Nerve Palsies Flashcards
Where can a nerve be trapped/injured/compressed?
Any point along its course
- nerve root
- plexus
- peripheral
What are the upper limb peripheral nerves?
Axillary Radial Musculocutaneous Ulnar Median
What are the lower limb peripheral nerves?
Sciatic
Femoral
Common peroneal
Lateral Femoral Cutaneous Nerve (LFCN)
What are the upper limb myotome patterns?
C5; elbow flexors C6; wrist extensors C7; elbow extensors C8; finger extensors T1; intrinsic hand muscles
What are the lower limb myotomes?
L2; hip flexors L3; knee extensors L4; ankle dorsiflexors L5; long toe extenosrs S1; ankle plantar flexors
What are brachial plexus palsies?
Erb’s; upper plexus C5, 6
Klumpke’s; lower plexus C8, T1
Total brachial plexus; C5-T1
Describe the presentation of Erb’s palsy
Traction of C5, 6 +/- 7
Waiter’s tip position
- shoulder adducted and IR
- elbow extended and pronated
- wrist flexed
Describe the presentation of Klumpke’s palsy
Traction C8, T1
Very rare
Affects small muscles of hand; claw hand
Describe Hilton’s law
A sensory nerve supplying a joint, also supplies the muscles moving the joint and the skin overlying the insertions of these muscles
Describe the axillary nerve (origin, course etc)
Posterior cord of brachial plexus, C5 C6
Wraps around surgical neck fo humerus
Supplies deltoid and teres minor
Supplies skin over lateral arm; regimental badge area
*Can be damaged with shoulder dislocation and surgical neck humerus fracture
Describe the musculocutaneous nerve (origin, course etc)
Lateral cord of brachial plexus, C5 C6 C7
Pierces coracobrachialis, runs inferiorly between biceps and brachialis (supplying both)
Gives supply to elbow joint
Terminates as lateral cutaneous nerve to forearm
Describe the radial nerve (origin, course etc)
Posterior cord brachial plexus, C5-T1
Supplies triceps, runs in radial groove of humerus as passes from medial to lateral
Supplies BCR, ECRL, ECRB before dividing into PIN (motor) and SRN (sensory) branches
Other terms for radial nerve palsy
Saturday night palsy
Crutch palsy
Describe the symptoms of radial nerve palsy
Depend on site of lesion
- in axilla; loss elbow extension, wrist extension and sensory changes in forearm and hand
- in arm; loss wrist extension and sensory loss
- in forearm; loss finger extension (PIN)
- at wrist; loss sensations (SRN) i.e. handcuffs
Describe the median nerve (origin, course etc)
Medial and lateral cords, C5-T1
Supplies flexors of forearm (bar FCU and medial FDP), LOAF muscles
LOAF = lateral two lumbricals, opponens pollicis, abductor pollicis brevis, flexor pollicis brevis
What does the pneumonic LOAF stand for?
4 small muscles of the hand supplied by median nerve
- Lateral two lumbricals
- Opponens pollicis
- Abductor pollicis brevis
- Flexor pollicis brevis
What are the contents of the carpal tunnel?
FDS tendons x4
FDP tendons x4
FPL tendon
Median nerve
9 tendons + nerve
What are some causes of carpal tunnel syndrome?
Developmental
Trauma i.e. distal radius fracture
Swellings i.e. ganglia, fibroma, lipoma
Inflammatory; rheumatoid, gout, TB, amyloid
Metabolic; preg, hypothyroidism
Describe presentation of carpal tunnel syndrome
- nocturnal pain and paraesthesia in part or all of medial nerve distribution
- wasting of thenar muscles
What to look for on examination of carpal tunnel syndrome?
Thenar wasting
Previous scars
Deformity (previous fracture?)
What are tests for carpal tunnel syndrome?
Tinnels; tapping over nerve
Phalens; hands in inverted prayer position for 60secs
Describe the ulnar nerve (origin, course etc)
Medial cord, C8 T1
No branches in arm; enters forearm between two heads of FCU
Supplies medial FDP, FCU and all intrinsic hand muscles except LOAF
Sensation to ulnar 1.5 digits
Where is the cubital tunnel?
Between medial epicondyle and olecranon
Fascial bands from FCU form roof
Describe cubital tunnel syndrome
Second most common nerve entrapment
Patient has numbness on ulnar side of hand and difficulty with fine tasks
Describe ulnar nerve palsy presentation
Muscle wasting
- 1st webspace (often most marked)
- Guttering
- Hypothenar wasting
Ulnar claw hand; hyperextension MCPJ, flexion IPJ
What is the ulnar paradox?
Distal lesion has worse clawing than proximal, due to intact long flexors with a distal lesion
Describe Froment’s test
Muscles;
- Adductor pollicis (UN)
- Flexor pollicis longus (MN)
If ulnar nerve not working patient will cheat and use FPL to maintain hold of paper instead of Adductor pollicis
Describe the common peroneal nerve (origin, course etc)
Branch of sciatic nerve
Wraps around neck of fibula
Divides into deep peroneal (supply ant compartment) and superficial peroneal (supply lat compartment)
Describe presentation of common peroneal nerve palsy
Foot drop
What is and what causes meralgia parasthetica?
Altered sensation and pain lateral thigh
Compression of lateral femoral cutaneous nerve of thigh as it travels under lateral border of inguinal ligament