Cervical Spine and Brachial Plexus Injuries: Return-to-Play Recommendations
Joseph S. Torg, MD; Julie A. Ramsey-Emrhein, MEd, ATC
THE PHYSICIAN AND SPORTSMEDICINE - VOL 25 - NO. 7 - JULY 97
In Brief: Great care is required in managing cervical spine and brachial plexus injuries. Athletes who suffer one or more burners (transient brachial plexus injuries) may return to contact activity when they are asymptomatic and neurologically normal and have full cervical motion. A vertebra displaced horizontally more than 3.5 mm or rotated more than 11° is an absolute contraindication to contact sports. Cervical cord neurapraxia is generally benign, but patients should be counseled about the probability of recurrence, depending on the spinal canal/vertebral body ratio. Unresolved spear tackler's spine is an absolute contraindication to collision sports, as are axial-load teardrop fracture and cervical spine fusion of more than three levels. Spinal cord resuscitation can include blood pressure maintenance and timely methylprednisolone.
All athletic injuries require careful attention, but evaluation and management of injuries involving the cervical spine and brachial plexus require particular caution. Possible nervous system involvement creates a high-risk situation with little room for error, particularly in athletes playing contact sports. An accurate diagnosis is imperative, and decisions about an athlete's return to contact activity should be based on clear criteria derived from data on athletic injuries to the cervical spine, spinal cord, and brachial plexus.
Regarding return to play, these injuries and associated problems fall into three general categories:
The recommendations for return to play presented here are based on data from over 1,200 cervical spine injuries documented by the National Football Head and Neck Injury Registry (1-3), a review of the literature, an understanding of recognized injury mechanisms (4), and the authors' experience. The more common cervical spine conditions are discussed below, and a more complete list of conditions, classified by return-to-play recommendations, is presented in table 1.
Most serious injuries to the cervical spine result from axial loading, as in spear tackling in football. Fortunately, few athletes have more than transient neurologic episodes, and even fewer incur permanent paralysis.
An athlete with a significant injury will usually have a slight torticollis (wry neck posture), limitation of cervical motion, and, if the condition is chronic, atrophy or decreased cervical paravertebral muscle bulk. A patient with torticollis, decreased range of cervical motion, and cervical muscle atrophy requires a complete neurologic examination and a radiographic study, including anteroposterior (AP), lateral, oblique, open-mouth, and lateral flexion and extension views. If the findings persist or if the patient presents acutely with neurologic signs and symptoms, a magnetic resonance imaging (MRI) study should also be performed.
Brachial Plexus and Nerve Root Neurapraxia
Acute, transient brachial plexus injuries, often called burners, are typically traction neurapraxias occurring in younger athletes as a result of shoulder depression and lateral neck deviation away from the side of injury (figure 1) (5). Chronic recurrent root neurapraxia, typically occurring in older players, results from compression of the nerve root in the intervertebral foramina secondary to hyperextension and ipsilateral deviation of the head and neck (6). Frequently the symptoms can be reproduced by Spurling's maneuver (figure 2). Nerve root neurapraxia is characteristically associated with foraminal stenosis (figure 3) and/or degenerative disk changes (figure 4), often in combination with developmental cervical stenosis.
Athletes who experience one or more burners should wear a cowboy collar (figure 5) to prevent extreme hyperextension and lateral bending of the cervical spine and should undertake a year-round neck and shoulder strengthening program. They may return to collision activities when they are asymptomatic, have normal strength, are neurologically normal, and have a full range of painless cervical motion. Recurrent burners do not increase the risk of a more serious neck injury.
Strains, Sprains, and Disk Injuries
Mild injuries to the ligaments, paravertebral muscles, and intervertebral disk are rarely associated with neurologic signs and symptoms. An injured player will initially complain of neck pain and have limited range of cervical motion. After appropriate treatment, these individuals may return to activity when they are asymptomatic, have normal muscle strength, and have a full range of pain-free cervical motion.
In individuals with injuries involving minor ligamentous laxity, the situation is less clear. Albright et al (7) showed that 10% of freshman football recruits at the University of Iowa demonstrated "abnormal motion." This finding is consistent with our experience and suggests that some high school and college football players may have minor laxity without apparent adverse effects. The degree of acceptable instability or laxity is, of course, the question.
