The Spine in Sports Injuries: Cervical Spine 22

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P. M. Parizel, MD, PhD, Professor of Radiology J. L. Gielen, MD, PhD, Associate Professor F. M. Vanhoenacker, MD, PhD

Department of Radiology, University Hospital Antwerpen, Wilrijkstraat 10, 2650 Edegem, Belgium

The Spine in Sports Injuries: Cervical Spine 22

Paul M. Parizel, Jan l. Gielen, and Filip M. Vanhoenacker

Box 22.1. Plain radiographs

● Remain useful in mild cervical spine trauma

● Underestimate fractures, especially near the cervico-thoracic junction

● Flexion-extension views are useful to show instability

22.1 Introduction

Injuries to the spine are commonly associated with all kinds of sports activities, both contact and non- contact sports, and at all levels of competition rang- ing from the high school level to the professional level (Tall and DeVault 1993). The spectrum of potential 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- vertebral disc lesions, acute cervical sprain/strain,

Box 22.2. CT

● Preferred technique in more severe trauma (fracture-dislocation)

● Very fast (MDCT requires only seconds to scan the cervical spine)

● Provides limited soft tissue contrast

Box 22.4. MR

● Method of choice for assessing spinal cord, liga- ments, muscles and soft tissues

● Fat-suppressed sequences are sensitive to bone marrow edema

Box 22.3. Myelography and CT myelography

● Have been largely supplanted by non-invasive cross-sectional imaging techniques

● Remain useful in the diagnosis of nerve root and brachial plexus avulsion

C O N T E N T S

22.1 Introduction 377

22.2 Anatomical Considerations 378 22.3 Biomechanics of the Cervical Spine 379 22.4 Radiological Examination 383 22.5 Cervical Disc Herniation 384 22.6 Impingement Syndromes and Spinal Stenosis 384

22.7 Burners and Stingers 385

22.8 Catastrophic Athletic Cervical Spine Injuries 386

22.9 Nerve Root and Plexus Avulsion 386 22.10 Differential Diagnosis 387

Things to Remember 388 References 388

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nerve root and brachial plexus injuries, transient (or in rare cases permanent) quadriplegia, unstable injuries with and without fracture dislocation.

In the media covering sports events, tragic cervi- cal spine injuries of well-known professional athletes are often brought to national attention. These cata- strophic cervical spine injuries most commonly occur in collision sports or motorized sports and can lead to devastating consequences for the athlete (Baner- jee et al. 2004). Fortunately, these serious injuries are rare in sports. An elaborate review of epidemiologic studies, involving all types of sports activities at all levels of competition, reveals that the overwhelm- ing majority of sports injuries related to the spine are soft-tissue injuries (sprains and strains) and are self-limiting (Tall and DeVault 1993). It is relatively rare for athletic injuries to the spine to result in sig- niﬁ cant neurologic compromise. However, in cases with neurologic symptoms, the cervical spine is most commonly involved.

Accurate and timely radiological examination of the cervical spine in athletes is therefore essential to establish a correct diagnosis and to prevent further injury.

22.2 Anatomical Considerations

Before proceeding with the radiological examination of the spine, we shall present a brief reminder of cervical spine anatomy. The cervical spine consists of seven vertebrae, numbered from C1 to C7. Cervical vertebrae are the smallest of the true vertebrae, and can be readily distinguished from those of the tho- racic or lumbar regions by the presence of a foramen in each transverse process. They are ring-shaped with the vertebral body anteriorly, the pedicles laterally, and the laminae and spinous process posteriorly. The ﬁ rst cervical vertebra, C1 or also known as the atlas because it supports the globe of the head, does not possess a vertebral body, but has two lateral masses, which articulate with the occipital condyles. The second cervical vertebra, C2 or also known as the axis because it forms the pivot on which the ﬁ rst vertebra rotates, has a vertical toothlike projection called the dens or odontoid process, on which the atlas (C1) pivots. Embryologically, the odontoid process can be thought of as representing the vertebral body of C1, and articulates with the anterior arch of C1. With the

notable exception of C1–C2, the cervical vertebrae articulate with one another anteriorly via the inter- vertebral disc and two uncovertebral joints. Laterally, they articulate via the facet joints (also known as zygoapophyseal joints).

