Stingers are the representation of a neural injury, typically of the cervical nerve root or a portion of the brachial plexus that is injured during athletic participation. The stinger is a symptom complex that is defined by its unilaterality, as opposed to cervical cord neurapraxia (CCN) (discussed separately in this book), which has bilateral symptoms. Stingers are also known as “burners.” A stinger is a more commonly used term and is used exclusively for this chapter.

The stinger manifests itself with a unilateral lancinating, burning dysesthesia that radiates down the upper extremity with a variety of sensory and motor findings. There may be pain along the cervical column to include posterior elements, musculoligamentous structures, and the trapezius on the involved side. The participant is usually able to remove him- or herself from the field of play, typically leaving the competition with the arm either dangling at the side or “shaking the arm out.” Weakness most commonly involves the deltoid, biceps, and spinati muscles.

Two classic mechanisms of injury account for the majority of injuries: (1) head contact with extension and rotation to the affected side (Figure 10-1), creating dynamic compression of the spinal nerve in the cervical neuroforamen creating a nerve root stinger, and (2) head abduction and shoulder depression (HA/SD) of the affected side, creating a traction injury to the brachial plexus (Figure 10-2). Also, to a much lesser degree, a cervical disk herniation may also pose as a nerve root stinger. Persistent neurologic symptoms in a unilateral arm that do not resolve should alert the practitioner to this possibility. Stinger symptoms can last from a few seconds to several weeks. Symptoms that persist for more than 12 to 24 hours should warrant a more careful imaging evaluation with a cervical spine MRI. A variety of sports are represented in the demographics of the injury. The most common are football, wrestling, rugby, mixed martial arts, rodeo, and hockey. Less common are gymnastics, baseball, body surfing, and cheerleading. The severity of the injury is closely correlated with the amount of initial force that occurred. Subsequent reinjuries require much less energy because the nerve is in a reparative state, as are the supporting musculoskeletal structures.

There are three types of neural injury patterns: (1) neurapraxia, (2) axonotmesis, and (3) neurotmesis, listed in order of severity. In a neurapraxic injury, the myelin sheath of the nerve undergoes degeneration, but the axon wall is intact. This gives a greater motor than sensory component, which is typically seen in the stinger injury pattern. These injuries usually recover in minutes to weeks. Axonotmesis represents an injury to the axon and myelin sheath, but the epineurium and perineurium are still intact. Wallerian degeneration occurs in 2 to 3 weeks, which produces fibrillation and denervation potentials on electromyography (EMG). Both motor and sensory are affected as well. These injuries usually result in motor loss in the deltoid, biceps, and spinati muscles and can last for weeks to months. Last, neurotmesis indicates a complete disruption of the nerve and has a poor prognosis. These are rare and usually involve penetrating trauma or a high-energy, closed injury to the shoulder girdle.

There is no exact pathophysiologic mechanism for this neural injury.¹ Traction/tension and compression are the two predominant mechanisms, but it is usually a combination of these.² In the HA/SD mechanism, there is a tensile overload caused by traction of the brachial plexus.^3,4,5 In the hyperextension-rotation pattern, it is usually a compressive force directed at the spinal nerve root in the neuroforamen. The former (brachial plexus) gives a diffuse, multiroot examination, and the latter (nerve root stinger) is usually a more discreet radiculopathy.

American football has a relatively high incidence of stingers.⁵ It is reported that as many as 65% of college players will be affected over a 4-year career.⁵ There are
trends associated with the type of injuries seen. Younger and less skilled players typically have HA/SD injuries of the brachial plexus. Poor core trunk strength, lack of technique, and perhaps a little less “stick your nose in there” attitude create this situation. Older, more experienced and accomplished players with better ­technique—“head up, see what you hit”—usually have an extension-rotation injury giving a nerve root or radicular finding. In older, professional players, the repair–injury mechanism seen in the facet and uncovertebral joints after many years of play can create neuroforaminal stenosis and predisposition to nerve root stinger injuries.

As in all cases, a thorough history should be taken to determine the likely mechanism, the quality and duration of symptoms, and a history of prior injuries. If bilateral symptoms are encountered, you are not dealing with a stinger but a CCN. Frequently, the athlete is able to articulate the mechanism of injury. At times, an injury video may be available (National Football League sideline injury surveillance). The key differentiating point is that a stinger is always unilateral, and any other pattern (arm/leg, both arms, both arms and legs) represents a more serious CCN.

As a matter of reference, the word “stinger” has several meanings to players. Approximately 30% of the time, a player who presents with isolated neck or trapezial pain without radiation will call it a stinger.⁶ This usually represents a musculoligamentous injury to the cervical column.