Cervical Spine Injuries in the Athlete

1. Cervical Spine Injuries in the Athlete

2. Key Points • If the space available for the spinal cord is reduced because of a narrow canal, an athlete is at greater risk • Cord compression can be anticipated when the diameter of the midsagittal cervical spinal canal is 10 mm or less • Cervical spine injuries can be classified as either catastrophic or noncatastrophic • The initial evaluation follows the ABCDE sequence of trauma care

3. Distinct regional differences exist between the upper cervical spine and the lower cervical spine • The occipitand the first two vertebrae make up the upper cervical spine • The atlas (C1) is a bony ring that articulates with the occipital condyles • The axis (C2) has a true vertebral body, from which the odontoid process, or dens, projects. • The major stabilizing force at this joint is the transverse atlantal ligament (TAL). • TAL crosses posterior to the dens and attaches to C1 on both sides; this prevents anterior translation of the atlas on the axis. • This specialized osseo-ligamentousanatomy allows C1 to rotate on C2 in a highly unconstrained manner, providing 60% of all cervical rotation

4. The lower cervical spine consists of the C3 through C7 vertebrae • Two contiguous vertebrae and supporting soft tissues make up a motion segment • Motion segments can be separated into an anterior and a posterior column • The anterior column include the posterior longitudinal ligament and all structures ventral to it • The posterior column consists of those structures dorsal to the posterior longitudinal ligament. ALL, anterior longitudinal ligament; D, division between anterior and posterior column; F, facet articulation; FC, facet joint capsule; IAP, inferior articular process; IS, interspinousligament; IVD, intervertebral disc; PLL, posterior longitudinal ligament; SAP, superior articular process; VB, vertebral body • Stability of a cervical motion segment is derived mainly from the anterior column elements • The vertebral bodies and inter-vertebral discs provide the majority of resistance to compression. • The surrounding paraspinal musculature and ligaments that resist shear forces.

5. The cervical spinal canal is funnel shaped from cephalad to caudal. • The cord occupies less than half the canal's cross-sectional area at the level of the atlas, but this space reduces significantly in the lower cervical spine. • Almost 75% of the cross-sectional area of the canal is occupied by the larger spinal cord between C4 and C7

6. The diameter of the midsagittal cord averages between 8 and 9 mm • A range of 14 to 23 mm exists for the vertebral canal at the corresponding level • Criteria for radiographic stenosis are anteroposterior dimensions measuring less than 13 mm on a lateral radiograph • When the diameter of the midsagittal cervical spinal canal is 10 mm or less, cord compression can be anticipated • Pavlov's ratio (canal-vertebral body width):           - should be 1.0, with < 0.85 indicating stensosis;           - ratio of < 0.80 is a significant risk factor for lateral neurologic injury

7. Catastrophic Cervical Spine Injuries • Defined as a structural distortion of the cervical spinal column associated with actual or potential damage to the spinal cord • Include • Unstable fractures and dislocations, • Transient quadriplegia, and • Acute central disc herniation • Only a very small percentage • Usually affect the extremities in a bilateral fashion

8. Non-Catastrophic Cervical Spine Injuries • The vast majority of injuries are noncatastrophic. These injuries include • Neuropraxia of the cervical root or brachial plexus (known as a “stinger” or “burner”) • Paracentralintervertebral disc herniation, • Stable fractures, • Spinal ligament injury, and • Intervertebral disc injury • Injured athletes display clinical findings in • (a) a single upper extremity, • (b) the neck and arm, or • (c) the neck only

9. Unstable Fractures and Dislocations • Make up the majority of catastrophic spinal injuries in athletes • Loss of the ability of the spine, under physiological loads, to maintain its premorbid patterns of motion, so there is no initial or additional damage to the spinal cord or nerve roots • Most fractures and dislocations in injured athletes occur in the lower cervical spine. • In football, mainly • compression injury (axial loading). • Hyperflexion. • Hyperextension, • lateral stretch, and • congenital instability also have been reported in cervical spine injury

10. Hyperflexion Injuries • Flexion-Compression Injuries • Teardrop Fracture • Burst Fracture • Flexion-Distraction Injuries • Unilateral Facet Dislocation • Bilateral Facet Dislocation

11. Most influential in determining specific injury patterns is the neck position at the time of impact Neutral alignment leaves the cervical spinal column slightly extended because of the normal lordotic posture Compressive forces in this position are dissipated by the anterior paravertebral musculature and vertebral ligaments (anterior longitudinal ligament) Slight flexion will eliminate cervical lordosis Direct force along the spine's longitudinal axis will result in large forces being transferred directly to the vertebrae as opposed to the surrounding soft tissues Cadaveric studies have shown that the cervical spine, when straight and colinear with the applied load, responds to compression by buckling A: With the neck in neutral alignment, the vertebral column is extended. The compressive force can be dissipated by the spinal musculature and ligaments. B: With the neck in a flexed posture, the spine straightens out and becomes colinear with the axial force. C: At the time of impact, the straightened cervical spine undergoes a rapid deformation and buckles under the compressive load

12. Burst Fracture • Pure Vertical Compression (the cervical spine is slightly flexed, eliminating the normal lordosis) results in equal force on the anterior and posterior columns, which may result in an axial loading fracture (“burst”) • Intradiscal pressure rises such that the adjacent end plate fractures and fails • Bone fragments often can displace in all directions secondary to forced, extruded disc material within the vertebral body. • These burst fractures are notable for retropulsion of osseous material into the spinal canal. In the “burst” fracture variant, comminution of the vertebral body can be associated with retropulsion of osseous fragments into the spinal canal