The successive openings in the articulated ring- shaped vertebrae, which are stacked upon one another, enclose the spinal canal (also known as ver- tebral or neural canal). On cross section, the spinal canal presents an isosceles triangular shape, with the base of the triangle anteriorly (formed by the poste- rior wall of the vertebral bodies and intervertebral discs), and the sides posterior and lateral (formed by the lamina on either side). The angle between the laminae (interlaminar angle) determines to a large extent the anteroposterior diameter of the spinal canal.

The spinal canal contains the spinal cord, nerve roots, blood vessels, and meninges. At each interver- tebral disc level, cervical spinal nerves originate from the spinal cord as the anterior (motor) and posterior (sensory) rootlets. Posterior and anterior rootlets join 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 the intervertebral foramen above the same-num- bered cervical vertebra (e.g. the seventh spinal nerve exits at the C6–C7 level). Though there are only seven cervical vertebrae, there are eight spinal nerves on either side. The eighth cervical nerve exits between the C7 and T1 segment.

The cervical intervertebral disc constitutes a

separate anatomic and functional entity, and is dis-

tinctly different from the lumbar intervertebral disc

(Mercer and Bogduk 1999). The anulus ﬁ brosus of

the cervical intervertebral disc does not consist of

concentric laminae of collagen ﬁ bers, as in the lumbar

discs. Rather, the anulus forms a crescent-shaped

mass of collagen, which is thickest anteriorly and

tapers laterally toward the uncinate processes. Poste-

riorly, the anulus is merely a thin layer of paramedian

vertically oriented ﬁ bers. The anterior longitudinal

ligament (ALL) covers the front of the disc, and the

posterior longitudinal ligament (PLL) reinforces the

deﬁ cient posterior anulus ﬁ brosus with longitudinal

and alar ﬁ bers. In this way, the cervical anulus ﬁ bro-

sus is likened to a crescentic anterior interosseous

ligament, rather than a ring of ﬁ bers surrounding the

nucleus pulposus (Mercer and Bogduk 1999).

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22.3 Biomechanics of the Cervical Spine

The cervical spine is the most mobile of all the seg- ments of the vertebral column. It allows an extensive range of motion in fl exion and extension, which is mainly due to the upwardly oriented inclination of the superior articular surfaces. In fl exion (forward movement), the anterior longitudinal ligament (ALL) is relaxed, while the posterior longitudinal ligament (PLL), the ligamenta fl ava, and the inter- and supraspinous ligaments are stretched. During fl exion, the intervertebral discs are compressed anteriorly, the interspaces between the laminæ are widened, and the inferior articular processes glide upward, upon the superior articular processes of the subjacent vertebræ. Flexion of the cervical spine is arrested just beyond the point where the cervical convexity is straightened. In extension (backward movement), the opposite motions occur. Extension can be carried farther than fl exion and is limited by stretching of the anterior longitudinal ligament (ALL), and by the approximation of the spinous processes. In the cervical spine lateral fl exion and rotation always occur as combined movements. The upward and medial inclinations of the superior 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. 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:

●

American football (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)

●

Diving in shallow water (Figs. 22.3–22.4) (head striking the ground)

●

Gymnastics (Fig. 22.5) (athlete accidentally land- ing head down while performing a somersault on a trampoline) (Torg 1987).

The spectrum of cervical spine injury is related to the mechanism, the force involved, and the point of application of the force (Tall and DeVault 1993).

Axial loading injuries of the cervical spine include vertebral fractures (Figs. 22.2 and 22.3), cervical disc herniations (Fig. 22.1), ligament rupture, facet fracture, and dislocations (Figs. 22.5 and 22.6). Neu- rologic deﬁ cits tend to be greater in athletes with spinal stenosis (Fig. 22.7), either developmental, or acquired through degenerative disease (Torg et al.

