Cervical Spine Workshop

1. Cervical Spine Workshop Chris Dillon, MD Regions Emergency Medicine Residency Program

2. Why is this important? • Cervical spine injuries are both common and potentially devastating. • Incidence(USA) • 7,000 to 10,000 patients with cervical spine injuries who present for treatment annually. • An estimated 5,000 additional patients with cervical spine injuries die at the scene of the accident. • Half of cervical spine injuries are associated with spinal cord injury. • Consequences of neck injuries range from simple neck pain, to quadriplegia, or even death • Spinal cord injury occurs at the time of trauma in 85% of patients and as a late complication in 15%. • Delayed recognition of an injury or improper stabilization of the cervical spine may lead to irreversible spinal cord injury and permanent neurologic damage.

3. Who and why • Spinal cord injury most often occurs in teenagers and young adults. • Mean age 30.7, most commonly occurs at age 19 • 82% males • motor vehicle accident (50%) • falls (25%) • sports injuries (10%).

4. Cost • Direct costs for the first year after injury • High of $417,067 for ventilator dependent quadriplegics patients to a low of $122,914 in the group with near normal neurologic function. • Indirect costs often greatly exceed the direct costs.

5. We see these patients every day • Due to high morbidity and mortality of injuries • Regions Hospital EMS Guidelines • “Backboard patient with C-collar if patient complains of head, neck, or back pain, or if suggested by mechanism of injury, or if history is unreliable due to unconsciousness or altered mental status.”

6. Anatomy and types of injury

7. Upper Cervical Spine Injuries • Most common injury is flexion. • Fracture of odontoid process. • Extension injuries may occur, but are rare. • Rotation-rare, possible unilateral facet joint dislocation. • Axial loading-fracture of thinner parts of atlas anteriorly and posteriorly • Neurologic deficit is rare because of size of vertebral foramen.

8. The atlas articulates with the occipital condyle superiorly and the axis inferiorly. Atlanto-occipital articulation is important in the flexion and extension of the neck. • Atlas-axis articulation is important in the lateral rotation of the neck.

9. Lower Cervical Spine Injuries C3-C7 • Spinal Canal less spacious • Injuries associated with forces applied to spine • Flexion-Dislocated facets and fracture. • Extension-Damage to anterior structures and compression of posterior structures. • Facet joints at 45º-lateral rotation is limited, but injuries may still occur. • Axial loading-combined with flexion injury.

10. Normal Anatomy-C4 • Typical cervical vertebra of C3 - C7. • Vertebral body is equal in height anteriorly and posteriorly. • Vertebra articulates with the next vertebra at the body and the articular processes. • Vertebral artery passes through the transverse foramen.

11. Stability The determination of whether a given injury is stable is extremely important in the initial evaluation of cervical spine trauma. The stability of the cervical spine is provided by the two vertical columns. Anterior column consists of the vertebral bodies, the disc spaces, the anterior and posterior longitudinal ligaments and annulus fibrosus. Posterior column consists of the pedicles, facets and apophyseal joints, laminar spinous processes and the posterior ligament complex. Generally speaking, if one of the two columns is intact, the injury is stable, if both columns are disrupted, the injury is unstable.

12. Plain films • Plain films provide the quickest way to survey the cervical spine • An adequate spine series includes three views: • true lateral view (which must include all seven. • cervical vertebrae as well as the C7-T1 junction) • AP view. • open-mouth odontoid view.

13. Lateral View • The single most important radiographic examination of the acutely injured cervical spine is the horizontal-beam lateral radiograph that is obtained before patient is moved. This film should be obtained and examined before any other films are taken. All 7 cervical vertebrae and C7-T1 junction must be visualized because the cervicothoracic junction is a common place for traumatic injury. Visualization of C7-T1 may be limited by the amount of soft tissue in the shoulder region and can be enhanced by: 1. traction on arms if no arm injury is present, or, 2. swimmer's view (taken with one arm extended over the head).

