A Pictorial Review of the Biomechanics and Imaging Findings in Cervical Spine Injuries

Transcription

1 A Pictorial Review of the Biomechanics and Imaging Findings in Cervical Spine Injuries Award: Certificate of Merit Poster No.: C-1741 Congress: ECR 2011 Type: Educational Exhibit Authors: A. Adams, A. Shawyer, J. Colledge, J. Evanson, N. Power, S Vaidya ; High Wycombe/UK, London/UK Keywords: Trauma, Acute, Conventional radiography, MR, CT, Neuroradiology spine, Musculoskeletal spine, Emergency DOI: /ecr2011/C-1741 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 49

2 Learning objectives Learning Objectives Review anatomy of the cervical spine and common sites of traumatic injury. Review the approach for the interpretation of cervical spine radiographs and computed tomography (CT) in the acute trauma setting Present a spectrum of traumatic cervical spine injuries with relation to the underlying mechanism of injury. Correlation with MR imaging is provided in selected cases and classification of some of the fracture patterns is provided. Page 2 of 49

3 Background Background Approximately 63% of spinal cord injuries involve the cervical spine[1]. In adults, approximately 75% of injuries occur in the lower cervical spine (C3-C7). A missed spinal injury can have devastating consequences therefore a spinal column injury must be presumed until it is excluded in the trauma setting. Plain Film Radiography Standard 3 view plain film series to include: 1. Lateral view (Figure 1) Base of the occiput to the first thoracic vertebra [2,3] Check spinal lines (Figure 1) Red line along the anterior margin of the vertebral bodies Brown line along the posterior margin of vertebral bodies Green line along bases of the spinous processes Brown line along the tips of the spinous processes All the lines should form smooth unbroken lines. Note that at the C2 level there can be a step in the Green line but this should measure no more than 2mm. Page 3 of 49

4 Distance between arch of C1 and anterior aspect of the odontoid peg Distance in adults <3mm, children <5mm) Assessment of prevertebral soft tissues - width < 7mm at the C1-C4 levels and width <22mm at the C5-7 levels. 2. Long AP view (Figure 2) Central ray is angled degrees cephalic and view should include all of the first thoracic vertebrae and as much of the proximal C-spine as is possible. Check alignment of the spinous processes as a straight line (Red line). The distance between the spinous processes should be approximately equal. Check vertebral body heights are preserved as well as the intervertebral disc heights (Green and Light blue lines). This is also assessed on the lateral view. 3. PEG view (Figure 3) Lateral margins of the C1 vertebra should align with the lateral masses of C2 (Blue line) Distance between the odontoid peg and lateral mass of C2 should be equal (Red line) Rotation of the neck may alter the appearances but the lateral masses should always be normally aligned. Computed Tomography Imaging of C Spine Approach will be outlined and during the interactive cases various aspects will be emphasised. Page 4 of 49

5 Ensure there is adequate coverage of the entire cervical spine from occipital condyles to the T1 vertebral body. Cervical spine should always be viewed in all three orthogonal planes. In the mid Sagittal plane, the same rules apply as for plain film radiography, with assessment of the spinal lines (Figure 4); Anterior vertebral (red), Posterior vertebral (brown), Spinolaminar (green) and interspinous line (blue). Assessment of vertebral body heights and outline should be made as well as assessment of intervertebral disc height. In the parasagittal plane, alignment of the facet joints should be made on both sides (Figure 5) and then correlated with the coronal and axial views. The latter demonstrating the normal 'hamburger' sign of normally aligned facets. Assessment of the craniocervical junction should also be made with assessment of congruity of between the occipital condyles and C1 as well as the C1-C2 articulation (Figure 6). Application of the Denis' concept of stability is frequently utilised in the emergency setting (Figure 7) Page 5 of 49

6 Images for this section: Fig. 0: Spinal lines on lateral radiograph. - High Wycombe/UK Page 6 of 49

7 Fig. 0: AP radiograph alignment. - High Wycombe/UK Page 7 of 49

8 Fig. 0: Open mouth / Odontoid PEG view. - High Wycombe/UK Page 8 of 49

9 Fig. 0: Spinal lines applied to sagittal CT images - High Wycombe/UK Page 9 of 49

10 Fig. 0: Facet joint alignment on the axial and sagittal CT images - High Wycombe/UK Page 10 of 49

11 Fig. 0: Cranicervical junction alignment. - High Wycombe/UK Page 11 of 49

12 Fig. 0: Denis' concept of stability. - High Wycombe/UK Page 12 of 49

13 Imaging findings OR Procedure details Interactive Cases Case 1 43 year old male patient involved as a driver in a high speed road traffic accident (RTA). Review the images from Figures 7 and 8 Fig.: Figure 7: Selected sagittal images of the cervical spine. Page 13 of 49

