Nerve Injury Degeneration Regeneration.pptx
- 1. Nerve Injury, Degeneration and Regeneration Dr Pranith
- 2. Introduction • 1862 Augustus Waller ------ Wallerian Degeneration • PNS v/s CNS • No full recovery • World war I
- 3. Common Causes • Transection • Crushing • Toxins • Ischaemia • Hyperpyrexia
- 4. Layers of Nerve Fibres
- 5. SEDDON’s Classification of Nerve Injuries
- 6. Grading of Injury “Sunderland” • First Degree Injuries • Second degree injuries • Third Degree injuries • Fourth degree injuries • Fifth Degree Injuries
- 9. Degeneration and Regeneration • Occur parallel • 3 stages - Changes in cell body - Changes in distal stump - Changes at the site of injury
- 11. Changes in Nerve Cell Body Chromatolysis Fragmentation of organelles Cell loses shape, swollen. Nucleus Depends on : 1. Variety of neurons affected 2. Distance of lesion from cell body 3. Nature of Injury Begin in 48 hrs May Take Upto 20 days for completion
- 12. Changes in the distal stump (Wallerian Degeneration) • Changes in axis cylinder • Changes in Myelin sheath - 8 days – Physical - 32 days – Chemical • Schwann cell nucleus (first responders) • Macrophages • Schwann cell cytoplasm fills up – 3 months • Neurolemmal tubes filled with ……. Begins in 24 hrs
- 13. Changes at the site of injury • Schwann cells bridge gaps from distal end, upto 3 cms • 1-2 mm/day
- 15. Changes in cell body 20 days starts ….80 days completed Nissl granules and golgi apparatus reappear Nucleus central Cell size normal
- 16. Changes in Distal stump • Axis cylinder ---- fibrils • Each axon 100 fibrils • Each endoneurium tube upto 30 fibrils after few weeks • All fibrils degenerate except one • Rate of growth increases distally 0.25mm/day to 3-4mm/day
- 17. Changes in Distal stump • In 15 days Schwann cells starts laying down myelin sheath – completed after 1 year • On reaching target new NMJ is formed • Increase in fibre diameter is slow and upto 85% of original • IN THE CNS - SCAR formed by astocytes - New synapses are not formed - Therefore, recovery is rare
- 18. Complications of Nerve Injury • Functional Complications • Anatomical Complications - Neuroma
- 19. THANK YOU