L7 - Upper limb nerve injuries COPY

Question 1

APPROACH TO A NEUROLOGICAL PROBLEM

i) what are you looking for when anatomically localising the lesion?
ii) what gives a clue to the pathophysiology? explain

Answer 1

i) anatomically localise > UMN vs LMN / single or multi site

ii) time course gives a clue to pathophys
- quick onset > likely to be vascular eg stroke
- hours/days > infective or inflam
- long term > degenerative

Question 2

UMN VS LMN PROBLEMS

i) where do UMN travel from and to?
ii) where do UMNs decussate? where do they synapse to LMNs?
iii) which cell does LMN arise from? what can damage to this area cause?
iv) label diagram

Answer 2

i) UMN from motor cortex > ant horn cell
ii) UMN decussate at foramen magnum and synapse to LMN at anterior horn of spinal cord

iii) LMN arise from anterior horn cells
- damage can cause LMN problems eg MND and polio

iv) A - motor cortex
B - LMN cranial nerve
C - LMN spinal nerve
D - corticospinal tract

Question 3

UMN VS LMN IN UPPER LIMB

i) how will reflexes change in UMN and LMN lesions?
ii) which lesion is charac by flexed posture, increased tone and pyramidal weakness?
iii) which lesion is charac by wasting/fasiculations, flaccid tone, reduced reflexes?
iv) which nerve injury will have clear sensory level eg pin prick areas of body and clear level where it changes?
v) which injury will have weakness/sensory loss in a myotomal distrib or peripheral nerve distribution?

Answer 3

i) UMN = brisk reflexes
- LMN - slow reflexes

ii) UMN
iii) LMN
iv) UMN injury has clear sensory level
v) weakness/sensory loss in myotomal etc distribution (not sensory level) = LMN

Question 4

ANATOMICAL LOCALISATION OF LESION

i) which three areas can it be localised to in the upper limb?
ii) what is a myotome? what does it refer to? where in the spinal cord does this sit?
iii) what is a dermatome? what does it refer to? where does it sit in the spinal cord?

Answer 4

i) nerve root, brachial plexus or peripheral nerve

ii) myotome = relationship between spinal nerve and muscle
- group of muscles supplied by a single ventral nerve root

iii) dermatome is area of skin supplied by nerve fibres from a single dorsal nerve root

Question 5

ROOTS AND MYOTOMES

name the myotome and muscle action of each root

C5,6,7,8 and T1

Answer 5

C5 - deltoid > shoulder abduc

C6 - biceps, brachialis, brachioradialus > elbow flexion

C7 > triceps, sup forearm extensors and flexors > eblow exten and wrist exten/flex

C8 - forearm extensors and deep flexors > finger exten & flex

T1 - intrinsic hand muscles > finger abduction

Question 6

REFLEXES

i) which root is biceps reflex? which nerve is it conveyed through?
ii) which root is supinator jerk? which nerve is it conveyed through?
iii) which root is triceps jerk? which nerve is it conveyed through?
iv) which root is finger jerk? which nerve is it conveyed through? (2)
v) what happens to reflexes in lower motor neuron lesions?

Answer 6

i) biceps > C5 reflex through musculocutaneous nerve
ii) supinator jerk > C6 jerk > radial nerve
iii) triceps jerk > c7 reflex through radial nerve
iv) finger jerk > C8 reflex through median and ulna nerve
v) reflexes are depressed in LMN lesions due to disrup of reflex arc

Question 7

NERVE ROOT IMPINGEMENT

i) what is it a common cause of?
ii) name four things it can cause? which happens first?
iii) how can it be elucidated what level its happened?
iv) what can cause impingement?

Answer 7

i) common cause of root problems

ii) pain that radiates/aggravated by neck movement
- sensory loss, weakness, reflex loss
- get pain first

iii) look at which fingers are affected to find out what level
iv) herniated disk can cause impingement

Question 8

TYPES OF NERVE INJURY

i) what is an avulsion?
ii) what is a rupture?
iii) what is a neuroma?
iv) what is neurapraxia?
v) which type of injury will need surgery?

Answer 8

i) avulsion - tear of rami at the attachment
ii) rupture - tear of nerve away from the attachment
iii) growth of the nerve eg along axon or myelin sheath
iv) neurapraxia - compression (still continuous but slower)
v) disruption of nerve continuinty needs surgery

Question 9

label the nerve injuries in the diagram

which has the best prognosis?

Answer 9

A - avulsion

B - rupture

C - neuroma

D - neurapraxia ( best prognosis)

Question 10

BRACHIAL PLEXUS INJURY

i) name four causes of this
ii) what is erb-duchenne type paralysis? which roots are affected? what type of injury is it?
iii) what is klumpe paralysis?

