FMC Test 2 *Neurotmesis, Neuropraxia, Axonotmesis*

Question 1

What is Neurotmesis?

Answer 1

The nerve is severed
- Results in loss of axon and connective tissue continuity
(Ex. GSW, Stab wound, avulsion injury)

Question 2

What is the difference between Klumpke’s Palsy and Erb’s Palsy?

Answer 2

Klumpke’s Palsy is a result of injury to the lower brachial plexus. (C8, T1), elbow is flexed, wrist is supinated, “claw-like” hand

Erb’s Palsy is a result of injury to the upper brachial plexus. (C5-C7), this has a classic limb posture of a waiters tip, the arm lies internally rotated at the side, with the elbow extended, the forearm pronated and wrist and fingers flexed. Paralysis in deltoid, bicep brachii, brachialis, brachioradialis

Both are result of Neurotmesis

Question 3

What are the Clinical Manifestations of Neurotmesis?

Answer 3

• Depends on nerve involvement and injury factors
• In peripheral nerve distribution distal to lesion:
  –Flaccid paralysis of muscles
  –If left untreated:
  -Health declines in target tissue
  -Rapid atrophy
• Loss of sensory function
• Loss of sympathetic function

Question 4

Do Neurotmesis require surgery?

Answer 4

Yes, surgical intervention is required
- Primary repair preferred

Operative delays lead to tissue fibrosis that would preclude repair or reconstruction

Question 5

What do Surgical repair options include for Neurotmesis?

Answer 5

• Nerve Graft
• Group Fascicular Repair
• Epieneural Connective Tissue Repair

Question 6

After a patient has neurotmesis surgery, what are the next steps?

Answer 6

Repair site protection is the most important factor after coaptation or autograft
- Post-operative splinting maintains slack in nerve
- Compressive dressing decreases venous congestion and edema
- ROM exercises with restrictions to allow CT to heal

Question 7

What is the healing time in the Inflammatory Stage, for Nerve Connective Tissue (Epineurium/Perineurium)? (For Neuropraxia)

Answer 7

Up to 3 days (most within 48 hours)

Question 8

What is the healing time in the Repair Stage, for Nerve Connective Tissue (Epineurium/Perineurium)?
(For Neuropraxia)

Answer 8

Day 4-Day 21 (Depends on the extent of the injury)

Question 9

What is the healing time in the Remodeling/Maturation Stage, for Nerve Connective Tissue (Epineurium/Perineurium)?
(For Neuropraxia)

Answer 9

21 days to several months

Question 10

What does the Rehabilitation looks like once the Connective Tissue conduit is healed (Epineurium/Perineurium)?

Answer 10

• Obtain and maintain full motion
• Teach safety to compensate for loss of sensation and/or motor function
• Sensory re-education exercises are initiated early and progressed
• Sensory stimulation tactics to decrease hypersensitivity
• Pain increases as healing progresses
  (Expect pain as regeneration of the nerve progresses)

Question 11

For Nerve (Axon), what is the time frame in the Inflammatory Stage of Tissue Healing?
(For Neurotmesis and Axonotmesis)

Answer 11

Up to several weeks associated with Wallerian Degeneration

Question 12

For Nerve (Axon), what is the time frame in the Fibroplasia/Repair Stage of Tissue Healing?
(For Neurotmesis and Axonotmesis)

Answer 12

Axons regenerate 1mm per day; can take months or longer

Question 13

For Nerve (Axon), what is the time frame in the Remodeling/Maturation Sate of Tissue Healing?
(For Neurotmesis and Axonotmesis)

Answer 13

If Axon not regenerated by 18 months, the muscle it innervates is likely not viable

Question 14

What happens after there is a complete Axonal Transection?

Answer 14

The Neuron undergoes a degenerative process called, Wallerian Degeneration. (This takes time and requires monitoring)

Question 15

What is Wallerian Degeneration?

Answer 15

Wallerian degeneration is an active process of anterograde degeneration of the distal end of an axon that is a result of a nerve lesion.

Question 16

What happens with New Axonal Growth?
What does success depend on?

