Brachial Plexus Traction Injury
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þ Cervical Plexus Anatomy
  cervical plexus (C1-4):
 - face, ear, neck and trapezius ridges.
 - preauricular and postauricular nerves (lower face and cheek, mastoid and
   ear).
 - C2 most frequent: brow and angle of jaw.
 - C3-4: anterior neck, dorsal shoulder, trapezius ridge.

þ Cervical and brachial plexus don't cause much wasting.

þ Brachial Plexus Anatomy

 - upper trunk, brachial plexus
  + medial scapular border, cap of shoulder, upper arm.
  + pain at the ventromedial tip of the scapula with hyperalgesia and
    allodynia (known as "notalgia")
  + Tinel's Sign in supraclavicular fossa (Erb's point), sometimes
    suprascapular notch.
  + may get swelling of face from changes in sympathetic fibers

 - lateral cord, brachial plexus ():
  + usually thumb, index, radial side middle fingers
  + sometimes just in palm, or medial upper arm
  + sometimes lateral chest wall, axilla (T2), behind and under breast to
    midline and to epigastrium (intercosticobrachial nerve)
  + median nerve derived from lateral cord, but which also includes the radial
    side of the _ring_ finger, too.
  + Tinel's sign:  infraclavicular fossa, lateral portion

 - Medial cord, brachial plexus ():
  + 4-5 fingers, ulnar side of 3rd finger, medial forearm, medial upper arm.
  + main pain is in the supraclavicular area, with paresthesias radiating into
    medial forearm and 4 + 5 fingers.

 - Posterior cord, brachial plexus ():
  + posterior humeral area, triceps and posterior deltoid regions.
  + gives off the posterior interossei nerve at Arcade of Froshe (medial to
    lateral epicondyle), supplies dorsal forearm and extensor surface of
    digits, anatomic snuff box; mostly dorsal thumb, index, middle fingers.

 - Lower trunk, brachial plexus
  + ulnar nerve derived from this trunk; in addition to 4+5 fingers, and ulnar
    side of 3rd finger, and triangular patch above the wrist (but not the
    forearm)
  + presentation:  dull ache in medial forearm, paresthesias of 4 + 5 fingers,
    weakness of abductor pollicis brevis, opponens pollicis, and adductor of
    thumb as well as dorsal and volar interossei.

þ Brachial Plexus Exams

 - Allison's

 - Roos'
  + hold arms out, above the horizontal, in adduction, hands up (surrender
    posture).
  + normally a patient can stay like this for 3 minutes without undue fatigue
  + with plexus injury, in less than a minute will get paresthesia and
    numbness in area supplied by affected cord, trunk or plexus distribution.
  + can increase sensitivity by having patient open and close hands 20 times.
  + may just complain of tenderness or heaviness of affected distribution.
  + cervical radiculopathy (e.g., cervical disc disease) will get _better_
    with this test!
  + particularly good for lateral cord traction injury (thumb, index, middle
    fingers; sometimes just in palm).

 - Wright's
  + arms straight and hands straight up, arms next to ears (high
    surrender posture)
  + if entire plexus is involved, patient often can't fully straighten arm in
    adduction.
  + if entire plexus is involved, may also get paresthesias down the medial
    scapular border and into the lower trunk.
  + if upper trunk and cervical plexus involved, may get pain in face, ear,
    neck and trapezius ridges.

þ Tinel's Sign
 - C nocioceptors of muscle, ligaments and the plexus itself are sensitized.
   Touch will then trigger pain.
 - Cervical and brachial plexus (see above).
Locations:
 - Cubital Tunnel:  ulnar nerve at elbow, pressure causes paresthesias in the
   4 + 5 fingers.
 - Guyon's Canal:  ulnar level canal at wrist.
 - Arcade of Froshe:  pressure medial to lateral epicondyle, on posterior
   interossei nerve off posterior cord, causes paresthesias of the dorsal
   forearm.
 - Carpal Tunnel
  + tip of the index finger usually most severely involved.
  + may go into 4+5 fingers because of anastomoses in the forearm in some
    people ("Martin-Gruber anastomses").
 - exit of nerve roots at cervical spine (Sperling's maneuver)

þ Young people with chest pain radiating down arm, and headache:
 - sounds like brachial plexus, specifically intercosticobrachial nerve
 - angina pain down arm is:
  + in T1-T4 distribution
  + never goes across wrist
 - if radiates 4+5 digits, _not_ angina
 - Rarely does radiculopathy from disc disease go into hand (sometimes C6 to
   thumb, or C6-7 into index finger, maybe into the third finger).

þ Pain radiating to C7-T1 area (thumb): disk disease very, very rare, so more
  likely to be a plexus injury.

þ Migraines and Plexus Injury
 - cervical plexus injuries may cause migraines
 - by changes in sympathetic fibers
 - not associated with family history
 - not triggered by usual migraine triggers (food, stress, sleep deprivation,
   pungent smells)

þ Blurred vision and Plexus Injury
 - plexus injury may cause blurred vision
 - caused by imbalance in symapthetic innervation between the two eyes.

þ Dizziness
 - plexus injury may cause dizziness
 - caused by change in symapthetic innervation to ear

þ "I always drop things"
 - indicates plexus injury, _not_ radicular injury.

þ "Muscle Strains":
 - pathologic examination shows about 10% of nerve fibers are
   ripped, but no actual damage to the muscle fibers [R.J. Schwarzman, Chair,
   Department of Neurology, Jefferson Medical College, 4/95].
 - Spasm is pathognomonic for nerve damage.

þ Treatment of RSD:
 - sympathetic blocks

þ Treatment of Brachial Plexus Traction injury:
 - early PT (gliding, not strengthening, which may aggravate it)
 - if PT fails, decompression