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BSMS204 Theme 2 Musculoskeletal > 11. Upper limb nerve injuries > Flashcards

11. Upper limb nerve injuries Flashcards

1
Q

Approach to a neurological problem

A

Anatomically localise the lesion
Consider the pathophysiology
Differential diagnosis

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2
Q

UMN vs LMN

A

LMN arises from the anterior horn cell (whereas UMN from motor cortex)

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3
Q

UMN disease examination findings

A 
Held in flexed posture if chronic.
Increased tone
Pyramidal weakness (Flexor muscles stronger than extensors)
Brisk reflexes.
Sensory level
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4
Q

LMN examination findings

A

Wasting/Fasciculations
Flaccid tone
Weakness in either a myotomal distribution or a peripheral nerve distribution
Reduced reflexes.
Dermatomal or peripheral nerve distribution of sensory loss.

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5
Q

UMN problem example

A

stroke

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6
Q

LMN problem example

A

ALS

polio (rare)

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7
Q

Anatomical localisation of upper limb nerve injuries

A

3 anatomical regions for localising the lesion:

Roots
Brachial plexus
Peripheral nerve

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8
Q

Myotome vs dermatome

A

Myotomes - Relationship between the spinal nerve & muscle
Dermatomes - Relationship between the spinal nerve & skin

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9
Q

dermatomes

A

A dermatome is an area of the skin supplied by nerve fibres originating from a single dorsal nerve root.

However, there is considerable overlap of innervation between adjacent dermatomes and
there is also considerable anatomical variation

Dermatome landmarks:
Middle finger is C7 and either side is C6 and C8
Nipple T4
Umbilical T10
Groin L1
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10
Q

C5 root and myotome

A

Deltoid

Shoulder abduction

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11
Q

C6 root and myotome

A

Biceps, Brachialis, brachioradialis

Elbow flexion

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12
Q

C7 root and myotome

A

Triceps
Superficial forearm extensors
Superficial forearm flexors

Elbow extension
Wrist extension
Wrist flexion

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13
Q

C8 root and myotome

A

Forearm extensors
Deep forearm flexors

Finger extension
Finger flexion

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14
Q

T1 root and myotome

A

Intrinsic hand muscles

Finger abduction

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15
Q

Biceps reflexe

A

Biceps reflex – C5 reflex conveyed through the musculocutaneous nerve.

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16
Q

Supinator jerk

A

Supinator jerk – C6 reflex conveyed through the radial nerve.

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17
Q

Triceps jerk

A

Triceps jerk – C7 reflex conveyed through the radial nerve.

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18
Q

Finger jerk

A

Finger jerk – C8 reflex conveyed through the median and ulnar nerve.

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19
Q

Reflexes in lower motor neuron lesions

A

reflexes depressed

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20
Q

Nerve root impingement

A

Causes – pain – radiates/ aggravated by neck movement

- sensory loss
- weakness
- reflex loss

Flexibility of cervical spine protects it from fractures or dislocation-
but may get injury to neural structures – hyper flexion/extension

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21
Q

Types of nerve (plexus) injury

A

avulsion
rupture
neuroma
neurapaxia

(Avulsion / rupture – brachial plexus trauma, neurapraxia blunt injury)

22
Q

Avulsion

A

Avulsion: Tearing of the nerves from its attachment at the spinal cord. – Require surgical repair

23
Q

Rupture

A

Rupture: Tearing of the nerves but not from its attachment to the spinal cord – Require surgical repair

24
Q

Neuroma

A

Neuroma: tumour or growth of the nerve tissue. Can arise from the axon or myeloma – Require surgical repair

25
Q

Neurapraxia

A

Neurapraxia: Axons remain intact, but myelin damage cause an interruption of the impulse down the nerve fibre – Good prognosis.

26
Q

Flail arm

A

C5-T1 lesions causing flail arm
Left shoulder subluxation
Atrophy of the left deltoid, supraspinatous and infraspinatous

27
Q

brachial plexus injury

A 
Trauma
Erb-Duchenne type paralysis: Avulsion of C5,C6 roots.
Klumpke paralysis: Avulsion of C8, T1 roots.
Cancer
Lung cancer: Pancoasts tumour
Radiotherapy
Inflammatory
Brachial neuritis
Structural
Thoracic outlet syndrome
28
Q

Erbs palsy

A
  • upper plexus palsy
    C5/C6 innervated muscles
    Superior trunk of brachial plexus
    (adults- blow to shoulder)
Weak muscles include -
Biceps (flexes the arm)
Brachioradialis (flexes the arm in semi-prone position)
Deltoid (abducts the arm) 
Supraspinatus (abducts the arm)
Supinator (externally rotates the arm)
29
Q

Symptoms of Erbs palsy aka waiters tip

A 
Arm cannot be-
Elevated
Abducted 
External rotated
Flexed at elbow

But fingers unimpaired
Hand works but arm does not!

30
Q

Klumpke’s palsy

A

Clutching for an object when falling from a height.
- Inferior trunk plexus injury involving C8/T1

Involves trunk that supplies median and ulnar nerves

Unable to flex wrist or fingers
Weakness of all small muscles of the hand
Sensory loss hand and inner border of forearm

May lead to a claw hand

Arm works but hand
does not!

