often present and identifies the site of rupture of the anterior longitudinalligament AP view: Usually not visible on AP cervical spine radiograph. 68. CT is valuable to exclude or verify fracture line extension into the vertebralforamina or vertebral body, or to detect subtle concurrent adjacent injuries. Axial images: Identify the sites of C2 ring fractures and extension into the vertebralforamina or vertebral body. Establish separation between fracture fragments of the pars inter-articularis of C2 Coronal reconstruction: Usually provides no additional information as to the nature of thehangman fracture, but can be valuable to detect concurrent adjacentinjuries. Sagittal reconstruction: Assess the fractures lines and posterior displacement of the C2spinolaminar line Assess C2-3 disc space Establish separation and angulation between fracture fragments of the parsinterarticularis of C2 69. Fat C2 signC2 ring sign 70. UNSTABLE: More than 3 mm of fragment displacement or >15-degree angle at the fracture site Abnormal C2-3 disc space C2-3 dislocationBecause multilevel fractures (C1 and C2) are consideredunstable, a cautious search for contiguous fractures iscritical. 71. Type I fracture - an isolated hairline fracture, with 3 mm of fragment displacement ormore than a 15-degree angle at the fracture site and anabnormal C2-3 disc space Type III consists - changes that characterize type IIinjury + C2-3 articular facet dislocation 72. Classification of dens fractures (Anderson and DAlonso ) -based upon the location of the fracture site with respect tothe dens Type I - an oblique fracture of the superior lateral aspectof the dens, avulsed by the alar (check) ligament; this isan extremely uncommon injury, occurring in < 4% ofodontoid fractures Type II - fracture at the base of the dens (most common -comprising 60% of dens fractures ) Type III - an oblique fracture of the superior portion of theaxis body caudal to its junction with the base of the dens 73. The radiologic diagnosis of odontoid fractures usually is establishedusing the lateral cervical and open-mouth odontoid view radiographs.Open-mouth odontoid view: Type II odontoid fractures - transverse or oblique transverse fracturethrough the lower portion of the dens.The transverse fracture at the base of the dens must be differentiatedfrom a developmental abnormality termed as os odontoideum.Os odontoideum is rounded, has a cortical margin around itsentire surface, and is usually more widely separated from the base ofthe odontoid than a fracture, and with smooth margin.Nonunion odontoid fractures may be impossible to distinguish from anos odontoideum. 74. Lateral view: (Difficult diagnosis on the lateral view) Minimal displacement often precludes demonstration of thefracture line. Positive axis ring sign will show posterior or anterior ringdisruption in type III fractures Type III fractures are almost always better visualized on the lateralprojection and may not be evident on the anteroposterior view Anterior or posterior displacement of the C2 spinolaminar line of>2 mm Fat C2 sign in type III fractures 75. If the odontoid fragment is displaced by >5 mm, a 75%nonunion rate results Odontoid fracture with anterior or posterior displacementof the C2 spinolaminar line of >2 mm Multilevel fractures (C1 and C2) are considered unstable Odontoid fractures with atlanto-axial dissociation. 76. Type I odontoid fracture 77. Type II odontoidfracture 78. Type III odontoidfracture 79. An isolated C2 lateral body fracture is rare is usually found incidentally when evaluating for other C2traumatic pathology If a C2 lateral body fracture is found, other C-spinepathology must be sought (ipsilateral occipital condyle, C1lateral mass, and lower cervical spine fractures) Mechanism - axial compression with concomitant lateralbending Radiographic findings include - impaction of the C2component of the atlantoaxial articulation surface,asymmetry of C2 lateral body height, and lateral tilting ofthe arch of C1. Atlanto-occipital and atlantoaxialdissociation can be seen 80. Defintion - Acute traumatic atlanto-axial dissociation(AAD) is a rare injury in which there is partial(subluxation) or complete (dislocation) derangement ofthe lateral atlantoaxial articulations Certain congenital conditions can be associated withAAD, including Down syndrome, osteogenesisimperfecta, neurofibromatosis, Morquiosyndrome, spondyloepiphyseal dysplasia congenita, andchondrodysplasia punctata. Neurologic symptoms occur when the spinal cord isinvolved 81. The three mechanisms of AAD - are flexionextension, distraction, and