AAOS Comprehensive Orthopaedic Review

Section 5 - Sports Medicine

Chapter 46. Neurologic Injuries Related to Sports Participation

I. Stingers/Burners

A. Overview/epidemiology

 

1. Stingers (also called burners) are transient unilateral upper extremity neurologic injuries seen in contact sports.

 

2. In the 1970s, 50% of football players had experienced at least one stinger during their careers; this number dropped to an incidence of 3.7% to 7.7% and prevalence of 15% to 18% by 1997, likely related to rule and equipment changes.

 

3. Having one stinger increases by threefold the risk of having another.

 

B. Pathoanatomy

 

1. The most common mechanism of injury is downward displacement of the shoulder and lateral flexion of the neck to the contralateral shoulder, producing brachial plexus traction.

 

2. Lateral head-turning toward the affected side may cause nerve root compression and may be a source of symptoms.

 

3. A direct blow to the supraclavicular fossa at the Erb point may cause injury as well and may be equipment related.

 

C. Evaluation

 

1. History

 

a. Patients experience a transient, unilateral tingling, burning, or numbing sensation in a circumferential, not dermatomal, distribution.

 

b. Ipsilateral sensory symptoms and motor weakness are typical findings in an acute stinger injury.

 

c. A C6 nerve root distribution is commonly involved, but the upper trunk of the brachial plexus and other cervical root involvement also has been described.

 

d. Symptoms typically resolve after 1 to 2 minutes.

 

e. Neck pain should not be a presenting symptom.

 

2. Physical examination

 

a. With chronic or repeated injury, atrophy may be noted.

 

b. The physical examination should assess the neck for stiffness, spasm, or pain.

 

c. A positive Spurling test and tenderness with percussion of the supraclavicular fossa may be present.

 

3. Differential diagnosis and natural history

 

a. Electromyographic (EMG) studies are indicated if symptoms do not resolve after 3 weeks. EMG will demonstrate abnormalities in the roots, cords, trunks, and peripheral nerves.

 

b. It is important to rule out other injury such as cervical fracture, dislocation, or spinal cord contusion.

 

c. Patients should be reexamined frequently.

 

d. Long-term muscle weakness with persistent paresthesias may result from severe or repeated stingers in 5% to 10% of patients.

 

e. Patients with cervical pain or findings should undergo a thorough workup of the neck.

 

D. Treatment

 

1. By definition, stingers are transient injuries and do not require formal treatment.

 

2. Systemic steroids have not been shown to be of benefit and may be harmful.

 

3. Return to play is allowed after rest and rehabilitation when the patient is symptom-free.

 

4. Players with residual muscle weakness, cervical abnormalities, restricted cervical motion, or abnormal EMG studies should be withheld from contact sports.

 

5. In football, equipment modifications to shoulder pads may reduce recurrence.



II. Long Thoracic Nerve Injury

A. Overview/epidemiology—Injury to the long thoracic nerve is uncommon but has been reported in nearly every sport.

 

B. Pathoanatomy

 

1. The long thoracic nerve arises from C5-C7, with a C8 contribution in 8% of individuals. It travels anterior to the scalenus posterior muscle and travels distally and laterally under the clavicle over the first or second rib. It runs along the midaxillary line over a distance of 22 to 24 cm.

 

2. Repetitive stretch injury is the cause of most of these injuries, which are typically neurapraxic.

 

3. Positions with the head tilted or rotated away and the arm overhead put the nerve at risk.

 

4. A fascial band from the inferior brachial plexus to the proximal serratus anterior muscle may contribute to traction injury.

 

5. Direct trauma to the thorax also may injure the nerve.

 

6. Compression of the nerve can occur at many sites.

 

C. Evaluation

 

1. History

 

a. Patients commonly report pain at the shoulder, neck, or scapula that is exacerbated by activity or tilting the neck.

 

b. Weakness is noted when lifting away from the body or with overhead activity.

 

c. Winging prominence may be noted when sitting against a chair back.

 

2. Physical examination

 

a. Static and dynamic winging of the scapula is seen, with weakness when testing shoulder strength.

 

b. The position of the resting scapula is superior and toward the midline as the trapezius dominates.

 

c. Resisted forward elevation or having the patient perform a push-up will accentuate the winging.

 

3. Ancillary studies

 

a. EMG and nerve conduction velocity (NCV) studies will confirm the diagnosis and delineate severity.

 

b. These studies also are used to follow recovery.

 

D. Treatment

 

1. Most long thoracic nerve palsies recover spontaneously.

 

2. Physical therapy to strengthen compensatory muscles and braces that help to hold the scapula to the chest may provide some comfort.

 

3. Recovery typically occurs within 1 year but may take 2 years in some patients.

 

4. If symptoms warrant and there is no spontaneous recovery, muscle transfers are considered. (Sternal head of pectoralis major to inferior border of scapula is most popular.)



III. Suprascapular Nerve Injury

A. Overview/epidemiology

 

1. Suprascapular nerve injury is an uncommon cause of shoulder pain.

 

2. Infraspinatus impairment is found in 45% of volleyball players, and 1% to 2% of painful shoulder disorders are related to suprascapular nerve compression.

