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Neuro > Lecture 10: Peripheral Neuropathy Part 1 > Flashcards

Lecture 10: Peripheral Neuropathy Part 1 Flashcards

1
Q

What are the 3 general types of PNS disorders and their characteristics?

A
  1. Nerve cell body: motor or sensory. rarely both at the same time
  2. Axonal: metabolic, distal to proximal symptoms, small fibers usually, causing burning or sharp pain
  3. Myelin sheath: Large fibers, causing slowed conduction, buzzing, and tingling
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2
Q

If vasa nervorum is present, what part of the limb is affected?

A

Distal 2/3

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3
Q

What is the MC mononeuropathy?

A

Carpal Tunnel Syndrome (CTS)

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4
Q

What is multiple mononeuropathy/mononeuritis multiplex and common diseases for it?

A
  • Damage to 2 separate and unrelated nerve areas
  • Seen in systemic diseases like DM, vasculitis, RA, SLE
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5
Q

How does polyneuropathy present?

A
  • Multiple nerves affected
  • Multifocal disease process
  • Symmetric deficits
  • Seen more distally

Example: Diabetic peripheral neuropathy

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6
Q

What is a plexopathy and the 2 MC types?

A
  • Damage or irritation to a nerve plexus
  • Brachial and lumbosacral
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7
Q

What is a radiculopathy and common types?

A
  • Damage or irritation to spinal nerve roots exiting the spine
  • Dermatomal distribution
  • Ex: herniated discs, VZV
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8
Q

What qualifies as acute, subacute, and chronic peripheral neuropathy?

A
  • Acute: days to 4 weeks
  • Subacute: 4-8 weeks
  • Chronic: > 8 weeks
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9
Q

What S/S might suggest upper motor neuron involvement in peripheral neuropathy?

A
  • Muscle weakness, spasms, spasticity
  • Hyperreflexia, clonus, hypertonia, Babinski

UMN lesion is like letting the dog off the leash.

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10
Q

What electrodiagnostic studies should be performed in initial evaluation of a peripheral neuropathy?

A
  • Nerve conduction study (NCS)
  • Electromyography (EMG)

Perform both

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11
Q

What exactly is a nerve conduction study? (NCS)

A
  • Speed at which an electrical impulse moves through a nerve
  • Determines both location and extent of neuropathy
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12
Q

What is the primary contraindication to NCS?

A

External pacemaker wires

For ICDs or internal pacemakers, consult cardio!

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13
Q

What slows nerve conduction speeds?

A
  • Slower in infants and children
  • Slower in men
  • Slower in cold temperatures
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14
Q

In a nerve conduction study, what does decreased amplitude suggest? Decreased conduction velocity?

A
  • Decreased amplitude = axonal degeneration
  • Demyelination = slow internodal conduction and reduced conduction velocity

A for A

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15
Q

What does electromyography (EMG) measure?

A
  • Electrical activity in the skeletal muscle fibers
  • Insertion of needles into muscles
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16
Q

What is an interfering factor with EMG?

A

Deep brain stimulators will cause electrical artifacts

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17
Q

What nerve is compressed in CTS?

A

Median nerve

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18
Q

What are the components of the carpal tunnel?

A
  • Transverse carpal ligament (Ventral)
  • Carpal bones (Dorsal)
  • Median nerves + 9 flexor forearm tendons pass through
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19
Q

Who is CTS MC in?

A

Women

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20
Q

What is the pathophysiology of CTS?

A

Increased pressure in the intracarpal canal

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21
Q

What are the RFs for CTS?

A
  • Obesity
  • Pregnancy
  • DM
  • RA
  • OA of the hand
  • Hypothyroidism
  • CT Diseases
  • Workplace factors
  • Aromatase inhibitors
  • Female
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22
Q

How does CTS typically present?

A
  • Median nerve distribution
  • Dull, aching
  • Paresthesias
  • Weakness/clumsiness of the hand
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23
Q

What aggravates CTS?

A
  • Sleep
  • Sustained hand or arm positions
  • Repetitive movements
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24
Q

What are alleviating factors for CTS?

A
  • Changing hand posture (only works early on)
  • Shaking/ringing of hands
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25
Q

When is atrophy of the thenar eminence seen in CTS?

A

Late

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26
Q

What are the late neurovascular findings seen in CTS?

A
  • Sensory changes only along median nerve
  • Weak thumb abduction and opposition
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27
Q

What is the median nerve distribution?

A
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28
Q

What is SEADS?

A
  • Swelling
  • Erythema
  • Atrophy
  • Deformity
  • Scars (surgical)

Inspection of the hand/wrist

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29
Q

What are the signs/tests associated with CTS?

A
  • Tinel: (the tapping one)
  • Phalen/Prayer: pain when prayer sign made
  • Carpal compression: numbness/tingling when direct pressure applied
  • Hand elevation test: Raising hands above head reproduces symptoms MOST SENSITIVE/SPECIFIC TEST
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30
Q

What is the most sensitive and specific CTS PE test?

