Peripheral Nerve Injuries Flashcards
Define Neuropraxia
(6 points)
- 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.
Define axonotmesis
(5 points)
- 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.
Define Neurotmesis
(5 points)
- 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.
Name five causes of nerve lacerations
(one extra)
- Stab wounds.
- Gunshots.
- Compound fractures.
- Unresolved ischemia.
- Burns.
- Nerve root/ spinal nerve compression.
Name seven common sites of injury
- 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.
What does the musculocutaneous nerve supply
Arm Flexors.
What does the median nerve supply
Anterior forearm and medial hand.
What does the ulnar nerve supply
Anteromedial forearm muscles and medial hand.
What does the axillary nerve supply
Deltoid and Teres minor.
What does the radial nerve supply
Posterior part of the limb.
Sensory innervation of the posterior hand (lateral to medial )
- Radial (dorsal thumb)
- Medial (anterior thumb to distal half of ring finger)
- Ulnar (Medial half of ring finger and pinky)
Sensory innervation of the anterior hand (lateral to medial )
- 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)
What is Erb’s / Erb-Duchenne palsy
- 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.
Describe a upper trunk injury
- 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
Describe a C5,C6 nerve root injury
(6 points)
- 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.
Describe a C8,T1 nerve root injury
- 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.
Describe a lower trunk injury
- 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.
Describe a Lower trunk and posterior cord injury
- Mechanism of injury: compression of the axilla (axillary crutches).
- Saturday night palsy (median, ulnar and radial nerve).
- Temporary paralysis.
Define and describe Horner’s syndrome
- 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.
Assessment of the brachial plexus in a preganglionic lesion
- Horner’s syndrome is present.
- Unable to elevate scapula.
Assessment of the brachial plexus in a postganglionic lesion
- Horner’s syndrome is absent.
- Able to elevate scapula.
- Tinel’s sign is present in later stages.
Treatment of Peripheral nerve injuries
- Splinting (Airplane splint for brachial plexus lesions)
- Pain Mx. (TENS to release endorphins and decrease pain messages)
Describe a below elbow, ulnar nerve injury
- 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.
Describe a above elbow, ulnar nerve injury
- 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.
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?
Long flexor of med 2 fingers (FDP) innervated higher than lesion.
Describe a high/low median nerve injury
- 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.
What injury results in waiter-tip deformity?
- Injury to upper trunk: C5,C6 Nerve roots.
- Causes erb’s paralysis due to damage to the musculocutaneous and radial nerve.
What injury results in the hand of benediction?
- Injury to the lower trunk: C8,T1 nerve roots.
- Causes klumpke’s palsy due to damage to median and ulnar nerves.
What injury results in Saturday night palsy?
- Damage to Lower trunk and the posterior cord
- Median, ulnar involvement with possible radial nerve involvement.
Describe the symptoms of a median nerve injury
- 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.
What is carpal tunnel syndrome?
- 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.
Describe a above elbow, radial nerve injury
- 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).
Describe a below elbow, radial nerve injury
- 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).
Describe causes of Sciatic nerve palsy
(4 points)
- Traumatic hip dislocations.
- Pelvic fractures.
- Incorrectly administered gluteal injections.
- THR. can cause it
Sciatic nerve palsy results in?
- 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.
Describe damage to the Common peroneal nerve
- 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.
Describe damage to the Posterior tibial nerve
- 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.
Describe the common complications of peripheral nerve injury
- Complex Regional Pain Syndrome(CRPS) may develop (Sudeck’s atrophy)
- Neuroma formation.
- Soft tissue damage due to impaired sensation.
Define Complex Regional Pain Syndrome (CRPS) and name a few symptoms
- Abnormal response to injury.
- Hypothesis: Results due to initial vasomotor spasm.
- Symptoms: Hyper aesthesia, allodynia (central sensitization), excessive pain, tropic changes, autonomic deregulation.
Define the mechanism of Complex Regional Pain Syndrome
(4 Points)
- 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.
Describe Complex Regional Pain Syndrome (CRPS) Stage 1
- Early- Excessive vasodilation
- Red, hot, sweaty, swollen.
- Tender muscles.
- Does not move: exudates organize.
Describe Complex Regional Pain Syndrome (CRPS) Stage 2
- Intermediate
- Vasoconstriction
- Cold, Cyanotic, Glazed.
- Hair loss, Brittle nails.
- Muscle wasting, osteoporotic bone.
- Joints are swollen, stiff and painful.
Describe Complex Regional Pain Syndrome (CRPS) Stage 3
- 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.
Define Sudeck’s Atrophy
- 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)
Outline Sudeck’s Atrophy treatment in the acute stage
- 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.
Outline Sudeck’s Atrophy treatment in the recovery stage
- 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.
Define Wallerian degeneration
- 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.
Define the clinical features associated with wrist drop.
- 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.
In which type of brachial plexus injury is paralysis of the scapular muscles present?
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)
State the mechanism of injury involved in a lower trunk brachial plexus injury
Distraction of the arm while the shoulder is in a flexed position, causing ulnar and median fallout (klumpke’s palsy)
State the mechanism of injury involved in a Upper Trunk brachial plexus injury
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.
State the mechanism of injury involved in a lower trunk and posterior cord brachial plexus injury.
Compression of the nerve in the axilla (axillary nerve when using axillary crutches). Causes Saturday nights palsy.
Name the type of paralysis that the lower trunk and posterior cord of the brachial plexus injury leads to
Saturday night palsy.
List three characteristics of Horner’s syndrome
- Ptosis (Drooping eyelid).
- Miosis (Constriction of the pupil).
- Anhidrosis (decreased sweating on ipsilateral side of the face).