 

B. Pathoanatomy

 

1. The suprascapular artery lies above the transverse scapular ligament, and the suprascapular nerve lies below the transverse scapular ligament.

 

2. The suprascapular nerve is from the upper trunk of the brachial plexus, with C5 and C6 (and occasionally C4) roots.

 

3. It travels laterally across the posterior cervical triangle to reach the scapular notch close to the posterior border of the clavicle.

 

4. Entrapment occurs in three places:

 

a. The suprascapular notch, by the transverse scapular ligament.

 

b. The spinoglenoid notch, by the spinoglenoid ligament.

 

c. The spinoglenoid notch, by a spinoglenoid notch ganglion cyst from the shoulder (usually associated with a small posterosuperior labral tear).

 

C. Evaluation

 

1. History—Patients present with a poorly localized dull ache over the lateral shoulder with weakness.

 

2. Physical examination may detect atrophy of the infraspinatus and sometimes supraspinatus, with weakness in external rotation.

 

3. MRI may demonstrate a ganglion cyst at the spinoglenoid notch or supraspinatus fossa. Patients with MRI scans that demonstrate a cyst in the spinoglenoid notch may have compression of the infraspinatus branch of the suprascapular nerve and may present with weakness in external rotation. The affected muscle is the infraspinatus.

 

4. An athlete who presents with shoulder pain, weakness in external rotation, and normal MRI scans may still have suprascapular nerve entrapment by the transverse scapular ligament or the spinoglenoid notch ligament.

 

5. EMG and NCV studies will isolate the lesion to the suprascapular notch (supraspinatus and infraspinatus) or spinoglenoid notch (supraspinatus is spared).

 

D. Treatment

 

1. Nonsurgical treatment can be used for athletes with a presumed microtraumatic source of injury.

 

2. Symptoms have been reported to resolve in 6 to 12 months after diagnosis.

 

3. Nonsurgical treatment usually includes rest and stretching of the posterior capsule of the shoulder.

 

4. Nonsurgical treatment is used for 4 to 6 weeks, followed by a repeat EMG study to assess recovery.

 

5. Surgery is indicated for masses compressing the nerve or for failure of nonsurgical treatment.

 

6. Surgery entails release of the transverse scapular ligament, release of the spinoglenoid ligament, or removal of the spinoglenoid notch ganglion cyst, either open or arthroscopically.



IV. Axillary Nerve Injury

A. Overview/epidemiology

 

1. Isolated injuries are uncommon and represent less than 1% of sports injuries; however, approximately 48% of patients with an anterior dislocation will have EMG changes in the axillary nerve. Older patients are at higher risk for neurologic injury with shoulder dislocation.

 

2. Quadrilateral space syndrome is very rare, affecting young, active adults between 20 and 40 years of age and commonly described in baseball players.

 

a. The boundaries of the quadrilateral space are the long head of the triceps medially, the humeral shaft laterally, the teres minor muscle superiorly, and the teres major and latissimus dorsi inferiorly.

 

b. The quadrilateral space contains the axillary nerve and the posterior circumflex humeral artery.

 

B. Pathoanatomy

 

1. The axillary nerve originates from C5 and C6 from the posterior cord of the brachial plexus. It travels below the coracoid process obliquely along the anterior surface of the subscapularis, then dives to the inferior border of the subscapularis. The nerve travels posteriorly adjacent to the inferomedial capsule, then through the quadrilateral space with the posterior circumflex humeral artery.

 

2. It innervates the teres minor and the deltoid from back to front.

 

3. The distance from the acromion to the nerve at the mid deltoid is 6 cm.

 

4. Injury can be from contusion, stretch (as in a dislocation), or entrapment in the quadrilateral space, or it may be iatrogenic (during a deltoid-splitting approach or vigorous retraction during surgery).

 

C. Evaluation

 

1. History and physical examination

 

a. Patients may be asymptomatic or may describe easy fatigability and weakness.

 

b. The physical examination will demonstrate deltoid atrophy. Weakness will also be noted, particularly in abduction, forward punching, and external rotation.

 

c. Numbness in the sensory distribution of the axillary nerve, which is a spot on the lateral side of the arm over the deltoid, may be present.

 

2. Ancillary studies

 

a. EMG and NCV studies will confirm diagnosis and assess severity. These studies also are used to follow recovery.

 

b. Patients with quadrilateral space syndrome have more vague symptoms, and the physical examination may be nonspecific.

 

c. In quadrilateral space syndrome, EMG is frequently not helpful; instead, an arteriogram with the arm in abduction and external rotation may show a lack of flow in the posterior circumflex humeral artery.