Though no available research sets the upper limits of instability clearly enough for clinical use, the work of White et al (8) is helpful. Using lateral radiographs, they clearly demonstrated that a vertebra displaced horizontally more than 3.5 mm or rotated more than 11° relative to an adjacent vertebra represents spinal instability—certainly an absolute contraindication to further participation in collision activities. Less vertebral displacement or rotation can be considered a relative contraindication, depending on the athlete's level of performance, physical habitus, playing position, and results of imaging studies to rule out disk disease or occult fractures (figure 6: not shown). An experienced sports medicine orthopedist should be consulted to assist in deciding if participation is safe.
Acute cervical disk disease associated with limited cervical motion and/or neurologic signs and symptoms is an absolute contraindication. However, chronic degenerative disk changes (figure 7: not shown) in individuals who are neurologically normal and have full muscle strength and range of cervical motion are a relative contraindication.
Cervical Cord Neurapraxia
Our research has previously described cervical cord neurapraxia (CCN) as a distinct clinical entity and, using x-ray measurements, has identified the cause as developmental narrowing of the AP diameter of the cervical canal in combination with acute mechanical deformation of the spinal cord (9).
The typical clinical case involves an athlete who has an acute transient neurologic episode of cervical cord origin. Neurologic findings may include both arms, both legs, all four extremities, or an ipsilateral arm and leg. The symptoms may result in sensory changes with or without motor findings. Sensory changes include burning pain, numbness, or tingling; motor changes consist of weakness or complete paralysis. An episode usually lasts less than 15 minutes, although some cases may take up to 48 hours to resolve. Complete motor function and full, pain-free cervical motion normally return.
'Pincers' mechanism. The relationship between developmental cervical canal narrowing and CCN has been clearly established (10). In the presence of cervical canal stenosis, CCN results from cord compression due to a "pincers" mechanism (figure 8). This mechanism occurs when hyperextension of the cervical spine causes the posterior inferior aspect of the superior vertebral body and the anterior superior aspect of the lamina of the subjacent vertebra to come together; conversely, in flexion the lamina of the superior vertebra and the posterior superior aspect of the subjacent vertebral body come together. In both cases the approximation causes a sudden decrease in the AP diameter of the canal at that cervical level, resulting in compression of the spinal cord.
The relationship between temporary neurologic dysfunction and cord deformation has been explained through the study of a squid axon injury model. Torg et al (11) correlated the clinical findings of reversible cord deficits with the histochemical response of isolated neural and vascular elements subjected to controlled mechanical deformation. Neurologic recovery from mechanical deformation is inversely proportional to a rise in the intracellular calcium ion concentration, which is directly proportional to the amount and rate of tension applied to the cervical cord. CCN appears to involve rapid cord deformation without loss of spinal stability or cell damage, and recovery of axonal function is not impeded by the deleterious effects of local anoxia from venous spasm.
A benign condition. In the absence of instability or structural deficiency of the cervical spine, CCN appears to be clinically benign. Torg et al (12), in a study of a large group of football players who had cervical spine stenosis and episodes of CCN, found that 109 of 110 athletes had complete neurologic recovery and that no permanent morbidity occurred in the 63 patients who returned to contact sports. (The one case of irreversible neurologic injury was a direct complication of surgery.) Further, a study (12) of MRI images of 25 professional football players who had CCN episodes with significant cervical canal stenosis and cervical spondylosis showed that all patients with actual cord compression from degenerative disks safely returned to contact activities. Thus, developmental or spondylitic stenosis, regardless of the degree of canal narrowing, does not result in irreversible cord injury.
Predicting recurrence. Though patients who have an episode of CCN are not at increased risk of permanent injury when they return to contact sports, they should be advised that they may have recurrent episodes. Thirty-five (56%) of the 63 aforementioned patients who returned to contact activities after a CCN incident had a recurrence. Participation in football and increased stenosis raise the risk of recurrence. MRI measurement of disk-level canal diameter was the best predictor of recurrence risk, followed by the ratio of the spinal canal diameter to the vertebral body diameter (figure 9a: not shown) and by the space available for the cord. Given the technical requirements for making an accurate MRI measurement, the ratio is the method of choice in general practice.
Although Herzog et al (13) have suggested that the ratio is overly sensitive in diagnosing cervical stenosis, it is a reliable, accurate, and accessible method for quantifying the risk of CCN recurrence when used with the probability-of-recurrence graph (figure 9b: not shown). With the ratio and the graph, a physician can counsel patients with CCN regarding their risk of recurrence. For example, a CCN patient with a spinal canal/vertebral body ratio of 0.5 has approximately a 75% risk of a recurrent episode. Because of the low specificity and low positive predictive value, however, the canal/vertebral body ratio should not be used as a screening test for athletes who have not had an episode of CCN.
