Nerve Injuries Flashcards
What are the layers that divide nerve fascicles and trunks?
- Perineurium
- Endoneurium
- Epineurium (trunk)
- Mesoneurium
What is the function of the connective tissue and fluid in nerve trunks?
Provides a blood/nerve barrier that filters out substances that may interfere with neural conduction
What is axoplasm?
- Fluid inside the cell body
- Provides nutrition, lubrication & cushioning
- Highly viscous
- Thixotropic (must be moved, otherwise becomes very thick)
What are terminal boutons?
At the end of axons, can be receptors or motor end plates
What does antegrade and retrograde refer to?
Axoplasmic flow:
Antegrade: Axoplasm flows away from the centre to the periphery
Retrograde: Axoplasm flows from the periphery to the centre
What is axoplasmic flow powered by?
Mitochondria
What does axoplasmic flow allow?
Maintenance factors & chemical mediators to travel up & down the nerve keeping the nerve healthy
What are the disadvantages of axoplasmic flow?
When a nerve becomes sick/pinched & inflamed, chemical mediators can hang around for a long time
What are nerves supplied by?
- Blood vessels
- Their own nerves (nervi nervorum)
What is the implication of nerves being supplied by nervi nervorum?
The nerve itself can become a source of pain, not just a conductor of pain
What are the 2 types of peripheral nerves?
- Myelinated (A alpha, A beta, A delta)
- Unmyelinated (C fibres)
What are some of the causes of peripheral nerve injury & disease?
- Trauma (direct pressure/blow or repetitive microtrauma)
- Chronic entrapment (e.g. CTS)
- Hereditary
- Infection
- Inflammation
- Ischaemic
- Toxic metabolic
What are the 3 types of traumatic peripheral nerve injuries?
- Neuropraxia
- Axonotmesis
- Neurotmesis
What are the features of neuropraxia?
- Focal damage of myelin fibres
- Axon/connective tissue intact
- Transient disruption of conduction
- Recovery days-weeks
What are the features of axonotmesis?
- Disruption of axon
- Connective tissue in tact
- Wallerian degeneration
- Axonal regeneration over months-years
What are the features of neurotmesis?
- Axon & connective tissue damaged
- Neuroma formed at proximal stump
- Requires grafting
- Recovery years, often incomplete
What are the differences between nociceptive, neurogenic and neuropathic pain?
- Nociceptive: Pain messages carried by normal nerves about trauma
- Neurogenic: Pain generated by a nerve, due to injured/diseased nerve or sensitisation of nervi nervorum
- Neuropathic: Due to injured/diseased nerve/nerve root, prolonged CNS symptoms
What are the techniques for differentiating nerve as a source of pain?
- Tinel’s test (tap it)
- Stretch it in a way that isolates it from muscle
- Dermatomes (assess distribution)
- Myotomes (assess weakness, reflex testing)
- Test it (nerve conduction studies)
- Nerve symptoms: May be unrelenting, not activity related
What is the difference in clinical presentation of nerve root injury and peripheral nerve injury?
- Nerve root: Line of pain that radiates
- Peripheral nerve: Patch of pain
What are the precautions for neural tissue provocation tests?
- High irritability
- Acute disc symptoms
- Neural/spinal surgery
- Spondylolisthesis
- Nerve root compromise
- Spinal cord compromise
- Bladder/bowel dysfunction
- Rapid progression of neurological disease
What is the role of physio in peripheral nerve injuries?
- Splinting/taping/bracing: Offload, decompress, support
- EPAs: decrease pain, stimulate muscle activity
- Manual therapy & neural glides: decrease pain, compression, sensitivity (subacute phase only)
- Exercises: maintain/increase range, strength, function
- Education/advice
What are some common upper limb peripheral nerve injuries?
- Brachial plexus stinger
- Thoracic outlet syndrome
- Quadrilateral space syndrome
- Radial tunnel syndrome
- Carpal tunnel syndrome
- Cubital tunnel syndrome
What are some common lower limb peripheral nerve injuries?
- Meralgia paraesthetica
- Femoral nerve compression
- Sciatic nerve compression
- Common peroneal nerve injury
- Tarsal tunnel syndrome
What are the features of brachial plexus stinger?
- C5-T1
- Compressive force down into shoulder while neck is stretched away
- Common in collision sports
What are the features of thoracic outlet syndrome?
- C6-T2
- Compression of tissue between clavicle & first rib or between anterior & middle scalene or under pec minor
- Diagnosed with Adsons’ & Wright’s tests
- Caused by trauma, repetitive strain, anatomical defects
What are the features of quadrilateral space syndrome?
- Axillary nerve (C5-C6) injury
- Quadrilateral space: Between humerus, teres major/minor & long head of triceps
- Caused by improper crutch use, repetitive overhead activities, shoulder dislocation
What are the features of radial tunnel syndrome?
- Posterior interosseous nerve (C6-T1) injury
- Radial tunnel: below triceps
- Commonly occurs with supracondylar fracture of elbow
- Caused by repeated pronation/supination
What are the features of cubital tunnel syndrome?
- Ulnar nerve (C8, T1) injury
- Cubital tunnel: Behind medial epicondyle
- Caused by repeated elbow flexion
What are the features of carpal tunnel syndrome?
- C5-T1
- Median nerve injury
- Caused by repeated wrist/finger flexion
What are the features of meralgia paresthetica?
- Lateral femoral cutaneous nerve injury (L2-L3)
- Anterolateral thigh
- Caused by compression of lateral femoral cutaneous nerve, e.g. tight belts/jeans
What are the features of femoral nerve compression?
- L2-L4
- Caused by direct trauma, compression, stretch injury
What are the features of sciatic nerve compression?
- L4-S3
- Near piriformis/origin of hamstrings
- Caused by muscle spasm/tightness with overuse/strain
What are the features of common peroneal nerve compression?
- L4-S2
- Most commonly caused by fractured head of fibula
What are the features of tarsal tunnel syndrome?
- Tibial nerve injury
- L4-S3
- Caused by eversion sprain or compression in tarsal tunnel
