|
With the growth of athletic participation there has been a commensurate
increase of sports-related neurologic disorders. Peripheral nerve injuries in
sports are caused by trauma, compression, and traction. Prompt evaluation and
treatment of the professional and recreational athlete enable an earlier return
to competition.
Introduction. Gowers in 1892 described a radial nerve injury in a patient “
throwing a stone with energy.”1 Forceful muscular effort resulted in a humerus
fracture with a radial nerve injury. Since this early report, sports have taken
on a larger role in our lives. With increased athletic participation, there has
been a rise in sports-related injuries.
Neurologic injuries involve the central nervous system, defined as the brain and
spinal cord, and the peripheral nervous system, the nerves and muscles lying
outside the spinal column in the extremities and trunk. Peripheral nerve
injuries in sports are caused by trauma, compression, and traction. These nerve
injuries follow Seddon’s rules of severity:
1. Neurapraxia (deformation of nerve fibers)
2. Axonotmesis (interruption of nerve fibers)
3. Neurotmesis (interruption of whole nerves)
Most sports-related traumatic peripheral nerve injuries result in transient
motor and sensory symptoms and fall under the first category, neurapraxia. They
are best evaluated by electromyography and nerve conduction velocities. These
studies confirm the diagnosis, identify neurologic disorders unrelated to the
sports injury, or may be normal. Absence of findings may redirect the evaluation
to alternative explanations for weakness or atrophy.2
Baseball and Throwing Sports. Nerve injuries to the throwing arm are caused by
the extreme stresses generated across joints during the throwing motion. These
stresses are greatest at the shoulder and elbow. Analysis of the throwing motion
is important to understanding the mechanisms of injury.3 The throwing motion is
divided into five phases:
1. Windup
2. Cocking
3. Acceleration
4. Release and deceleration,
5. Follow-through
Ulnar Neuropathy. Recurrent valgus stress on the elbow during the throwing
motion results in ligamentous inflammation and joint laxity.4 Increased joint
mobility allows recurrent stretch, compression and subluxation of the ulnar
nerve. Intermittent and persistent symptoms and signs appear, such as elbow
pain, numbness and tingling in the ulnar digits, and weakness of ulnar
innervated muscles. The syndrome occurs in adults and in adolescents in what is
termed, “The Little Leaguer’s Elbow.”5, 6 Early evaluation by a
sport-physician is important to management. Electrophysiologic evaluation,
electromyography and nerve conduction studies, may reveal conduction delay
across the elbow and denervation of ulnar muscles. Some athletes respond to rest
while others require repair of the ligament with submuscular or subcutaneous
transposition of the nerve.7
Suprascapular Neuropathy. Stress across the shoulder is greatest during the
acceleration and deceleration phases. A commonly observed syndrome in throwing
athletes, such as volleyball players, baseball players, and javelin throwers, is
the suprascapular neuropathy.8, 9 As the nerve courses over the scapula to
innervate the supraspinatus and infraspinatus, 2 sites of compression and
stretch are the suprascapular notch and the spinoglenoid ligament. Athletes
complain of pain and exhibit weakness of abduction and external rotation of the
shoulder. Nerve conduction studies may reveal delay across the points of
entrapment. Electromyography demonstrates denervation and axonal loss depending
on the severity of the injury. Additional imaging is required to identify cysts
or ganglia in the spinoglenioid region.10 The athlete should be removed from
competition. Therapy is directed at maintaining range of motion and
strengthening shoulder abductor and external rotator muscles. In
some instances, the nerve may be surgically explored and released to diminish
pain and improve strength.
Football. The 5th through the 8th cervical roots exit the spinal canal to form
the trunks and cords of the brachial plexus before dividing into the nerves of
the arm. The plexus lies in close proximity to the shoulder, the 1st rib, and
clavicle. Sudden depression of the shoulder with contra lateral distension of
the head places compressive and traction forces on the nerves of the plexus, the
cervical roots and even the spinal cord.
Following a collision or tackle, the “stinger or burner” describes the
burning and tingling experienced by the player from the shoulder to the hand.