rotation. The most common abnormalities involve thetransverse ligament or odontoid process 82. Type I AAD: AAD with rotatory fixation without anterior displacementof the atlas.The odontoid acts as the pivot and the transverse and alar ligaments areintact.This is the most common type of rotatory fixation and occurs within thenormal range of rotation of the atlanto-axial joint Type II AAD: Rotatory fixation with < 5 mm of anterior displacement ofthe atlas. This is the second most common type and is associated withdeficiency of the transverse ligament. Type III AAD: Rotatory fixation with > 5 mm of anterior displacementof the atlas. This degree of displacement implies deficiency of the TAL . Type IV AAD: Rotatory fixation with posterior displacement of theatlas. This is the most uncommon type and occurs with deficiency ofthe dens, such as in type II odontoid process fractures or unstable osodontoideum (congenital or posttraumatic). 83. Atlantoaxial rotatory subluxation associatedwith left lateral mass of C1 fractureA: shows rotation of C1 to the right.B: fracture of the left lateral mass of C1C: asymmetry of the lateral atlanto-dental spaces(black arrows) and a difference in the atlantoaxialjoint spaces (white arrows) secondary torotational malalignment. Increased transversediameter of the left lateral mass of C1 (black dot)and truncated appearance on the right (whitedot) indicate rotation of C1 to the right. 84. Anterior translation of C1evidenced by theabnormally wide (>> 5mm) anterior atlanto-dental interval (AADI) Anterior position of itsspinolaminar line (yellowline in B) with respect tothat of C2-3 spinolaminarlines 85. Atlanto-axial rotational injury must be distinguished fromtorticollis Torticollis, or wry neck, is more precisely defined as acuterotational displacement and may be due to a variety of conditions It is clinically manifested by simultaneous lateral tilt and rotationof the head The causes of torticollis can be subdivided in two groups o Disorders of rotation of the atlantoaxial joint resulting in fixed orlimited rotation of the neck. This may occurspontaneously, secondary to trauma, or in association withcongenital anomalies or arthritides.o Other disorders causing limited rotation of the neck withoutprimarily involving the atlantoaxial joint, where the primaryabnormality is in the sternocleidomastoid muscle (congenitalfibrosis, lymphadenitis, tumors of the cervical spine, painful neck). 86. Rotatory subluxation is sometimes observed after upperrespiratory infection or after head and neck surgery. Grisel syndrome is the occurrence of atlanto-axialsubluxation (AAS) in association with inflammation ofadjacent soft tissues. Torticollis is usually self-limited and occurs mainly inchildren to young adolescents. The symptoms usuallydisappear in 4 to 5 days. Most cases resolve spontaneously, although in a fewinstances the rotatory deformity becomes fixed andirreducible. The fixation usually occurs within thenormal range of rotation of the atlanto-axial joint. 87. Case of torticollis due to congenital fibrosis of sternocleidomastoid History helps in differentiating Torticollis from traumatic AAR 88. Flexion Injuries Clay-shoveler fracture, Anterior Subluxation , Simple WedgeCompression Fracture, Flexion Teardrop Fracture Flexion rotation injuries -Unilateral Facet Dislocation Extension injuries Dislocation, Extension teardrop fracture,Laminar fractures Extension rotation pillar fracture Vertical Compression - Burst Fracture 89. Avulsion injury of the spinous process of C6, C7, or T1 (inorder of frequency). The fracture results from abrupt flexion of the head andneck against the tensed ligaments of the posterior aspect ofthe neck The name is derived from the cervical spine injury sustainedby Australian clay miners Posterior longitudinal ligament remains intact The typical clay-shoveler fracture is both mechanically andneurologically stable. 90. Occurs when posterior ligamentous complexes (nuchalligament, capsular ligaments, supraspinous and infraspinousligaments, ligamenta flava, posterior longitudinal ligament)rupture and a minor tear of the annulus posteriorly The anterior longitudinal ligament remains intact. No associated bony injury is seen. Mechanism - Anterior subluxation is caused by acombination of flexion and distraction. Anterior subluxation is considered clinically significantbecause of the morbidity associated with the 20% to 50%incidence of failure of ligamentous healing or delayedinstability. 