Peripheral Nerve Injuries Flashcards

1
Q

Define Neuropraxia
(6 points)

A
  • Temporary block of conduction and physiological function of the nerve without disturbing the anatomical structures.
  • Complete motor loss, with some sensory sparing.
  • Presence of distal nerve conduction.
  • Nerve conduction does occur above and below area of injury is intact.
  • Least severe injury and occurs due to traction, compressive or concussive injury.
  • Full, spontaneous and rapid recovery recovery and is usually complete.
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2
Q

Define axonotmesis
(5 points)

A
  • Disruption to the nerve axon with Wallerian degeneration, while the connective tissue remains intact.
  • Complete motor and sensory loss.
  • Wallerian degeneration occurs 48 to 96 hours after transection
  • Occurs in closed fractures and dislocations
  • Spontaneous recovery from incident can occur but will be incomplete, will take long as the distance is far in terms of nerve growth.
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3
Q

Define Neurotmesis
(5 points)

A
  • Full Transection of the Axon, Myelin sheath, Schwann cell & Connective Tissue.
  • Complete Sensory and Motor Fallout.
  • Traumatic and Wallerian degeneration occurs distally.
  • Poor recovery and Surgical intervention is usually required.
  • Occurs along with most severe injuries like Open fractures or gunshot/stab wounds.
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4
Q

Name five causes of nerve lacerations
(one extra)

A
  • Stab wounds.
  • Gunshots.
  • Compound fractures.
  • Unresolved ischemia.
  • Burns.
  • Nerve root/ spinal nerve compression.
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5
Q

Name seven common sites of injury

A
  • Soft tissue tunnels.
  • Branches of the nervous system.
  • Where the system is relatively fixed.
  • Where the system is exposed to friction forces.
  • Tension points.
  • Superficial.
  • Coursing across a joint.
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6
Q

What does the musculocutaneous nerve supply

A

Arm Flexors.

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7
Q

What does the median nerve supply

A

Anterior forearm and medial hand.

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8
Q

What does the ulnar nerve supply

A

Anteromedial forearm muscles and medial hand.

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9
Q

What does the axillary nerve supply

A

Deltoid and Teres minor.

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10
Q

What does the radial nerve supply

A

Posterior part of the limb.

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11
Q

Sensory innervation of the posterior hand (lateral to medial )

A
  • Radial (dorsal thumb)
  • Medial (anterior thumb to distal half of ring finger)
  • Ulnar (Medial half of ring finger and pinky)
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12
Q

Sensory innervation of the anterior hand (lateral to medial )

A
  • Radial (dorsal thumb to mid phalangeal joints of the index, middle and medial half on ring finger)
  • Medial (anterior thumb, distal segment past middle phalangeal joint of the index, middle and lateral ring finger)
  • Ulnar (Medial half of ring finger and pinky)
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13
Q

What is Erb’s / Erb-Duchenne palsy

A
  • Occurs due to Injury to the upper trunk / C5,C6 Nerve roots.
  • Presents with internal rotation of the arm, elbow extension, slight wrist flexion wrist.
  • Musculocutaneous and radial nerves are affected.
  • “Waiter’s tip hand”.
  • Sensory loss over the back and outer aspect of the forearm and arm.
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14
Q

Describe a upper trunk injury

A
  • C5,C6 nerve root injury.
  • Mechanism of injury: distraction of shoulder and arm from neck: common in birth and a fall from height.
  • Causes Erb’s Palsy/Erb-Duchenne paralysis.
  • Musculocutaneous and radial nerves are affected.
  • Paralysis of scapular muscles. (arm hangs by side).
  • Results in “waiters tip hand” (internal rot, elbow ext, wrist pronation and slight flx.)
  • Sensory loss over the back and outer aspect of arm and forearm
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15
Q

Describe a C5,C6 nerve root injury
(6 points)

A
  • Upper trunk injury
  • Mechanism of injury: distraction of shoulder and arm from neck: common in birth and a fall from height.
  • Causes Erb’s Palsy/Erb-Duchenne paralysis.
  • Musculocutaneous and radial nerves are affected.
  • Paralysis of scapular muscles. (arm hangs by side).
  • Results in “waiters tip hand” (internal rot, elbow ext, wrist pronation and slight flx.)
  • Sensory loss over the back and outer aspect of arm and forearm.
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16
Q

