The Spine in Sports Injuries: The Cervical Spine 377 The Spine in Sports Injuries: Cervical Spine 22 Paul M. Parizel, Jan l. Gielen, and Filip M. Vanhoenacker CONTENTS Box 22.1. Plain radiographs 22.1 Introduction 377 ● Remain useful in mild cervical spine trauma 22.2 Anatomical Considerations 378 ● Underestimate fractures, especially near the 22.3 Biomechanics of the Cervical Spine 379 cervico-thoracic junction 22.4 Radiological Examination 383 ● Flexion-extension views are useful to show 22.5 Cervical Disc Herniation 384 instability 22.6 Impingement Syndromes and Spinal Stenosis 384 22.7 Burners and Stingers 385 22.8 Catastrophic Athletic Cervical Spine Box 22.2. CT Injuries 386 22.9 Nerve Root and Plexus Avulsion 386 ● Preferred technique in more severe trauma (fracture-dislocation) 22.10 Differential Diagnosis 387 Things to Remember 388 ● Very fast (MDCT requires only seconds to scan References 388 the cervical spine) ● Provides limited soft tissue contrast 22.1 Introduction Box 22.3. Myelography and CT myelography Injuries to the spine are commonly associated with ● Have been largely supplanted by non-invasive all kinds of sports activities, both contact and non- cross-sectional imaging techniques contact sports, and at all levels of competition rang- ing from the high school level to the professional level ● Remain useful in the diagnosis of nerve root (Tall and DeVault 1993). The spectrum of potential and brachial plexus avulsion spinal injuries is wide; some resolve on their own, others might require conservative therapy, and still others might require surgical intervention. Sports injuries involving the cervical spine include inter- Box 22.4. MR vertebral disc lesions, acute cervical sprain/strain, ● Method of choice for assessing spinal cord, liga- ments, muscles and soft tissues P. M. Parizel, MD, PhD, Professor of Radiology J. L. Gielen, MD, P hD, Associate Professor ● F. M. Vanhoenacker, MD, PhD Fat-suppressed sequences are sensitive to bone Department of Radiology, University Hospital Antwerpen, marrow edema Wilrijkstraat 10, 2650 Edegem, Belgium 378 P. M. Parizel, J. L. Gielen, and F. M. Vanhoenacker nerve root and brachial plexus injuries, transient notable exception of C1–C2, the cervical vertebrae (or in rare cases permanent) quadriplegia, unstable articulate with one another anteriorly via the inter- injuries with and without fracture dislocation. vertebral disc and two uncovertebral joints. Laterally, In the media covering sports events, tragic cervi- they articulate via the facet joints (also known as cal spine injuries of well-known professional athletes zygoapophyseal joints). are often brought to national attention. These cata- The successive openings in the articulated ring- strophic cervical spine injuries most commonly occur shaped vertebrae, which are stacked upon one in collision sports or motorized sports and can lead another, enclose the spinal canal (also known as ver- to devastating consequences for the athlete (Baner- tebral or neural canal). On cross section, the spinal jee et al. 2004). Fortunately, these serious injuries are canal presents an isosceles triangular shape, with the rare in sports. An elaborate review of epidemiologic base of the triangle anteriorly (formed by the poste- studies, involving all types of sports activities at all rior wall of the vertebral bodies and intervertebral levels of competition, reveals that the overwhelm- discs), and the sides posterior and lateral (formed ing majority of sports injuries related to the spine by the lamina on either side). The angle between the are soft-tissue injuries (sprains and strains) and are laminae (interlaminar angle) determines to a large self-limiting (Tall and DeVault 1993). It is relatively extent the anteroposterior diameter of the spinal rare for athletic injuries to the spine to result in sig- canal. nifi cant neurologic compromise. However, in cases The spinal canal contains the spinal cord, nerve with neurologic symptoms, the cervical spine is most roots, blood vessels, and meninges. At each interver- commonly involved. tebral disc level, cervical spinal nerves originate from Accurate and timely radiological examination of the spinal cord as the anterior (motor) and posterior the cervical spine in athletes is therefore essential to (sensory) rootlets. Posterior and anterior rootlets join establish a correct diagnosis and to prevent further to form a spinal nerve, which lies within the interver- injury. tebral foramen. The posterior rootlet has a nerve root ganglion at the inner portion of the intervertebral foramen. The spinal nerve divides into a posterior and anterior ramus at the outlet of the intervertebral foramen. In the cervical spine, the spinal nerves exit 22.2 the intervertebral foramen above the same-num- Anatomical Considerations bered cervical vertebra (e.g. the seventh spinal nerve exits at the C6–C7 level). Though there are only seven Before proceeding with the radiological examination cervical vertebrae, there are eight spinal nerves on of the spine, we shall present a brief reminder of either side. The eighth cervical