Answer 10

i) trauma - erb duchenne paralysis/klumpe paralysis
- cancer eg lung cancer pancoast tumour
- inflammatory - brachial neuritis
- structural - thoracic outlet syndrome

ii) erb duchenne > avulsion of C5 and C6 roots
iii) klumpe paralysis - avulsion of C9 and T1 roots

Question 11

ERBS PALSY

i) which part of the plexus does it affect? affects muscles innervated by which two roots?
ii) how can this happen in infants and adults?
iii) name four muscles that become weak?
iv) what is another name for this lesion? are the fingers affected? is the arm affected?

Answer 11

i) affects the upper plexus
- muscles innervated by C5/C6

ii) infants > head pulled out in birth stretches C5-C6
- adults > blow to the shoulder

iii) biceps, brachioradialis, deltoid, supraspinatus

iv) waiters tip
- fingers unaffected by arm is affected

Question 12

KLUMPKES PALSY

i) which part of the brachial plexus does it affect? which nerve roots are affected? (2) does the arm work? does the hand work?
ii) how can it happen? which two nerves are implicated
iii) what happens to wrist and fingers? where is there sensory loss?
iv) what posture can it lead to?

Answer 12

i) affects the inferior brachial plexus
- affects C8 and T1
- arm works but hand does not

ii) can happen if clutching for an object if falling from a height or pulled out by arm in childbirth
- implicates median and ulnar nerves

iii) wrist and fingers cant be flexed
- sensory loss to hand and inner border of forearm

iv) can lead to claw posture

Question 13

BRACHIAL PLEXUS INJURY AND CANCER

i) which type of tumour can impact on the brachial plexus? which area of the arm/hand is affected?
ii) which two areas may pain be felt in this tumour? what syndrome can it be associated with?
iii) what part of the plexus may RT damage? where do you get weakness? is this associated with pain?
iv) name three cancers that giving RT for may damage the plexus? how many years post RT does this typically occur?

Answer 13

i) pancoast timour
- affects hand as the inferior brachial plexus is affected

ii) feel pain in shoulder girdle and inner arm
- can be associated with ipsilateral horners syndrome (interrup of symp nerves > ptosis and myosis)

iii) RT can damage the superior part of the plexus > get weakness in the arm
- not associated with pain

iv) RT for breast, lung or lymphoma
- usually happens 6yrs post RT

Question 14

IDIOPATHIC BRACHIAL NEURITIS

i) what is it aka
ii) what is the likely aetiology?
iii) what pattern of pain is seen? what two things follow this
iv) is it usually bilateral?
v) what will MRI show? what contrast may be used?
vi) name two ways to treat? is there good evidence for steroid use?

Answer 14

i) aka parsonage turner syndrome
ii) probably post infectious eg HSV
iii) see severe pain over days then as the pain diminishes get weakness and wasting
iv) not usually bilateral
v) MRI w gadolinum shows thickening and enhancement of the brachial plexus

v) treat with analgesia and physio
- limited evidence for steroids

Question 15

THORACIC OUTLET SYNDROME

i) what happens?
ii) name three areas that are vulnerable
iii) if the vasculature to the plexus is compromised - name two symptoms seen? where is fatigue seen? how may BP be affected in the arm?
iv) if the nerves are compromised - name two things that may be seen? how may this be reproducibly aggravated?

Answer 15

i) get compression at various sites of the plexus due to variations in anatomy
ii) between ant and middle scalene, bet clavicle and costoclavic space and beneath tendon of pec minor

iii) vaculature > swelling/cyanosis
- fatigue in forearm after mins of use
- low BP in affected arm

iv) nerves > paresthesia, numb, weak
- reprod aggravated by elevation or sustained use of arms or hands

Question 16

LONG THORACIC NERVE

i) give two ways it may be injured?
ii) what surgical procedure may injure it?
iii) what deformity can it lead to? what muscle is implicated in this? how can this be tested?

Answer 16

i) blow or pressure in the posterior triangle of the neck
ii) radical masectomy

iii) can lead to winged scapula > seratus anterior
- test by asking to stand up and push against a wall

Question 17

which nerve is indicated by A? what muscle does it supply?

what is seen if this is damaged?

Answer 17

long thoracic nerve

supplies serratus anterior > damage = winged scap

Question 18

MEDIAN NERVE

i) what are the two most common sites for compression?
ii) which hand muscles does it innervate? LOAF
iii) where is wasting seen in CTS? how is this rectified?

