Brachial Plexus Injury

Where does the brachial plexus exit? Where are the proximal and distal parts

• between anterior and middle scalene
  

• Proximal parts: posterior triangle of neck
  

• Distal parts: surround axillary artery

How can the brachial plexus be injured? Differentiate between pre/postgang injuries and why this distinction is important

• Result from forceful widening of the shoulder-neck angle causing traction to the nerve elements

• preganglionic injury: prox. to DRG (dorsal root ganglion)

• postganglionic: distal to the DRG

• Importance:

  • in prognostication/timing of surgery

  • spontaneous recovery is not expected in preganglionic injury

    • thats why early intervention (surgical/reconstruction) is needed

describe consequences of injury to upper trunk (C5,C6)

• Sensory loss in C5-C6 distribution

• Weakness or paralysis of proximal muscles of the upper extremity:

  • deltoid, coracobrachialis, brachialis and biceps

describe consequences of injury to C7

Weak/paralyze elbow, wrist, finger extension

describe consequences of injury to lower trunk (C8,T1)

Varying weakness or paralysis of Long flexors and intrinsic muscles of the hand

Describe pathology of Erb’s Palsy? What is Erb’s Point

• excessive displacement of the head to the opposite side and depression of the shoulder on the same side

  • results in stretch or compression of C5 and C6 roots

• Common causes:

  • Difficult delivery (shoulder dystocia in cephalic
    presentation; extraction of aftercoming head in
    breech presentation)

  • blow to or fall on the shoulder; motorcycle accidents

Erb’s point: the area in the upper trunk where 6 nerves meet and injury to this area leads to erb’s palsy

Describe Waiter’s Tip position and why this occurs in Erb’s Palsy

• Arm Adducted (no abductors)

  • Supraspinatus (suprascapular nerve [C5.C6])

  • Deltoid (axillary nerve [C5, C6])

• Arm Extended (no arm flexors)

  • Biceps brachii (musculocutneous nerve [C5, C6, C7])

  • Coracobrachialis (musculocutneous nerve [C5, C6, C7])

  • Deltoid, anterior fibers (axillary nerve [C5,C6])

• Arm medially rotated (no lateral rotation)

  • Infraspinatus (suprascapular nerve [C5, C6])

  • Teres minor (axillary nerve [C5,C6])

  • Deltoid, posterior fibers (axillary nerve [C5,C6])

• Forearm extended (no forearm flexors)

  • Brachialis (musculocutaneous nerve [C5,C6,C7])

  • Biceps brachii (musculocutaneous nerve [C5,C6,C7])

• Forearm pronated (weakened supinator)

  • Biceps brachii (musculocutaneous nerve [C5,C6,C7])

Describe Klumpke’s Palsy (C8/T1)

• Cause: Traction injuries caused by excessive abduction of the arm (fall from a height clutching at an object; difficult delivery such as hand dystocia)

• Symptoms

  • Clawed appearance of hand

    • (hyperextension of MCPJs and flexion of IPJs)

  • Weakness of wrist and finger flexion, paralysis of intrinsic hand muscles

  • Horner’s Syndrome

    • damage to sympathetic nerves (white rami of T1 fibers contribute to sympathetic supply to head and neck)

    • anhidrosis, miosis, ptosis

What is the consequenes of total brachial plexus palsy/Pan-Plexus (C5-T1)? treatment?

• Occurs in 50% to 75% of patients with Supraclavicular injuries

• Completely flail arm and insensate hand
  

• Free functional muscle transfer; stabilization of wrist through fusion

What is thoracic outlet syndrome?

• compressive neuropathy that may include all of the nerves to the upper extremity, neck, shoulder, upper back and chest

• Share characteristics or mimic other compressive neuropathies

• Diagnosis is by exclusion and suspicion

• No definitive electrodiagnostic test

• 2 basic types:

  • vascular

  • neurogenic
    

What are the three Anatomic corridor which are points of compression in thoracic outlet syndrome

1. Interscalene triangle: most common site;

   • anterior scalene anteriorly, middle scalene posteriorly, first rib posteriorly
     

2. Costoclavicular triangle:

   • anteriorly by clavicle, subclavius and
     costocoracoid ligament,

   • posteromedially by first rib;

   • posterolaterally by superior border of scapula
     

3. Subcoracoid or pectoralis minor space:

   • deep to the pectoralis
     minor below the clavicle

What are the causes of thoracic outlet syndrome? What are the provocative tests?