14 Fig.: Figure 8: Selected CT and MR images for case 1. The sagittal CT images reveal a craniocervical distraction injury (Figure 9). Note the increased basion-dens interval (yellow line) and abnormal alignment of the posterior spinolaminar line (red line). Page 14 of 49

15 Fig.: Figure 9: Case 1 explained. Note the bone fragments (purple arrow) associated with disrupted occipitoatlanto joints representing fractures of the occipital condyles. In addition there is widening between the occipital condyles and C1 on the coronal image (dark blue line). Extensive prevertebral soft tissue swelling also present (green line). On the selected MRI images, there is extensive signal change within the lower medulla extending into the proximal cord consistent with contusions (yellow asterisk) but there was no evidence of haemorrhage or intraspinal haematoma. In addition, there is significant cervical pre-vertebral soft tissue swelling with a fluid collection immediately anterior to the C1-C3 (red asterisk). There is also considerable soft tissue signal abnormality in the posterior high cervical soft tissues (green asterisk). Page 15 of 49

16 Atlanto-occipital dislocation usually results from high speed RTAs and represents <1% cervical spine injuries [5]. This is a type of distraction injury which results in disruption of the stabalising ligaments between C1 and the skull as well as between the dens and the skull. Distraction refers to pulling apart of the spine which can result in ligamentous and spinal cord damage. Often fatal with high incidence of neurological deficits in survivors. Treatment requires fusion of occiput to C2. Case 2 38 year old male patient involved in a RTA at 70 miles/hour with low GCS at the scene. Refer to the images from Figure 10 and subsequent imaging in Figure 11. Page 16 of 49

17 Fig.: Figure 10: Selected sagittal, coronal and axial images for case 2. Fig.: Figure 11: Selected sagittal images for case 2. There is malalignment at the cranio-cervical junction with evidence of atlanto-axial dissociation with marked widening of the C1-C2 facets best appreciated on the coronal CT image (also refer to yellow asterisk on parasagittal MRI). This also forms part of the spectrum of injuries that can result from distraction and extension forces. On the CT images, note again the widening of the basion-dens interval (abnormal > 12mm), malalignment of the posterior spinolaminar line and associated prevertebral soft tissue swelling. Page 17 of 49

18 The images also reveal a fracture of C1 vertebral body. The fracture involving the anterior neural arch is displayed on the sagittal and axial views. Further fractures of the left articular pillar and the posterior neural arch were identified (not shown). On the MRI images note the ligamentous disruption (cruciform ligament and anterior longitudinal ligament - yellow arrows). Contusional changes noted within the cord extending from lower medulla to the C4 level (blue arrow). There is also evidence of prevertebral haematoma extending along the cervical spine (green asterisk) and in the soft tissues of the neck posteriorly (orange asterisk). Also note the C6/C7 hyperintensity through the disc which would suggest a hyperextension injury at this level. Case 3 78 year female having sustained a fall down a flight of stairs. Complaining of neck pain post fall and CT imaging of the head and cervical spine was performed; selected CT images from the study provided in Figure 12. Page 18 of 49

19 Fig.: Figure 12: Selected CT images for case 3. The CT images reveal a compression fracture of the C1 vertebra Jefferson Burst fracture. Note the fractures through the anterior and posterior arches of the C1 vertebra. Result of axial compressive force applied to the skull vertex and hence transmitted through the occipital condyles. On the coronal and sagittal view of the craniocervical junction note the fracture of the left sided occipital condyle - Type I fracture. This fracture is not uncommonly associated with other fractures of the vertebral column. On plain radiography (Figure 13) there is lateral displacement of both articular masses of C1 from those on C2 on the open mouth view. On a lateral view there may be separation of the dens and C1 anterior arch. Page 19 of 49

20 Fig.: Figure 13: Jefferson Burst fracture radiography. On CT imaging various patterns of arch disruption are identified. Unstable fractures are present if there is disruption of the transverse or posterior longitudinal ligaments or if there is severe comminution of the anterior arch. Case 4 74 year old male found collapsed on the floor. Initially underwent a CT head examination followed by imaging of cervical spine (Figure 14). Page 20 of 49

21 Fig.: Firgure 14. Selected images for case 4. This is an example of bilateral avulsion of the C2 vertebral body from its arch - a Hangman's C2 fracture (yellow arrows figure 15) - type II. Note also involvement of the right sided foramina transversaria (blue arrow Figure 15) and risk of vertebral artery injury. Page 21 of 49

