Nerve palsies [limbs] Flashcards
What is a dermatome?
Sensory area of skin supplied by a single spinal nerve
What is a myotome?
Group of muscles supplied by one segment of spinal cord
What is the brachial plexus?
- Large network of nerves supplying the upper limb, extending from the cervical spine to the axilla
- Anatomical variations common -eg. C4-8 = pre-fixed plexus, C6-T2 = post-fixed plexus
What are the myotome patterns?
What are palsies affecting the brachial plexus?
- Erb’s palsy
- Klumpe’s palsy
- Total brachial plexus
What are palsies effecting the peripheral nerves?
- Musculocutaneous (nil)
- Axillary
- Axillary nerve palsy secondary to trauma
- Radial
- Radial nerve palsy secondary to compression or entrapment
- Median
- Carpal tunnel syndrome
- Ulnar
- Cubital Tunnel Syndrome
What does Erb’s palsy effect and how does it present?
- C5,6 +/- 7
- Waiter’s Tip position:
- Shoulder is adducted and IR
- Elbow is extended and pronated
- Wrist is flexed
What does Klumpe’s palsy effect and where?
- Traction of C8/T1
- Very rare
- Affects small muscles of hand- claw hand
What is 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.”
What can cause axillary nerve palsy?
- Shoulder dislocation
- Fracture surgical neck of humerus
How can radial nerve palsy present?
Symptoms depend on SITE of lesion
- In axilla: loss of elbow extension, wrist extension and sensory changes forearm and hand
- In arm: loss of wrist extension and sensory loss
- In forearm: loss of finger extension (PIN)
- At wrist: loss of sensation (SRN) eg. handcuffs
What are causes of carpal tunnel syndrome?
- Developmental
- Trauma
- distal radius fracture
- Swellings
- ganglion
- fibroma
- lipoma
- Inflammatory
- rheumatoid
- gout
- tb
- Metabolic
- pregnancy
- hypothyroid
How will patients present with carpal tunnel syndrome?
- Nocturnal pain and parasthesia in part or all of median nerve distribution
- Wasting of thenar muscles
How do we examine for suspected carpal tunnel syndrome?
- LOOK
- thenar wasting
- previous scars
- deformity
- FEEL
- sensation
- MOVE
- APB power
- SPECIAL TESTS
- tinnels, phalens
What is cubital tunnel syndrome?
- Second most common nerve entrapment
- Cubital tunnel between Medial epicondyle and olecranon, with fascial bands from FCU as roof
- Patient has numbness on ulnar side of hand and difficulty with fine tasks
Ulnar nerve palsy: where is there muscle wasting?
- 1st webspace (often most marked)
- Guttering
- Hypothenar wasting
What is Ulnar claw hand?
- Hyperextension at MCPJ, flexion at IPJ’s
What is ulnar paradox?
- A distal lesion has worse clawing than a proximal lesion, due to intact long flexors with a distal lesion
What is Froment’s test?
- Test for ulnar nerve palsy which specifically tests the action of adductor pollicis. The patient is asked to hold a piece of paper between the thumb and a flat palm as the paper is pulled away. Normally an individual will be able to hold the paper there with little or no difficulty.
- If Ulnar is not working patient will cheat and use FPL instead of adductor pollicis
- This is a froment’s positive result
What is the sacral plexus?
- Ventral Rami of L4 to S4
- Superior Gluteal N. supplies Gluteus medius and minimus and TFL
- Inferior Gluteal supplies gluteus maximus
How does common peroneal nerve palsy present?
What is 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