1997). Moreover, the biochemistry and biomechanics of the intervertebral disc and spine are age related.

Thus, the adolescent and older athlete may have dif- ferent concerns with regards to diagnosis, treatment, and prognosis after injury to the spine.

Recent studies have indicated that there also is a gender differential regarding injuries of the cervi- cal spine (Kelley 2000). Cervical strain injuries are more prevalent in female athletes than male athletes.

For cervical disc injury and cervical disc herniation, the male to female incidence is approximately equal.

With increasing participation of women in contact sports that cause major structural injury, a greater incidence of these injuries may be seen in women.

The radiologist examining an athlete with cervi- cal spine trauma, should recognize and understand the mechanism of injury (Pavlov and Torg 1987).

Fig. 22.1. Acute cervical disc herniation in a 32-year-old man who was injured during a football game. Contrast-enhanced CT scan of the cervical spine. At C5–C6, there is a disc herniation extending into the left lateral recess and into the intervertebral foramen. Note the asymmetric deformation of the dural sac and impingement on the left C6 nerve root

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Fig. 22.2a,b. Hyperﬂ exion injury with simple anterior wedge fracture 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

Fig. 22.3a–c. Jefferson fracture 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)

a

c b

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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 c

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

a b

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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- like deformation of the spinal canal

a

c

b

Fig. 22.7a,b. Cord contusion second- ary to spinal stenosis in a 49-year- old recreational tennis player, who complained of neck pain and pares- thesias in both arms after a collision with another player. MRI examina- tion with sagittal T1-weighted (a) and sagittal T2-weighted images (b).

Sagittal images show severe narrowing of the spinal canal due to chronic disc herniations and posterior osteophytes. There is a focal intramedullary area of increased signal intensity indicating cord contusion

a b

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Accurate radiological evaluation of the cervical spine must be performed immediately following the pos- sibility of injury and in such a manner as not to com- promise the neurologic status of the patient. Subtle radiographic fi ndings indicating ligamentous inju- ries must be recognized in order to prevent cervical spine instability. Occult fractures are often diffi cult to diagnose on plain fi lms. Therefore, in many trauma centers, computed tomography (CT) is increasingly being used to detect fractures.

22.4 Radiological Examination

The radiological investigation of the cervical spine must be guided by the clinical presentation. Three major issues should be addressed (Mintz 2004):

●

Stability of the cervical spine is essential element in sports. Instability of the cervical spine indicates damage to one or several of structural elements including the intervertebral disc, the ligaments, the osseous structures (vertebral bodies, facet joints) and the facet joint capsule. Instability should be suspected when there is lack of alignment of the vertebral bodies or facet joints, which may reﬂ ect subluxation (White and Panjabi 1987).

●

Impingement can be deﬁ ned as encroachment on either the spinal cord (through narrowing of the spinal canal) or the nerve roots (through narrow- ing of the intervertebral foramina).

●

The term impairment indicates loss of function, ranging from pain to paraplegia. Impairment can be due to structural causes (e.g. disc herniation, fracture-luxation, ligament injury) or to mild functional causes.

The purpose of the radiological investigation in the injured athlete is to document lesions that must be treated, such as disc disease or instability. Pain in itself is not an indication for imaging (for example, most acute burner or stinger injuries do not require imaging, see section 22.7) (Mintz 2004). On the other hand, when the athlete shows signs or symptoms of instability or neurological deﬁ cit, imaging studies are required to document potentially serious lesions.

In most cases, the radiological examination of the cervical spine in sports injuries starts with plain radiographs, including frontal, lateral and odontoid projections. Additional views should be added as

needed, in order to decrease the incidence of missed fractures. When instability due to ligamentous injury is suspected, ﬂ exion and extension views should be obtained; this can only be done when a fracture has been ruled out.

In more severe sports injuries, the use of com- puted tomography (CT) is required. Since the 1980s it has been shown that CT can document cervical spine fractures that are difﬁ cult or impossible to see 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 multiplanar reformations in axial, sagittal and coro- nal planes. The cervico-thoracic junction, which is often difﬁ cult to assess on plain radiographs to over- projection of the shoulders, is well depicted on CT.