22 Fig.: Figure 15; Case 4 plain radiograph and CT explained. Different types of Hangman's fractures are described - also known as traumatic spondylisthesis of axis; Type I (65%); hairline fracture. Normal C2/3 intervertebral disc. Type II (28%); displaced C2 and disrupted C2/3 intervertebral disc, C3 antero- superior compression fracture - Unstable Type III (7%); displaced C2 with unilateral/bilateral facet dislocation at C2/3 - unstable. Additional fractures are seen in a third of cases - commonly C1. Classic hanging with knot in submental position produces complete disruption of C2/3 and intervertebral disc with contusion/tearing of cord by a combined distraction and hyperextension force. Page 22 of 49

23 Traumatic spondylisthesis of axis can result from either hyperextension with axial loading or hyperflexion with compression. Case 5 68 year old female complaining of neck pain following a fall 3 days ago Figure 16. Fig.: Figure 16: Case 5 plain radiography and CT images. This case reviews a number of fractures already described; Note on the plain radiographs that there is malignment of the lateral masses of C1 and C2 due to the Jefferson burst fracture of C1. The axial image of C2 vertebra also reveals a fracture through the pedicles of C2 with no disruption or dislocation of C2/3 - type I Hangmans fracture. Page 23 of 49

24 On the Sagittal CT image and lateral radiograph note the transverse fracture through the odontoid peg - Type II fracture (Figure 17). Fig.: Fgure 17: Odontoid peg fracture types. Case 6 32 year male sustained a fall from height. Patient intubated on scene and transferred to our trauma centre. Selected images on figure 18. Page 24 of 49

25 Fig.: Figure 18: Case 6 selected CT images. Axial loading compression force accounts for the pattern of injuries. Again note the burst fracture of C1 and associated prevertebral soft tissue swelling. Lung contusions at the apices of both lungs are visible on the coronal view. Comminuted odontoid peg fracture with involvement of the body - type III (Figure 17). There is disruption of all three vertebral lines representing an unstable fracture. Page 25 of 49

26 Fig.: Figure 19: Case 6 selected MR images. MR images (Figure 19) depict the prevertebral haematoma (red arrow), oedema and/or blood in the interspinous tissues between the C1 and C2 (yellow arrow) which is tracking into the posterior epidural space at the C1 level. The anterior longitudinal ligament is disrupted (blue arrow) and the posterior longitudinal ligament was also incomplete. The cord itself does not demonstrate any evidence of contusion or oedema. Case 7 26 year old male sustained a fall from height. Selected CT images of the craniocervical junction (Figure 20). Page 26 of 49

27 Fig.: Figure 20: Selected CT images for case 7 This is another example of a Type I occcipital condylar fracture resulting from a high-energy trauma. Occipital condylar fractures can be subdivided into 3 types based on the morphology and mechanism of injury. Type I and II injuries are generally stable because the alar ligament and tectorial membrane are preserved, while type 3 is potentially unstable. Type I fracture (15%) - impaction fracture of the occipital condyle due to axial compression. Type II fracture (50%) - base of skull fracture that extends to involve the occiptal condyle usually due to a direct blow to the skull. Type III fracture (35%) - avulsion injury of the alar ligament attachment due to forced contralateral bending and rotation. Considered potentially unstable. Page 27 of 49

28 Case 8 27 year old male presented with severe neck pain having fallen off a trampoline. Selected CT and MR images are provided on Figures 21 and 22. Fig.: Figure 21: Case 8 radiograph and selected CT images. Page 28 of 49

29 Fig.: Figure 22: selected CT ad MR images. On the CT images there are bilateral facet dislocations at the C5-C6 level, with the C5 facets jumped anterior to the C6 facets ('reverse hamburger' sign noted on the axial images with normal C4/5 articulation for comparison). At the C5-C6 level there is disruption of all the spinal lines and traumatic injury of the intervertebral disc at this level. On the MRI there is signal change within the cord at the C5-6 level with a small haematoma dorsal to the cord at the level of C6. This type of injury is the result from sudden and forceful rotation and flexion force on skull/spine. Flexion-rotation injuries can occur at any level of the spinal cord but usually involve the cervical area, particularly C5 and C6 (Figure 23). Page 29 of 49

30 Fig.: Figure 23: plain radiography explained. The near-horizontal articulation of the cervical facets predisposes to easy subluxation once ligaments are torn. The cervical vertebrae can be dislocated by a sudden impact, the impact shearing supporting ligaments and blood vessels. Associated abnormalities therefore include dissection of vertebral or carotid arteries as well as spinal cord damage. Case 9 34 year old female attempted suicide with jump from a building from first floor. Transferred to our trauma centre - selected CT images provided Figures 24 and 25. Page 30 of 49