Answer 18

i) elbow and wrist
ii) lateral two lumbricals, opponens pollicis, abductor policis brevis, flexor policis brevis (thenar muscles)

iii) see thenar wasting
- need to release pressure on the carpal tunnel (break in the flexor retinaculum)

Question 19

CARPAL TUNNEL SYNDROME

i) which nerve is compressed? what can be another cause of this?
ii) name four causes
iii) what can reproduce the symptoms? (2)

Answer 19

i) median nerve > also caused by wrist fracture
ii) diabetes, pregnancy, hypothyroid, RA

iii) tinels test - tap on CT and get pain
phalens test - flex wrist to compress tunnel > pain

Question 20

ANTERIOR INTEROSSEOUS NERVE

i) where does it arise from? what action does it allow?
ii) two heads of which muscle are prone to compress it?
iii) what can cause damage to it? (2)
iv) is it motor or sensory? what does it supply?
v) what will a patient do if asked to grip something if they have AIN injury? why?

Answer 20

i) arises from median nerve just above the elblow
- allows gripping with forced pronation eg screwdriver

ii) prone to compression between two heads of pronator teres
iii) careless blood taking and prolonged use of screwdriver
iv) purely motor > long flexors eg FPL and FDP
v) asked to grip > will straighten index finger and thumb to grip as cant flex thumb and DIP

Question 21

SENSORY INNERVATION TO THE HAND

i) which nerve supplies the first 3.5 fingers?
ii) which nerve supplies cutaneous sensation to 2/3 palm of hand? why is this not implicated in CTS?
iii) if there is a lesion in the carpal tunnel - is the palm/dorsum of the hand affected?
iv) label diagram

Answer 21

i) median nerve

ii) palmar cutaneous branch of the median nerve
- not implicated in CTS as it branches off before the CT

iiii) no
iv) A - lesion in forearm, B - lesion in carpal tunnel

Question 22

ULNAR PALSY

i) what is seen if there is ulnar palsy at the elbow?
ii) what is seen if there is ulnar palsy at the wrist? is this more or less severe than if at elbow?
iii) what is spared if there is palsy at the wrist? what does this lead to?

Answer 22

i) hyperextension at MCP and flexion at PIP
ii) at wrist - flexion (long flexors are spared so there is lots of flexion in all joints) - looks worse
iii) spare long flexors > flexion

Question 23

ULNAR CLAW

i) if there is a lesion high in the upper limb - what part of FDP is paralysed? name two other muscle groups paralysed?
ii) are the ring and little finger flexed in high lesions? is there an ulnar claw?
iii) which two joints are flexed in the hand if there is a lesion at the wrist? what happens to MCP? is FDP in tact? name two muscle groups that are paralysed

Answer 23

i) upper lesion - ulnar/median half of FDP is paralysed as well as lumbricals and interossei
ii) ring and little finger are not flexed and no ulnar claw

iii) flex DIP and PIP and hyperextend MCP
- FDP is in tact
- lumbricals and interossei are paralysed

Question 24

SENSORY INNERVATION OF THE ULNAR NERVE

i) name two branches of the ulna nerve in the forearm
ii) where would a lesion be that takes out sensation to all 1.5 fingers?
iii) where would a lesion be that spares the dorsum of the hand
iv) where would a lesion be that spares the palmar side?

Answer 24

i) dorsal cutaneous branch and palmar cutaneous branch
ii) all 1.5 fingers = lesion above dorsal cut branch
iii) lesion that spares the dorsum = below DCB
iv) spares palmar = below PCB

Question 25

ULNAR NERVE DAMAGE

i) which branch of the nerve comes off in the distal forearm above the wrist? what type of injury can damage this branch?
ii) which canal does the deep ulnar branch run in? what is it motor to? name two activities that can damage it
iii) which sign is seen when asking a patient with ulnar palsy to grip a piece of paper? which muscle is implicated here?

Answer 25

i) superficial sensory comes off distal forearm above wrist
- fracture > damage

ii) deep ulnar branch runs in guyons canal > motor to intrinsic hand muscles > damage by occupation, cycling, RA
iii) see froments sign (grip from side) > adduct policis brevis isnt working (used to grip)

Question 26

RADIAL NERVE

i) which muscles are affected in radial nerve palsy?
ii) which anatomical area may there be numbness if radial nerve is damaged?
iii) why does it rarely cause extensive sensory loss?

Answer 26

i) extensors
ii) anatomical snuffbox (exclusively innervated by radial nerve)
iii) overlap with median/ulnar nerve except at anatomical snuff box

Question 27

NERVE CONDUCTION STUDIES

i) what is it useful in determining in relation to a peripheral nerve (2)
ii) what is decreased in an axonal injury? what is decreased in demyelinating injury?
iii) what does needle EMG measure? what can the electrical activity seen help distinguish between?

Answer 27

i) amplitude and velocity of a peripheral nerve

ii) axonal injury = decrease in amplitude
demyelinating = decrease in velocity

iii) needle EMG > measures elec activity of a muscle during volutnary contraction
- helps disting between a lesion arising from the nerve (neurogenic) or muscle (myopathic)