• scalene muscle abnormalities (hypertrophy of
  anterior scalene, scalene minimus)

• Pancoast tumors

• Cervical rib, abnormal clavicle or first rib

• Chronic overuse (frequent lifting above shoulder level, hyperabduction)

  • rowers, swimmers, weightlifters, pitchers)

• Vascular (aneurysm, compression on subclavian vein or artery)

Provocative tests:

• Roos Test – most sensitive; 90 degree abduction
  external rotation test
  

• Upper-Limb Tension Test: arm abducted
  followed by wrist extension, head away from
  affected side → recreate symptoms -> relief
  noted when head is brought back to affected
  side

How can the long thoracic be injured and the consequence

Injury: radical mastectomy, axillary lymph node dissection; chest tube insertion; stab wound

Winging of the scapula → scapula fails to move forward over the thoracic wall

How can the suprascapular nerve be damaged

• entrapment at the suprascapular foramen or spinoglenoid notch

• repetitive overhead use

What would be the consequences of a damaged lateral pectoral nerev

• Weak adduction and medial rotation of the arm

• Weak flexion (clavicular head) of the arm

• Weak extension (sternocostal head) of the arm

What would be the consequences of damage to the musculocutaneous nerve

• affected in injuries to the spinal nerve root C5-C7, upper trunk or lateral cord
  

• weak arm flexion, forearm flexion, supination

How can the upper/lower subscapular be damaged? Result?

• injured during surgery or by encroachment from a tumor

• results: weakened adduction and medial rotation of the arm

How can the thoracodorsal nerve be injured? Results?

• At risk during radical mastectomy

• Results in weak adduction, medial rotation and extension of the arm

How can the axillary nerve be damaged?

• Can be injured in shoulder dislocation or fractures of the surgical neck of the humerus → paralysis of deltoid and teres minor

• Loss of sensation over the lower half of the deltoid (deltoid patch)

What are some causes of radial nerve injury? Consequences?

• Pressure of upper end of a badly fitting crutch pressing up into the armpit
  

• Drunkard falling asleep with one arm over the back of a chair (compression)
  

• Fractures and dislocations of the proximal end of the humerus (excessive stretching)

Consequence:

Motor: paralysis of triceps, anconeus and Long extensor
of wrist (inability to extend elbow, wrist and fingers);
Wrist drop with flexion of the wrist due to unopposed
flexors of the wrist); brachioradialis and supinator
paralyzed but some supination due to biceps brachii

Sensory: loss of skin sensation down the posterior
surface of the lower part of the arm and narrow strip on
back of forearm; variable sensory loss on lateral part of
dorsum of the hand, on dorsal surface of lateral three
and a half fingers

Describe how the radial nerve can be injured near the spiral groove of humerus? Where specifically does this injury happen? Consequences?

• Radial nerve can be injured at the time of humeral shaft fracture or callus formation
  

• Pressure on operating table in unconscious patient or prolonged tourniquet time
  

• Injury occurs in the distal part of the groove beyond the origin of the nerves to the triceps and anconeus and beyond origin of the cutaneous nerves

Consequences:

• Motor: inability to extend the wrist and fingers wrist drop

• Sensory: variable small area of anesthesia over dorsal surface of hand and dorsal surface of lateral three and a half fingers

Describe the causes, symptoms or radial nerve injury to PIN

Causes:

• Fracture of the proximal end of radius or during dislocation of radial head;

• trauma (stab or laceration);

• improper application of external fixator to radius fracture
  

Clinical findings:

• No wrist drop (intact ECRL, supinator)

• weak wrist extension and adduction (ECU)
  

• Inability to extend the MPJ of 2nd to 5th digits and IPJ of thumb (EPL, EPB), weak thumb abduction APL)
  

• No sensory loss to dorsolateral of hand

What is a common site of injury for the ulnar nerve?

