Musculoskeletal Growth, Injury And Repair Flashcards
Define an axon?
Long processes of neurones which are coated in endometrium and grouped into fascicles
Define fascicles?
Nerve bundles covered with perineurium
What is a nerve covered with?
Epineurium
A alpha fibre function?
Muscle stretch and tension sensory axons
A beta fibre group function?
Touch, pressure, vibration and joint position sensory axons
A gamma fibres function?
Gamma efferent motor axons
A delta fibres function?
Sharp pain, very light touch and temperature sensation
B fibres function?
Sympathetic preganglionic motor axons
C fibres function
Dull, aching, burning pain and temperature sensation
Classes of trauma that can cause nerve injury?
Direct (blow, laceration) or
Indirect (avulsion, traction)
Define neurapraxia
Disorder of peripheral nuron system in which there is temporary loss of motor and sensory function due to blockage of nerve conduction
Define Axonotmesis
Axons and myelin of peripheral nerve are damaged but endoneurium, epineurium and perineurium remain intact
Define Neurotmesis?
Nerve and neuron sheath are damaged
Common cause of neurapraxia
Stretched or bruised
Common cause of axonotmesis
Stretched, crushed or direct blow
Prognosis of axonotmesis?
Fair
Sensory recovery better than motor
Can peripheral nerve regenerate?
Yes
Common cause of neurotmesis?
Laceration or avulsion
Grading system used to grade nerve trauma injury?
Sunderland grade 1-5
The grades of Sunderland grading systems?
Grade1- neurapraxia
Grade 2- axonotmesis
Grade 3- neurotmesis
Grade 4- neurotmesis + (loss of perineurium)
Grade 5- neurotmesis ++ (loss of perineurium + epineurium)
Define closed nerve injuries
Associated with nerve injuries in continuity eg neuropraxis, axonotmesis
How do you treat closed nerve injury?
Surgery after 3 months 1
Define open nerve injuries
Frequently related to nerve division eg neurotmetic injuries
Often caused by knives/ glass
How are open nerve injuries treated?
Early surgery
What happens 2-3 weeks after an open nerve injury in the distal portion of the nerve?
Wallerian degeneration
Clinical features of a peripheral nerve injury?
Dysaethesiae, paresis or paralysis, dry skin, diminished or absent reflexes
How fast is regeneration of peripheral nerves?
Rate of 1mm/day
Maybe 3-5mm/day in children
What is the 1st modality to return in the healing process of peripheral nerves?
Pain
What is the prognosis of regenerating peripheral nerves dependent on?
Whether nerve is “pure” or “mixed” and
How distal the lesion is (proximal is worse_
How can you monitor the recovery of regenerating peripheral nerves?
Tinel’s test,
Electrophysiological nerve conduction studies
What are the indications for nerve grafting?
Nerve loss, late repair
What is the surgical timing in a traumatic peripheral nerve injury?
Immediate surgery within 3 days for clean and sharp injuries,
Early surgery within 3 weeks for blunt/ contusion injuries
Delayed surgery 3 months after injury, for closed injuries