Answer 16

• Cell increases in metabolic activity, protein synthesis, and mitochondrial activity
• New Terminal sprouts project from proximal segment

(Success depends on location, type of injury, inflammatory response, and scar tissue formation)

Question 17

What would be the prognosis for Neurotmesis?

Answer 17

• Recovery after neurotmesis depends on whether the nerve was repaired and the length of the nerve that nerve must be regenerated
• After transection, muscle atrophy rapidly, and after 2 years, they have undergone irreversible changes and have become fibrotic
• If re-innervation occurs after 1 year, function is poor; with a delay of 18-24 months, there is no hope for return of function

Question 18

What is Neuropraxia?

Answer 18

Injury or inflammation the peripheral nerve. Can lead to Axonotmesis if left untreated

Question 19

In neuropraxia, there is reduction in nerve conduction at the site of injury due to?

Answer 19

• Compression, traction, repetitive movements (Friction)
• Causes ischemia or Schwann cell damage
• Functional recovery in minutes, weeks, or a couple months

Question 20

In Neuropraxia, what is a conduction block?

Answer 20

• The least sever injury
• Conduction across the zone of nerve injury in inhibited, HOWEVER, conduction within the nerve both proximal and distal to the lesion remain intact
• Continuity of all structures is preserved
• Wallerian Degeneration DOES NOT occur (No axonal loss)

Question 21

Which peripheral nerves are at risk for compression, tension, and friction neuropathy?

Answer 21

• Spinal nerve roots (Cervical and Lumbar)
• Brachial Plexus
• Median, Radial, Ulnar nerve
• Fibular, Tibial, Sural nerve

Question 22

If compression, traction, friction, tensile, or shear forces become excessive, the nervous tissue has a biological response to injury, these responses include? (6)

Answer 22

• Tissue anoxia (absence of O2)
• Local Ischemia
• Nerve fiber deformation
• Vascular Permeability
• Intraneural Edema
• Fibroblastic proliferation

Question 23

How can Neurogenic Inflammation occur?

Answer 23

Its sympathetically mediated inflammation. From excessive mechanical loading of the nerve

Question 24

What are some neurogenic inflammatory reactions?

Answer 24

• Vasodilation
• Edema
• Sensitization of nerve endings
• Waking of sleeping or ineffective nociceptors
  etc.

Question 25

How does Intraneural edema increase?

Answer 25

• Intraneural edema increases following nerve injury
  (Plays a major role in acute and chronic nerve lesions, even a moderate pressure increases can interface with endoneural capillary flow, causing hypoxia and electrolyte imbalance)

Question 26

What are the results of Intraneural edema?

Answer 26

• Mechanical constriction and inflammatory biproducts further decrease blood flow and perpetuates congestion within the nerves.
• Poor edema resolution, which can lead to nerve death.
• Disrupts axoplasmic flow

Question 27

What are the classifications of Neuropraxia?

Answer 27

• Neuropraxia involves segmental demyelination, which slows or blocks conduction of the action potential at the point of demyelination in a myelinated nerve
• Neuropraxia often occurs after nerve compression that induces mild ischemia in nerve fibers
• Conduction of the action potential is normal above and below the point of compression; because the axon remains intact, muscle does not atrophy
  (May identify myotomal weakness or specific muscle weakness due to decreased conductivity)

Question 28

What is the mechanism of Burner-Stinger Syndrome?

Answer 28

• Tensile load on brachial plexus
• Head and neck are rotated and laterally bent away from depressed shoulder.
• Shoulder is hyper-abducting
• Scapular depression

Question 29

What is Axonotmesis? How can it occur?

Answer 29

Damage/Injury to the axons, due to sever compression, friction/shear or traction.
- Epineurium/Perineurium/Endoneurium remain intact

• Due to prolonged low loads or short duration high loads

Question 30

In order to regenerate, can Axonotmesis undergo Wallerian Degeneration like Neurotmesis?

Answer 30

Yes it will under go Wallerian’s, and will undergo the same process for “New Axonal Growth”.

Question 15 and 16 for review

Question 31

Is surgery needed for Axonotmesis?

Answer 31

Yes, surgery is often required to achieve functional recovery