 

D. Treatment

 

1. Treatment of axillary nerve injury is typically nonsurgical.

 

2. As the nerve regenerates, the posterior deltoid and teres will recover before the anterior deltoid.

 

3. Surgery is indicated in symptomatic patients with no evidence of recovery after 3 to 6 months.

 

4. Surgery can include neurolysis, neurorrhaphy, nerve grafting, nerve transfer, and neurotization.

 

5. For patients with quadrilateral space syndrome, resection of fibrous bands around the nerve is usually curative if nonsurgical treatment has failed.



V. Lateral Femoral Cutaneous Nerve Injury

A. Overview/epidemiology

 

1. The lateral femoral cutaneous nerve originates from L2 and L3 in the lumbar plexus.

 

2. It lies on the surface of the iliopsoas and exits the pelvis under the inguinal ligament, passing just medial to the anterior superior iliac spine.

 

3. It supplies cutaneous innervation to the front of the thigh to the knee.

 

B. Pathoanatomy

 

1. Entrapment is known as meralgia paresthetica. The injury also is seen in patients with tight belts or trousers.

 

2. The lateral femoral cutaneous nerve can be injured during surgery, especially when harvesting bone graft or during anterior approaches to the hip.

 

C. Evaluation

 

1. Patients report pain or numbness in the anterolateral thigh.

 

2. In athletes, it is common that no identifiable cause is found.

 

3. A positive Tinel sign is frequently seen on examination.

 

4. Local nerve block with lidocaine can be diagnostic.

 

5. Plain radiographs or MRI can rule out other causes.

 

6. NCV studies demonstrate prolonged latency or decreased conduction velocity.

 

D. Treatment

 

1. Nonsurgical treatment includes heat, physical therapy, local steroid injections, and nonsteroidal anti-inflammatory drugs.

 

2. If symptoms remain and are disabling, surgical release of the fascial bands constricting parts of the inguinal ligament to decompress the nerve has been successful.

 

3. Transection of the nerve leaves hypoesthesia and possible painful neuromas.



Top Testing Facts

1. Ipsilateral sensory symptoms and motor weakness are typical findings in an acute stinger injury.

 

2. Injury to the long thoracic nerve results in a scapula that is positioned superior and toward the midline when at rest. Winging of the scapula will be noted with strength testing.

 

3. The suprascapular artery lies above the transverse scapular ligament, and the suprascapular nerve lies below the transverse scapular ligament.

 

4. An athlete who presents with shoulder pain, weakness in external rotation, and normal MRI scans may still have suprascapular nerve entrapment by the transverse scapular ligament or the spinoglenoid notch ligament.

 

5. Patients with MRI scans that demonstrate a cyst in the spinoglenoid notch may have compression of the infraspinatus branch of the suprascapular nerve and may present with weakness in external rotation. The affected muscle is the infraspinatus.

 

6. Subtle axillary nerve injury is common in anterior dislocations. Older patients are at higher risk for neurologic injury with shoulder dislocation. The axillary nerve often is injured.

 

7. The boundaries of the quadrilateral space are the long head of the triceps medially, the humeral shaft laterally, the teres minor muscle superiorly, and the teres major and latissimus dorsi inferiorly. The quadrilateral space contains the axillary nerve and the posterior circumflex humeral artery.

 

8. The axillary nerve is 6 cm from the lateral acromion at the mid deltoid region.

 

9. Recovery of the injured axillary nerve begins in the posterior deltoid, followed by the middle head. The anterior head of the deltoid is the last to recover.

 

10. The lateral femoral cutaneous nerve is a terminal branch of the second and third lumbar roots.



Bibliography

Bigliani LU, Dalsey RM, McCann PD, April EW: An anatomic study of the suprascapular nerve. Arthroscopy 1990;6: 301-305.

Castro FP: Stingers, cervical cord neuropraxia, and stenosis. Clin Sports Med 2003;22:483-492.

Kuhn JE, Plancher KD, Hawkins RJ: Scapular winging. J Am Acad Orthop Surg 1995;3:319-325.

McCrory P, Bell S: Nerve entrapment syndromes as a cause of pain in the hip, groin, and buttock. Sports Med 1999;27:261-274.

Moore TP, Fritts HM, Quick DC, Buss DD: Suprascapular nerve entrapment caused by supraglenoid cyst compression. J Shoulder Elbow Surg 1997;6:455-462.

Romeo AA, Rotenberg DD, Bach BR: Suprascapular neuropathy. J Am Acad Orthop Surg 1999;7:358-367.

Safran MR: Nerve injury about the shoulder in athletes: Part 1. Suprascapular nerve and axillary nerve. Am J Sports Med 2004;32:803-819.

Safran MR: Nerve injury about the shoulder in athletes: Part 2. Long thoracic nerve, spinal accessory nerve, burners/stingers, thoracic outlet syndrome. Am J Sports Med 2004; 32:1063-1076.

Steinmann SP, Moran EA: Axillary nerve injury: Diagnosis and treatment. J Am Acad Orthop Surg 2001;9:328-335.

Visser CP, Coene LN, Brand R, Tavy DL: The incidence of nerve injury in anterior dislocation for the shoulder and its influence on functional recovery. A prospective clincial and EMG study. J Bone Joint Surg Br 1999;81:679-685.