Moreover, CT is now the ﬁ rst choice modality to dem- onstrate osseous causes of instability such as frac- tures of the vertebral bodies, the posterior elements (facet joints, laminae and pedicles), and the odontoid.

The less time-consuming CT examination, with sag- ittal and coronal reconstructions, has replaced con- ventional tomography for the detection of odontoid fractures and provides equivalent or greater diagnos- tic accuracy (Weisskopf et al. 2001).

The most important limitations of MDCT in assessing the cervical spine are its relative inability to demonstrate damage to the neural elements (spinal cord, cervical nerve roots) and to the ligaments (transverse, alar, facet joint capsule, supraspinous, anterior and posterior longitudinal ligament). This is where magnetic resonance imaging (MRI) becomes useful, because of its intrinsically higher soft tissue contrast resolution. In an in vitro model with cadaver spine specimens, it has been shown that MRI reliably and directly allows assessment of spinal ligament tears of various types (White and Panjabi 1987;

Emery et al. 1989; Kliewer et al. 1993). The founda-

tion of any cervical spine MRI protocol consists of

sagittal and axial T1- and T2-weighted scans. For sag-

ittal scans, we use turbo spin echo (TSE) sequences

with ﬂ ow compensation to eliminate artifacts from

CSF pulsations. Excellent T2-weighted contrast, with

bright CSF signal can be obtained through the use

of Restore (Siemens) or Drive (Philips) sequences

which add a supplementary 90q pulse at the end of

the TSE pulse train. For axial images with bright

CSF, T2- or T2*-weighted sequences can be used; it

is important to use thin section (3 mm or less slice

thickness) contiguous axial images, to prevent miss-

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ing a facet, pedicle or soft-tissue injury (Mintz 2004).

Gradient echo T2*-weighted scans provide excellent myelographic contrast, but are less sensitive for the detection of intramedullary lesions such as edema or contusion. Gradient echo images can be degraded by susceptibility (“blooming”) artifacts; this can be avoided through the use of 3D gradient echo scans with thinner slices. Fat suppression techniques, either with spectral fat saturation or inversion recovery, are important to demonstrate osseous and soft tissue injuries. In addition to the sagittal and axial imaging planes, a coronal sequence with intermediate to long TE is useful to show muscle injury (Mintz 2004).

Diffusion-weighted imaging, with optional diffusion tensor ﬁ ber tracking techniques, is under study for the spinal cord.

22.5 Cervical Disc Herniation

Traumatic sports injuries of the cervical spine can 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 including paraplegia, neuralgia and spasticity of the lower extremities due to compression of the spinal nerve roots and/or of the spinal cord. For example, acute traumatic herniation of a cervical interver- tebral disk may lead to spinal cord injury. In one reported case, the injury was sustained during a “tug- of-war” game, and the patient also suffered a brachial plexus injury in addition to a ruptured spleen (Lin et al. 2003).

The radiological examination should focus on the detection of narrowing of the intervertebral foram- ina and spinal canal. Recent disc herniations tend to have a higher signal intensity on T2- or T2*-weighted images, whereas osteophytes present a low signal intensity. T2-weighted MR images are the method of choice to demonstrate abnormal intramedullary signal intensity due to extrinsic compression by an intervertebral disc. On MRI it can be difﬁ cult to dis- tinguish between a disc herniation (“soft” disc) and an osteophyte (“hard” disc).

The association between participation in several speciﬁ c sports, and herniated lumbar or cervical intervertebral discs has been examined in a case-

controlled multicenter epidemiologic study (Mundt et al. 1993). The authors analyzed 287 patients with lumbar disc herniation and 63 patients with cervi- cal disc herniation, each matched by sex, source of care, and decade of age to one control who was free of disc herniation and other conditions of the back or neck. Speciﬁ c sports considered were baseball or softball, golf, bowling, swimming, diving, jogging, aerobics, and racquet sports. The authors found that most sports are not associated with an increased risk of herniation, and may in fact be protective. Relative risk estimates for the association between individual sports and lumbar or cervical herniation were gen- erally less than or close to 1.0. There was, however, a weak positive association between bowling and 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 risk, 1.87; 95% conﬁ dence interval, 0.74 to 4.74). Cer- vical disc herniation occurring in close association with playing football (soccer) has also been reported (Fig. 22.1) (Tysvaer 1985).