A

Hand Elevation Test

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31
Q

What is the MC DDx for CTS?

A

Cervical radiculopathy

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32
Q

What are the first-line diagnostics for CTS?

A

NCS/EMG to confirm Dx and assess severity

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33
Q

What is considered mild CTS based on NCS/EMG? Mod/Sev?

A
  • Mild: sensory conduction delay only
  • Mod: sensory and motor
  • Sev: Axon loss = amplitude decrease
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34
Q

When is US or MRI indicated for CTS?

A

Only if we suspect structural abnormalities

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35
Q

What are the nonsurgical options for helping CTS?

A
  • Modifying activities
  • Cock-up wrist splints
  • Glucocorticoid/anesthetic injections
  • OT/PT
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36
Q

What is the surgery for CTS?

A

Surgical decompression

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37
Q

For mild-mod CTS or pregnant, what is the treatment recommendation? Sev?

A
  • Mild-Mod: Conservative therapy or surgery for non-pregnant once conservative failed.
  • Sev: Conservative while awaiting surgery
38
Q

What is tarsal tunnel syndrome?

A

Compression of tibial nerve through the tarsal tunnel underneath the flexor retinaculum at the level of the medial ankle, affecting the plantar flexors

39
Q

What is the MCC of tarsal tunnel syndrome?

A

Fx or dislocation

MC in athletes

40
Q

How does tarsal tunnel syndrome present?

A
  • Paresthesias + diffuse localized pain of the sole, distal foot, toes, and heel
  • Tenderness over the tunnel
  • Decreased sensation over the plantar surface
  • Possible Tinel’s sign
  • Weakness
  • Severe: Atrophy of the abductor hallucis
41
Q

What worsens tarsal tunnel syndrome?

A
  • Nighttime
  • Walking
  • Prolonged standing
  • Dorsiflexion
  • Eversion
42
Q

If NCS is positive for tarsal tunnel syndrome, what would be seen?

A

Prolonged tibial motor latencies and slowing of conduction velocity

43
Q

When are XRAY and MRI used for tarsal tunnel syndrome?

A
  • XRAY only if fx suspected
  • MRI only if soft tissue mass or tumor suspected
44
Q

How do we treat tarsal tunnel syndrome?

A
  • Conservative with NSAIDs, shoe mods, and orthotics
  • Steroid injection after failure of conservative
  • Surgical decomp not as effective as with CTS
45
Q

When is referral indicated for tarsal tunnel syndrome?

A
  • No response to conservative tx
  • Significant discomfort/impairment in ADLs
  • Noted muscle weakness or atrophy
46
Q

What are the two possible locations for ulnar nerve palsy?

A
  • Cubital Tunnel (Elbow)
  • Guyons’ canal (Wrist)
47
Q

What can damage the cubital tunnel?

A
  • Trauma
  • Funny bone trauma
  • Compression/fricture
48
Q

What two bones surround Guyons’ canal?

A
  • Hamate
  • Pisiform
49
Q

What can cause ulnar nerve palsy via Guyons’ canal?

A
  • Trauma
  • Space occupying lesions
50
Q

What is the 2nd MC focal neuropathy?

A

Ulnar nerve palsy

51
Q

What are the RFs for ulnar nerve palsy?

A
  • Occupations where you lean on your elbows
  • Baseball
  • Cycling
  • Karate
52
Q

How does ulnar nerve palsy present?

A
  • Paresthesias in the 4th and 5th digit
  • Less commonly motor changes
53
Q

What triggers ulnar nerve palsy?

A
  • Sustained elbow flexion
  • Sustained/repetitive grip
  • Leaning on elbow/wrist
  • Repeated pronation/supination
54
Q

What are the 3 possible branches of Guyons’ canal that can produce symptoms in ulnar nerve palsy?

A
  • Superficial terminal branch
  • Palmar cutaneous branch
  • Dorsal cutaneous branch
55
Q

How does a PE present for Ulnar nerve palsy?

A
  • Tenderness over Cubital/Guyons’
  • Decreased ulnar sensations everywhere
  • Tinel’s at elbow or wrist
  • Reproducible symptoms by extreme flexion
  • Weakness/atrophy of the hypothenar eminence
  • Claw hand, worse in Guyons’
  • Froment sign: Thumb adduction weakness against resistance
56
Q

When are MRI and US used for ulnar nerve palsy evaluation?

A

Only if electrodiagnostics are non-confirming

57
Q

What is the conservative management for Ulnar nerve palsy without wasting?

A
  • Avoid prolonged flexion of elbow
  • Padding wrists
58
Q

What are the surgical interventions for ulnar nerve palsies?

A
  • Elbow: Decomp or transposition
  • Wrist: Decomp
59
Q

When is surgery indicated for ulnar nerve palsy?

A
  • Compression due to trauma or structural abnormality
  • Mod-Sev symptoms > 6 mo
  • Refractory
  • Progression
  • Muscle wasting
  • ADL impairment
60
Q

What phenomenon is characteristic of radial nerve palsy?

