Burners and Stingers (Brachial Plexopathy)

Burners and stingers are injuries to the brachial plexus that arise from traction, compression, and direct trauma. The brachial plexus consists of the cervical nerve roots from C5 to T1, and the most commonly affected roots are the upper plexus roots of C5 and C6 ( Fig. 21-1 ). Stingers are the most common cervical spine injury in athletes and are notoriously prevalent in contact and collision sports. As many as 65% of college football players have reported sustaining a stinger in their 4-year career.

The upper trunk of the brachial plexus is often involved with stingers and burners with resultant weakness of the deltoid, biceps, and rotator cuff muscles. The clavicle and chest wall are juxtaposed structures to the brachial plexus.

( A, Modified DeLee JC, Drez D Jr, Miller MD, editors: DeLee and Drez’s orthopaedic sports medicine, vol 1, ed 2, Philadelphia, 2003, Saunders, p 797; B, Copyright William B. Westwood, 1997. In Miller MD, Hart JA, MacKnight JM, editors: Essential orthopaedics, Philadelphia, 2010, Saunders, p 488.)

Symptoms include reversible, unilateral upper extremity pain, numbness, and weakness, but neurologic symptoms rarely follow a strict dermatomal distribution. The symptoms typically resolve within minutes of the injury.

Transient inability to use the arm actively, termed dead arm syndrome, can exist in addition to paresthesias of the entire arm ( Fig. 21-2 ). If the symptoms are bilateral, concern for transient quadriparesis should be raised.

Common presentation of dead arm syndrome in which the contralateral arm supports the weight of the affected arm as a result of pain or muscle weakness.

(From Pritchard JC: Football and other contact sports injuries: diagnosis and treatment. In Buschbacher RM, Braddom RL, editors: Sports medicine and rehabilitation: a sport specific approach, Philadelphia, 1994, Hanley & Belfus, p 172.)

The injury characteristically has three main etiologic patterns: (1) traction, (2) compression, and (3) direct trauma to the brachial plexus. Traction of the plexus from sudden shoulder depression with lateral head deviation is more common in younger athletes without fully developed neck musculature. The compression mechanism from extension, ipsilateral deviation, and rotation to the affected side is more typical in mature athletes as a result of developmental foraminal stenosis and foraminal osteophytes ( Fig. 21-3 ). Finally, direct trauma from a direct blow or compression from the shoulder pad and the superomedial border of the scapula (Erb point) can injure the brachial plexus.

Classic ipsilateral extension and lateral deviation mechanism of brachial plexopathy.

(From Warren WL, Bailes JE: On the field evaluation of athletic neck injury. Clin Sports Med 17:99-110, 1998. In Miller MD, editor: SMART! Sports medicine assessment and review textbook, Philadelphia, 2010, Saunders.)

During examination of patients who have sustained stingers, recreation of the direction of the injury can trigger arm symptoms. The Spurling test with cervical extension, lateral flexion to the injured side, and gentle axial compression can reproduce arm symptoms. Similarly, ipsilateral shoulder depression and contralateral head deviation can produce symptoms if the original mechanism was a traction injury to the brachial plexus. Additionally, a Tinel sign may be present on palpation of the Erb point. The athlete may attempt to splint the affected arm with the contralateral extremity because of the nondermatomal motor deficit that occurs with stingers. The clavicle and spinous processes of the cervical spine should also be palpated to help evaluate for coexisting trauma.

Imaging of patients with stingers includes an anteroposterior view to assess coronal alignment and a lateral view to assess for decreased cervical lordosis from cervical perimuscular spasm that often accompanies brachial plexopathy. Additionally, oblique views may be helpful to evaluate the caliber of the cervical foramina. However, flexion and extension views of the cervical spine have limited utility in the acute posttraumatic setting.

Magnetic resonance imaging (MRI) is helpful in evaluating for suspected spinal cord or nerve root injury. Herniated cervical disks, foraminal or canal stenosis, and spinal cord edema are also clearly visualized on MRI. Greenberg and colleagues demonstrated the mean subaxial space available for the cord index as a predictor of chronic stinger syndrome. At every level of the subaxial spine from C3 to C6, the difference between the space available for the spinal cord and the cord anteroposterior diameter is averaged over the four levels. An index value of less than 4.3 mm has been demonstrated to correlate with a 13-fold increase in the risk of developing multiple stingers, or chronic stinger syndrome ( Table 21-1 ).

The use of computed tomography (CT) and CT myelogram is typically not necessary and may be reserved mainly for patients who cannot tolerate or undergo MRI. CT may have some benefit in patients with congenital stenosis or substantial cervical spondylosis who sustain a spinal cord injury. In these patients, CT scan with or without myelography can help identify whether the cervical neuroforaminal stenosis is secondary to bony or soft tissue compression. As would be expected, in the patient with suspect brachial plexus disorders, CT has a limited role and typically provides insufficient imaging information, whereas CT myelography does not identify the injury because the pathologic process is beyond the neuroforamen and within the brachial plexus.

The utility of electromyography and nerve conduction studies has been called into question. As many as 80% of patients show electromyographic abnormalities more than 5 years after the onset of a stinger. However, persistent symptoms 2 to 4 weeks after the injury may warrant electromyographic studies to help with evaluation and long-term assessment of the injury. Red flags that warrant further testing include bilateral symptoms, lower extremity involvement, painful range of motion, axial tenderness, persistent burning, neurologic deficit, and altered consciousness. These findings may suggest other injuries such as the following: cervical spine injury; cervical cord neurapraxia (CCN), especially if the symptoms are bilateral; clavicle fracture; and cervical disk herniations. In addition, rotator cuff injury, first rib stress fracture, thoracic outlet syndrome, and Parsonage-Turner syndrome should be included in the differential diagnosis.

Initial treatment of stingers and burners should include removing the athlete from play until symptoms resolve completely and cervical spine injury can be excluded. Treatment is largely supportive, including physical therapy and possibly a sling to relieve traction on the brachial plexus. A focused rehabilitation program should include restoration of strength in the upper extremity and cervical spine. Emphasis should also be placed on proper posture, including chin-tuck exercises and cervical retraction.

The prognosis is based on the severity of the injury, which can be graded from least severe ( neurapraxia ) to more severe ( neurotmesis ). With neurapraxia, the most common variant of stingers, all nerve structures remain intact, and symptoms typically resolve in minutes, although they may take as long as 6 weeks. Intermediate injury, termed axonotmesis, occurs with axonal disruption in which wallerian degeneration takes place distal to the injury site. Recovery is usually complete, but it may take months because an intact epineurium allows axonal regrowth at a rate of approximately 1 mm per day. Severe injuries (neurotmesis) arise with complete disruption of axons, endoneurium, perineurium, and epineurium. The prognosis is often variable, and complete loss of function is common.

Athletes should not be allowed to return to competition without a full, pain-free cervical arc of motion because this is paramount in preventing more serious spinal cord injury. On return to contact sports, the use of neck rolls, such as a neck-shoulder-cervical orthosis (cowboy collar) or pads at the base of the neck in football players, can help minimize recurrences of stingers. Unfortunately, the long-term implications of recurrent stingers are unknown at present.