Brachial Plexus Injuries

• Brachial Plexitis
• Sudden, unexplained pain around shoulder associated with upper extremity weakness and tenderness, 35% are bilateral
• Does not affect single root or peripheral nerve and spares the thromboids and serratus anterior
• Probable immunologic etiology
• Upper plexus injury (Erb-Duchenne palsy, often occurs at birth)
• C5-6 – deltoid, biceps, brachioradialis, supinator, supra/infraspinatous, rhomboids
• Arm hangs at side, internally rotated and extended at elbow
• Movements of hand and forearm unaffected
• Weakness of shoulder girdle, biceps, brachioradialis, and supinator leave arm hanging at side and internally rotated
• Damage is to the upper brachial plexus (C_{5, 6} roots)
• Etiology:  Forcibly stretching shoulder from neck (difficulty birth, motorcycle accident)
• Lower plexus injury (Degerine-Klumpke’s palsy)
• Traction on abducted arm, operation on axilla, tumor of lung apex, compression by cervical ribs or bands
• Birth injury (breech)
• Claw hand deformity
• May have partial Horner’s syndrome
• Weak and atrophied hand
• Damage is to the lower brachial plexus (C₈T₁ roots)
• Etiology:  Placing traction on body while arm abducted (difficulty birth, falls), Pancoast tumor
• Thoracic Outlet Syndrome
• Pain in medial arm/hand, paresthesias in C₈T₁ distribution, cold intolerance, thenar and abductor pollicis brevis atrophy
• Symptoms in many early reported cases of thoracic outlet syndrome were probably really caused by carpal tunnel syndrome
• Etiology:  Kinking of the lower portion of the plexus over a cervical rib or fibrous band
• Rx:  Surgical decompression
• Infraclavicular lesions of cords
• Lateral cord – musculocutaneous nerve, lateral root of median nerve; causes weakness of flexors and pronators of forearm, intrinsic hand muscles spared
• Medial cord – medial root of median nerve, ulnar nerve
• Posterior cord – weak deltoid, extensors of wrist, elbows, fingers
• Brachial plexus neuropathy (Parsonage-Turner Syndrome)
• Severe pain and weakness, sensory and reflex impairment
• Progresses over 3-10 days, eventual recovery over 6-12 weeks
• Mostly shoulder and upper arm
• Loss of DTR’s
• May be bilateral
• Possibly associated with CMV or AIDS
• No leukocytosis or increased ESR
• Suprascapular nerve
• Supplies supraspinatous/infraspinatous
• Weakness of first 15 degrees of shoulder abduction and external rotation
• Axillary nerve
• C5-6
• supplies teres major and deltoid
• Weakness of shoulder abduction from 15 to 90 degrees
• Radial nerve
• C6,7,8 (mostly C7)
• supplies triceps, brachioradialis, supinator, extensors of wrist and fingers, abductors of thumb
• Posterior Interosseous supplies supinator, extensor digitorum, abductor pollicis longus, extensor carpi ulnaris
• Lesion causes brachioradialis weakness with inability to flex forearm midway between pronation and supination
• Median nerve
• C5,6,7,T1 (mostly C6)
• Supplies pronators of forearm, long finger flexors, abductor brevis and opponens of thumb, 1^st and 2^nd lumbricals
• Anterior Interosseous supplies pronator quadratus, flexor pollicus longus, and flexor digitorum longus 1-2
• Lesion causes
• inability to pronate forearm or flex hand
• paralysis of flexion of index finger and terminal phalanx of thumb
• weakness of opposition and abduction of thumb (abductor and flexor pollicis brevis)
• Ulnar nerve
• C8,T1
• Supplies ulnar flexors of wrist, ulnar flexor profundii digitorum, adductors and abductors of fingers, adductor of thumb, 3^rd and 4^th lumbricals, muscles of hypothenar eminence
• Complete paralysis (elbow fracture) produces claw hand deformity
• May see compression distal to medial epicondyle of elbow beneath aponeurosis of flexor carpi ulnaris (cubital tunnel)
• Anterior and Posterior Interosseous Nerves – branches of median and radial, respectively; motor only; 3 opposing muscle groups:
• 1. pronator quadratus (anterior) and supinator (posterior)
• 2. flexor pollicus longus (anterior) and abductor pollicis longus (posterior)
• 3. extensor digitorum (anterior) and flexor digitorum longus 1-2 (posterior)
• posterior interosseous also supplies extensor carpi ulnaris