The Spine in Sports : 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 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 (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- . 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 (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 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 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 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 . 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 fl exion with axial loading (Torg et al. 1987). Neck fl exion causes the physiological cervical lordosis to disappear. The axial loading of the head is thus dissipated through a straight spine (Torg et al. 1987). Examples of axial loading injuries to the cervical spine are found in a variety of sports, such as: ● (Fig. 22.1) (player striking opponent with the crown of his helmet) or rugby (Fig. 22.2) (during the scrum phase of the game) ● Ice hockey (player striking his head on the board while doing a push or check) ● in shallow water (Figs. 22.3–22.4) (head Fig. 22.1. Acute cervical disc herniation in a 32-year-old man who was injured during a football game. Contrast-enhanced striking the ground) CT scan of the cervical spine. At C5–C6, there is a disc hernia- ●  (Fig. 22.5) (athlete accidentally land- tion extending into the left lateral recess and into the interver- ing head down while performing a somersault on tebral foramen. Note the asymmetric deformation of the dural a trampoline) (Torg 1987). sac and impingement on the left C6 nerve root 380 P. M. Parizel, J. L. Gielen, and F. M. Vanhoenacker

Fig. 22.2a,b. Hyperfl exion injury with simple anterior wedge frac- ture of C7 in a 23-year-old rugby player. MRI scan with sagittal T2-weighted (a) and sagittal T1- weighted (b) images. The antero- superior corner of the vertebral body C7 is depressed, and there is band of bone marrow edema subjacent to the upper endplate. The posterior wall is not dis- placed, the diameter of the spinal canal remains normal, and there is no medullary contusion

a b

b

c

a

Fig. 22.3a–c. of C1 in a 26-year-old man patient who was injured in a diving accident. Non-contrast axial CT scan (a) with coronal (b) and three-dimensional reformatted images (c). There is a comminuted fracture of the anterior arch and a linear fracture of posterior arch (a). The coronal reformatted image shows lateral displacement of the lateral masses of C1 with respect to the superior articular surfaces of C2 (b). The 3-D volume rendered image confi rms the comminuted fracture in the anterior arch of C1 (c) The Spine in Sports Injuries: The Cervical Spine 381

a b c

Fig. 22.4a–c. Catastrophic neck injury (diving accident) with contusion and partial transsection of the spinal cord in a 23-year- old man. MRI examination with sagittal T1-weighted (a), sagittal T2-weighted (b) and coronal T2-weighted (c) scans. The study was obtained after anterior fi xation at C5–C6–C7 with titanium plate. Despite the magnetic susceptibility artifacts caused by the instrumentation, the spinal cord contusion is clearly identifi ed as a focal intramedullary high intensity abnormality on the T2-weighted scans

a b

Fig. 22.5a,b. Distracted hyperfl exion injury in a young gymnast with anterior subluxation at C6–C7. Plain radiographs of the cervical spine in AP (a) and cross-table lateral (b) pro- jection. The marked anterior displacement of C6 indicates disruption of all ligamentous structures and interfacetal dislocation. This fi nding is only visible on the lateral view. The cervicothoracic prevertebral soft tissue shadow is widened, indicating the presence of a hematoma secondary to the injury 382 P. M. Parizel, J. L. Gielen, and F. M. Vanhoenacker

a b

Fig. 22.6a–c. Bilateral interfacetal dislocation with anterior translation of C6 with regard to C7 in a 34-year-old woman following a catastrophic skiing injury. Non-contrast CT scans with axial images (a,b) and mid-sagittal reformatted image (c) show anterior displacement of C6 on C7 with marked step- c like deformation of the spinal canal

Fig. 22.7a,b. Cord contusion second- ary to spinal stenosis in a 49-year- old recreational tennis player, who complained of neck and pares- thesias in both after a collision with another player. MRI examina- tion with sagittal T1-weighted (a) and sagittal T2-weighted images (b). Sagittal images show severe narrow- ing of the spinal canal due to chronic disc herniations and posterior osteo- phytes. There is a focal intramedul- lary area of increased signal intensity a b indicating cord contusion The Spine in Sports Injuries: The Cervical Spine 383