13. Teardrop Fracture • Results from a compressive–flexion injury is present as a result of a combination of axial force and bending • The anterior column shortens under loading. We then see compressive failure of the vertebral body and tensile failure of the posterior spinal ligaments • This pattern can be highly unstable both anteriorly and posteriorly, with displacement of the anterior fracture and widening of the posterior elements, and it often may be associated with spinal cord injury The “teardrop” fracture variant is characterized by compressive failure of the anterior column with a coronal plane fracture extending through the vertebral body. Tensile forces cause disruption of the posterior spinal ligaments

14. Flexion–Distraction Injuries • Can be created either by a direct blow to the occipital region or by a rapid deceleration of the torso • The most common injury is bilateral facet dislocation • An axial rotation force in conjunction with the flexion–distraction injury may produce a unilateral facet dislocation (spinal cord injury in up to 25% of cases) Lateral cervical spine radiographs showing bilateral facet dislocation of C6 on C7. This pattern of injury results from disruption of the supraspinous and interspinous ligament, facet capsules, ligamentumflavum, posterior longitudinal ligament, and the dorsal portions of the annulus fibrosus. The soft tissue damage can be associated with fractures of the superior articular processes. B: Unilateral facet dislocation usually is caused by the combination of flexion and rotational forces. The addition of shear or compressive forces can cause fracture of the articularprocess

15. Upper cervical spinal fractures and dislocations Although significant injuries, rarely cause spinal cord damage The spinal canal in the upper cervical region has a much greater proportion of space to spinal cord. Therefore, even with displacement, cord compression is unlikely in relation to upper cervical spinal injury. In fact, a burst fracture of the atlas (Jefferson fracture) and traumatic spondylolisthesis of the axis (Hangman fracture) expand the dimensions of the spinal canal, making cord compression and neurological injury improbable. Odontoidfractures or ruptures of the transverse ligament will destabilize the atlantoaxial joint. Typically, high cervical cord injuries can cause respiratory compromise secondary to high-cord/low-brainstem injury as well as diaphragmatic paralysis from trauma to the anterior horn cells of the phrenic nerve

17. Transient Quadriplegia • A momentary cord compression at the extremes of neck extension or flexion (The Pincer Mechanism) • Congenital cervical stenosismay predispose • A Pavlov ratio of less than 0.8 was documented in 93% of football players with cervical cord neuropraxia • S&S of transient quadriplegia include pain, tingling, or loss of sensation bilaterally in the upper and/or lower extremities. • A mild quadriparesis usually exists, but usually no motor weakness • Rarely complete quadriplegia also is possible • May last from 15 minutes to 48 hours, but full recovery often is expected The “pincer mechanism” effect of hyperextension causes dynamic compression of the spinal cord between the end plate of the cranial vertebral body and the spinolaminar line of the subjacent vertebra

18. Intervertebral Disc Herniation • Extrusion of the nucleus pulposus posteriorlycan cause acute cord compression. • Unlike the more common lower lumbar disc herniations, cervical disc herniations can produce permanent cord injury. • Posterior neck pain, paraspinal muscle spasm, and either transient or permanent acute paralysis are the most common symptoms. • Radiating (radicular) pain or referred pain unilaterally down the shoulder and arm also may be present

19. Congenital Spinal Anomalies • Many are completely asymptomatic, discovered at the time of injury • Predispose athletes to certain forms of spinal cord injury • Klippel-Feil syndrome, which reduces the number of motion segments in the spine, may lead to progressive instability or degenerative stenosis. • Multiple fusions in the cervical spine in this condition make it difficult to dissipate loads that are applied to the cervical spine • Hypoplasia of the dens (i.e., a failure of formation involving the second vertebra) and developmental osodontoideum can both result in atlantoaxial instability

20. Noncatastrophic Cervical Spine Injuries • Neuropraxia of the cervical root or brachial plexus (the “stinger” or “burner”) • Paracentralintervertebral disc herniation • Stable fractures • Spinal ligament injury • Intervertebral disc injury

21. Neuropraxia of a cervical nerve root or the brachial plexus • Foraminal compression of a nerve root from forceful neck extension and rotation toward the affected side • Traction (tensile forces) may injure the brachial plexus, resulting in a neuropraxia

23. Signs and symptoms • Burning pain, weakness, or paresthesias in the shoulder girdle and arm. • Neck tenderness usually is absent, and range of motion often is full • Transient motor, sensory, and/or reflex deficit can occur, but these symptoms resolve within several minutes. • Some athletes may not gain full strength until 24 to 48 hours later. • Although muscle weakness is variable, it is unlikely to represent permanent motor loss

24. Paracentral disc herniation • A tear in the posterolateral aspect of the annulus fibrosus allows the nucleus pulposus to protrude posteriorly • Causes range from high-energy impact loading to a minor twisting injury to the neck • Cause unilateral upper limb and neck symptoms associated with nerve root compression • Monoradiculopathy, paresthesias, and/or weakness in the upper extremity often are present

25. Spasm and neck pain almost always are present. • Localized neck symptoms usually signify more minor injuries • stable fractures, • spinal ligament injuries (cervical sprains), • intervertebral disc injury

26. Stable Fractures • Stable fractures of the anterior column generally are secondary to compressive forces • Fractures of the posterior elements typically result from a hyperextension injury

28. Management of Cervical Spine Injuries • Primary Survey • Assess for immediately life-threatening conditions and to prevent further injury. The initial evaluation follows the ABCDE sequence of trauma care • Primary survey will determine how the player is subsequently treated. • One of three clinical scenarios will become apparent

29. Scenario 1: Cardiorespiratory Compromise