22.6 Impingement Syndromes and Spinal Stenosis

Neurological symptoms indicating a cervical spinal cord lesion, which occur after a spine injury from con- tact sports, require a precise work up to detect cervi- cal spinal stenosis. In these instances, advanced imag- ing techniques such as CT and MRI more accurately identify true spinal stenosis than radiographic bone measurements alone can provide (Cantu 1998).

The presence of a narrow cervical spinal canal constitutes a signiﬁ cant risk factor for the develop- ment of traumatic neck injuries (including sports- related injuries) even without a fracture or dis- location (Epstein et al. 1980). In a study of 39,377 athletes, a decreased antero-posterior diameter of the spinal canal was found to be a predisposing factor to the occurrence of cervical spinal cord neurapraxia with transient quadriplegia (Torg and Pavlov 1987).

This distinct clinical syndrome is characterized by

sensory changes (including burning pain, numb-

ness, tingling, and loss of sensation) as well as motor

changes (ranging from weakness to complete paraly-

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sis) (Torg et al. 1986). Neuropraxia of the cervical spinal cord with transient quadriplegia is caused by spinal cord compression during forced hyperexten- sion or hyperfl exion, in athletes with diminution of the anteroposterior diameter of the spinal canal. In one study, there was a statistically signifi cant spinal stenosis (p<0.0001) in patients having suffered cervi- cal neuropraxia and transient quadriplegia, as com- pared with the control subjects (Torg et al. 1986). If on plain radiographs of the cervical spine, the sagittal diameter of the spinal canal is <12.5 mm (corrected for magnifi cation), MRI of the cervical spine is rec- ommended.

Computed tomography (CT) provides an excellent way of studying the sagittal and transverse diameters of the cervical spinal canal. The sagittal diameter of 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 not be made on measurements of the diameter of the bony canal alone but should be made instead on imaging studies that document the relative size of the neural tissue relative to the size of the spinal canal. The functional reserve of the spinal canal is defi ned as the amount of CSF surrounding the spinal cord. MRI is excellent for demonstrating this param- eter. “Functional” cervical spinal stenosis, defi ned as a loss of CSF around the spinal cord, and/or in more extreme cases deformation of the cervical spinal cord, should be the criteria for defi ning cervical spinal stenosis.

Patients can become quadriplegic after a minor trauma to the spine, even without suffering a spinal fracture dislocation (Fig. 22.7). Predisposing factors are marked developmental stenosis of the spinal canal, with superimposed degenerative changes (e.g.

disc herniation, osteophytic spurs, calciﬁ cation of posterior longitudinal ligament) (Firooznia et al.

1985). It appears that the spinal cord can tolerate slowly increasing mechanical pressure for many years and conform to the shape of the spinal canal without causing any neurological symptoms. However, when the spinal stenosis is severe, any additional pressure, for example, swelling and edema from trauma, may cause a neurologic catastrophe. Therefore, patients with severe cervical spinal stenosis have been advised to discontinue participation in contact sports (Ladd and Scranton 1986). This recommendation has been recently revised such that stenosis of the cer- vical spine in itself does not constitute a absolute

contra-indication to participation in contact sports (Mintz 2004; Cantu 1998; Torg et al. 2002). Accord- ing to currently accepted guidelines, an episode of neuropraxia with cervical spine stenosis is a relative contra-indication to participation in contact sports;

instability, or abnormal intramedullary signal inten- sity on MRI are absolute contra-indications (Torg et al. 2002).