31 Fig.: Figure 24: slected sagittal CT images. Page 31 of 49

32 Fig.: Figure 25: further selected CT images. On the CT note the burst fracture of C4 with retropulsion and central canal compromise. These injuries may be clinically & radiographically similar to a flexion-teardrop fracture and difficult to differentiate. There is bilateral posterior element involvement of the C4 vertebra. On the Sagittal view note the separation between the C4 and C5 spinous processes as well as the subluxed facet joints at this level. As noted on the CT images, features of burst fracture include disruption and vertical fracture through the vertebral body, posterior element fractures and anterior wedge deformity of the vertebral body. Given the mechanism of injury, this injury was attributed mainly to axial loading with flexion as the secondary force. Page 32 of 49

33 Case year old female transferred to our trauma unit following a fall from height. Selected CT and MR images provided in Figures 26 and 27. Fig.: Figure 26: selected CT images for case 10. Page 33 of 49

34 Fig.: Figure 27: selected CT and MR images for case 10. On the CT images note the anterior wedge compression fracture of the C7 vertebral body. In addition there are avulsion fractures from the anteroinferior aspect of C6 ('teardrop') and anterosuperior aspect of C7. Note the widening of the C6 and C7 facets as well as the lateral mass and posterior arch fracture of the C6 vertebra. On the MRI there was evidence of intervertebral disc injury at the C6-7 level with prevertebral haematoma and high signal with the soft tissues posteriorly. Altered signal was identified within the cord but no evidence of haemorrhage or haematoma. This type of injury was the result of a combination of flexion and compressive forces. Typically, flexion teardrop fractures involve failure of the anterior column, with or without middle column disruption, with concomitant disruption of the posterior ligamentous complex (Figure 28). Page 34 of 49

35 Fig.: Figure 28: flexion teardrop radiography. Tear drop may either involve an anteroinferior body fragment, or a posterior inferior fragment which may encroach into the canal and cause paralysis. Case year old female involved in a low speed RTA. Complaining of neck pain and underwent plain film radiography followed by a subsequent CT - Figures 29 and 30. Page 35 of 49

36 Fig.: Figure 29: case 11 plain radiography. Page 36 of 49

37 Fig.: Figure 30: case 11 selected CT images. On the AP radiograph note the abnormal alignment of the spinous processes at the C6 to C7 level. Although the lateral view is not adequate, the perched facet of C6 on C7 can be identified. On the CT images the right sided facet dislocation can be identified in keeping with unilateral facet dislocation of C6 on C7. On the axial images, note that this creates the 'reverse hamburger' sign. On the contralateral side, the C6 facet is perched on the inferior C7 facet. In addition, note the anterior subluxation of the C6 vertebral body in relation to C7. Simple unilateral facet dislocation is often a stable injury even though there is disruption of the posterior ligament complex Page 37 of 49

38 This type of injury involves forward rotation of one side of the vertebral body about the contra-lateral facet joint. Combined with a simultaneous flexion force, this produces a unilateral facetal dislocation. Case year old male admitted following an injury whilst playing rugby with the patient complaining of severe neck pain and bilateral arm parasthesiae. Selected CT and MR images in Figure 31. Fig.: Figure 31: case 12 selected CT and MR images. On the CT there is anterior widening between the C6 and C7 vertebrae, a C6 spinous process fracture and associated prevertebral soft tissue swelling. Also note the subtle widening between C6 and C7 facets. Page 38 of 49

39 On the MRI images there is disruption of the C6/7 intervertebral disc with widening of the disc space. Abnormal signal intensity within the spinal cord is noted from the level of C3 - T1 with appearances in keeping with cord contusion. This type of injury was associated with forced extension (hyperextension) where the head is sharply thrust back and the upper spinal segments are hyperextended [6]. This type of injury can disrupt supporting ligaments, rupture intervertebral discs and they typically fracture the posterior elements of the lower cervical vertebrae. This type of injury also occurs with increased frequency in patients with limited spinal mobility e.g. ankylosing spondylitis. Case year old male pedestrian hit by a car at approx 30 mph with loss of consciousness at the scene. Imaging of the head and cervical spine was performed with selected images on Figures 32 and 33. Page 39 of 49

