CHAPTER 55 • UPPER EXTREMITY NERVE ENTRAPMENT 321RISK FACTORS AND ASSOCIATED
MEDICAL CONDITIONS
- Anatomy:Narrowed space in bony and/or muscular/
tendinous/fibrous canals/tunnels. - Examples: Thoracic outlet, quadrilateral space,
Struthers ligament, anomalous bone spurs, muscles or
fibrous bands, cubital-, radial- and carpal tunnel,
Guyon’s canal, excessive callous formation after
(especially malunited) fractures. - Functional/Injury:Acute or chronic such as through
repetitive motion, percussion, compression, stretch,
excessive pressure from equipment. - Medical conditions:Endocrine problems (pregnancy,
hypothyroidism), compartment syndrome, peripheral
neuropathy (PN), genetic PN with propensity to
develop compression syndromes (hereditary neuro-
pathic peripheral polyneuropathy).
CLINICAL FEATURES
- Symptoms and signs: Numbness, tingling, pain, and
weakness in the distribution of the affected nerve.
Feeling of coldness, heaviness, or burning (paresthe-
sias). - Common signs are sensory loss in the distribution of
the affected nerve except in lesions of pure motor
nerves, e.g., anterior, posterior interosseous, supras-
capular, and long thoracic nerves; weakness and/or
atrophy of muscles supplied by the compressed nerve. - Special tests include Tinel’s, Phalen’s, Spurling’s,
Adson’s maneuver, pectoralis minor and costoclavic-
ular maneuvers, and stress-abduction test that may or
may not be positive. - Persistent minor pain due to entrapment may cause a
regional pain syndrome—reflex sympathetic dystro-
phy (RSD).
ELECTRODIAGNOSIS
- Eletromyography(EMG) and nerve conduction stud-
ies(NCS) are significant factors in establishing the
correct diagnosis of entrapment syndromes. Typical
findings include the following:- Conduction delay across the site of the lesion.
Amplitudes are reduced due to blocking or axonal
loss (with normal duration), or secondary to
demyelination (with increased duration). - Electromyography shows decreased recruitment,
increase in polyphasic waves, action potential
durations and amplitudes, and in more severe cases
fibrillations and positive sharp waves. Complex
- Conduction delay across the site of the lesion.
repetitive discharges (CRD) denote chronicity. EMG
demonstrates the severity of the abnormality—
especially if there is evidence of denervation—that
has considerable impact on treatment decisions.- In compression syndromes, major diagnoses to be
ruled out with EMG and NCS are: radiculopathy,
peripheral neuropathy, plexopathy including neuralgic
amyotrophy (brachial plexitis), myopathy, and malin-
gering.
SPECIFIC NERVE ENTRAPMENTS OF
THE UPPER EXTREMITY- Radiculopathy:Radiculopathy is caused by pressure
on a spinal nerve as it exits the spine. It is the most
significant differential diagnosis for upper extremity
compression syndromes. Primary anterior compres-
sion (disk herniation) may selectively affect motor
fibers. It may spare the dorsal ramus, sparing sensa-
tion. Posterior compression may selectively affect
sensory fibers. Compression of the nerve root can
occur from any direction within the intervertebral
foramen, but most commonly occurs due to postero-
lateral disk herniation or facet degeneration. - Risk factors: For cervical radiculopthy include
patients with cervical spondylosis, cervical disk her-
niation, facet degeneration, space occupying lesions,
and prior C-spine trauma or surgery. The most com-
monly affected level is C7 (31–81% of all cervical
radiculopathy), followed by C6 (19–25%), C8
(4–12%), and C5 (2–14%) (Wilbourn and Aminoff,
1998). - Symptoms and signs:Sensory complaints (findings
are in root distribution), weakness, and reflex changes.
Provocative maneuvers include Spurling’s—pressure
on laterally and posteriorly tilted head reproduces
symptoms in the affected nerve root distribution. - Treatment:Indications for immediate surgical refer-
ral are progressive neurologic deficit, bowel or blad-
der dysfunction, and severe pain refractory to other
approaches. Surgery usually includes decompression
of the nerve root, diskectomy if needed, and possibly
cervical fusion.- Conservative treatment includes pain medications,
nonsteroidal anti-inflammatory drugs (NSAIDs),
antispasmodics, antiepileptics, and antidepressants.
Physical therapy modalities include cervical trac-
tion, strengthening exercises, biomechanical mobi-
lization (flexibility), and alignment techniques as
indicated. Epidural steroid injections can help facil-
itate physical therapy when needed. Transcutaneous
electrical nerve stimulation (TENS) units and
biofeedback may help.
- Conservative treatment includes pain medications,