Describe a C8,T1 nerve root injury

A
  • Lower trunk injury.
  • Mechanism of injury: Distraction of the arm from a flexed shoulder.
  • Klumpke’s paralysis (median and ulnar nerve)
  • “Claw hand (wrist flx, finger bent but open hand… tiger fist)”.
  • Decreased sensation along medial side of the arm, forearm and hand.
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17
Q

Describe a lower trunk injury

A
  • C8,T1 nerve roots are compressed/ injured.
  • Mechanism of injury: Distraction of the arm from a flexed shoulder.
  • Klumpke’s paralysis (median and ulnar nerve)
  • “Claw hand (wrist flx, finger bent but open hand… tiger fist)”.
  • Decreased sensation along medial side of the arm, forearm and hand.
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18
Q

Describe a Lower trunk and posterior cord injury

A
  • Mechanism of injury: compression of the axilla (axillary crutches).
  • Saturday night palsy (median, ulnar and radial nerve).
  • Temporary paralysis.
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19
Q

Define and describe Horner’s syndrome

A
  • Characterized by ptosis (drooping eyelid).
  • Miosis (Pupil constriction).
  • Anhidrosis (decreased sweating of the ipsilateral face) .
  • Indicates avulsion of the ipsilateral proximal C8 and or T1 spinal nerve roots.
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20
Q

Assessment of the brachial plexus in a preganglionic lesion

A
  • Horner’s syndrome is present.
  • Unable to elevate scapula.
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21
Q

Assessment of the brachial plexus in a postganglionic lesion

A
  • Horner’s syndrome is absent.
  • Able to elevate scapula.
  • Tinel’s sign is present in later stages.
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22
Q

Treatment of Peripheral nerve injuries

A
  • Splinting (Airplane splint for brachial plexus lesions)
  • Pain Mx. (TENS to release endorphins and decrease pain messages)
23
Q

Describe a below elbow, ulnar nerve injury

A
  • Common injury area where Ulnar nerve passes past the medial epicondyle.
  • Extensive loss of motor and sensory innervation on the ulnar border of the hand (hard to write)
  • Loss of function of the Flexor carpi ulnaris, medial part of flexor digitorum profundus and medial lumbricals as well as hypothenar muscles and adductor pollicis.
  • Impaired power of ulnar deviation.
  • Cannot make a fist (cannot flex 4rth and 5th metacarpal joints).
  • Atrophy of the hypothenar eminence.
  • Loss of thumb adduction.
24
Q

Describe a above elbow, ulnar nerve injury

A
  • Impaired flx. and adduction of the wrist.
  • Impaired movement of the thumb, ring and little finger (grip strength is lower than 50%).
  • Inability to adduct or abduct medial two digits (loss of ulnar innervation to interosseous muscles).
  • Abductor digit minimi abduction of the little finger.
25
Q

In a High ulnar nerve lesion (above elbow) the 4th & 5th digits does not claw that much as lower nerve lesion (below elbow) = it is a paradox why?

A

Long flexor of med 2 fingers (FDP) innervated higher than lesion.

26
Q

Describe a high/low median nerve injury

A
  • Loss of control of the Proximal- and Distal Inter phalangeal joints. (Loss of ability to flex and extend the proximal and distal interphalangeal joints, due to loss of innervation of the lateral 2 lumbricals and the lateral half of the flexor digitorum profundus.)
  • Appears normal when at rest.
  • Pope’s hand or Sign of benediction.
  • Flat thenar eminence and lack of opposition of the thumb.
  • Thumb in abduction due to unopposed pull of adductor pollicis.
  • Power grip is affected due to loss of thumb.
  • Extensive loss of sensation.
  • Usual injury is a laceration to the wrist.
  • Lively splint or thumb rotation strap is used to bring the palmar abduction and opposition to facilitate pinch grip.
27
Q

What injury results in waiter-tip deformity?

