Peripheral Nerve Injury Flashcards Preview

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Flashcards in Peripheral Nerve Injury Deck (19):

Structures in the PNS

- Muscle spindle receptors
- Golgi tendon organ
- Motor endings
- Axons


Types of Axons
-efferent vs. afferent
- large vs. small

Efferent - send signals from CNS to body
Afferent - brings information from other parts of the body back to the CNS

Large,efferent = extrafusal muscle fibers
Large, afferent = GTO, spindles, touch & pressure receptors
**large & fast innervate muscles

Small, efferent = presynaptic autonomic
Small, afferent = temp, touch, pain & visceral receptors

Unmyelinated efferent = postsynaptic autonomic
Unmyelinated afferent = temp, pain, visceral
**small & slower innervate autonomic/visceral & sensory areas


-defn & cause
-disrupted element

structure of the nerve remains intact but the conduction down the axon is impaired typically due to ischemia or compression injury

- disrupted element: nerve conduction
-prognosis: full recovery w/n hours-weeks


-defn & cause
-disrupted element

disruption of the neuronal axon but the myelin sheath is intact; typically due to a crush injury

-disrupted element: axon
-prognosis: may regain conduction IF neuronal tubules still intact & can take weeks-years (1mm/day)


-defn & cause
- disrupted element

loss of nerve conduction AND damage to surrounding nerve trunk connective tissue; typically due to laceration, electrical shock, etc

- disrupted element: epineurium
- prognosis: none or minimal return of function; usually neuroma forms at end of nerve preventing normal regeneration to occur


Upper BP Injury
-clinical presentation


MOI - shoulder depression & lateral cervical bend
Clinical Presentation - Waiter's tip: loss of shoulder abduction, weakness of flexion & forearm supination

aka Erb's Palsy


Lower BP injury
-clinical presentation


MOI - compression of cervical rib or stretching of the arm overhead (painting a ceiling)

Clinical presentation - paralysis of intrinsic muscles of the hand (claw hand)

aka Backpackers Palsy


Thoracic Outlet Syndrome
-what is it

BP pain, parasthesia, numbness & weakness

Nerve tension is felt when the plexus is stretched


Axillary Nerve Injury
-clinical presentation


MOI - acute dislocation or fracture of proximal humerus

Clinical presentation - Deltoid atrophy (square shoulder appearance), loss of sensation in lateral deltoid, shoulder abduction & ER weakness


Musculocutaneus Nerve Injury
-clinical presentation


MOI - projectile wounds

Clinical presentation - atrophy along flexor surface of upper arm, weakness of elbow flexion & supination & loss of sensation on radial side of forearm


Median Nerve Injury
-clinical presentation

C5-8, T1

MOI - impingement of hypertrophied pronator teres (pronator syndrome) or CTS

Clinical presentation - N/T in 3 1/2 fingers on palmar side
**APE HAND: atrophy of thenar eminence, no arm pronation, weak grip, no thumb abd or opposition & loss of sensation on thenar region


Ulnar Nerve Injury
-clinical presentation


MOI - compression at medial epicondyle (cubital tunnel syndrome) or Guyon's canal

Clinical presentation - pain, N/T in 1 1/2 fingers on palmar & dorsal side
**CLAW HAND: partial claw w/ atrophy between MT & hypothenar region, loss of spherical grip w/ 4th & 5th fingers, loss of thumb ADDuction & PAD/DAB, loss of sensation in hypothenar region


Radial Nerve Injury
-clinical presentation

C5-8, T1 - "saturday night palsy"

MOI - pressure under arm at radial sulcus OR compression at radial head (PINS) OR compression at ECRB & supinator (Arcade of Frohse)

Clinical presentation -
- PINS: weakness of FINGER extensor muscles & pain & tenderness (no numbess)
-Radial tunnel syndrome - more painful sensation
-superficial radial compression - hand sensation altered

**WRIST DROP - unable to make fist & grasp unless wrist is stabilized in extension
- high lesions also affect triceps


Sciatic Nerve Injury
-clinical presentation

L4-5, S1-3)

MOI - compression at piriformis, hip dislocation or fracture of the femur

Clincal presentation - N/T & pain posterior thigh/leg, atrophy of posterior leg muscles, weak knee flexion, loss of ankle/foot control, loss of sensation in lateral & posterior leg & plantar aspect of foot


Common Peroneal Nerve Injury
- deep & superficial
-clinical presentation


MOI - compression from crossing legs, fracture at head/neck of fibula

Clinical Presentation -
deep = foot drop
superficial = loss of eversion
& loss of sensation in dorsal aspect of foot & anterior/lateral leg


Tibial Nerve Injury
-clinical presentation


MOI - compression between medial malleolus & flexor retinaculum (tarsal tunnel syndrome)

Clinical presentation - N/T at medial part of ankle and/or plantar aspect of foot
- inability to flex the foot or toes & gait impairments


Acute Phase of Nerve Injury Management (4)

immediately after injury or surgery

1. Immobilization
2. Movement
3. Splinting/bracing - prevent deformities or tension
4. Patient education - protection


Subacute Phase of Nerve Injury Management (3)

signal of re-innervation (muscle contraction & increased sensitivity)

1. Motor retraining
2. Desensitization
3. Discriminative sensory reeducation


Chronic Phase of Nerve Injury Management (2)

re-innervation potential peaked w/ minimal or no signs of neurological recovery

1. Compensatory function
2. Preventative care - inspect skin, avoid handling hot/cold/sharp objects, avoid sustained grips, wear gloves, protective & proper shoes, no barefoot, shift weight frequently