Upper limb nerve injuries Flashcards
UMN in the upper limb
Held in flexed posture if chronic
Increased tone
Pyramidal weakness (flexor muscles stronger than extensors)
Brisk reflexes
Sensory level
LMN in the upper limb
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
3 anatomical regions for localising lesions
Roots
Brachial plexus
Peripheral nerve
Myotomes
Relationship between the spinal nerve and muscle
Dermatomes
Relationship between the spinal nerve and skin
Roots and myotomes
C5- deltoid; shoulder abduction
C6- biceps, brachialis, brachioradialis; elbow flexion
C7- triceps, superficial forearm extensors, superficial forearm flexors; elbow extension, wrist extension, wrist flexion
C8- forearm extensors, deep forearm flexors; finger extension, finger flexion
T1- intrinsic hand muscles; finger abduction
Biceps reflex
C5 reflex conveyed through the musculocutaneous nerve
Supinator jerk
C6 reflex conveyed through the radial nerve
Triceps jerk
C7 reflex conveyed through the radial nerve
Finger jerk
C8 reflex conveyed through the median and ulnar nerve
Reflex in LMN lesions
Depressed
Brachial plexus injury
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
Erbs palsy
Upper plexus palsy
C5/6 innervated muscles
Weak muscles include
- biceps
- brachioradialis
- deltoid
- supraspinatus
- supinator
Klumpke’s palsy
Clutching for an object with 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 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
Metatastic brachial plexopathy
Pancoast tumour (lung)- infiltration of the lower brachial plexus
Pain in shoulder girdle and inner arm
Ipsilateral horners syndrome
Radiation induced brachial plexopathy
Mean 6 years post radiation
Associated with treatment for breast, lung cancer and lymphoma
Pain is not a consistent feature
Predilection for upper brachial plexus
Idiopathic brachial neuritis
Aetiology not clear, infectious, post infectious
Severe pain over days; as pain diminishes, it is followed by weakness and wasting
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
Thoracic outlet syndrome
Variations in anatomy cause compression sites:
- between anterior and middle scalene muscles
- beneath clavicle in the costoclavicular space
- beneath tendon of pectoralis minor
Thoracic outlet syndrome: neurogenic
Paresthesia, numbness, weakness
Not localised to spcific nerve distribution
Reproducibly aggravated by elevation or sustained use of arms or hands
Thoracic outlet syndrome: vascular
Forearm fatigue within minutes of use
Swelling and cyanosis
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
2 common sites of compression of the median nerve
Wrist (carpel tunnel syndrome)
Elbow
Median nerve innervated hand muscles
L- lateral 2 lumbricals
O- opponens pollicis
A- abductor pollicis brevis
F- flexor pollicis brevis
Causes of carpal tunnel syndrome
Diabetes
Pregnancy
Hypothyroidism
Rheumatoid arthritis
Repetitive strain
Anterior interosseous nerve
Arises from median nerve just above elbow
Prone to compression between 2 heads of pronator teres muscle
Gripping tightly with forced pronation
May also be damaged in careless blood taking
Anterior interosseous nerve syndrome
Pure motor branch of the median nerve
Weakness in flexors of ip joint of thumb (flexor pollicis longus) and dip joints of index and middle fingers (flexor digitorum profundus) weakness of pronation
Higher lesion in the upper limb
Paralysis of the ulnar half of the flexor digitorum profundus, 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)
Flexion at the PIP (interossei are paralysed)
Hyperextension at the MCP (lubricals are paralysed)
Long thoracic nerve
May be injured by blows or pressure in the posterior triangle of the neck or during radical mastectomy
Leading to winged scapula
Supplies the serratus anterior muscle