Weakness of the shoulder may accompany sensory symptoms. In most cases, the
symptoms and signs are brief, lasting seconds to minutes. The anatomic origin of
the symptoms is debated. The athlete with persistent motor or sensory findings
should not compete. Recurrent trauma with progressive symptoms likewise limits
return to play. Persistent weakness and sensory loss require electromyographic
and radiographic evaluation of the cervical spine and brachial plexus. 3, 11, 12
Running. Long-distance runners do not develop peripheral neuropathy as a result
of running. They frequently experience transient paresthesias associated with
minor injuries to the feet and toes.13 Runners and dancers complain of deep
burning, lancinating pain
of the toes due to recurrent microtrauma to the interdigital nerves resulting in
web space neuroma formation. Deep pain and numbness on the sole of the foot
provoked by running
or jogging raises the possibility of focal entrapment or trauma to the medial
plantar cutaneous branch of the distal posterior tibial nerve at the ankle. This
is called the tarsal tunnel syndrome. Lateral and calcaneal branches may also be
involved. The electrophysiologic features of these syndromes include distal
latency prolongation and denervation of intrinsic foot muscles. Treatments
include rest, orthotics, local injection, and in some instances surgery.14
Upper extremity peripheral nerve syndromes may be seen in runners. We observed a
distal median neuropathy at the wrist in an athlete competing in an Ultra
Marathon in New York City’s Shea Stadium. Ice taped to his wrists to promote
cooling during the race caused distal median paresthesias. Symptoms resolved
over 6 weeks. Electrophysiologic studies were not performed.
Cycling. Mechanical compression and ischemia also cause neuropathies in
bicyclists. Numbness and weakness of the hands common in cyclists are due to
handlebar compression of ulnar nerve at Guyon’s canal (hypothenar aspect of
the palm) or the
median nerve at the carpal tunnel.15 Nerve conduction studies demonstrate
conduction delays across these regions of compression or may be entirely normal.16 Pudendal and genitofemoral neuropathies are caused by compression on
the bicycle seat.17 Symptoms fortunately remit with technical adjustments, such
as specialized gloves, padded handlebars, and alteration of hand and trunk
positions.
Conclusion. Patients frequently present to physicians with peripheral nerve
injuries sustained in sports. Awareness of these syndromes and the special needs
of athletes are important. In most cases, early diagnosis and treatment provide
a favorable prognosis for return to competition.
|
References
1. Gowers WR. A Manual of Diseases of the Nervous System. London, England: J and
A Churchill; 1892:85.
2. Wilbourn AJ. Electrodiagnostic testing of neurologic injuries in athletes.
Clin Sports Med. 1990;9:229-245.
3. McLeod WD. The pitching mechanism. In: Zarins B, Andrews JR, Carson WG, eds.
Injuries to the throwing Arm. Philadelphia, PA: WB Saunders Company; 1985:22-29.
4. Conway JE, Jobe FW, Glousman RE, Pink M. Medial instability of the elbow in
throwing athletes. J Bone Joint Surg. 1992;74-A(1):67-83.
5. Jobe FW, Nuber G. Throwing injuries of the elbow. Clin Sports Med.
1986;5(4):621-636.
6. Pappas AM. Elbow problems associated with baseball during childhood and
adolescence. Clin Ortho Rel Res. 1982;164:30-41.
7. Andrews JR, Timmerman LA. Outcome of elbow surgery in professional baseball
players. Am J Sports Med. 1995;23(4):407-413.
8. Ringel SP, Treihaft M, Cary M, et al. Suprascapular neuropathy in pitchers.
Am J Sports Med. 1990;18(1):80-86.
9. Treihaft MM. Neurologic injuries in baseball players. Semin Neurol.
In press.
10. McClusky L, Feinberg,
D, Dolinskas C. Suprascapular neuropathy related to a glenohumeral joint cyst.
Muscle Nerve. 1999;772-777.
11. Markey K, DiBenadetto M, Curl WW. Upper trunk brachial plexopathy. The
stinger syndrome. Am J Sports Med. 1993;21:650-655.
12. Meyer SA, Schulte KR, Callhaghan JJ, et al. Cervical spine stenosis and
stingers in collegiate football players. Am J Sports Med. 1994;22:158-166.
13. Dyck PJ, Classen SM, Stevens JC, O’Brien PC. Assessment of nerve damage in
the feet of long-distance. Mayo Clin Proc 1987;62:568-572.
14. Schon LC, Baster DE. Neuropathies of the foot and ankle in athletes. Clin
Sports Med. 1990;9:489-509.
15. Rettig AC. Neurovascular injuries in the hands and wrists of athletes. Clin
Sports Med. 1990;9:389-417.
16. Jackson DL. Electrodiagnostic studies in median and ulnar nerves in
cyclists. Phys Sports Med. 1989;17:137-148.
17. Mellion MB. Common cycling injuries. Sports Med: Management and Prevention.
Sports Med. 1991;11:52-70.
|
|