Accurate radiological evaluation of the cervical spine needed, in order to decrease the incidence of missed must be performed immediately following the pos- fractures. When instability due to ligamentous injury sibility of injury and in such a manner as not to com- is suspected, fl exion and extension views should be promise the neurologic status of the patient. Subtle obtained; this can only be done when a fracture has radiographic fi ndings indicating ligamentous inju- been ruled out. ries must be recognized in order to prevent cervical In more severe sports injuries, the use of com- spine instability. Occult fractures are often diffi cult to puted tomography (CT) is required. Since the 1980s diagnose on plain fi lms. Therefore, in many trauma it has been shown that CT can document cervical centers, computed tomography (CT) is increasingly spine fractures that are diffi cult or impossible to see being used to detect fractures. on plain radiographs (Mace 1985). With new genera- tion multi-row detector CT (MDCT) scanners, it only takes a few seconds to examine the entire cervical spine, from the clivus to the upper thoracic segments. The volumetric MDCT dataset can be used to make 22.4 multiplanar reformations in axial, sagittal and coro- Radiological Examination nal planes. The cervico-thoracic junction, which is often diffi cult to assess on plain radiographs to over- The radiological investigation of the cervical spine projection of the , is well depicted on CT. must be guided by the clinical presentation. Three Moreover, CT is now the fi rst choice modality to dem- major issues should be addressed (Mintz 2004): onstrate osseous causes of instability such as frac- ● Stability of the cervical spine is essential element tures of the vertebral bodies, the posterior elements in sports. Instability of the cervical spine indicates (facet joints, laminae and pedicles), and the odontoid. damage to one or several of structural elements The less time-consuming CT examination, with sag- including the intervertebral disc, the ligaments, the ittal and coronal reconstructions, has replaced con- osseous structures (vertebral bodies, facet joints) ventional tomography for the detection of odontoid and the facet joint capsule. Instability should be fractures and provides equivalent or greater diagnos- suspected when there is lack of alignment of the tic accuracy (Weisskopf et al. 2001). vertebral bodies or facet joints, which may refl ect The most important limitations of MDCT in subluxation (White and Panjabi 1987). assessing the cervical spine are its relative inability to ● Impingement can be defi ned as encroachment on demonstrate damage to the neural elements (spinal either the spinal cord (through narrowing of the cord, cervical nerve roots) and to the ligaments spinal canal) or the nerve roots (through narrow- (transverse, alar, facet joint capsule, supraspinous, ing of the intervertebral foramina). anterior and posterior longitudinal ligament). This is ● The term impairment indicates loss of function, where magnetic resonance imaging (MRI) becomes ranging from pain to paraplegia. Impairment can useful, because of its intrinsically higher soft tissue be due to structural causes (e.g. disc herniation, contrast resolution. In an in vitro model with cadaver fracture-luxation, ligament injury) or to mild spine specimens, it has been shown that MRI reliably functional causes. and directly allows assessment of spinal ligament tears of various types (White and Panjabi 1987; The purpose of the radiological investigation in Emery et al. 1989; Kliewer et al. 1993). The founda- the injured athlete is to document lesions that must tion of any cervical spine MRI protocol consists of be treated, such as disc disease or instability. Pain in sagittal and axial T1- and T2-weighted scans. For sag- itself is not an indication for imaging (for example, ittal scans, we use turbo spin echo (TSE) sequences most acute burner or stinger injuries do not require with fl ow compensation to eliminate artifacts from imaging, see section 22.7) (Mintz 2004). On the other CSF pulsations. Excellent T2-weighted contrast, with , when the athlete shows signs or symptoms of bright CSF signal can be obtained through the use instability or neurological defi cit, imaging studies are of Restore (Siemens) or Drive (Philips) sequences required to document potentially serious lesions. which add a supplementary 90q pulse at the end of In most cases, the radiological examination of the TSE pulse train. For axial images with bright the cervical spine in sports injuries starts with plain CSF, T2- or T2*-weighted sequences can be used; it radiographs, including frontal, lateral and odontoid is important to use thin section (3 mm or less slice projections. Additional views should be added as thickness) contiguous axial images, to prevent miss- 384 P. M. Parizel, J. L. Gielen, and F. M. Vanhoenacker

