Final - Peripheral Nerve Injuries Flashcards

(33 cards)

1
Q

Etiology of Nerve Injuries

A
  • Tension: stretch injury
  • Compression: tumor
  • Trauma: penetrating wound
  • Ischemia: diabetic neuropathy
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2
Q

Pathophysiology of nerve injuries

A
  • injury may result in demyelination or axonal degeneration
  • results in disruption of the sensory and/or motor function of the injured nerve
  • specific sensory deficits and weakness depend on which nerve has been affected and the location of the injury
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3
Q

Wallerian Degeneration

A
  • injury to an axon
  • cell body nucleus recognizes that something in the periphery has changes
  • Retrograde loss of the axon to at least the first uninjured Node of Ravier
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4
Q

What does Wallerian Degeneration cause?

A
  • increase in cell body size
  • migration of the nucleus to the periphery
  • increased protein and RNA metabolism
  • myelin phagocytosis
  • muscle atrophy
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5
Q

How is Wallerian Degeneration fixed?

A
  • schwann cell proliferation
  • axonal sprouting
  • possible increased activity of nerve growth factor
  • Axonal regeneration at a rate of 1-4 mm/day
  • contact with appropriate distal target cell and synapse is formed
  • “unused” sprouts are reabsorbed
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6
Q

What can form when nerve regeneration is unsuccessful?

A

neuroma

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7
Q

Partially successful nerve regeneration

A
  • axonal regeneration to the incorrect distal target

- decreased target tissue viability

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8
Q

What correlates closely with the prognosis of recovery?

A

the nerve injury classification

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9
Q

first degree injury

A
  • Seddon’s neuropraxia
  • Localized conduction block but axon remains viable
  • Focal demyelination may occur
  • Recover is usually complete 2-3 weeks
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10
Q

Second Degree Injury

A
  • Seddon’s Axonotmesis
  • Injury to axon
  • Supporting structures are intact
  • Wallerian degeneration occurs
  • Recovery at 1mm/day as axon follows connective tissue tubule
  • can be monitored with an advancing Tinel’s sign
  • recovery is poor in lesions requiring > 18 mo to reach target site
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11
Q

Third Degree Injury

A
  • Seddon’s Axonotmesis
  • Endoneurium is disrupted
  • Perineurium and epineurium are intact
  • recovery may range from poor to complete and depends on the degree of intrafascicular fibrosis
  • nerve may not appear seriously damages on gross inspection
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12
Q

Fourth Degree Injury

A
  • Seddon’s axonotmesis
  • Interruption of all neural and supporting elements
  • epineurium is intact
  • the nerve is usually enlarged
  • Tinel’s sign does not advance
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13
Q

Fifth Degree Injury

A
  • Seddon’s Neurotmesis

- Complete Transection wit loss of continuity

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14
Q

sixth degree injury

A
  • recently introduced by MacKinnon

- Mixed nerve injury –> some fascicles of a nerve are working normally while other fascicles may be recovering

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15
Q

Proper Diagnosis of Nerve Injury

A
  • History
  • strength and sensory testing
  • nerve conduction studies
  • EMG
  • imaging studies (MRI and CT scans) for suspected brachial plexus avulsion injuries or tumors
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16
Q

Medical Management of Open Injuries

A
  • immediate exploration of the nerve following a laceration
  • nerve repair if indicated:
    approximate nerve ends and suture together
    microscopic technique (microsurgery) to align internal fascicles
    limit amount of tension
17
Q

Nerve Tension

A
  • intraneural pressure increases with tension of nerve

- blood supply is compromised

18
Q

Nerve Grafts - Indications

A
  • tissue loss
  • tension with approximation of nerve endings
  • tension on nerve with joint movement
19
Q

Nerve Grafts - Autografts

A
  • sural nerve

- medial cutaneous nerve of the forearm

20
Q

Nerve Grafts - Allografts

A

need for immunosuppression medication - no longer necessary

21
Q

Nerve Grafts - nerve conduits

A
  • silicon tubes

- neurotubes

22
Q

Nerve Transfers

A
  • use of viable nerve which is sacrificed to its target tissue to reinnervate a new target tissue
  • generally used for motor function
23
Q

Medical Management of Closed Injuries

A
  • symptom management
  • Periodic rechecks for recovery –> clinical observation/testing, electrodiagnostic testing
  • surgical exploration 3 months after injury if no improvements is noted
  • crush injuries are similarly managed
24
Q

Medications for Nerve Pain

A
  • antidepressants
  • anticonvulsants
  • Baclofen
25
General therapeutic management
- protection of anatomical structures from further stresses - pain management - prevention of PROM loss - prevention of strength loss in unaffected musculature; unable to strengthen affected musculature - pt education (diagnosis/therapy process, compensatory strategies for loss of function)
26
Therapy following surgical management
- period of immobilization to avoid tension on nerves - edema management - scar management
27
Developmental consideration in therapy
- lack of compressive and tensile forces may affect normal bone and muscle development - inability to get into normal developmental positions may cause tissue tightness
28
Presentation of Brachial Plexus Upper Trunk Injury
- upper trunks of brachial plexus (c5 and c6) - most commonly injured - mechanism of injury is forcible increase in the angle between the neck and the shoulder - muscles in C5 and C6: shoulder abductors, elbow flexors and supinators, wrist extensors - Sensory deficits in the C5 and C6 dermatomes - lateral arm, forearm, and hand
29
Therapeutic Management for Upper Brachial Plexus Injury
- Problems: shoulder stability compromised - Pain management: muscle tightness related to muscular imbalance --> STM to decrease tightness - patient education: exercises to maintain PROM, functional compensatory strategies, safety for sensory deficits
30
Presentation of Radial n injury
- common mechanisms of injury are mid shaft humeral fracture, trauma, saturday night palsy - musculature affected: elbow extensors, wrist, thumb, and MCP joints of digits depending on site of injury - small area of sensory deficit in the posterior and lateral thumn - classic presentation is wrist drop - unable to effectively use finger flexors because of synergistic function of wrist extensors needed
30
Therapeutic Management for Radial Nerve injury
- splint to position wrist in extension - pt education: contracture prevention compensatory function strategies HEP
31
Medical Management for Unresolved Nerve Injury
- tendon transfer --> transfer tendon of a working muscle to the tendon of a muscle with no nerve supply
32
E Stim
- In theory, can be used to prevent muscle atrophy - inclusive research - muscle tissue can be directly stimulated with direct current - questionable, peripheral nerve injury application because sensation over the muscle belly to be stimulated generally is intact