Peripheral Nerve Injuries Flashcards

1
Q

What is the endoneurium? What is it’s role?

A

sheath that encompasses the axon or nerve fiber that plays an important role in protecting against transmission of substances across the nerve membrane

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2
Q

What is the perineum? What does it provide?

A

Sheath that surrounds each fascicle and provides a perineural diffusion barrier capable of controlling flow of substances bi-directionally

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3
Q

What is the epineurium?

A

outermost connective tissue that is highly vascular and provides no diffusion barrier function

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4
Q

What are the 3 typical mechanisms of injury for nerves?

A

Acute ischemia
segmental demyelination
axonal degeneration

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5
Q

What are the 3 nerve injury classifications according to Seddon’s classification scheme?

A

Neurapraxia
Axonotmesis
Nuerotmesis

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6
Q

What are the common etiology classification for mononeuropathies?

What are the classifications for poly neuropathies?

A

traumatic and non-traumatic

metabolic
nutritional
hereditary
immunologically mediated
infectious disease
paraneoplastic
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7
Q

What are the clinical features of mononeuropathies?

What are the clinical features of polyneuropathies?

A

motor and sensory deficits limited in distribution

  • bilateral and fairly symmetric
  • effect large fibers distally first
  • sensory loss precedes motor
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8
Q

What are common clinical features for peripheral nerve injuries?

A
  • tendon hyporeflexia
  • tremor
  • autonomic dysunction such as anhidrosis (not producing sweat), orthostatic hypotension, trophic changes, and loss of erector pilae function
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9
Q

How does weakness and sensory loss differ between mononeuropathies and polyneuropathies?

A

Mono:

  • weakness is proportional to motor neurons effected
  • sensory loss in nerve field distal to lesion

Poly:

  • weakness is symmetrical and distal
  • sensory loss is distal in feet and hands
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10
Q

What syndromes are associated with median nerve mononeuropathy?

A
  • pronator teres syndrome
  • anterior interosseous syndrome
  • carpal tunnel syndrome
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11
Q

What is the etiology of pronator teres syndrome?

What are the clinical features of this syndrome?

A
  • pierces 2 heads of pronator teres
  • trauam, fracture, muscle hypertrophy, fibrotic band, and bicipital aponeurosis
  • pain and TTP over PT which increases w/ activity
  • sensory changes to thenar eminence, D1-3 and possibly D4
  • motor involvement: FPL, FDP 1/2, APB, OP, 1/2 FPB; PT may be spared (sparing FCR, PL, and FDS)
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12
Q

What tests will indicate a positive diagnosis for pronator teres syndrome?

A

(+) pronator teres syndrome test
(+) Tinel’s in forearm
(-) Phalen’s

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13
Q

What is the etiology of anterior interosseous syndrome?

What are the clinical features of this syndrome?

A
  • elbow dislocation
  • fibrotic bands

clinical features:

  • prox. forearm pain
  • no sensory loss but have aching
  • motor loss of FPL. FDP 1/2, and PQ
  • no “OK” sign (Kilo Nevin)
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14
Q

What is the etiology of carpal tunnel syndrome?

A
  • most common compression neuropathy
  • may be predisposed by polyneuropathy
  • ganglia, tumor
  • RA-thickening tendon sheath
  • effects females more than males
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15
Q

What are the clinical features of carpal tunnel syndrome?

A
  • painful paresthesias with use and at night
  • sensory deficits median distribution sparing thenar eminence
  • atrophy of thenar muscles
  • may describe pain radiating distal to proximal
  • may report “dropping” objects
  • (+) Tinel’s at wrist
  • (+) Phalen’s and Rev. Phalen’s
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16
Q

What is the clinical prediction rule for carpal tunnel syndrome?

How does the probability of CTS changes with each positive sign?

A
  • hand shaking improves symptoms
  • wrist ratio index over .67
  • symptom severity score over 1.9
  • diminished sensation in median sensory field 1 (thumb)
  • age over 45

if 2 are (+)=44% probability
if 3 are (+)=52%
If 4 are (+)=70%
if all 5 are (+)=90% and a .99 specificity

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17
Q

True or False: Splinting for carpal tunnel syndrome is a better intervention than exercise or oral steroids.