nerve exits between cervical spine anatomy. The cervical spine consists of the C7 and T1 segment. seven vertebrae, numbered from C1 to C7. Cervical The cervical intervertebral disc constitutes a vertebrae are the smallest of the true vertebrae, and separate anatomic and functional entity, and is dis- can be readily distinguished from those of the tho- tinctly different from the lumbar intervertebral disc racic or lumbar regions by the presence of a foramen (Mercer and Bogduk 1999). The anulus fi brosus of in each transverse process. They are ring-shaped with the cervical intervertebral disc does not consist of the vertebral body anteriorly, the pedicles laterally, concentric laminae of collagen fi bers, as in the lumbar and the laminae and spinous process posteriorly. The discs. Rather, the anulus forms a crescent-shaped fi rst cervical vertebra, C1 or also known as the atlas mass of collagen, which is thickest anteriorly and because it supports the globe of the head, does not tapers laterally toward the uncinate processes. Poste- possess a vertebral body, but has two lateral masses, riorly, the anulus is merely a thin layer of paramedian which articulate with the occipital condyles. The vertically oriented fi bers. The anterior longitudinal second cervical vertebra, C2 or also known as the axis ligament (ALL) covers the front of the disc, and the because it forms the pivot on which the fi rst vertebra posterior longitudinal ligament (PLL) reinforces the rotates, has a vertical toothlike projection called the defi cient posterior anulus fi brosus with longitudinal dens or odontoid process, on which the atlas (C1) and alar fi bers. In this way, the cervical anulus fi bro- pivots. Embryologically, the odontoid process can be sus is likened to a crescentic anterior interosseous thought of as representing the vertebral body of C1, ligament, rather than a ring of fi bers surrounding the and articulates with the anterior arch of C1. With the nucleus pulposus (Mercer and Bogduk 1999). The Spine in Sports Injuries: The Cervical Spine 379 The spectrum of cervical spine injury is related to 22.3 the mechanism, the force involved, and the point of Biomechanics of the Cervical Spine application of the force (Tall and DeVault 1993). Axial loading injuries of the cervical spine include The cervical spine is the most mobile of all the seg- vertebral fractures (Figs. 22.2 and 22.3), cervical ments of the vertebral column. It allows an extensive disc herniations (Fig. 22.1), ligament rupture, facet range of motion in fl exion and extension, which is fracture, and dislocations (Figs. 22.5 and 22.6). Neu- mainly due to the upwardly oriented inclination of rologic defi cits tend to be greater in athletes with the superior articular surfaces. In fl exion (forward spinal stenosis (Fig. 22.7), either developmental, or movement), the anterior longitudinal ligament acquired through degenerative disease (Torg et al. (ALL) is relaxed, while the posterior longitudinal 1997). Moreover, the biochemistry and biomechanics ligament (PLL), the ligamenta fl ava, and the inter- of the intervertebral disc and spine are age related. and supraspinous ligaments are stretched. During Thus, the adolescent and older athlete may have dif- fl exion, the intervertebral discs are compressed ferent concerns with regards to diagnosis, treatment, anteriorly, the interspaces between the laminæ are and prognosis after injury to the spine. widened, and the inferior articular processes glide Recent studies have indicated that there also is a upward, upon the superior articular processes of gender differential regarding injuries of the cervi- the subjacent vertebræ. Flexion of the cervical spine cal spine (Kelley 2000). Cervical strain injuries are is arrested just beyond the point where the cervical more prevalent in female athletes than male athletes. convexity is straightened. In extension (backward For cervical disc injury and cervical disc herniation, movement), the opposite motions occur. Extension the male to female incidence is approximately equal. can be carried farther than fl exion and is limited With increasing participation of women in contact by stretching of the anterior longitudinal ligament sports that cause major structural injury, a greater (ALL), and by the approximation of the spinous incidence of these injuries may be seen in women. processes. In the cervical spine lateral fl exion and The radiologist examining an athlete with cervi- rotation always occur as combined movements. The cal spine trauma, should recognize and understand upward and medial inclinations of the superior the mechanism of injury (Pavlov and Torg 1987). articular facet joint surfaces convey a rotary move- ment during lateral fl exion, while pure rotation is prevented by their slight medial slope. During lat- eral fl exion, the sides of the intervertebral discs are compressed, and the extent of motion is lim- ited by the resistance offered by the surrounding ligaments. In sports-related injuries, the most common mech- anism of cervical spine trauma is neck fl exion with axial loading (Torg et al.