91. Lateral view:The findings of AS seen in neutral position become exaggerated uponflexion and are reduced in extension Abrupt hyperkyphotic angulation at the level of ligamentous injury Widening of the interspinous distance at one level (fanning), relative toadjacent levels Incongruity and lack of parallelism of the contiguous facets Disc space is widened posteriorly and narrowed anteriorly Small anterior superior compression fractures of the subjacent vertebralbody Increased thickness of the prevertebral soft tissues as a result ofhematoma formation 92. AP view: Widening of the interspinous distance. This signrepresents the fanning seen on the lateralradiograph. Lateral dislocation (also called lateral translation) mayoccur without significant anterior or posteriordisplacement. 93. Subtle anterior subluxation 94. UNSTABLE: Anterior translation of the vertebral body >3.5 mmrelative to the subjacent vertebra Vertebral body angulation >20 degrees relative to theadjacent vertebra. 95. Mechanism - result of compression of the anterior aspectof the vertebral body Loss of vertebral body height, predominantly anteriorly The simple wedge fracture is characterized radiographicallyby an impaction fracture of the superior endplate of theinvolved vertebral body while the inferior endplate remainsintact The simple wedge fracture is considered mechanicallystable. 96. Extreme form of anterior subluxation Ligamentous disruption and significant anteriordisplacement of the spine at the level of injury It usually occurs in the lower cervical spine The spinal canal is severely compromised by thisdisplacement, and spinal cord injuries are frequent MRI is the modality indicated for subsequent imaging ofpatients with BFD as it best assesses the nature and extent ofspinal cord injury as well as any associated disc andligamentous injury 97. Plain film findings:Lateral view: Displacement of >50% of the antero-posterior diameter of thevertebral body Dislocation of articular facets Narrowing of the disc space at the injured level Dislocation may be incomplete (perched facets), with varyingdegrees of antero-listhesis of facets of one body relative toanother.. Increased thickness of the pre-vertebral soft tissues secondary tohematoma formation.AP view: Increased inter-spinous distance at the level of dislocation. 98. Anterior subluxation< 25 %Unilateral facetdislocation25 50 %Bilateral facetdislocation>> 50 % 99. CT findings:CT is valuable for detection of radiographically occultfractures of the posterior arch or articular facets.Axial images: Fractures undetectable at plain radiography may berevealed. Reverse hamburger bun sign is useful in establishing adiagnosis of facet dislocation Naked facet sign: refers to the CT appearance ofuncovered articulating processes. On axial CTimages, there are bilateral solitary non-articulatingfacets with loss of the joint space 100. Bilateral facet dislocation Double vertebral body sign 101. Naked facet sign 102. represents the most severe injury of the cervical spine highly unstable injury typically involving the lower cervical spine (especially C5) there is also complete disruption of all soft tissues at the levelof injury, including the posterior longitudinalligament, intervertebral disc, and anterior longitudinalligament typical large triangular fracture fragment of theanteroinferior margin of the upper vertebral body (teardropfragment) The flexion teardrop fracture can be distinguished from thesimilarly named hyperextension teardrop fracture by thelarger size of the triangular fragment and by distraction ofthe posterior elements (indicating the flexion mechanism). 103. most often encountered in elderly patients with severespondylosis or with spinal ankylosis from other etiologies Mechanism - In hyperextension fracture dislocation theposterior spinal elements experience impactionforces, producing loading fractures of the articularpillars, posterior vertebral body, laminae, spinousprocess, or pedicles Characteristically, the spine above the level of injury isposteriorly displaced (retrolisthesis), the intervertebral discspace is widened anteriorly and narrowed posteriorly andthe facet joints are disrupted 104. Plain film findings: Cervical hyperextension injuries often show minimalradiographic abnormalities, even with severe or unstable lesions. The momentaryposterior displacement of the involved vertebra is usually completely reduced whenthe causative force disappears.Lateral view: Prevertebral soft tissues Avulsion fracture fragment from the anterior aspect of the inferior endplate of thesuperior vertebra. The transverse dimension of the avulsed fragment exceeds itsvertical height (c/w flexion tear drop fragment) Normally aligned vertebrae. Anteriorly widened disc space.UNSTABLE: Hyperextension dislocation is mechanically unstable. 