15. Lateral view

16. AP and Open-Mouth Views • The complete radiographic examination includes AP and open-mouth views.If there are no obvious fractures or dislocations on the lateral view and the patient's condition permits, then proceed with the AP and the open-mouth views. It is important to obtain technically adequate films. The most frequent cause of overlooked injury is an inadequate film series. Patient should be maintained in cervical immobilization, and plain films should be repeated or CT scans obtained until all vertebrae are clearly visible. The AP view and Odontoid view are obtained as follows

17. AP/Odontoid

18. AP

19. Odontoid

20. CT • Up to 20 % of fractures are missed on conventional radiographs. CT can help.CT scan is not mandatory for every patient with cervical spine injury. Most injuries can be diagnosed by plain films. However, if there is a question on the radiograph, CT of the cervical spine should be obtained. CT scan are particularly useful in fractures that result in neurologic deficit and in fractures of the posterior elements of the cervical canal (e.g. Jefferson's fracture) because the axial display eliminates the superimposition of bony structures.The advantages of CT are: 1. CT is excellent for characterizing fractures and identifying osseous compromise of the vertebral canal because of the absence of superimposition from the transverse view. The higher contrast resolution of CT also provides improved visualization of subtle fractures.2. CT provides patient comfort by being able to reconstruct images in the axial, sagittal, coronal, and oblique planes from one patient positioning.The limitations of CT are: 1. difficult to identify those fractures oriented in axial plane (e.g. dens fractures).2. unable to show ligamentous injuries. 3. relatively high costs. Sagittal, coronal, 3D reconstructions are possible.

21. CT

22. MRI • MRI is indicated in cervical fractures that have spinal canal involvement, clinical neurologic deficits or ligamentous injuries. MRI provides the best visualization of the soft tissues, including ligaments, intervertebral disks, spinal cord, and epidural hematomas.The advantages of MRI are: 1. excellent soft tissue constrast, making it the study of choice for spinal cord survey, hematoma, and ligamentous injuries.2. provides good general overview because of its ability to show information in different planes (e.g. sagital, coronal, etc.).3. ability to demostrate vertebral arteries, which is useful in evaluating fractures involving the course of the vertebral arteries.4. no ionizing radiation.The disadvantages of MRI are:1. loss of bony details.2. relatively high cost. Here is an example of a MRI image of the cervical spine demostrating a ligamentous injury. Notice that the spinal cord is also very well delinated. A dens fracture is not obvious on the lateral film, but is clearly revealed on MRI.

24. Evaluation of images • A adequacy • A alignment • B bone • C cartilage • D disc • S soft tissue

25. Lateral View • The lateral view is the most important film of all. • Interpretation follows the mnemonic AABCDS. • First, is the film Adequate? • An adequate film should include all 7 vertebrae and C7-T1 junction. • It should also have correct density and show the soft tissue and bony structures well.

27. Alignment • Assess four parallel lines. These are: 1. Anterior vertebral line (anterior margin of vertebral bodies) 2. Posterior vertebral line (posterior margin of vertebral bodies)3. Spinolaminar line (posterior margin of spinal canal)4. Posterior spinous line (tips of the spinous processes) These lines should follow a slightly lordotic curve, smooth and without step-offs. Any malalignment should be considered evidence of ligmentous injury or occult fracture, and cervical spine immobilization should be maintained until a definitive diagnosis is made.

28. Alignment

29. Bony Landmarks • Trace the unbroken outline of each vertebrae (including Odontoid on C2). The vertebral bodies should line up with a gentle arch (normal cervical lordosis) using the anterior and posterior marginal lines on the lateral view. Each body should be rectangular in shape and roughly equal in size although some variability is allowed (overall height of C4 and C5 may be slightly less than C3 and C6) . The anterior height should roughly equal posterior height (posterior may normally be slightly greater, up to 3mm).

30. Bony Landmarks

31. Bony Landmarks • Pedicles project posteriorly to support the articular pillars, forming the superior and inferior margins of the intervertebral foramen. The left and right pedicels should superimpose on true lateral views. If fracture is suspected, get oblique views or CT. • Facets: the articular pillars are osseous masses connected to the posterolateral aspect of vertebral bodies via the pedicles. The facet joints are formed between each lateral mass. On the lateral view, the lateral masses appear as rhomboid-shaped structures projecting downward and posterior. "Double cortical lines" results from slight obliquity from lateral projection. The distance of the joint space should be roughly equal at all levels. • Lamina: the posterior elements are seen poorly on the lateral film. They are best demostrated by CT. • Spinous process: generally get progressively larger in the lower vertebral bodies. The C7 cervical spine is usually the largest.

