Degeneration and regeneration of nerve fibres

1. NERVE INJURYAND ITS
CLASSIFICATION
Dr. Bhumika Chaudhari
[BPT, MPT Neuro]

2. What are you going to learn today ???
 Normal Structures & Functions of a nerve
 What is nerve injury ?
 Mechanisms of nerve injury
 Effects of nerve injury
 Classification of nerve injury
 Why is it important to know the classification ?
NERVE INJURY AND ITS CLASSIFICATION

3. NERVE INJURY AND ITS CLASSIFICATION
1. WHAT ARE THE NORMAL
STRUCUTRES OF A NERVE ??
2. WHAT IS THE NORMAL
FUNCTION OF A NERVE ??

4. Nerve Injury
 Can be complete or partial i.e damage can occur to the entire nerve, a part of nerve, the axon or
the connective tissues.
 Can be acute (trauma) or chronic (repetitive trauma)
 May result in motor, sensory and/or sympathetic impairments.
NERVE INJURY AND ITS CLASSIFICATION
MECHANISMS OF INJURY
• Laceration (knife, gunshot, surgical complication, misplaced injection )
• Compression (sustained pressure applied externally or internally)
• Stretch (excessive tension, tearing from traction forces)
• Radiation
• Electricity
Most common as a result of compression, friction, and stretch.

5.  Demyelination: A process in which the physiological
events lead to the destruction of myelin and are directed to
primarily at myelin sheaths or at schwann cells, whereas
axons are relatively spared.
Wallerian degeneration: The pathological change that
occur in distal end of nerve fibre (axon).
NERVE INJURY AND ITS CLASSIFICATION

6. Compression
Affect micro-circulation of the nerve, causing venous congestion and reduction of axoplasmic transport.
Compression for up to 20- 30 mins produces tingling due to mild ischaemia.
 More prolonged/repetitive compression causes disruption of myelin sheath (demyelination) by
combination of ischaemic and mechanical factors.
 If sustained, ultimately leads to disruption of axons (wallerian degeneration) due to infarction and
necrosis.
Stretch
At approx. 6-8% of elongation, blood flow will be slow; and if strain is held for an hour, it will adversely
affects nerve conduction.
At approx. 15% of elongation, complete arrest of blood will occur.
NERVE INJURY AND ITS CLASSIFICATION

7. EFFECTS OF NERVE INJURY
 Injury to peripheral nerve leads to loss of functions below the lesion.
Motor: Muscle weakness or flaccid paralysis; over a period of time muscles loses bulk and
become thinner.
Sensory: Tingling, numbness, burning pain or complete loss of sensation
Trophic: Initially warm & dry skin; later becomes scaly. Growth of hairs and nails becomes slow.
NERVE INJURY AND ITS CLASSIFICATION

8. Classification of Nerve Injuries
 Using Seddon’s (3 levels) or Sunderland’s (5 levels) classification.
 Both describes the degrees of injury to nerve substructures and the effect on prognosis.
NERVE INJURY AND ITS CLASSIFICATION

9. Based on…
 Structural Changes
 Functional Changes
1.
• NEURAPRAXIA
2.
• AXONOTMESIS
3.
• NEUROTMESIS
NERVE INJURY AND ITS CLASSIFICATION

10. 1. Neurapraxia
 Segmental demyelination
 AP slowed or blocked at point of demyelination
 Axon is usually preserved
 Causes: Compression / Traction (mild ischemia)
 Temporary sensory symptoms (tingling & numbness)
 Muscles does not atrophy
NERVE INJURY AND ITS CLASSIFICATION

11. 2. Axonotmesis
 Loss of axonal continuity
BUT connective tissue coverings remain intact.
 Wallerian Degeneration (axon distal to injury, 3-5 days)
 Causes: Prolonged compression/traction (infarction &
necrosis)
 Sensory loss
 Muscle fibre atrophy
NERVE INJURY AND ITS CLASSIFICATION

12. 3. Neurotmesis
 Complete anatomical division of the axons and connective
tissue of a nerve.
Wallerian Degeneration (axon distal to injury; 3-5 days)
 Causes: Gunshot, stab wound, severe traction of nerve during
displaced fracture, misplaced injections
 Sensory loss
 Muscle fibre atrophy
NERVE INJURY AND ITS CLASSIFICATION

13. Prognosis
NERVE INJURY AND ITS CLASSIFICATION
Axonotmesis
Recovery is incomplete.
Surgical intervention may be
required.
Functional recovery is more
rapid, complete and accurate
after axonotmesis than after
suture repair of a complete
division.
Neurapraxia
Recovery is complete.
Fairly rapid, usually beginning
after a few days or weeks.
Complete within 9-12 weeks
occasionally and complete
restoration of functions may
delayed until6 months.
Neurotmesis
No recovery without surgery
– recovery depends upon on
surgical intervention & correct
regrowth od individual nerve
fibres in endoneural tubes.

14.  By knowing the mechanism of injury and clinical signs & symptoms helps to
determine the potential outcome for the patient and develop a plan of care.
NERVE INJURY AND ITS CLASSIFICATION

15. References
1. Michael Donaghy. Brain’s Diseases of the Nervous System, 12e. Oxford University Press;
2009.
2. Kisner C, Colby L, Borstad J. eds. Therapeutic Exercise: Foundations and Techniques, 6e.
McGraw Hill; 2012.
3. Maheshwari J. Essential Orthopaedics. New Delhi: Interprint; 1993.
4. Ebnezar, John. Textbook of Orthopedics. India, Jaypee Brothers Medical Publishers Pvt.
Limited, 2016.
NERVE INJURY AND ITS CLASSIFICATION