40 Fig.: Figure 32: Case 13 selected CT images. Page 40 of 49

41 Fig.: Figure 33: case 13 selected CT and MR images. There is a comminuted fracture of C7 involving the left lateral mass that extends anteriorly into the vertebral body. The fracture also extends to involve the facet joint and its articulation with the C6 vertebrae. This type of injury is predominantly the result of lateral forces - lateral flexion injury. This is typically defined by a fracture of the articular mass associated with fractures of the transverse, uncinate processes and vertebral body. Lateral flexion injuries are commonly associated with neurological deficits in terms of plegia and radiculopathy and assessment/imaging of the brachial plexus is required. Case 14 Page 41 of 49

42 24 year old builder transferred to our trauma unit after falling off scaffolding from approximately 15 feet with immediate loss of consciousness. Selected images on Figures 34 and 35. Fig.: Figure 34: case 14 selected CT images. Page 42 of 49

43 Fig.: Figure 35: case 14 selected MR images. On the CT images note the vertical fractures through the C4-C6 vertebral bodies with concomitant loss of anterior vertebral body height. The spinous process and left lateral mass of the C4 vertebrae are also fractured with extension into the foramina transversaria (Subsequent CTA was normal). Note the postero-inferior teardrop fracture arising from the body of the C4 vertebra with retropulsion into the spinal canal and malalignment of the C5 and C6 vertebral bodies. On the axial MRI image, the subarachnoid space is effaced and there is intramedullary T2 hyperintense signal change, suggesting cord contusion / odema. Post traumatic soft tissue changes are noted in the cervical prevertebral plane and soft tissues of the neck posteriorly. This combines the fracture pattern identified with severe axial loading compression and flexion forces. Page 43 of 49

44 Case year old male involved in a high speed RTA. Selected cervical spine images on Figures 36. Fig.: Figure 36: case 15 selected CT images. These images combine a number of different injuries. There are fractures of the C2 pedicles bilaterally. There is disc disruption of the C4/5 disc with associated anterior subluxation of the C4 verteba on C5 with a teardrop fracture involving the anteroinferior aspect of C5. The bilateral lamina fractures of C4 extend in to the facet joints and are associated with a right unilateral facet joint dislocation at the C4/5 level and subluxation on the left. Page 44 of 49

45 This trauma combined a number of injuries which suggest the mechanism involved a combination of rotation as well as significant Case year old male involved in a high speed RTA. Selected images provided in figure 37. Fig.: Figure 37: Case 16 selected CT and MR images. There is a comminuted burst fracture-dislocation of the C5 vertebral body with marked retropulsion into the spinal canal. Unilateral dislocation of the C4/5 facet and contralateral perched facet at the same level. Page 45 of 49

46 The C5 fracture also involves the left lamina and left transverse process extending into the left foramen transvesarium- a CTA was then performed Fig.: Figure 38: CT angiogram performed for suspected vertebral artery injury. The left vertebral artery arises directly from the aortic arch and the proximal intrathoracic portion of the left vertebral artery enhances normally. However, it tapers down at the root of the neck with no flow visible within it up to the C4/5 fracture level There is distal contrast enhancement seen likely due to retrograde flow. The appearances are in keeping with traumatic dissection of the left vertebral artery. Page 46 of 49

47 Conclusion Conclusion A review of basic cervical spine anatomy has been provided on both plain film radiography and CT. The approach to plain film and CT imaging interpretation of the cervical spine in the trauma setting has been reviewed. A spectrum of cervical spine injuries has been demonstrated from the cranicervical junction down to the lower cervical spine and with correlation with the underlying biomechanics. Rapid and accurate detection of cervical spine injuries is required in the acute trauma setting and this is aided by interaction with the trauma team and understanding the mechanism of injury. Page 47 of 49

48 Personal Information Thank you for taking the time to look at our electronic poster. We hope it was of educational value and if there are any queries feel free to contact us; Dr Ashok Adams Specialist Registrar Clinical Radiology Barts and the London NHS Trust Page 48 of 49

49 References References 1. Acheson M et al. High resolution CT scanning in the evaluation of cervical spine fractures: comparison with plain film examinations. American Journal of Roentgenology, Vol 148: , Raby N, Berman L, De Lacey G. Accident and Emergency Radiology. A survical guide. Elsevier Saunders, Berquist T. Imaging of adult cervical spine trauma. Radiographics. Volume 8, Number 4, July Diagnostic Imaging: Emergenc. Jeffrey R. Amirsys Deliganis A et al. Radiologic spectrum of craniocervical distraction injuries. Radiographics, 20:S237-S250, Rao S et al. Spectrum on Imaging Findings in Hyperextension Injuries of the neck. Radiographics, 25: , Page 49 of 49