Peripheral nerve injuries and palsies Flashcards
Give 6 examples of peripheral nerve injury conditions:
1) brachial plexus injury
2) peroneal foot drop
3) spinal accessory nerve injury
4) carpal tunnel syndrome
5) Charcot-Marie-Tooth Disease
6) Guillain-Barre syndrome
Give the ABCDE non-traumatic causes of peripheral neuropathy:
1) alcohol
2) B12 deficiency
3) cancer (myeloma) and CKD
4) diabetes and drugs
5) every vasculitis
Name 4 drugs that cause peripheral neuropathy:
1) isoniazid
2) amiodarone
3) leftunomide
4) cisplatin
Give 5 general symptoms of peripheral nerve injuries:
1) severe burning, pain
2) muscle weakness
3) reduced reflexes
4) reduced sensation/ paraethesia
5) muscle wasting
What is the same of the classification system for peripheral nerve injury?
Sunderland Classification System
Describe a first degree peripheral nerve injury:
a reversible conduction block at the site of injury (neuropraxia)
Describe second degree peripheral nerve injury:
the loss of the continuity of the axon and its covering myelin but preservation of the connection of the nerve (axonotmesis)
Describe third degree peripheral nerve injury:
damage to the axon and their supporting structures
Describe fourth degree peripheral nerve injury:
damage to the axons and the surrounding tissues sufficient to create scarring that prevents nerve regeneration
Describe fifth degree peripheral nerve injury:
complete transection of the next including the epineurium (neurotmesis)
What two muscles does the spinal accessory nerve innervate?
1) sternocleidomastoid
2) trapezius
Give two causes of spinal accessory nerve injury:
1) severing during neck surgery
2) trauma
Give 3 presentations associated with spinal accessory nerve injury:
1) shoulder pain
2) winging of the scapulae
3) weakness and atrophy of the trapezius muscle
Where is the carpal tunnel found?
between the carpal bones and flexor retinaculum in the wrist
What is carpal tunnel syndrome?
compression, swelling or narrowing of the carpal tunnel, compressing the median nerve
What structures pass through the carpal tunnel?
1) median nerve
2) flexor tendons
What is the motor function of the median nerve in the hand?
innervation to the thenar eminence
What three muscles make up the the thenar eminence?
1) abductor pollicis brevis
2) opponens pollicis
3) flexor pollicis brevis
What is the sensory function of the median nerve in the hand?
sensory innervation to the thumb, index and middle finger and lateral half of the ring finger
Give 7 risk factors for carpal tunnel syndrome:
1) acromegaly
2) rheumatoid arthritis
3) diabetes
4) hypothyroidism
5) repetitive strain
6) obesity
7) perimenopause
Are carpal tunnel syndrome symptoms worse in the day or night?
Night
Give 5 symptoms of carpal tunnel syndrome:
1) weakness of thumb movement and grip strength
2) wasting of the thenar muscles
3) numbness in distribution of the median nerve supply
4) burning sensations
5) paraesthesia (pins and needles)
Name the 2 special tests for carpal tunnel syndrome:
1) Phalen’s test
2) Tinel’s test
Describe Phalen’s test for carpal tunnel syndrome along with the positive result:
have the patient put the backs of their hands together with their wrists at 90 degrees - a positive result is numbness and paraesthesia in this position
Describe Tinel’s test for carpal tunnel syndrome along with the positive result:
tapping the wrist in the location where the median nerve travels through the carpal tunnel - the positive result is numbness and paraesthesia during this
What investigation is used to diagnose carpal tunnel syndrome?
nerve conduction studies
Describe the nerve conduction studies used to test for carpal tunnel syndrome:
where a small electrical current is applied by an electrode to the median nerve - recording electrodes over the median nerve record the current that reaches them
Give 3 treatment options for carpal tunnel syndrome:
1) wrist splints
2) steroid injections
3) surgery
Describe carpal tunnel syndrome surgery:
under local anaesthetic, the flexor retinaculum is cut to release the pressure on the median nerve
What structure is injured in Erb’s palsy?
the superior trunk of the brachial plexus (C5/C6)
What is the most common cause of Erb’s palsy?
difficult childbirth (damage to neonate’s neck)
What mechanism causes Erb’s palsy (damage to the superior trunk of the brachial plexus)?
excessive lateral neck flexion
What 4 nerves are affected by Erb’s palsy?
1) musculocutaneous nerve
2) axillary nerve
3) suprascapular nerve
4) nerve to subclavius
Give three areas where sensation is lost in Erb’s palsy:
1) sergeant’s patch
2) lateral arm
3) lateral forearm
Give 4 muscles/ muscle groups that waste in Erb’s palsy:
1) deltoid
2) supraspinatus
3) infraspinatus
4) anterior compartment of the arm
Give 4 movements that are difficult in Erb’s palsy:
1) shoulder abduction
2) shoulder external rotation
3) elbow flexion
4) forearm/ wrist supination
What structure is injured in Klumpke’s palsy?
inferior trunk of the brachial plexus (C8/T1)
What mechanism causes Klumpke’s palsy?
excessive force placed on an abducted shoulder
What two nerves are injured in Klumpke’s palsy?
1) median
2) ulnar
Give 4 areas that lose sensation in Klumpke’s palsy:
1) median distribution to the hand
2) ulnar distribution to the hand
3) medial forearm
4) medial arm
Give 5 movements that are lost in Klumpke’s palsy:
1) metacarpophalangeal flexion
2) interphalangeal extension
3) finger abduction
4) finger adduction
5) opposition of the thumb
What structure is injured in Horner’s syndrome?
T1 nerve root and sympathetic chain
Give the 4 characteristic features of Horner’s syndrome:
1) ptosis (drooping eye lid)
2) anhidrosis (loss of sweating on the affected side of the face)
3) enophthalmos (eye appears sunken)
4) miosis (constricted pupil)
What is Charcot-Marie-Tooth Disease?
an autosomal dominant inherited disease that affects peripheral nerves by causing myelin or axon dysfunction
Give 4 classical features of Charcot-Marie-Tooth Disease:
1) pes cavus (high foot arch)
2) distal muscle wasting (causing inverted champagne bottle legs)
3) reduced reflexes
4) limb weakness and reduced muscle tone
What is the name of the acute paralytic polyneuropathy characterised by ascending weakness following infection?
Guillain-Barre Syndrome
Give 3 infective triggers of Guillain-Barre Syndrome:
1) Campylobacter jejuni
2) Ctyomegalovirus
3) Epstein-Barr virus
Describe the pathogenesis of Guillain-Barre syndrome:
the body’s immune response to an infection produces antibodies, but due to biomimicry, these also attach to proteins on peripheral neurones
Do symptoms progress upwards or downwards in Guillain-Barre syndrome?
Upwards
Give two diagnostic investigations for Guillain-Barre syndrome and their positive results:
1) nerve conduction studies (reduced signal)
2) lumbar puncture (CSF will show raised protein but normal cell count and glucose)
What is the first line management for Guillain-Barre syndrome?
IV immunoglobulins
Give 3 general investigations for peripheral nerve injuries:
1) nerve conduction studies
2) electromyography
3) MRI cerograph/ CT scan
What is the most common intervention for peripheral nerve injuries?
surgery