32. Bony Landmarks

33. Cartilaginous Space • The Predental space (distance from dens to C1 body) should not measure more than 3 mm in adults and 5mm in children. If the space is increased, a fracture of the Odontoid process or disruption of the transverse ligament is likely. If fracture is suspected, CT should be obtained. If ligamentous disruption is suspected, a MRI should be obtained. • Predental space should be: • < 3 mm in adults.

34. Predental space

35. Disc Spaces • Disc spaces should be roughly equal in height at anterior and posterior margins. • Disc spaces should be symmetric. • Disc space height should also be approximately equal at all levels. In older patients, degenative diseases may lead to spurring and loss of disc height.

36. Disc Spaces

37. Soft Tissue Space • Preverteral soft tissue swelling is important in trauma because it is usually due to hematoma formation secondary to occult fractures. Unfortunately, it is extremely variable and nonspecific. Maximum allowable thickness of preverteral spaces is as follows: Nasopharyngeal space (C1) - 10 mm (adult)Retropharyngeal space (C2-C4) - 5-7 mmRetrotracheal space (C5-C7) - 14 mm (children), 22 mm (adults). Soft tissue swelling in symptomatic patients should be considered an indication for further radiographic evaluation. If the space between the lower anterior border of C3 and the pharyngeal air shadow is > 7 mm, one should suspect retropharyngeal swelling (e.g. hemorrhage). This is often a useful indirect sign of a C2 fracture. Space between lower cervical vertebrae and trachea should be < 1 vertebral body.

38. Soft Tissue Space

39. AP View • Alignment on the A-P view should be evaluated using the edges of the vertebral bodies and articular pillars.The height of the cervical vertebral bodies should be approximately equal on the AP view.The height of each joint space should be roughly equal at all levels.Spinous process should be in midline and in good alignment. If one of the spinous process is displaced to one side, a facet dislocation should be suspected.

40. AP

41. Odontoid View • Adequate? • An adequate film should include the entire odontoid and the lateral borders of C1-C2. • Alignment? • Occipital condyles should line up with the lateral masses and superior articular facet of C1.The distance from the dens to the lateral masses of C1 should be equal bilaterally Any asymmetry is suggestive of a fracture of C1 or C2 or rotational abnormality. It may also be caused by tilting of the head, so if the vertebrae is shifted in on one side, then it should be shifted out on the other side. The tips of lateral mass of C1 should line up with the lateral margins of the superior articular facet of C2. If not, a fracture of C1 should be suspected. • Bony Margins.the Odontoid should have uninterrupted cortical margins blending with the body of C2.

42. Odontoid View

43. Mechanism of Injury • The cervical spine may be subjected to forces of different directions and magnitude. The most common mechanisms of cervical spine injury are hyperflexion, hyperextension and compression.

44. Hyperflexion • Excessive flexion of the neck in the sagital plane. It results in disruption of the posterior ligament. A common cause of hyperflexion injury is diving in shallow water, which may result in flexion tear drop fracture.

45. Hyperextension • Excessive extension of the neck in the sagital plane. A common cause of hyperextension injury is hitting the dash board in MVA, which may result in Hangman's fracture.

46. Axial compression • Force applied directly over the vertex in the caudal direction. This compression force "like smashing a cracker" may result in Jefferson fracture, a bursting fracture on the atlas.

47. Atlanto-occipital Disassociation • Description: Disruption of the atlanto-occipital junction involving the atlanto-occipital articulations. Mechanism: Hyperflexion or hyperextension.Radiographic features: 1. Malposition of occipital condyles in relation to the superior articulating facets of the atlas.2. Increased ratio of Basion - spinolaminar line of C1 to Opisthion - posterior cortex of C1 anterior arch for incomplete anterior atlanto-occipital dislocation. (Refer to atlanto-occipital alignment for further explaination).3. Cervicocranial prevertebral soft tissue swelling. Stability: unstable  

48. Atlanto-occipital Disassociation

49. Jefferson Fracture • Description: compression fracture of the bony ring of vertebra C1, characterized by lateral masses splitting and transverse ligament tear.Mechanism: axial blow to the vertex of the head (e.g. diving injury).Radiographic features: the key radiographic view is the AP open mouth, which shows displacement of the lateral masses of vertebrae C1 beyond the margins of the body of vertebra C2. A lateral displacement of >2 mm or unilateral displacement may be indicative of a C1 fracture. CT is required to define the extent of fracture and to detect fragments in the spinal canal. Stability: unstable

50. Jefferson Fracture