A
  • Injury to upper trunk: C5,C6 Nerve roots.
  • Causes erb’s paralysis due to damage to the musculocutaneous and radial nerve.
28
Q

What injury results in the hand of benediction?

A
  • Injury to the lower trunk: C8,T1 nerve roots.
  • Causes klumpke’s palsy due to damage to median and ulnar nerves.
29
Q

What injury results in Saturday night palsy?

A
  • Damage to Lower trunk and the posterior cord
  • Median, ulnar involvement with possible radial nerve involvement.
30
Q

Describe the symptoms of a median nerve injury

A
  • Power grip is affected due to loss of thumb.
  • Extensive loss of sensation.
  • Usual injury is a laceration to the wrist.
  • Lively splint or thumb rotation strap is used to bring the palmar abduction and opposition to facilitate pinch grip.
31
Q

What is carpal tunnel syndrome?

A
  • Numbness or pain in of the palmar aspect of the hand.
  • Due to Compression of the median nerve at the wrist.
  • Does present with some paresthesia or anesthesia or hypo anesthesia of some digits.
  • Function of the three most lateral digits may be impaired.
    Common between ages of 40-60.
32
Q

Describe a above elbow, radial nerve injury

A
  • Proximal origin of triceps
  • Loss of sensation to the tip of the shoulder.
  • Complete paralysis of the triceps, brachioradialis, supinator & extensors of the wrist & digits.
  • Wrist drop (waiters hand with towel against abdomen/ Adam and God painting).
  • Damage to Radial groove.
  • Partial paralysis of the triceps.
  • Complete paralysis of the brachioradialis, supinator and extensors of the wrist.
  • Wrist drop (waiters hand with towel against abdomen/ Adam and God painting).
33
Q

Describe a below elbow, radial nerve injury

A
  • Usually deep laceration of the forearm.
  • Loss of active extension of thumb and MCP of the other digits.
  • If the other digits are severed: loss of sensation on the posterior surface of the forearm, hand and proximal phalanges.
  • Dropped wrist results. (waiters hand with towel against abdomen/ Adam and God painting).
34
Q

Describe causes of Sciatic nerve palsy
(4 points)

A
  • Traumatic hip dislocations.
  • Pelvic fractures.
  • Incorrectly administered gluteal injections.
  • THR. can cause it
35
Q

Sciatic nerve palsy results in?

A
  • Affects the hamstring muscles and all muscles below the knee are affected.
  • Sensation is lost below the knee except on the medial side of the leg (take care to avoid damage to the desensitized skin).
  • High stepping gait.
  • Drop foot: splint should be fitted.
36
Q

Describe damage to the Common peroneal nerve

A
  • Damage to neck of fibula.
  • Pressure from a badly applied cast.
  • Denham pins for surgical fixation.
  • Drop foot due to anterior tibial and peroneal muscles.
  • Sensory loss over the dorsum of the foot and lateral leg.
37
Q

Describe damage to the Posterior tibial nerve

A
  • Fracture or dislocation of the ankle.
  • Motor paralysis of the intrinsic muscles with active long flexors: clawing of the toes.
  • Loss of sensation of the sole of the foot.
38
Q

Describe the common complications of peripheral nerve injury

A
  • Complex Regional Pain Syndrome(CRPS) may develop (Sudeck’s atrophy)
  • Neuroma formation.
  • Soft tissue damage due to impaired sensation.
39
Q

Define Complex Regional Pain Syndrome (CRPS) and name a few symptoms

A
  • Abnormal response to injury.
  • Hypothesis: Results due to initial vasomotor spasm.
  • Symptoms: Hyper aesthesia, allodynia (central sensitization), excessive pain, tropic changes, autonomic deregulation.
40
Q

Define the mechanism of Complex Regional Pain Syndrome
(4 Points)

A
  • Original injury: pain impulse carried to central NS.
  • Pain impulse triggers an impulse in the SNS which returns to the original site of injury.
  • SNS triggers the inflammatory response which causes vessels to spasm and swelling occurs and increases pain..
    Pain again triggers another response and thus establishes a feedback cycle.
41
Q