• Common sites of injury:

  • elbow

  • wrist

What is cubital tunnel syndrome? What are the causes and symptoms?

• A compressive neuropathy of the UN due to compression at the medial elbow
  

• Causes: mechanical compression; fractures/nonunions; osteophytes, tumors/ganglions; post-traumatic; Leprosy
  

• Symptoms: loss of sensation (LF, ulnar half of RF, ulnar dorsal hand); atrophy of interossei and first web space; ring and little finger clawing; weak grasp (loss of MPJ flexion power); weak pinch (loss of
  thumb adduction); Froment’s sign; Tinel’s sign over cubital tunnel

What is ulnar tunnel syndrome? Causes? Symptoms

Compressive neuropathy of UN at the level of the wrist (Guyon’s canal)

Cause: ganglion (80%); lipoma; repetitive trauma; fracture /nonunion of hook of hamate

Symptoms: paresthesia of LF and RF with intrinsic weakness with Tinel’s sign over Guyon’s canal

What are some injuries to the median nerve? Consequences?

Supracondylar fractures

Stab wounds/lacerations

Entrapment: Pronator syndrome, Anterior Interosseous syndrome, Carpal tunnel syndrome

Symptoms:

• Forearm in supination (weakness of pronators, long flexors except FCU and medial half of FDP)

• weak wrist flexion (adducted); no flexion IPJs of index, middle fingers; loss of flexion of IPJ of thumb

• wasting of thenar eminence; apelike hand

• loss of sensation lateral half of palm and lateral 3 and a half fingers; distal dorsum of lateral 3 and a half fingers

What is pronator syndrome? Symptoms? Areas of compression

Compressive neuropathy of MN at the elbow level

Symptoms: pain at proximal forearm (no night symptoms), sensory changes at palmar cutaneous branch distribution (palm of hand), Tinel’s sign over proximal volar forearm, weakness in forearm pronation, wrist flexion, finger flexion of lateral 2 fingers, thumb flexion;

Papal Benediction – inability to flex the index and middle finger when making a fist due to loss of function of the lateral half of FDP

Areas of compression:

• Supracondylar process;

• ligament of Struthers,

• bicipital aponeurosis (lacertus fibrosus),

• between 2 heads of pronator teres,

• FDS aponeurotic arch

What is anterior interosseus syndrome due to? Symptoms?

Can be due to entrapment/compression of the anterior interosseous nerve; trauma;

Symptoms:

• weakness of thumb and index finger (loss of flexion of FPL and of thumb loss of DIP flexion of index and middle fingers due to FDP weakness); weakness in forearm pronation; transient pain in wrist and forearm

• “Okay sign”: intact FPL and FDP of index fingers
  

• “Pinch sign”: failure to make an “okay sign” due to inability to flex thumb IPJ and index finger DIPJ

What is carpal tunnel syndrome? Causes? Symptoms

Compression of MN at the carpal tunnel

• Causes: inflammation; trauma (distal radius fracture; lunate
  dislocation; repetitive vibratory exposure; space occupying
  lesions (gout, lipoma, tumor)
  

• Symptoms:

  • pain and paresthesia (worse at night);

  • numbness and tingling sensation in radial 3 and ½ digits

  • clumsiness
    

  • No paresthesia over thenar eminence ( supplied by the palmar cutaneous branch of the median nerve which pass superficial to the flexor retinaculum)
    

  • Atrophy of thenar muscles (apelike) and difficulty of thumb opposition and abduction → chronic symptoms

What is the phalen’s test, Durkan’s test, Tinel’s sign

How can we surgically treat carpal tunnel syndrome?

Describe the path of the recurrnet branch of median nerve and the 3 variations? How can it be damaged?

• Originates near distal margin of flexor retinaculum → pass
  proximally over FPB → pass inbetween FPB and APB → ending in OP
  

• 3 variations

  • extraligamentous – most common

  • subligamentous

  • Transligamentous
    

• Can be damaged during carpal tunnel release if incision too radial