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MedPsych Exam 3 > Peripheral Nerve Injury > Flashcards

Peripheral Nerve Injury Flashcards

1
Q

what are traumas that cause injury to peripheral nerves?

A

Penetrating injury
Crush
Traction
Ischemia

Thermal
Percussion
Vibration

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2
Q

what causes laceration of PN’s?

A

glass, knife, fan, saw, metal or long bone fractures = 30% of serious nerve injuries

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3
Q

what PN is most commonly injured? 2nd most common?

A

ulner n.

median n.

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4
Q

what are the types of crush injuries?

A
  1. acute: arm impingement, immediate attention.

2. overuse crush: caused by overuse. double crush if 2 injured

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5
Q

what is a stretch injury?

A

Injury to the nerves of the neck and shoulder under high velocity that cause burning or stinging feeling
aka brachial plex injury

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6
Q

what can PNI cause?

A

Injury may result in demyelination or axonal degeneration,

Both can disrupt sensory and/or motor function

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7
Q

when does recovery occur in PNI?

A

When re-myelination with axonal regeneration occurs

AND re-innervation of sensory and motor receptors

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8
Q

what systems do PNI’s effect?

A

Motor
Sensory
Reflex
Autonomic

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9
Q

what is the anatomy of a PN (outer-inner)

A

Epineurial sheath (outside covering)
Epineurium (ground substance)
Bundle: perineurium
Fascicle: endoneurium (axon inside)

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10
Q

what are Seddons 3 levels of PNI?

A
  1. neuropraxia
  2. axonotmesis
  3. neurotmesis
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11
Q

what is neuropraxia?

A

least sever PNI
axonal continuity preserved, recovery rapid
only at site of injury

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12
Q

what is axonotmesis?

A

axons disrupted
recovery depends on distance from injury to end organ
spontaneous recovery

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13
Q

what is neurotmesis?

A

most sever
complete anatomical disruption
no spontaneous healing

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14
Q

what are Sunderlands 5 levels of PNI?

A

First Degree = Neuropraxia
Second Degree = Axonotemesis
Third Degree = Endoneurial covering severed
Fourth Degree = Perineurium disrupted
Fifth Degree = Complete disruption of nerve trunk, little hope of spontaneous recovery

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15
Q

where is the emphasis placed in sunderlands 5 levels of PNI?

A

fascicle structure of PN

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16
Q

what do response from sensory end organs depend on?

A

Atrophy
Degeneration
disappearance of PN
time spent detached (shorter recovery window)

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17
Q

what are the 3 most common sensory end organs?

A

Meissner Corpuscle
Merkel Cell
Pacinian Corpuscle

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18
Q

what are the implications of injured motor end organs?

A

Muscle atrophies, ceases to function
Progressive shrinkage of muscle fibers
longer window for recovery

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19
Q

what are internal forces of compression?

A

Tumors, fractures, callus

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20
Q

what are external forces of compression?

A

Tourniquet, crutches

21
Q

what are sensory consequences of nerve injury?

A

Joints may become traumatized
Pt may injure themselves
Loss of hand function (dont know how much things weigh)

22
Q

what are motor loss consequences of PNI?

A

Venous & lymphatic
stasis
Fibrosis
Muscle Atrophy

23
Q

what are the vasomotor consequences of PNI?

A

Nutrition of bone & joints impaired
Sweat response abnormality
Sympathetic vasomotor instability

24
Q

what are the timing considerations of PNI surgery?

A

12-18 months irreversible muscle atrophy has occurred, surgery not helpful

18-24 months edoneurial tube viable, if it doesn’t receive regenerating axon within time frame, tube will degenerate

25
Q

what are other surgical considerations for PNI?

A

Condition of pt

Status of associated injuries

26
Q

what is end to end repair?

A

sewing fascicles and outside of nerve together

27
Q

what are surgical problems with end to end repair?

A

degeneration
wrong receptor
no connection
misdirection

28
Q

what is a nerve graft?

A

used when there is wide gap

sew smaller nerves from different part of body to est. alignment (sural)

29
Q

what is conduit repair?

A

man made structure stitched around nerves to allow regrowth

30
Q

what defines regeneration?

A

when nerve allows impulse

31
Q

what are mechanical factors that influence regeneration?

A

Scar tissue

Alignment of fascicles

32
Q

what delay factor affects regeneration?

A

Time related changes in distal nerve

segment & target end organs

33
Q

how does age affect regeneration?

A

pts over 18 are harder to regenerate

34
Q

how does level of injury affect regeneration?

A

More proximal = worse prognosis

inch of regeneration a month

35
Q

what is the reparation process called?

A

axonal regeneration

36
Q

what is needed for successful PN regeneration?

A

Central neuron must survive
Axon growth in supportive environment
Axon must make appropriate distal contact
CNS must integrate peripheral nerve signal appropriately

37
Q

what are the implications for tendon (muscle) transfer?

A

lose grade of strength but regain fxing

therapists must train muscles to do different actions

38
Q

what nerve can do transfers to any muscle?

A

MC n.

39
Q

what does injury to median nerve cause?

A 
“ape hand”
Deficits
– Inability to oppose
thumb
– Decrease in web space
– Inability to perform 3 jaw chuck pinch
40
Q

what is there a decrease in after median nerve injury?

A 
power grasp
FDS (high lesion) 
FDP index & long
fingers
pronation
41
Q

what does injury to the radial nerve cause?

A 
Wrist drop
– Inability to extend fingers at MCP
Deficits
– Loss of finger, wrist, thumb extension
– Decrease in forceful opposition
42
Q

what are signs of ulnar nerve injury?

A 
Froment’s = FPL substitutes for adductor
Wartenburg = Inability to Adduct small finger
43
Q

what does injury to the ulnar nerve cause?

A 
Deformity
– claw hand, hand of benediction
Deficits
– Loss of IV & V extension
– Loss of key pinch
– Weak hook and power grasps
Sensory Loss
– Ulnar border of hand, small finger easily injured
44
Q

how do you test for positive Froments sign?

A

place piece of paper in hand between thumb. clawing with FPL instead of adducting thumb

45
Q

what are the tendon/muscle transfers for the radial nerve?

A

Pronator Teres M. for wrist extension (ECRL & B)

FCU or FDS for finger extension (EDC)

PL or FDS for thumb extension (EPL)

46
Q

what is the fx of the median n?

A
  1. flexion of index & middle fingers using FDP tenodesis, ECU
  2. thumb flexion using brachioradialis
  3. thumb opposition Using EIP, FDS #3 & 4, ECRL, Abductor DM, EDM, ECU, PL
47
Q

what is the role of OT in PNI?

A 
Assist with evaluation/diagnosis – MMT
– Sensibility
Splinting 
Patient Education
Physical Rehab 
– Muscle re-education
– Sensory re-education
48
Q

how do OTs teach sensory re-education?

A

once sensory return begins use extra stimulations on the outside to re learn input

MedPsych Exam 3 (7 decks)

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