CHAPTER 55 • UPPER EXTREMITY NERVE ENTRAPMENT 323
other collision sports. Some investigators believe that
the lesion is more likely in the spinal nerves than the
plexus, because of the lack of protective epi- and per-
ineurium at that site (Weinstein, 1998); however, long
thoracic nerve involvement with scapular winging is
not a typical manifestation of most stinger injuries.
Other risk factors include backpacking, especially car-
rying heavy loads for a long time; foraminal stenosis
(Castro, 2003; Kelly et al, 2000), especially during
extension–compression injuries; poor technique, ill fit-
ting equipment (shoulder pads) (Markey, Di Benedetto,
and Curl, 1993). Risk factors for Erb’s (birth) palsy
include difficult childbirth, instrumentation (forceps).
- Symptoms and signs:Symptoms and signs of the
stinger syndrome include burning pain and dysesthe-
sia in the affected arm on impact lasting seconds to
hours, followed by mostly transient weakness and no
sensory symptoms. At times there is prolonged loss of
strength (Di Benedetto and Markey, 1984). Cervical
cord neurapraxia(CCN) has to be ruled out (Castro,
2003). Occasionally, the only objective change may
be seen as postural abnormality (drooping of the
shoulder, especially if the accessory nerve is also
involved). Confirmation by objective tests is often dif-
ficult. Findings include weakness in supra- and infra-
spinatus, deltoid and biceps. Check for positive
Tinel’s sign at Erb’s point and Spurling’s sign to con-
sider root involvement. More severe injuries may
involve the middle and lower trunk and/or nerve roots.
- Treatment: There is no direct treatment for the
stinger syndrome, other than prevention of recurrence.
Shoulder pad and neck orthosis selection should be
optimal to ensure best protection. Gradually increas-
ing collision work and improved tackling techniques
are recommended. Prolonged weakness will require a
reconditioning program before returning to competi-
tive contact sports (Cramer, 1999). Emphasis is placed
on postural exercises with cervicothoracic stabiliza-
tion training and resistive exercises to shoulder mus-
cles (when no more evidence of denervation).
- The athlete may return to participation in contact
sports on reestablishment of pain-free motion and full
recovery of strength and functional status.
- Contraindication for return to play is two or more
episodes of transient CCN, imaging confirmation of
cervical myelopathy, evidence of neurological deficit,
decreased ROM and/or neck pain (Weinberg, Rokito,
and Silber, 2003).
LOWER TRUNK PLEXOPATHY
- Anatomy and origin:The 8th cervical and first tho-
racic roots/spinal nerves. The lower trunk lies between
the clavicle and the first rib. It carries sensory and
motor fibers of C8–T1 distribution (median and ulnar
nerves). The closeness of median motor and ulnar sen-
sory fibers at this level has diagnostic significance.
- The best known and most debated compression syn-
drome here is the thoracic outlet syndrome (TOS).
- Thoracic outlet syndromes: Several are identified:
(1)between the anterior and middle scalene muscles,
(2)the scalenus anticus syndrome (nerve entrapment
between the insertion of the scalenus anticus, the clav-
icle and the first rib—more severe in the presence of a
cervical rib), (3)the costoclavicular syndrome, and
(4)the pectoralis minor syndrome.
- Risk factors:Risk factors include the presence of a
cervical rib (with fibrous bands to the 1st rib)
(Wilbourn, 1999), and slim asthenic females with
long “swan” necks and droopy shoulders. Sternotomy
places patients at risk for a pectoralis minor syn-
drome, especially those with premorbid impaired
shoulder motion. Space occupying lesions (e.g.,
Pancoast tumor) or bulky lymphadenopathy (of what-
ever etiology), and radiculopathy. Entrapment may be
of several types:
- Vascular etiology:Entrapment of subclavian or axil-
lary artery or vein.
- Neurogenic etiology: Neurogenic etiology (much
debated) specifically affects the lower trunk (Dumitru,
Amato, and Zwarts, 2002). The incidence of true neu-
rogenic TOS is thought to be near one in one million
(Wilbourn, 1999).
- Symptoms and signs:With vascular etiology there is
vague pain and fatigue (claudication), color change
(pallor or cyanosis), distended veins of the arm and
chest wall, and cool temperature of the upper limb.
Confirmatory tests are arteriography or venography.
Neurogenic etiology causes paresthesias along the
medial aspect of the affected hand and forearm noted
in conjunction with thenar wasting and weakness of the
abductor pollicis brevis(APB). The ulnar hand intrin-
sics may also be weak and atrophic. Characteristic
EDX finding include reduced median motor and ulnar
sensory response amplitudes.
•Provocative maneuvers include Adson’s maneuver
(decreasing the space between the clavicle and the
first rib, by placing the shoulders in military position,
head turned to the side and taking a deep breath,
which elevates the ribcage). It is considered positive if
the radial pulse can no longer be palpated, or if the
neurologic symptoms increase. Unfortunately, there
are many false positive and false negative results. Test
for costo-clavicular compression with shoulders in
military positions and then forcing clavicles down-
ward posteriorly. The hyperabduction–extension test
is used for pectoralis minor syndrome.
