T2 L11 Upper limb nerve injuries Flashcards
What are the 3 steps when approaching a neurological problem?
Anatomically localise lesion
Consider pathophysiology
Differential diagnosis
What are the signs of an UMN?
Held in flexed posture if chronic Increased tone Pyramidal weakness (flexor muscles stronger than extensors) Brisk reflexes Sensory level
What are the signs of a LMN?
Wasting / fasciculations
Flaccid tone
Weakness in either a myotomal distribution or peripheral nerve distribution
Dermatomal or peripheral nerve distribution of sensory loss
What is a dermatome?
Area of skin suppled by nerve fibres originating from single dorsal nerve root
What myotome and muscle action does C5 root have?
Deltoid
Shoulder abduction
What myotome and muscle action does C6 root have?
Biceps, brachialis, brachioradialis
Elbow flexion
What myotome and muscle action does C7 root have?
Triceps, superficial forearm extensors and flexors
Elbow extension, wrist extension, wrist flexion
What myotome and muscle action does C8 root have?
Forearm extensors
Deep forearm flexors
Finger extension, finger flexion
What myotome and muscle action does T1 root have?
Intrinsic hand muscles
Finger abduction
What is the biceps reflex?
C5 reflex
Supplied by musculocutaneous nerve
What is the supinator jerk?
C6 reflex
Radial nerve
What is the triceps jerk?
C7 reflex
Radial nerve
What is the finger jerk?
C8 reflex
Median and ulnar nerve
What are the signs and symptoms of a nerve root impingement?
Pain - can radiate - can be aggravated by neck movement Sensory loss Weakness Reflex loss
What are the 4 types of nerve injury?
Avulsion
Rupture
Neuroma
Neurapraxia
What is avulsion?
Tearing of nerve from its attachment at the spinal cord
What is rupture?
Tearing of nerves but not from attachment to the spinal cord
What is neuroma?
Tumour or growth of nerve tissue
What is neurapraxia?
Axons remain intact but myelin damage causes interruption of impulse down nerve fibre
Give examples of causes of brachial plexus injuries
Trauma - Erb-duchenne type paralysis - Klumpke paralysis Cancer - lung cancer - pancoasts tumour Inflammatory - brachial neuritis Structural - thoracic outlet syndrome
What is Erb-duchenne type paralysis?
Avulsion of C5 and C6 roots
Upper plexus palsy
What are the causes of Erb-duchenne type paralysis?
Blow to shoulder or during delivery of the head
What muscles does Erbs palsy affect?
Biceps Brachioradialis Deltoid Supraspinatus Supinator
What is Klumpke’s palsy?
Avulsion of C8 and T1 roots
What can cause Klumpke’s palsy?
Clutching for an object when falling from a height
What are the signs and symptoms of Klumpke’s palsy?
Unable to flex wrist or fingers
Weakness of all small muscles of the hands
Sensory loss to hand and inner border of forearm
Claw hand
How can you differentiate between Erb’s palsy and Klumpke’s palsy?
Erb’s palsy - arm doesn’t work, hand works
Klumpke’s palsy - arm works, hand doesn’t work
What are the signs and symptoms of pancoast tumour?
Pain in shoulder girdle and inner arm Ipsilateral horners syndrome - miosis - ptosis - anhidrosis
Describe radiation-induced brachial plexopathy
Occurs 6 years after radiation
Associated with treatment for breast, lung cancer and lymphoma
Pain isn’t a consistent feature
Predilection for upper brachial plexus
What are the causes of idiopathic brachial neuritis?
Unclear
Could be infectious or post-infectious
What are the signs and symptoms of idiopathic brachial neuritis?
Severe pain over days
As pain diminishes it is followed by weakness and wasting
What investigations are done for idiopathic brachial neuritis?
MRI to look for thickening and enhancement
NCS / EMG for prognostication
What is the treatment of idiopathic brachial neuritis?
Analgesia
Physiotherapy
Steroids (limited evidence)
Where are the common compression sites in thoracic outlet syndrome?
Between anterior and middle scalene muscles
Between clavicle in costoclavicular space
Beneath tendon of pectoralis minor
What are the signs and symptoms of neurogenic thoracic outlet syndrome?
Predominantly affects abductor policies brevis leading to thenar wasting
Paraesthesia
Numbness
Weakness
Not localised to specific nerve distribution
Aggravated by elevation or sustained use of arms or hands
what are the signs and symptoms of vascular thoracic outlet syndrome?
Forearm fatigue within minutes
Swelling and cyanosis
Collateral venous patterning over ipsilateral shoulder, chest wall and neck
Rarely pain
Pallor and coldness
Lower BP on affected arm with diminished distal pulses
Why does damage to long thoracic nerve cause winging of scapula?
Long thoracic nerve normally supplies serrates anterior which pulls medial border of scapula to posterior thoracic wall and stabilises it there
What are the causes of damage to the long thoracic nerve?
Blows or pressure in posterior triangle of neck
Radical mastectomy
What are the 2 common sites of compression of the median nerve?
Wrist - carpal tunnel syndrome
Elbow
What hand muscles does the median nerve innervate?
Lateral 2 lumbricals
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis
What are the causes of carpal tunnel?
Diabetes Pregnancy Hypothyroidism Rheumatoid arthritis Repetitive strain
Where does the anterior interosseous nerve come from?
Median nerve just above elbow
Where is the anterior interosseous nerve prone to compression?
Between 2 heads of pronator teres muscle
What are the causes of anterior interosseous nerve compression?
Gripping tightly with forced pronation
Prolonged use of screwdriver
Damaged during blood-taking
What does anterior interosseous nerve syndrome cause weakness of?
Flexors of interphalangeal joint of thumb - flexor pollicis longus
Distal interphalangeal joints of index and middle fingers - flexor digitorum profundus
Pronation
Where is sensation lost if there is a lesion in the forearm which is proximal to palmar cutaneous sensory branch?
Lateral palm D1 D2 D3 1/2 D4
What muscles will be paralysed if there is a higher lesion in the upper limb affecting the ulnar nerve?
Ulnar 1/2 flexor digitorum profundus
Interossei
Lumbricals
Where does the superficial sensory branch come off the ulnar nerve?
In distal forearm above wrist
What does the deep ulnar branch supply?
Motor innervation to intrinsic hand muscles
What can cause Guyon’s canal to become inflammed?
Overuse such as occupation or cycling
Rheumatoid arthritis
What nerve passes through Guyon’s canal?
Deep ulnar branch
What does C8 supply?
All finger extensors via radial nerve
Flexor digitorum profundus of index / middle finger via median nerve
What is the clinical sign of radial nerve palsy?
Wrist drop
How is axonal differentiated from demyelinating in a nerve conduction study?
Axonal - decrease in amplitude
Demyelinating - decrease in velocity
What does a needle EMG do?
Measures electrical activity of muscle during voluntary contraction
Pattern of electrical activity helps distinguish a lesion arising from a nerve vs a muscle