105. 1. Introduction, clinical considerations and imagingtechniques overview2. Plain Film Radiography and CT of the Cervical Spine:Normal Anatomy3. Plain Film Radiography and CT of the Cervical Spine:Classification and Subtypes of Spinal Injury4. Imaging of Thoracolumbar Spinal Injury5. Magnetic Resonance Imaging of Acute Spinal Trauma6. Imaging of Pediatric Spinal Injury 106. Lumbar spine Thoracic spine 107. The spinal canal size in the thoracic region averages 16(AP) by 16 mm (trans), whereas in the lumbar spine thecanal averages 17 (AP) by 16 mm (trans) Thoracolumbar junction is a region of transition andaccounts for a greater propensity for injuries in thisregion - 2/3rd of all thoracolumbar fractures occur atT12, L1, or L2 Thoracic spinal trauma has more chances of neurologicaldamage because lumbar spine is more capacious cord terminating as the conus medullaris at the L1 level cauda equina, unlike the spinal cord, are relativelyresistant to blunt trauma 108. Radiologic Hallmarks of Instability in thoraco-lumbarspine1. Displacement/translation >2 mm, indicative of disruption to the mainligamentous supports.2. Widening of the interspinous space, widening of facet joints and/orwidening of the interpediculate distance.3. Disruption of the posterior vertebral body line equates to a disruptedanterior and posterior column or articular process fractures.4. Widened intervertebral canal, indicative of sagittally orientated vertebralbodytrauma.5. Vertebral body height loss >50%.6. Kyphosis >20 degrees.Source: Daffner et al. 109. Denis Three column theory:CompressionType A: Both endplates fracturedType B: Superior endplate fractureType C: Inferior endplate fractureType D: Lateral wedgingBurstType A: Both endplates fracturedType B: Superior endplate fractureType C: Inferior endplate fractureType D: Burst fracture with rotatorycomponentType E: Burst fracture with lateralflexionFlexion-distractionType A: Single level, classic Chancefracture with bone disruption onlyType B: Single level, softtissue/ligamentous disruptionType C: Two level disruption throughbone at middle columnType D: Two level disruption through softtissues at middle columnFracture-dislocationType A: Flexion rotations through bodyType B: Flexion rotation through discType C: Posteroanterior shear injuryType D: Posteroanterior shear injury withfloating laminaType E: Anteroposterior shear injuryType F: Flexion distraction 110. typical anterior wedge compression fracture upper and mid-thoracic spine due to the kyphotic curvature Neurologic instability is rare in this fracture Usually involves only the superior endplate It is distinguished from Scheuermann disease and physiologicanterior vertebral wedging; the latter two usually involve bothsuperior and inferior endplate Bimodal distribution, occurring in the young (in the contextof high-speed trauma) and in the elderly (osteoporosis). Axial/burst fractures, in contradistinction, have symmetricalreduction in height of the anterior and posterior vertebralmargins 111. burst fractures of the thoracolumbar junction andlumbar spine classically occurs after landing on both feet or buttocksfollowing a fall from a height (lovers fractures whenassociated with bilateral calcaneal fractures) Rarely, due to seizure or electrocution 112. Mechanism Axial compression of the vertebral body from above by thenucleus pulposus, which explodes into the superior vertebralendplate to result in centripetal displacement of the bodyand its fracture fragments The retropulsion of the posterior aspect of the vertebral bodyinto the spinal canal is pathognomonic of a burst fracture As the PLL is often intact, spinal traction can reduce thisdisplaced fragment by tightening the PLL Applying the three-column principle, there is a minimumtwo-column disruption (the anterior and middle) in a burstfracture 113. Determinants of Burst Fracture Instability Widened interspinous and interlaminar distance Kyphosis >20 degrees Dislocation Vertebral body height loss greater than 50% Articular process fractures 114. Posterior bowing of thevertebral body marginis diagnostic of an axialcompression (burst)fracture. 115. Laminar spitfracture 116. Essential to alert the clinician about the presence of a laminar splitfracture high association with posterior dural laceration Impaction of the thecal sac with the vertical fracture results in thischaracteristic laceration The laminar split fracture almost exclusively occurs with the burstfracture, with an incidence of 7.7% of such fractures having adural tear The presence of a dural tear requires detection prior to surgery, asreduction of the neural extrusion and closure of the durallaceration requires a posterior approach and should be performedprior to any spinal reduction maneuver, which would worsencompression of the extruded neural contents. 