ing a facet, pedicle or soft-tissue injury (Mintz 2004). controlled multicenter epidemiologic study (Mundt Gradient echo T2*-weighted scans provide excellent et al. 1993). The authors analyzed 287 patients with myelographic contrast, but are less sensitive for the lumbar disc herniation and 63 patients with cervi- detection of intramedullary lesions such as edema cal disc herniation, each matched by sex, source of or contusion. Gradient echo images can be degraded care, and decade of age to one control who was free by susceptibility (“blooming”) artifacts; this can be of disc herniation and other conditions of the back avoided through the use of 3D gradient echo scans or neck. Specifi c sports considered were baseball or with thinner slices. Fat suppression techniques, either softball, golf, bowling, swimming, diving, jogging, with spectral fat saturation or inversion recovery, are aerobics, and racquet sports. The authors found that important to demonstrate osseous and soft tissue most sports are not associated with an increased risk injuries. In addition to the sagittal and axial imaging of herniation, and may in fact be protective. Relative planes, a coronal sequence with intermediate to long risk estimates for the association between individual TE is useful to show muscle injury (Mintz 2004). sports and lumbar or cervical herniation were gen- Diffusion-weighted imaging, with optional diffusion erally less than or close to 1.0. There was, however, tensor fi ber tracking techniques, is under study for a weak positive association between bowling and the spinal cord. herniation at both the lumbar and cervical regions of the spine. Use of weight lifting equipment was not associated with herniated lumbar or cervical disc, but a possible association was indicated between use of free weights and risk of cervical herniation (relative 22.5 risk, 1.87; 95% confi dence interval, 0.74 to 4.74). Cer- Cervical Disc Herniation vical disc herniation occurring in close association with playing football (soccer) has also been reported Traumatic sports injuries of the cervical spine can (Fig. 22.1) (Tysvaer 1985). occur at the level of the disc, resulting in disc hernia- tion, disc degeneration, and ultimately developmental stenosis. Acute disc pathology is the most common cause of sports-induced impingement syndromes. It can cause a variety of neurological complications 22.6 including paraplegia, neuralgia and spasticity of the Impingement Syndromes and lower extremities due to compression of the spinal Spinal Stenosis nerve roots and/or of the spinal cord. For example, acute traumatic herniation of a cervical interver- Neurological symptoms indicating a cervical spinal tebral disk may lead to . In one cord lesion, which occur after a spine injury from con- reported case, the injury was sustained during a “tug- tact sports, require a precise work up to detect cervi- of-war” game, and the patient also suffered a brachial cal spinal stenosis. In these instances, advanced imag- plexus injury in addition to a ruptured spleen (Lin ing techniques such as CT and MRI more accurately et al. 2003). identify true spinal stenosis than radiographic bone The radiological examination should focus on the measurements alone can provide (Cantu 1998). detection of narrowing of the intervertebral foram- The presence of a narrow cervical spinal canal ina and spinal canal. Recent disc herniations tend to constitutes a signifi cant risk factor for the develop- have a higher signal intensity on T2- or T2*-weighted ment of traumatic neck injuries (including sports- images, whereas osteophytes present a low signal related injuries) even without a fracture or dis- intensity. T2-weighted MR images are the method location (Epstein et al. 1980). In a study of 39,377 of choice to demonstrate abnormal intramedullary athletes, a decreased antero-posterior diameter of the signal intensity due to extrinsic compression by an spinal canal was found to be a predisposing factor to intervertebral disc. On MRI it can be diffi cult to dis- the occurrence of cervical spinal cord tinguish between a disc herniation (“soft” disc) and with transient quadriplegia (Torg and Pavlov 1987). an osteophyte (“hard” disc). This distinct clinical syndrome is characterized by The association between participation in several sensory changes (including burning pain, numb- specifi c sports, and herniated lumbar or cervical ness, tingling, and loss of sensation) as well as motor intervertebral discs has been examined in a case- changes (ranging from weakness to complete paraly- The Spine in Sports Injuries: The Cervical Spine 385 sis) (Torg et al. 1986). Neuropraxia of the cervical contra-indication to participation in contact sports spinal cord with transient quadriplegia is caused by (Mintz 2004; Cantu 1998; Torg et al. 2002). Accord- spinal cord compression during forced hyperexten- ing to currently accepted guidelines, an episode of sion or hyperfl exion, in athletes with diminution of neuropraxia with cervical spine stenosis is a relative the anteroposterior diameter of the spinal canal. In contra-indication to participation in contact sports; one study, there was a statistically signifi cant spinal instability, or abnormal intramedullary signal inten- stenosis (p<0.0001) in patients having suffered cervi- sity on MRI are absolute contra-indications (Torg et cal neuropraxia and transient quadriplegia, as com- al. 2002). pared with the control subjects (Torg et al. 1986). If In cases of fracture-dislocation, one study in a on plain radiographs of the cervical spine, the sagittal group of 98 patients (45 without neurologic defi cits, diameter of the spinal canal is <12.5 mm (corrected 39 with incomplete quadriplegia, and 14 with com- for magnifi cation), MRI of the cervical spine is rec- plete quadriplegia) concluded that small diameter ommended. canals were correlated signifi cantly with neurologic Computed tomography (CT) provides an excellent injury, while large diameter canals allowed protec- way of studying the sagittal and transverse diameters tion from neurologic injury in cervical fracture dis- of the cervical spinal canal. The sagittal diameter of location (Eismont et al. 1984). the spinal canal of some individuals may be inher- ently smaller than normal, and that this reduced size may be a predisposing risk factor to spinal cord injury (Matsura et al. 1989). The defi nition of cervical spinal stenosis should 22.7 not be made on measurements of the diameter of Burners and Stingers the bony canal alone but should be made instead on imaging studies that document the relative size The most common cervical injury in players of con- of the neural tissue relative to the size of the spinal tact sports is a transient loss of function (weakness) canal. The functional reserve of the spinal canal is with burning pain, numbness or tingling irradiat- defi ned as the amount of CSF surrounding the spinal ing down one following a collision (Weinstein cord. MRI is excellent for demonstrating this param- 1998). The phenomenon is known as a “stinger” or eter. “Functional” cervical spinal stenosis, defi ned as “burner” injury. These lesions are often underdiag- a loss of CSF around the spinal cord, and/or in more nosed or inadequately assessed (Weinstein 1998). extreme cases deformation of the cervical spinal Symptoms usually resolve within a few minutes; how- cord, should be the criteria for defi ning cervical ever, recurrences are common and can lead to perma- spinal stenosis. nent neurologic defi cits (Feinberg 2000). The most Patients can become quadriplegic after a minor commonly affected muscle groups in terms of motor trauma to the spine, even without suffering a spinal weakness are abductors, elbow fl exors, fracture dislocation (Fig. 22.7). Predisposing factors external humeral rotators, and wrist and fi nger exten- are marked developmental stenosis of the spinal sors. Function gradually returns from the proximal canal, with superimposed degenerative changes (e.g. muscle groups to the distal muscle groups. Though disc herniation, osteophytic spurs, calcifi cation of the burner or stinger syndrome is one of the most posterior longitudinal ligament) (Firooznia et al. common injuries in American football, it can occur 1985). It appears that the spinal cord can tolerate in other sports such as , ice hockey, bas- slowly increasing mechanical pressure for many years ketball, boxing, and weightlifting (Feinberg 2000). and conform to the shape of the spinal canal without Prospective studies performed at Tulane University causing any neurological symptoms. However, when have shown a 7.7% incidence of stingers in a group of the spinal stenosis is severe, any additional pressure, college football players (Castro et al. 1997). In high- for example, swelling and edema from trauma, may school football players experiencing signifi cant neck cause a neurologic catastrophe. Therefore, patients pain during the season, the incidence of radiologic with severe cervical spinal stenosis have been advised evidence of neck injuries was as high as 32% and to discontinue participation in contact sports (Ladd was related to years of experience. In the preseason and Scranton 1986). This recommendation has examination, half the players who volunteered a his- been recently revised such that stenosis of the cer- tory of signifi cant neck pain had abnormal X-ray vical spine in itself does not constitute a absolute fi lms (Albright et al. 1976). 386 P. M. Parizel, J. L. Gielen, and F. M. Vanhoenacker

