Upper limb nerve injuries Flashcards
UMN vs LMN
UMN- arises from motor cortex or brainstem.
LMN- arises from. the anterior horn cell.
UMN lesions
Increased tone
Held in flexed posture if chronic
- Flexors stronger than extensors due to pyramidal weakness
Brisk reflexes
Sensory level
LMN lesions
Muscular atrophy
Fasciculation
Flaccid tone
Weakness at myotomal or peripheral nerve distribution
Reducd reflexes
Dermatomal/ peripheral nerve sensory loss.
C5 myotome
Deltoid
- Shoulder abduction
C6 myotome
Elbow flexors:
Biceps
Brachialis
Brachiradialis
C7 myotome
Triceps- elbow extensor
Superficial forearm extensors and flexors
C8 myotome
Finger extension and flexion:
Fore arm extensors
Deep forearm flexors
T1 myotome
Intrinsic hand muscles
- Finger abduction
Biceps reflex
C5 reflex
- Musculocutaneous nerve
Supinator jerk
C6 reflex
- Radial nerve
Triceps jerk
C7 reflex
- Radial nerve
Finger jerk
C8 reflex
- Median and ulnar nerve
Avulsion
Tearing of the nerves from its attachment at the spinal cord
Can present with flail arm if lesion is in C5-T1
– Requires surgical repair
Rupture nerve plexus injury
Tearing of the nerves but not from its attachment to the spinal cord
- Requires surgical repair
Neuroma
Tumour or growth of the nerve tissue
- Can arise from the axon
Requires surgical repair
Neurapraxia
Axons remain intact, but myelin damage cause an interruption of the impulse down the nerve fibre.
- Good prognosis.
Types of brachial plexus injuries
Trauma
Cancer
- Infiltration (i.e pancoast tumour)
- After radiation damage
Inflammatory
- Brachial neuritis
Structura;
- Thoracic outlet syndrome
Erb-duchenne type paralysis
Paralysis of the arm caused by severing of C5-6 roots.
- Seen in trauma
- Fingers unimpaired
Paresis of:
- Biceps
- Bracioradialis
- Deltoid
- Supraspinatus
- Supinator.
Arm cannot:
- Elevate
- Abduct
- Externally rotate
- Flex at elbow
Klumpke Paralysis
Partial paralysis of the lower roots of the brachial plexus (C8-T1)–> affects median and ulnar nerves
- Paralysis of intrinsic hand muscles
- Weakness of shoulder/arm muscles
- Unable to flex wrist of fingers
- Sensory loss of hand and medial forearm
Claw hand
Pancoast tumour
Lung tumour that can infiltrate the Lower brachial plexus
Symptoms
- Pain in shoulder girdle and inner arm
- Ipisilateral horners syndrome (sympathetic nerve damage)
Radiation induced brachial plexopathy
Typically around 6 years post-radiation
- Tends to affect upper brachial plexus
- Not always presenting with pain
Associated with breast, lung cancer and lymphoma
Parsonage – Turner Syndrome
Idiopathic brachial neuritis
Symptoms
- Sever pain over days
- Weakness and wasting follows after pain diminishes
Features
- Monophasic
- Mainly unilateral
- Thickening and enhancement in MRi
Treatment
- Analgesia
- Physiotherapy
Thoracic outlet syndrome
Compression around thoracic inlet.
Sites:
- Between anterior and middle scalene muscles
- Under clavicle in cost-clavicular space
- Beneath tendon of Pec.minor
Can be neurogenic or vascular
Neurogenic Thoracic outlet syndrome
Compression of nerve at thoracic inlet.
- Mainly affects median nerve
Symptoms
- Parethesia/ numbest/ weakness
- Aggravated by elevation or sustained use of hand/arms.
Vascular Thoracic outlet syndrome
Compression of vessel at high rib
- Causes stenosis with a post-stenotic dilation.
Symptoms
- Forearm fatigue with mins of use
Signs
- Oedema and cyanosis
- Collateral venous patterning over ipsilateral shoulder/ chest wall/ neck.
- Low BP on affected arm, diminished distal pulses.
Winged scapula
Caused by injury to long thoracic nerve–> paralysis of serrates anterior
- Blow/ pressure in posterior triangle of the neck
- Radical mastectomy
Median nerve innervation
LOAF
Lateral 2 lumbricals
Thenar muscles:
Opponens pollicus
Abduction pollicus brevis
Flexor policus brevis
Carpal tunnel syndrome causes
Diabetes
Pregnancy
Hypothyroidism
Rheumatoid arthritis
Repetitive strain
Wrist fracture.
Anterior interosseous nerve syndrome
From median nerve
- Below elbow
Prone to compression by pronator trees.
Signs
- Flexor policis longus weakness
- Weakness in FGP
- Weak pronation
Causes:
- Prolonged use of screwdriver (gripping tightly with forced pronation)
- Careless blood taking
Ulnar lesions
Higher lesion in upper limb
- Paralysis of ulnar half of FGP
- Interossei and lumbrical paralysis
- No claw
Lesion at the wrist
- Intact FDP
- Flexion of DIP and PIP (paralysis of interossei)
- Hyperextension at the MCP (paralysis of lumbricals)
Froment’s sign
Test for palsy of the ulnar nerve
- Especially the action of adductor pollicis.
Saturday night palsy
Wrist drop
- Inability to extend the wrist due to radial nerve palsy
Rarely causes sensory loss due to extensive overlap with median nerve (XC anatomical snuff box)
Axonal vs demyelination nerve conduction study (NCS)
NCS determines amplitude and velocity of peripheral nerve
Axonal loss
- Decrease in amplitude
Demyelination
- Decreased velocity (speed)
Needle EMG
Measures electrical activity of muscle during voluntary contract.
The pattern can predict if a lesion is neurogenic or myopathic