Several investigators have observed an inverse relationship between increased posttraumatic myelopathy and sagittal diameter of the cervical canal in patients suffering fracture, dislocation, or instability of the cervical spine (14,15). In the series of Torg et al (11), there was no correlation between the severity of the clinical manifestations of CCN and the degree of narrowing. But unlike patients in the other studies, the latter patients did not have loss of cervical spine stability.
Return-to-play recommendations. Though we believe that CCN is a benign entity, all patients should undergo a routine plain-film radiographic and MRI examination. Patients with uncomplicated CCN may be advised that they can return to contact activities without increased risk of permanent neurologic injury. However, since the overall recurrence rate of 56% (12) is related to the degree of cervical canal narrowing, patients can be counseled regarding the risk of recurrence using the following recommendations:
Spear Tackler's Spine
Spear tackler's spine is a condition that occurs in football players who habitually use the head as the initial point of contact (16). Plain radiographs (figure 10: not shown) of the condition show cervical stenosis, posttraumatic changes, and loss of the normal cervical lordosis. An erect lateral view of the neck in neutral alignment best shows the loss of the normal cervical lordosis. The straightening of the cervical spine is the result of repeated axial loading and microtrauma to the spinal structures and may or may not be reversible. The straightened cervical spine acts like a segmented column (figure 11), predisposing the spine to permanent neurologic injury with further axial loading; thus, the combination of spear tackler's spine and head-first tackling is extremely dangerous. Spear tackler's spine is therefore an absolute contraindication to further participation in contact sports.
In patients whose loss of cervical lordosis is reversible, a return to activity may be considered when the normal lordotic curve returns. Counseling regarding the perils of head-first impact is imperative, as is the teaching of safe tackling techniques.
In a patient with or without ligamentous laxity, an acute fracture of either the vertebral body or the posterior elements is an absolute contraindication to participation. However, depending on the type and location of the fracture, healed lesions may or may not preclude further participation (table 1). Consultation with an experienced sports medicine orthopedist should be obtained to assist in deciding whether further participation is prudent.
The axial-load teardrop fracture. This fracture is a variant of the burst fracture and is different from the isolated tear-drop fracture (17). The latter (figure 12a: not shown) is a fracture of the anteroinferior corner of the vertebra and is not usually associated with permanent neurologic sequelae.
In contrast, the axial-load teardrop fracture (figures 12b, 12c, and 12d: not shown) is a three-part, two-plane fracture including a sagittal vertebral body fracture and a fracture of the posterior neural arch. It is caused by severe compression. Although the name focuses attention on the anteroinferior vertebral body fracture, the unstable fracture pattern is actually responsible for encroachment on the spinal cord, which results in the paralysis that frequently accompanies this injury.
Cervical Spine Fusion
A patient who has undergone spine fusion does not necessarily have to avoid contact activities, but recommendations vary according to the individual's signs and symptoms and the level of vertebral fusion:
Spinal Cord Resuscitation
Research over the past 20 years has clearly established the principles of brain resuscitation in the management of closed head injuries. The pathophysiologic and mechanistic phenomena causing morbidity in these head injuries are the same as those causing morbidity in acute spinal cord trauma (18). Specifically, secondary spinal cord injury caused by hypoxia, edema, and aberration of cell membrane potential is largely responsible for neurologic deficits. The methods of spinal cord resuscitation seek to minimize hypoxia, edema, and aberrations of cell membrane potential in an attempt to reverse secondary changes and enhance neurologic recovery. These methods include the following:
The proposed recommendations for managing cervical spine injuries are based on the best available information. As more data are gathered, however, changes may be necessary. In deciding whether or not an athlete can safely return to contact sports, the athlete's age, experience, ability, position, and level of participation should be considered along with the recommendations.
For more information on this subject, see Torg JS, Ramsey-Emrhein JA: Management guidelines for participation in collision activities with congenital, developmental, or postinjury lesions involving the cervical spine. Med Sci Sports Exerc 1997;29(7, clinical suppl), to be published.
Dr Torg is a professor of orthopedic surgery at Allegheny University for Health Sciences in Philadelphia; Ms Ramsey-Emrhein is head athletic trainer at Dickinson College in Carlisle, Pennsylvania. Dr Torg is an editorial board member of The Physician and Sportsmedicine. Address correspondence to Joseph S. Torg, MD, Allegheny University Hospitals-Center City, Broad and Vine, Philadelphia, PA 19102-1192; send e-mail to [email protected].
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