The stinger or burner syndrome most likely repre- et al. 2002). Potentially catastrophic athletic cervical sents an upper cervical root injury. The pathogenesis spine injuries have been reported to occur in as many can be twofold (Albright et al. 1976): as 10–15% of all American football players (Torg et ● Stretching or distraction injury to the upper cords al. 1979). In one study, the American National - of the brachial plexus due to forced depression of ball Head and Neck Injury Registry has documented the ipsilateral shoulder, with movement of the 1129 injuries that involved hospitalization for more head to the side opposite the painful arm. than 72 h, surgical intervention, fracture-dislocation, ● Compression and rotation of the cervical spine permanent , or death (Torg et al. 1979). Of toward the painful arm. This causes tethering of this group of injuries, 550 were fracture-dislocations the cervical nerves between the vertebral arter- of the cervical spine, of which 176 were associated ies and the distal foramina at each cervical level. with permanent quadriplegia. The introduction of These dentate ligament attachments become taut a protective helmet-face mask system in American and stretch the cervical nerve roots as they leave football has decreased the incidence of head injuries the spine. associated with intracranial hemorrhage, and inju- ries associated with death. Conversely, cervical spine The severity of the injury correlates with the injuries with fracture-dislocation and with perma- underlying pathophysiology. Neuropraxia refers to nent quadriplegia have increased. a selective demyelination of the nerve sheath, and it In a more recent study analyzing epidemiologi- is the most benign form of injury. is a cal and medical data from 1977 through 1998, 118 disruption of the and the myelin sheath, but the athletes died as a direct result of participation in epineurium remains intact. The most severe injury is American football, with 200 football players received a or a compete disruption of the endo- a permanent cervical cord injury, and 66 sustained neurium. This injury is associated with the most a permanent cerebral injury (Cantu and Mueller unfavorable prognosis. 2000). The most commonly reported mechanism of Because stinger or burner injuries are usually injury has been hyperfl exion of the cervical spine, self-limited, the most important treatment obliga- resulting in fracture dislocation of C4–C5 or C5–C6 tion is to rule out an unstable cervical injury. The (Quarrie et al. 2002). The axial loading mechanism clinical assessment should focus on determining the of spinal cord injury was identifi ed in 27% of tackling full pain-free neck range of motion. If neck motion injuries (Cantu and Mueller 2000). Most cervical is decreased or painful, a radiological investigation injuries occurred to defensive players during the act should be performed to rule out fracture/dislocation. of tackling. If the symptoms persist for three to four weeks follow- ing injury, an electromyogram should be obtained to evaluate upper trunk function. The differential diag- nosis of stinger and burner injuries includes: acute cervical disk herniation, foraminal stenosis, and 22.9 extradural intraspinal mass lesion. Nerve Root and Plexus Avulsion

