Nerve Degeneration, Repair and their Consequences in the Peripheral NS Flashcards
What does cytoplasm survival depend on
Metabolic interaction with nucleus
How will neurones die and what happens when they do?
Neurones die if cell body is damaged. replaced by fibrous tissue eg. astrocytes/fibroblast
What makes it easier to repair
Closer to Motor End Plate - less fibre to repair
Compression of nerve (Cut unlikely)
Younger patients
Sequence of nerve compression
Terminal degeneration - uncontrolled release of neurotransmitter due to synapatic bouton degeneration
Walleian Degeneration - Schwann cells become phagocytic and recruit macrophages to degenerate myelin and axon
Chromatolysis - Eccentric nucleus increase nissl substance and pn synthesis
Describe how nerves repair themselves
Schwann cells align longitudinally with endoneurial sheath to guide axon sprouts to bridge gap
Growth cone will reach end of proximal segment
Re-innervation within 8 weeks to 6 months
What determines type of fibre at re-innervation
Re-innervating fibre
What do you call a transient block that causes temporary interruption of conduction?
Neuropraxia
What is axonotmesis
Axon damaged but endoneurial sheath intact
What do you call a complete severance of nerve fibre
Neurotmesis
What are the consequences of nerve degeneration
Fasciculation + Fibrillation
Flaccid Paralysis
Atrophy
What occurs in prolapsed intervertebral disc
Disc pushes into spinal nerve affecting root below.
Severe pain, spinal ache
Patient presents with pain, numbness and bladder problems. There s narrowing on spinal canal.
Spinal Canal stenosis
Patient presents with numbness in fingers, pain in forearm, thenar atrophy. Median nerve is compresesed due to swelling
Carpal Tunnel Syndrome