A

False, evidence does not prove one is superior to the other

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18
Q

True or False: Surgical treatment for carpal tunnel syndrome helps relieve symptoms far better than splinting

A

True

19
Q

What conditions can occur due to ulnar nerve injury?

A
  • tardy ulnar palsy/cubital tunnel syndrome

- Guyon’s Canal

20
Q

What is the etiology of tardy ulnar palsy/cubital tunnel syndrome?

What are the clinical features for this syndrome?

A
  • 2nd most common peripheral nerve compression injury
  • ulnar nerve injury at elbow due to repetitive trauma, prolonged compression, and/or immobilization
  • tardy implies the injury occurred long before SxS

Clinical Features:

  • sensory deficits 5th digit and ulnar 1/2 of 4th
  • vague pain
  • atrophy ulnar intrinsics, FCU usually spared, unless lesion is above elbow
  • (+) elbow flexion test
  • (+) Tinel’s at cubital tunnel
21
Q

What is the etiology for compression at Guyon’s canal?

What are the clinical features?

A
  • less common than at elbow
  • ganglion, trauma, RA
  • athletes: mainly bicyclists and racket sports

Clinical Features:

  • sensory deficits depend on zone compromised (zone 1 is motor and sensory, zone 2 is motor only, and zone 3 is sensory only)
  • vague pain
  • atrophy ulnar intrinsics, FCU usually spared, unless lesion is above elbow
  • (+) Phalen’s/ Rev Phalen’s
  • (+) Tinel’s at cubital tunnel
  • (+) Froment’s sign
  • (+) Wartenberg’s sign
22
Q

How does the specificity and sensitivity change for the elbow flexion test as the time increases from 30 to 60 seconds?

How does the specificity and sensitivity change for the elbow pressure provocation test as the time increases from 30 to 60 seconds?

Is Tinel’s sign at the elbow more sensitive or specific?

A

specificity does not change but sensitivity jumps from .32 to .74

same as elbow flexion except sensitivity changes from .55 to .89

More specific

23
Q

What conditions can be caused do to an injury to the radial nerve?

A

Upper arm lesion
Posterior interosseous syndrome
radial tunnel
Wartenberg’s syndrome

24
Q

What is the etiology of an upper arm radial nerve lesion?

What are the clinical features for a lesion at the spiral groove?

What are the clinical features for a lesion proximal to the spiral groove?

A
  • fracture/trauma
  • compression (crutch palsy or Saturday night palsy)

spiral groove:

  • most common site
  • sensory loss dorsum of hand and 1st two digits
  • triceps spared
  • weakness is distal to triceps (complete wrist drop)

Prox. to Spiral Groove:

  • sensory loss to posterior arm and post. 1/3 forearm plus dorsum of hand and web space
  • triceps affected plus all distal radial n. innervates muscles
25
Q

What is the etiology of posterior interosseous nerve (PIN) syndrome?

What are the clinical features for PIN syndrome?

A
  • fracture, fibrotic tissue, RA
  • may occur at Arcade of Frohse (between 2 heads of supinator)

Clinical Features:

  • lateral elbow pain subsides rapidly w/ onset of weakness
  • no sensory deficits
  • motor weakness in wrist extensors and cannot extend MCP joints unless wrist is flexed
26
Q

What are the clinical features of radial tunnel syndrome?

A
  • lateral elbow pain, usually 4-6 cm below epicondyle
  • no sensory deficits
  • motor wekaness is rare

-not a true neuropathy; if neuropathic changes present then formally a PIN

27
Q

What is the etiology of Wartenburg’s Syndrome?

What are the clinical features for this syndrome?

A
  • compression of superficial radial nerve branch
  • most common as nerve exits from the musculotendinous junction
  • chronic pressure, repetitive provocation, direct trauma (handcuffs)

Clinical Features:

  • numbness and/or pain in dorsal-radial wrist and hand
  • symptoms exacerbate w/ pronation, wrist/finger flexion, and ulnar deviation
  • symptoms exacerbation possible w. forced grip and resisted pronation
28
Q

What common deformity of the hand is due to damage to the median nerve?

What common deformity of the hand is due to damage to the ulnar nerve?

What common deformity of the hand is due to damage to the radial nerve?

What common deformity of the hand is due to damage to the median and ulnar nerves combined?