A severe type of brachial plexus lesion is the brachial plexus avulsion, which is an uncommon but seri- ous injury associated with contact sports ( Williams 22.8 and Hoeper 2004), and motorized sports, especially Catastrophic Athletic Cervical Spine Injuries motorcycle racing. The term refers to complete or incomplete avulsion of one or more cervical nerve Contact and collision sports, such as rugby, Ameri- roots from the spinal cord. Traumatic brachial plexus can football or ice hockey, expose the athlete to a avulsion is usually associated with a dural tear, through wide array of potential injuries, including serious which CSF leakage occurs to form a pseudomeningo- injuries to cervical spine (Wilson et al. 2006). This cele. Traditionally cervical myelography, followed by is equally true for motorized sports involving high CT myelography, has been the gold standard for dem- speeds. The outcome of athletic neck injuries ranges onstration of these lesions, showing both complete from complete recovery to death, depending on the and incomplete traction injuries (Vol le et al. 1992). degree of spinal cord damage sustained (Quarrie The combination of CT and CT myelography can dif- The Spine in Sports Injuries: The Cervical Spine 387

ferentiate pre- from post-ganglionic lesions, and this medium, provides imaging in multiple projections, information is essential for deciding whether explo- and is comparable in diagnostic ability to the more ration of the plexus or a motor substitution operation invasive, time-consuming techniques of conventional is indicated (Vol le et al. 1992). Moreover, CT has the myelography and CTM. added advantage of being able to rule out an asso- ciated fracture of the spinal column. Conventional MRI scanning of the cervical spine is useful to reveal traumatic pseudomeningoceles or additional lesions, such as intramedullary or extradural haematomas, 22.10 but root avulsions are diffi cult to depict (Vielvoye Differential Diagnosis and Hoffmann 1993). With the use of high reso- lution, thin-section slices (Fig. 22.8), the sensitivity Finally, as a word of caution, it should be remembered for detection of cervical nerve root avulsion was the that injuries are not the only cause of neck pain in the same (92.9%) with MRI as myelography/CT myelog- athlete. Disorders simulating athletic injury include, raphy (Doi et al. 2002). Using overlapping coronal- among others, tumors and infl ammatory connective oblique slices, the roots of the brachial plexus can tissue disease (Harvey and Tanner 1991). As the be adequately assessed in order to decide whether number of middle-aged or elderly recreational ath- to proceed with exploration, nerve repair, primary letes increases steadily, we should keep in mind that reconstruction, or other imaging modalities. Alter- these athletes can also have tumors, infection, rheu- natively, MR myelography provides excellent accu- matologic disorders, and other non-traumatic etiolo- racy for detection of damaged nerve roots or root gies of pain (Tall and DeVault 1993). For these con- sleeves (Nakamura et al. 1997). MR myelography is ditions, radiological examination should be guided non-invasive, relatively quick, requires no contrast by an adequate and precise clinical work-up.

a b

Fig. 22.8a,b. Left brachial plexus nerve root avulsion with formation of a pseudomenin- gocele fi lled with cerebrospinal fl uid. The patient is a 29-year-old man who was injured in a cross-country motorcycle racing accident. Coronal thin section turbo spin echo T2- weighted MRI scans (a,b) reveal a CSF-fi lled pseudomeningocele extending to the apex of the left lung 388 P. M. Parizel, J. L. Gielen, and F. M. Vanhoenacker

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