117. Once a burst fracture is diagnosed, as with manyvertebral fractures, radiographic survey of the entirespine is recommended as noncontiguous levelinvolvement may occur in as many as 6.4% to 34% Neurologic instability (actual or impending) has beendefined as spinal canal stenosis 50% of normal 118. most common at the thoracolumbar junction separation in a cranial-caudal direction Mechanism - result of hyperflexion of the upperthoracic spine while the lower spine remains relativelyfixed classically caused by a deceleration-type motor vehicleaccident 119. The resultant fracture has been classically described asthe Chance fracture With the routine use of conventional three-pointrestraint (shoulder harness and lap belt), the incidenceof the classic Chance fracture has decreased and burstfractures are now more prevalentChancefractureClassic Variants 120. Classic Chance fracture : The classic Chance fracture accounts for approximately50% of Chance-type injuries A classic Chance fracture - consists of a pure osseousinjury in which there is a horizontal split through thespinous process, lamina, pedicles, resulting in a smallanteroinferior corner fracture of the lower vertebral body acutely unstable purely an osseous disruption; it also has excellent healingpotential with good prognosis for long-term stability Incidence of neurologic deficit is low, estimated at 10% 121. AP radiographs - double spinousprocess, interspinous distance widening, andhorizontal fractures through the pedicles lateral radiograph is often unreliable due to overlapChance variants are either a combined osseous/soft tissue injury or pure The fracture may extend through the posteriorelements as for the classic Chance fracture, butcontinues anteriorly through the disc or it may involvethe posterior ligaments and vertebral body. soft tissuedisruption. 122. typically results in a severe and unstable three-columninjury, with anterior, posterior, or lateral subluxation, aswell as posterior element fracture or ligamentousdisruption The force vectors in this type of injury are bothenormous and complex neurologic impairment is frequent high association with thoracic and abdominal injury 123. The resultant radiographic pattern is characterized byposterior element impaction, with fractures (oftencomminuted) of the spinous process, lamina, orfacets, in association with anterior disc widening oravulsion fracture of the anterior endplate If severe enough, the injury may result in thelumberjack fracture-dislocation in which there iscomplete loss of continuity of the upper and lowerspinal segment associated with an extremely high rateof paraplegia and dural tear 124. Mechanism 125. The injury should serve as a sentinel sign, alerting one tothe possibility of other injury For example, an isolated L5 transverse process fracture iscommonly seen in association with a vertically orientedsacral fracture (Malgaigne fracture/dislocation) on thesame side 126. Transverse process fractureassociated with a sacralfracture 127. Isolated sacral fracturesare uncommonTransverse fractures- most common type Common at S3-S4level High horizontalfractures occur fromhigh falls (suicidaljumpers fracture)Vertical fractures Usually indirecttrauma to pelvis Usually runs entirescrap length 128. Most are transversely oriented AP radiograph not useful Lateral radiography anteriorly tilted / displacedcoccyx 129. 1. Introduction, clinical considerations and imagingtechniques overview2. Plain Film Radiography and CT of the Cervical Spine:Normal Anatomy3. Plain Film Radiography and CT of the Cervical Spine:Classification and Subtypes of Spinal Injury4. Imaging of Thoracolumbar Spinal Injury5. Magnetic Resonance Imaging of Acute Spinal Trauma6. Imaging of Pediatric Spinal Injury 130. The greatest impact that MRI has made in theevaluation of SCI has been in assessment of theintracanalicular and paraspinal soft tissues MRI has replaced myelography and CT myelography asthe primary imaging option to assess for compressionof the spinal cord An MRI examination in the acute period is warrantedin any patient who has a persistent neurologic deficitafter spinal trauma 131. Requires special consideration before MRI with regard topatient transfer, life support, monitoring of vitalsigns, fixation