A

Median: Ape Hand

Ulnar: Bishop’s (benediction) hand

Radial: Wrist Drop

Median/Ulnar: claw or intrinsic minus hand

29
Q

What is the etiology of thoracic outlet syndrome?

What are the common locations of ischemic compression?

A

non-neurogenic

  • Scalenes due to hypertrophy, fibromuscular bands, and overuse
  • 1st rib and clavicle- assoc. w/ cervical rib, old clavicle fracture, or poor posture
  • pec minor-posture, tight pec minor
30
Q

What are the clinical features of thoracic outlet syndrome?

What interventions are indicated for TOS?

A
  • more common in middle aged women
  • subjective: UE pain/paresthesias (C8/T1), vasomotor changes, chest/shoulder pain
  • Objective: poor posture, no neurologic changes, TOS provocative tests

Interventions:

  • based on etiology and anatomical considerations
  • posture education
  • stretching/strengthening to improve posture
31
Q

What is the common MOI for an axillary nerve injury?

What are the signs and symptoms of an axillary nerve injury?

A

often the result of a dislocation

SxS:

  • sensory deficits in axillary patch
  • motor weakness in teres minor and deltoid
  • atrophy
  • associated pain
32
Q

What is the etiology for a suprascapular nerve injury?

What are the clinical features of this injury?

A
  • Traction
  • direct blow
  • cysts

Clinical features:

  • often mistaken as an RC tear
  • deep burning worse w/ horizontal adduction
  • tender over suprascapular or spinoglenoid notches
  • no sensory deficit
  • RC weakness and atrophy of supra and infraspinatus fossa
33
Q

What is the etiology of an injury to the long thoracic nerve?

What are the associated clinical features?

A
  • often idiopathic
  • fall/landing on slide, digital palpation in the posterior triangle

Clinical Features:

  • winging
  • aching or may be painless
  • secondary shoulder symptoms
34
Q

What is the etiology of brachial plexus birth injuries?

What is the prognosis for these injuries?

A
  • birth trauma due to birth canal or assisted delivery forces (forceps, rotation)
  • brachial plexus injuries can range from mild neuropraxia w/ early recovery to complete disruption w/ no potential for recovery

Prognosis:

  • greater than 80% of affected children will attain near-normal function
  • patients who show evidence of biceps function before 6 months of age have near normal to excellent function
35
Q

What are the clinical features for Erb’s Palsy?

A
  • shoulder becomes extended, internally rotated, and slightly abducted
  • active abduction of joint decreases and external rotation ceases
  • shoulder is posteriorly subluxated and may dislocate

-in half of the patients the elbow will be affected such as radial head may be dislocated posteriorly and in those the ulna may be posteriorly bowed, in most severe deformities the elbow progressively dislocated posteriorly and medially

36
Q

What are the clinical features of Klumpke’s Palsy? (lower roots C8 and T1 and/or C7)

A
  • lesions usually preganglionic
  • may have an assoc. Horner’s Syndrome
  • sensory deficit is along the medial aspect of the arm, forearm, and hand
  • may follow forceful abduction of shoulder, produces weakness in intrinsics of hand as well as long flexors and extensors of the fingers
37
Q

How successful is surgical intervention for nerve injuries?

A

the results vary and depend on the nerve affected and severity of lesion

the prognosis also depends on location, severity, and duration of the lesion

38
Q

What are the non-operative treatment options for nerve injuries?

A
  • education
  • pain control
  • Maintain ROM/strength- be aware of antagonist relationships predisposing to contracture, use of tenodesis
  • monitor compensations/posture
  • support/brace as needed
39
Q

True or False: E-stim is very effective for nerve injuries

A

False, E-stim has not been shown to be beneficial

40
Q

True or False: Low-load strengthening exercises are indicated for nerve injuries

A

True, low load is better than high load to avoid muscle fatigue and more importantly avoid axonal fatigue which may worsen their condition

Remember to do no harm!!!

41
Q

What tissues are injured in neuropraxia injuries?

A

Myelin-leads to numbness and “pins and needles” feeling

42
Q

What tissues are injured in an axonotmesis injury?

A

Myelin and axons- this injury is like when a football player gets a “stinger”

43
Q

What tissues are injured in neurotmesis injuries?

A

depends on grade but injures the myelin and axons as well as some level of neuronal sheath such as endoneurium or epineurium

Worst prognosis with this injury as it is a complete disruption of the nerve