31
Q

Metastatic brachial plexopathy

A

Pancoast tumour (lung) – infiltration of the lower brachial plexus
Pain in shoulder girdle and inner arm.
Ipsilateral horners syndrome

32
Q

Radiation induced brachial plexopathy

A

Mean 6 yrs post radiation
Associated with treatment for breast, lung cancer and lymphoma
Pain is not a consistent feature
Predilection for upper brachial plexus

33
Q

Idiopathic brachial neuritis aka Parsonage-Turner syndrome

A 
Aetiology not clear, infectious, post-infectious 
Severe pain over days; as pain diminishes, it is followed by weakness and wasting (motor>sensory)
Typically monophasic 
Rarely bilateral
MRI shows thickening and enhancement.
NCS/EMG is useful for prognostication.
Treatment:
Analgesia, physiotherapy
Limited evidence for the use of steroids
34
Q

Thoracic outlet syndrome

A

Variations in anatomy cause compression sites:

  • Between anterior and middle scalene muscles
  • Beneath clavicle in the costoclarvicular space
  • Beneath tendon of Pectorlis minor
35
Q

Causes of thoracic outlet syndrome

A

Neurogenic and vascular

Neurogenic: predominantly affects the median-innervated abductor pollicis brevis muscle (thenar wasting)

Vascular: High rib causes area of stenosis with a poststenotic dilatation. Clots may form in the dilated vessel with small fragments that then become detached and pass down the brachial artery into the hand. Acute ischaemic changes lead to Raynaud’s phenomenon.

36
Q

neurogenic thoracic outlet syndrome

A

Paresthesia, numbness, weakness
Not localised to specific nerve distribution
Reproducibly aggravated by elevation or sustained use of arms or hands.

37
Q

vascular thoracic outlet syndrome

A

Forearm fatigue within minutes of use.
Swelling and cynaosis
Collateral venous patterning over the ipsilateral shoulder, chest wall and neck.
Rarely pain, pallor and coldness (arterial involvement).
Lower BP on affected arm, diminished distal pulses.

38
Q

Long thoracic nerve injuries

A

Long thoracic nerve
may be injured by blows or pressure
in the posterior triangle of the neck

or during a radical mastectomy.

Long thoracic nerve supplies the serratus anterior muscle.

The serratus anterior muscle pulls the medial border of the scapula
to the posterior thoracic wall and stabilises it there

Impairment of the long thoracic nerve leads to “winging” of the scapula

39
Q

Median nerve

A

2 common sites of compression
Wrist (Carpel tunnel syndrome)
Elbow

40
Q

Median nerve innervated hand muscles

A

L ateral 2 lumbricalsO pponens pollicisA bductor pollicis brevisF lexor pollicis brevis

41
Q

Median nerve compression signs

A

thenar wasting

42
Q

Carpal tunnel syndromes

A 
Causes include:
Diabetes
Pregnancy
Hypothyroidism
Rheumatoid arthritis
Repetitive strain

Median N. entrapment at carpal Tunnel (also damaged in wrist fractures)

43
Q

Anterior interosseous nerve

A

arises from
median nerve just above elbow.

Prone to compression between 2 heads of pronator teres muscle

Gripping tightly with forced pronation

Prolonged use of a screwdriver!

May also be damaged in careless blood taking

44
Q

Anterior interosseous nerve syndrome

A

Pure motor branch of the median nerve
weakness in flexors of ip joint of thumb (flexor policis longus)
& dip joints of index and middle fingers – (flexor digitorum profundus)
weakness of pronation

45
Q

Ulnar claw

A

Higher lesion in the upper limb:
Paralysis of the ulnar half of the flexor digitorum profundus (FDP), interossei and lumbricals. The ring and little fingers are not flexed and there is no claw.

Lesion at the wrist:
Flexion at the DIP (FDP is intact)
Flexion at the PIP (interossei are paralysed)
hyperextention at the MCP (lubricals are paralysed).

46
Q

ulnar nerve branches around medial epicondyle

A

superficial sensory branch comes
off in distal forearm above wrist)

Deep ulnar branch
Guyon’s canal motor only to intrinsic hand muscles

Occupation, cycling, rheumatoid arthritis

47
Q

Ulnar nerve palsy sign

A

Froment’s sign (crab grip) due to weakness of adductor pollicis

48
Q

ulnar vs c8

A

C8
All finger extensors (radial nerve)
FDP of Index/middle (median nerve)
Ulnar nerve d5 and 1/2 d4. Test d5

49
Q

Radial nerve palsy aka Saturday night palsy

A

Radial nerve damage rarely causes extensive sensory loss

Extensive overlap with median/ulnar excepting anatomical snuff box

Radial nerve dorsum of hand thumb and proximal par of index and quarter of d3

50
Q

Nerve conduction studies

A

Useful in determining the amplitude and velocity of a peripheral nerve

51
Q

Axonal vs demyelinating

A

Axonal loss results in a decrease in amplitude

Demyelinating results in a decrease in velocity

52
Q

Neurogenic vs myogenic

A

Needle EMG measures the electrical activity of the muscle during voluntary contraction. The pattern of the electrical activity can help distinguish a lesion arising from the nerve (neurogenic) vs muscle (myopathic)

BSMS204 Theme 2 Musculoskeletal (22 decks)

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