devices, choices of surface coils, and pulsesequences several manufacturers offer MRI-compatible ventilators MRI-compatible monitors are now available that can relayheart rate, respiration, blood pressure, and oxygenationinformation directly into the MRI control area. Indwelling central venous catheters with thermocouples andconventional intravenous medication pumps are prohibitedin the MRI environment 132. Currently, MRI does not offer any advantage over plainradiography or high-resolution multidetector CT(MDCT) in the evaluation of associated osseousinjuries following spinal traumaChance fracture(GRE) 133. MRI is the only imaging modality available that directlyvisualizes changes to the ligaments as a result of trauma ligaments appear relatively hypointense to other structureson all MRI pulse sequences Edema or tear - increase in signal intensity on T2-weightedor GE images because of an increase in free water contentfrom extracellular fluid or adjacent hemorrhage Because of the similarity in imagingcharacteristics, distinction between a ligament fragmentand cortical bone fragment may prove difficult on MRI 134. Extensive degenerativechanges noted but nogross evidence ofmalalignment The ALL, LF andPLL are disrupted. There is wideningof the interspinousdistance Edema in theposterior paraspinalsoft tissues damagedintervertebral disc 135. Discontinuity of the ligamentum flavum andedema in the posterior paraspinal musculature 136. Standard MR pulse sequences are typically capable ofreceiving signals from tissues that have T2 relaxationproperties greater than 10 milliseconds However, the intrinsic T2 relaxation of ligaments istypically 10 mm inlength on sagittal images) in the spinal cord is oftenindicative of a complete neurologic injury 149. small focus ofhyperacute hemorrhageat C1-2 (arrow) and verysubtle high-intensityedemaTwo days later, moreobvious edemaextending down to C4and clear hemorrhagein deoxyhemoglobinstate isseen, particularly onaxial GRE (C), wherehemorrhage is notedwithin central portionof spinal cord 150. focus of abnormal high signal intensity on T2-weightedimages Edema involves a variable length of spinal cord aboveand below the level of injury, with discrete boundariesadjacent to uninvolved parenchyma 151. 1. Introduction, clinical considerations and imagingtechniques overview2. Plain Film Radiography and CT of the Cervical Spine:Normal Anatomy3. Plain Film Radiography and CT of the Cervical Spine:Classification and Subtypes of Spinal Injury4. Imaging of Thoracolumbar Spinal Injury5. Magnetic Resonance Imaging of Acute Spinal Trauma6. Imaging of Pediatric Spinal Injury 152. In children, fractures and severe injuries to the spine arerelatively rare The anatomy and biomechanics of the growingspine, larger head size relative to body size, greater flexibility of the spine and supporting structures, incomplete ossification, as well as greater elasticity and compressibility of the bone,produce failure patterns different from those seen inadults Anatomic differences between the pediatric and adultcervical spine are prominent until approximately 8 10years of age 153. SCIWORA is far more common in younger children thanin older children Pseudosubluxation normal physiologic displacement of C2 on C3, and to alesser extent C3 on C4, can mimic the appearance of a truecervical spine injury ~ 40% of children under the age of 8 demonstratepseudosubluxation at the C2-3 level 154. Spino-laminar line displacementwithin 1.5 mm of each other onboth flexion and extensionviews confirms the pseudo-subluxation A measurement of >2 mm isdefinitely abnormal, indicatinga true injury Measurement of 1.6 to 1.9 mm isconsidered indeterminate 155. Imaging plays a pivotal role in assessing the mechanical andneurologic stability of the traumatized thoraco-lumbar spine. Radiography is still preferred in low risk reliable(awake, alert, normal mental status, and no significant distractingpain) subjects. CT is the preferred imaging modality in subjects at high risk ofinjury, however, because of higher sensitivity and specificity. CT, with the use of high-resolution multiplanar and 3Dreformations, has resulted in improved fracture patternclassification with better differentiation between stable or unstableinjuries. MRI is still the only imaging method that demonstrates the softtissue components of injury and provides an objective assessmentof the damaged spinal cords internal architecture 156. Spinal Trauma: Imaging, Diagnosis, andManagement, 1st Edition, Schwartz, Eric D.;Flanders, Adam E. (Copyright 2007 LippincottWilliams & Wilkins) Internet