T2 L7: Injuries of the upper limb Flashcards
What is the difference between a upper and lower motor neurone?
Upper motor neurones originate in the cerebral cortex
Lower motor neurone originate in the spinal cord
What is the difference in symptoms of lower and upper motor neurone disease?
Upper motor neurons are responsible for motor movement, whereas lower motor neurons prevent excessive muscle movement.
Upper motor disorders usually cause spasticity; lower motor disorders usually cause flaccidity
What are myotomes?
The relationship between muscles and the spinal cord
What are the myotomes of the upper limb?
C5: Deltoid (musculoskeletal nerve)
C6: Biceps, brachialis, brachioradialis (radial nerve)
C7: Triceps, superficial forearm extensors and flexors (radial nerve)
C8: Forearm extensors, deep forearm flexors (median and ulnar nerve)
T1: Intrinsic hand muscles
What is avulsion?
When the nerve is pulled off the cord
What is a neuroma?
A lesion on the nerve that causes compression
What is neuropraxia?
Stretching of the nerve that damages myelin and causes conduction problems
What can cause 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
Inflammation
-Brachial neuritis
Structural
-Thoracic outlet syndrome
What is structural outlet syndrome?
Caused by a narrowing of the thoracic outlet at the shoulder
There are variations in anatomy that causes compression sites: between anterior and middle scalene muscles, beneath clavicle in the costoclavicular space, beneath tendon of pectoralis minor
What is Erbs palsy?
Upper plexus palsy affecting C5/C6 innervated muscles
It’s caused when the upper brachial plexus roots are torn during birth complications or a blow to the shoulder in adults
Symptoms: weak muscles including biceps, brachioradialis, deltoid, supraspinatus, supinator
Fingers are unimpaired but the arm doesn’t work
What is Klumpske’s palsy?
Causes the arm to work but not the hand
Caused when you clutch for an object while falling which causes inferior trunk plexus injury involving C8/T1
Symptoms: patient is unable to flex wrist or fingers, there is weakness of all small muscles of the hand, and there is sensory loss to hand and inner border to forearm
What is Horner’s syndrome?
A condition that affects the face and eye on one side of the body
It’s caused by the disruption of a nerve pathway from the brain to the head and neck
What is a Pancoast tumour?
Cancers that start at the apex of the lung that infiltrates the lower brachial plexus
It causes ipsilateral Horner’s syndrome
What is radiation induced brachial plexopathy?
Usually presents about 6 years after radiation that causes injury to the brachial plexus
What is idiopathic brachial neuritis?
Begins as pain over days and as pain diminishes, it’s followed by weakness and wasting rarely bilateral
An MRI would show thickening and enhancement
The patients get better by themselves. Analgesia and physiotherapy are provided
What is the difference between neurogenic and vascular thoracic outlet syndrome?
Neurogenic
- Paraesthesia, numbness, weakness
- Not localised to specific nerve distribution
- Aggravated by elevation or sustained use of arms and legs
Vascular
- Forearm fatigue within minutes if use
- Swelling and cyanosis
- collateral venous patterning over the ipsilateral shoulder, chest wall, and neck
- Rarely pain, pallor, and coldness
- Lower BP on affected arm and diminished distal pulse
What is paraesthesia?
Burning or prickling sensation in arms and legs
How can the long thoracic nerve be injured?
By blows or pressure in the posterior triangle of the neck or during a radical mastectomy
What is the function of the long thoracic nerve?
It supplies the serratus anterior muscle.
Impairment of this nerve causes winging of the scapula because the serratus anterior can’t pull the medial border of the scapula to the posterior thoracic wall to stabilise it there
What are the 2 most common sites of compression of the median nerve?
The wrist (carpal tunnel syndrome) Elbow
Which hand muscles are innervated by the median nerve?
LOAF
Lateral 2 lumbricals
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis
What are the causes of carpal tunnel syndrome?
Diabetes Pregnancy (general swelling) Hypothyroidism Rheumatoid arthritis Repetitive strain (due to occupation) Wrist fractures
What are the 2 tests used to look for carpal tunnel syndrome?
Tinel’s test
-Tap over the carpal tunnel along the wrist
Phalen’s test
-Inverted prayer and hold the wrists together for 1min
Positive test for both is if tingling is felt in the thumb and lateral 3.5 digits (where the nerve supplies)
What is anterior interosseous nerve syndrome?
Motor branch of the median nerve only affected
Causes weakness in flexor pollicis longus, flexor digitorum profundus and pronator quadratus muscle in the forearm
Causes weakness of the thumb joint, digit joint, and weakness on pronation
What is ulnar palsy at the elbow?
Compression of the ulnar nerve as it passes through the elbow
Causes an ‘ulnar claw’
What is Froment’s sign?
Grabbing a piece of paper between the thumb and index finger
Weakness indicates ulnar nerve palsy
What is meant by Saturday night palsy?
Radial nerve palsy caused when people fall asleep in a chair with their arm over it after drinking and this compresses the radial nerve at the elbow
Why are nerve conduction studies useful?
They determine amplitude and velocity of the peripheral nerve
Axonal loss causes decrease in amplitude
Demyelination causes decrease in velocity