Describe Complex Regional Pain Syndrome (CRPS) Stage 1

A
  • Early- Excessive vasodilation
  • Red, hot, sweaty, swollen.
  • Tender muscles.
  • Does not move: exudates organize.
42
Q

Describe Complex Regional Pain Syndrome (CRPS) Stage 2

A
  • Intermediate
  • Vasoconstriction
  • Cold, Cyanotic, Glazed.
  • Hair loss, Brittle nails.
  • Muscle wasting, osteoporotic bone.
  • Joints are swollen, stiff and painful.
43
Q

Describe Complex Regional Pain Syndrome (CRPS) Stage 3

A
  • Late stage.
  • Skin cold, pale and smooth.
  • No hair.
  • Muscles atrophied and fibrosis (Sudecks’s).
  • Joints atrophied and stiff.
  • Bones are osteoporotic.
  • Limb withered and wasted.
  • Cutaneous hypersensitivity.
44
Q

Define Sudeck’s Atrophy

A
  • A type of CRPS
  • Fractures or crushing injuries to the wrist and hand
  • Intense burning pain, swelling, redness, dryness and sweating.
  • Wrist and hand is rested in position of function (Elevation to avoid swelling).
  • Treatment of sympathetic outflow (TENS/IF)
45
Q

Outline Sudeck’s Atrophy treatment in the acute stage

A
  • Graded motor imagery/movement.
  • Encourage function.
  • Pain control - electrotherapy is CI with impaired sensation.
  • Education on pathology and dangers of sensory impairment.
  • Posture correction and OT for splinting.
  • Psychological support.
  • Oedema: elevation and massage.
  • Stiffness: passive movements(teach patient of passives and sensory re-education).
  • Do not over mobilize/ overstretch.
  • Maintain strength of unaffected muscles.
46
Q

Outline Sudeck’s Atrophy treatment in the recovery stage

A
  • Re-education of the muscle in midrange, then outer and finally inner range.
  • Threshold of the recovering nerve is high and facilitation is NB: ice, quick brushing, electrical stim.
  • Application of specific resistance, direct movement, increase sensory input by manual techniques e.g. PNF.
47
Q

Define Wallerian degeneration

A
  • Active process of degeneration of a distal segment of nerve axon, past the traumatic degenerating segment after the point where the nerve has been transected. break up withing first 48 hrs.
  • The axon and myelin sheath degenerate and macrophages clear the debris.
  • Degeneration occurs because the axon is dependent on the connected cell for survival.
48
Q

Define the clinical features associated with wrist drop.

A
  • Usually an injury associated with radial nerve damage.
  • Occurs in both high and low lesions of the radial nerve.
  • May present with loss of sensation of the posterior surface of the forearm, hand and proximal phalanges innervated by the radial nerve. (Low lesion)
  • May present with paralysis of of brachioradialis, supinator and extensors of the wrists and digits.
49
Q

In which type of brachial plexus injury is paralysis of the scapular muscles present?

A

Upper trunk injury. (C5,C6 nerve root injury) leads to paralysis of the scapular muscles.
Preganglionic lesions lead to inability to elevate the scapula. (Along with Horner’s syndrome)

50
Q

State the mechanism of injury involved in a lower trunk brachial plexus injury

A

Distraction of the arm while the shoulder is in a flexed position, causing ulnar and median fallout (klumpke’s palsy)

51
Q

State the mechanism of injury involved in a Upper Trunk brachial plexus injury

A

Distraction of the shoulder and arm from the neck (Common in birth and a fall from a height onto side of head and shoulder leading to damage of the musculocutaneous and radial nerve) Leads to Erb’s palsy.

52
Q

State the mechanism of injury involved in a lower trunk and posterior cord brachial plexus injury.

A

Compression of the nerve in the axilla (axillary nerve when using axillary crutches). Causes Saturday nights palsy.

53
Q

Name the type of paralysis that the lower trunk and posterior cord of the brachial plexus injury leads to

A

Saturday night palsy.

54
Q

List three characteristics of Horner’s syndrome

A
  • Ptosis (Drooping eyelid).
  • Miosis (Constriction of the pupil).
  • Anhidrosis (decreased sweating on ipsilateral side of the face).