In cases of fracture-dislocation, one study in a group of 98 patients (45 without neurologic deﬁ cits, 39 with incomplete quadriplegia, and 14 with com- plete quadriplegia) concluded that small diameter canals were correlated signiﬁ cantly with neurologic injury, while large diameter canals allowed protec- tion from neurologic injury in cervical fracture dis- location (Eismont et al. 1984).

22.7 Burners and Stingers

The most common cervical injury in players of con- tact sports is a transient loss of function (weakness) with burning pain, numbness or tingling irradiat- ing down one arm following a collision (Weinstein 1998). The phenomenon is known as a “stinger” or

“burner” injury. These lesions are often underdiag- nosed or inadequately assessed (Weinstein 1998).

Symptoms usually resolve within a few minutes; how- ever, recurrences are common and can lead to perma- nent neurologic defi cits (Feinberg 2000). The most commonly affected muscle groups in terms of motor weakness are shoulder abductors, elbow fl exors, external humeral rotators, and wrist and fi nger exten- sors. Function gradually returns from the proximal muscle groups to the distal muscle groups. Though the burner or stinger syndrome is one of the most common injuries in American football, it can occur in other sports such as wrestling, ice hockey, bas- ketball, boxing, and weightlifting (Feinberg 2000).

Prospective studies performed at Tulane University

have shown a 7.7% incidence of stingers in a group of

college football players (Castro et al. 1997). In high-

school football players experiencing signiﬁ cant neck

pain during the season, the incidence of radiologic

evidence of neck injuries was as high as 32% and

was related to years of experience. In the preseason

examination, half the players who volunteered a his-

tory of signiﬁ cant neck pain had abnormal X-ray

ﬁ lms (Albright et al. 1976).

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The stinger or burner syndrome most likely repre- sents an upper cervical root injury. The pathogenesis can be twofold (Albright et al. 1976):

●

Stretching or distraction injury to the upper cords of the brachial plexus due to forced depression of the ipsilateral shoulder, with movement of the head to the side opposite the painful arm.

●

Compression and rotation of the cervical spine toward the painful arm. This causes tethering of the cervical nerves between the vertebral arter- ies and the distal foramina at each cervical level.

These dentate ligament attachments become taut and stretch the cervical nerve roots as they leave the spine.

The severity of the injury correlates with the underlying pathophysiology. Neuropraxia refers to a selective demyelination of the nerve sheath, and it is the most benign form of injury. Axonotmesis is a disruption of the axon and the myelin sheath, but the epineurium remains intact. The most severe injury is a neurotmesis or a compete disruption of the endo- neurium. This injury is associated with the most unfavorable prognosis.

Because stinger or burner injuries are usually self-limited, the most important treatment obliga- tion is to rule out an unstable cervical injury. The clinical assessment should focus on determining the full pain-free neck range of motion. If neck motion is decreased or painful, a radiological investigation should be performed to rule out fracture/dislocation.

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 extradural intraspinal mass lesion.

22.8 Catastrophic Athletic Cervical Spine Injuries Contact and collision sports, such as rugby, Ameri- can football or ice hockey, expose the athlete to a wide array of potential injuries, including serious injuries to cervical spine (Wilson et al. 2006). This is equally true for motorized sports involving high speeds. The outcome of athletic neck injuries ranges from complete recovery to death, depending on the degree of spinal cord damage sustained (Quarrie

et al. 2002). Potentially catastrophic athletic cervical spine injuries have been reported to occur in as many as 10–15% of all American football players (Torg et al. 1979). In one study, the American National Foot- ball Head and Neck Injury Registry has documented 1129 injuries that involved hospitalization for more than 72 h, surgical intervention, fracture-dislocation, permanent paralysis, or death (Torg et al. 1979). Of this group of injuries, 550 were fracture-dislocations of the cervical spine, of which 176 were associated with permanent quadriplegia. The introduction of a protective helmet-face mask system in American football has decreased the incidence of head injuries associated with intracranial hemorrhage, and inju- ries associated with death. Conversely, cervical spine injuries with fracture-dislocation and with perma- nent quadriplegia have increased.

