Managing Transient Cervical Neurapraxia in the Athlete
Transient cervical neurapraxia is characterized by paresthesia and/or weakness in the arms, legs or both. Episodes typically last a few seconds and resolve completely.
Most cases occur on the football field, following a severe collision in which the athlete's neck is either axially loaded or forcefully extended (Figures 1a and 1b). While no player is immune, the problem most commonly affects positions such as free safety, which involve high-speed collisions and open-field tackling.
Figure 1a: T 2 -weighted sagittal MRI of a professional football player who sustained an episode of transient cervical neurapraxia following a collision as wide receiver. Note the relative lack of high-signal-intensity spinal fluid surrounding the spinal cord.
Figure 1b: Non-contrast axial CT scan of the same player shows an oval canal measuring less than 10 mm in sagittal diameter. After recovering from transient neurapraxia, he was advised to retire.
Due to Dr. Torg's findings, "spearing," or lowering the head and hitting an opponent with the crown of the helmet, has been outlawed by the National Football League and throughout other levels of football. Lowering the head even slightly reverses the normal curvature of the cervical spine, resulting in a straightened cervical spine that cannot properly absorb the force applied in a collision (axial loading). Vertebral body fracture with spinal cord injury can result (Figures 2a, 2b, 2c).
Figure 2a: Sagittal MRI of a rugby player with an os odontoideum who sustained an episode of cervical neurapraxia during a game.
Figure 2b: T 2 -weighted sagittal MRI of the same player shows an area of increased signal intensity opposite the os odontoideum, representing edema from a spinal cord contusion.
Figure 2c: Axial MRI at level of os odontoideum shows spinal canal narrowing and deformation of the player's dural sac.
Neurapraxia can occur in a normal spine. It can also be associated with any condition that results in a functional narrowing of the spinal canal, such as disc herniation, congenital stenosis, acquired stenosis due to degenerative changes, fractures, or instability due to laxity in the ligaments.
In contrast, the common "stinger" ("burner") is characterized by numbness or electrical shock down one arm only. This is caused by either stretching or contusion of the brachial plexus, or by nerve-root compression from intervertebral disc herniation or from an osteophyte impinging on the nerve root.
When a player is down on the field with an episode of neurapraxia, the team physician must immediately immobilize the head and neck, then ensure safe transport off the field and to the hospital for evaluation. If the transient episode affects only the arms and the player walks off the field, a careful history and physical exam must be performed by the physician.
Following an episode of cervical neurapraxia, the player should be seen on an urgent basis by an orthopaedic surgeon or a spinal surgeon for evaluation. The workup should include a complete neurological evaluation and a radiographic assessment for structural abnormalities in the cervical spine. Routine cervical X-rays, flexion/extension cervical X-rays, an MRI and, in some cases, a myelogram followed by a CT scan should be ordered to determine the presence or absence of instability, fracture, spinal canal narrowing or cord contusion.
Dr. Torg believes that neurapraxia does not lead to permanent paralysis, since no player with neurapraxia from the National Football Head and Neck Registry has subsequently developed spinal cord injury. In addition, no player with permanent paralysis could recall a prior episode of neurapraxia.
However, neurapraxia indicates that a transient alteration in spinal cord function has occurred, and this cannot be ignored. Patients should be informed that after one episode of transient cervical neurapraxia, they face an approximately 50 percent chance of a repeat episode if they choose to continue playing. Should any structural abnormalities be identified, we generally recommend that the athlete not return to a collision sport.
If no abnormalities are found, deciding whether to continue playing can be difficult. At the recreational or high school levels, players and their parents know it is not worth the risk. However, at collegiate and professional levels, with scholarships, careers and financial futures at stake, players face a difficult decision. About 60 percent return to contact play, according to a 1997 follow-up study by Dr. Torg. Higher-level players may explore surgical options in order to continue playing, with a reduced risk of neurapraxia or permanent cord injury. If a patient has a disc herniation, for instance, diskectomy and fusion may be considered. This lowers the player's risk for future episodes of neurapraxia, though it does not completely eliminate it.
When observing or evaluating players involved in collision sports such as football, physicians should take that opportunity to reinforce the importance of proper tackling technique (keeping the head up during tackling). On the sidelines, physicians should bring any instances of spearing to the coach's attention.