In a more recent study analyzing epidemiologi- cal and medical data from 1977 through 1998, 118 athletes died as a direct result of participation in American football, with 200 football players received a permanent cervical cord injury, and 66 sustained a permanent cerebral injury (Cantu and Mueller 2000). The most commonly reported mechanism of injury has been hyperﬂ exion of the cervical spine, resulting in fracture dislocation of C4–C5 or C5–C6 (Quarrie et al. 2002). The axial loading mechanism of spinal cord injury was identiﬁ ed in 27% of tackling injuries (Cantu and Mueller 2000). Most cervical injuries occurred to defensive players during the act of tackling.

22.9 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 and Hoeper 2004), and motorized sports, especially motorcycle racing. The term refers to complete or incomplete avulsion of one or more cervical nerve roots from the spinal cord. Traumatic brachial plexus avulsion is usually associated with a dural tear, through which CSF leakage occurs to form a pseudomeningo- cele. Traditionally cervical myelography, followed by CT myelography, has been the gold standard for dem- onstration of these lesions, showing both complete and incomplete traction injuries (Volle et al. 1992).

The combination of CT and CT myelography can dif-

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ferentiate pre- from post-ganglionic lesions, and this information is essential for deciding whether explo- ration of the plexus or a motor substitution operation is indicated (Volle et al. 1992). Moreover, CT has the 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, but root avulsions are difﬁ cult to depict (Vielvoye and Hoffmann 1993). With the use of high reso- lution, thin-section slices (Fig. 22.8), the sensitivity for detection of cervical nerve root avulsion was the same (92.9%) with MRI as myelography/CT myelog- raphy (Doi et al. 2002). Using overlapping coronal- oblique slices, the roots of the brachial plexus can be adequately assessed in order to decide whether to proceed with exploration, nerve repair, primary reconstruction, or other imaging modalities. Alter- natively, MR myelography provides excellent accu- racy for detection of damaged nerve roots or root sleeves (Nakamura et al. 1997). MR myelography is non-invasive, relatively quick, requires no contrast

medium, provides imaging in multiple projections, and is comparable in diagnostic ability to the more invasive, time-consuming techniques of conventional myelography and CTM.

22.10 Differential Diagnosis

Finally, as a word of caution, it should be remembered that injuries are not the only cause of neck pain in the athlete. Disorders simulating athletic injury include, among others, tumors and inﬂ ammatory connective tissue disease (Harvey and Tanner 1991). As the number of middle-aged or elderly recreational ath- letes increases steadily, we should keep in mind that these athletes can also have tumors, infection, rheu- matologic disorders, and other non-traumatic etiolo- gies of pain (Tall and DeVault 1993). For these con- ditions, radiological examination should be guided by an adequate and precise clinical work-up.

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

a b

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Things to Remember

1. Cervical spine injuries occur in many sports.

Most lesions are benign and resolve spontane- ously; serious injuries are mostly associated with contact sports and motorized sports.

2. In sports-related injuries, the most common mechanism of cervical spine trauma is neck ﬂ exion with axial loading.

3. Cervical strain injuries are more prevalent in female athletes than male athletes. For cervi- cal disc injury and cervical disc herniation, the male to female incidence is approximately equal.

4. Pain in itself is not an indication for imaging;

conversely imaging studies are required when there are signs or symptoms of instability or neurological deﬁ cit.

5. Plain radiographs of the cervical spine with ﬂ exion-extension views remain useful in mild injuries to assess instability. However, plain radiographs underestimate fractures.

6. In more severe cervical spine trauma, CT scanning is the method of choice to detect traumatic bone lesions.

7. MRI is the preferred technique to demonstrate soft tissue injuries, e.g. medullary contusion, ligament disruption, muscle injury, as well as bone marrow contusion.

8. Severe sports-related injuries of the cervical spine can occur in athletes with spinal canal stenosis (developmental and or acquired degenerative changes). Imaging studies must take into account the relative diameter of the spinal canal.

9. Nerve root and brachial plexus avulsion is an unusual but severe type of sports injury.

It can be investigated with myelography and

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