A

Wrist drop

Inability to extend the wrist, so it drops down.

61
Q

What are the possible locations that can compress the radial nerve?

A
  • Axilla: Crutches
  • Humerus spiral groove: fx, injury, compression due to tourniquets or sleep
  • Proximal forearm (radial tunnel): radial fx
  • Wrist: fx
62
Q

What are the RFs for radial nerve palsy?

A
  • Crutch use
  • Inebriation
  • Improper positioning
  • Frequently tight fitting straps or gloves
  • Trauma
63
Q

Where is sensation decreased with radial nerve palsy?

A
64
Q

How is radial nerve palsy typically diagnosed?

A

Clinically with just H&P.

Only need electrodiagnostics if atypical.

65
Q

What is the conservative tx for radial nerve palsy?

A
  • Wrist splint
  • PT
  • Pain management
66
Q

What would prompt us to do surgery or follow-up EMG for radial nerve palsy?

A
  • Surgery: If symptoms persist more than 6-8 weeks
  • Trauma: follow up with EMG
67
Q

When is referral warranted in radial nerve palsy?

A
  • No improvement after 2-3 weeks
  • Need for EMG/NCS to confirm and determine severity.

Normally, radial nerve palsy improves in 6-8 weeks on its own

68
Q

What are the 3 branches of the trigeminal nerve? (CN V)

A
  • Ophthalmic
  • Maxillary
  • Mandibular
69
Q

What is the typical demographic/Hx of trigeminal neuralgia (TN)?

A
  • Women
  • 40+ years with typical onset of 60-70
  • HTN
  • Migraines
70
Q

What is the underlying physiology behind classic TN?

A
  • Compression of nerve root, causing demyelination around the area.
  • MCC: Abnormally positioned artery/vein
71
Q

What typically precipitates secondary TN?

A
  • MS
  • Tumors
  • Cysts
  • Aneurysms
  • AV malformations
72
Q

How does TN present?

A
  • Paroxysms of intense, superficial UNIlateral pain along a branch.
  • electric, shock-like, stabbing
  • pain lasting seconds
  • Facial spasms used to be called tic doloureux
73
Q

How does V1 TN specifically present?

A
  • Increased lacrimation
  • Conjunctival injection
  • Rhinorrhea
74
Q

What are the typical branches affected in TN?

A

V2 and V3

75
Q

How does chronic TN present?

A
  • Dull aching pain between episodes
  • Reproducible by light touch of trigger zones
76
Q

How does PE typically present for TN?

A

Normal

77
Q

What is the diagnostic criteria for classic TN?

A
  1. 3+ attacks of unilateral facial pain fulfilling criteria 2 and 3
  2. Occurs in 1+ divisions of trigeminal nerve without radiating beyond
  3. 3 out of 4 of: Recurring in paroxysms, severe intensity, electric shock-like/stabbing, or 3+ attacks precipitated by innocuous stimuli
  4. No neurologic deficit
  5. Not better accounted for by another ICHD-3 diagnosis.
78
Q

What are the 4 possible characteristics for TN pain?

A
  1. Recurring in paroxysms for seconds to 2 mins
  2. Severe intensity
  3. Electric, shock-like, stabbing
  4. 3+ attacks precipitated by innocuous stimuli

3 must be met to qualify.

79
Q

What features would suggest secondary TN over classic?

A
  • Shingles or hx of shingles
  • Trauma near nerve in the past 3-6mo
  • Younger than 40
  • Bilateral
  • Hx of MS
  • Sensation loss in a branch
80
Q

What imaging is used to differentiate between secondary and classical TN?

A

MRI brain w/ and w/o con

81
Q

What is the primary drug to treat TN?

A

Carbamazepine

82
Q

What is the MOA and risk of carbamazepine?

A
  • MOA: Reducing neuron excitability
  • Risk: Assess for HLA-B*15:02 allele in asians. Predisposes to SJS or TEN.
83
Q

When do you taper carbamazepine dosing?

A

Once pain control is achieved.

84
Q

What two drug classes can be added on for breakthrough symptoms in TN?

A
  • Neuroleptics: lamotrigine, gabapentin, topiramate
  • Muscle relaxants: Tizanidine, baclofen
85
Q

How do you treat refractory TN?

A
  • Botox
  • Surgery
86
Q

What is Bell’s palsy also known as?

A

CN VII palsy/Facial nerve palsy

87
Q

Who is Bell’s Palsy MC in?

A
  • Colder months
  • 20-40y/o who are pregnant or diabetic
88
Q

How does Bell’s palsy present?

A
  • Acute onset facial weakness in 48hrs.
  • Poor eyelid closure
  • Hyperacusis
  • Decreased tearing
  • Tingling of cheek/mouth
  • Reduced sense of taste
89
Q

How do you workup Bell’s Palsy?

A
  • Clinical Dx
  • Labs/imaging only for r/o of DDx
  • NCS difference of 90% or more = poor prognosis
  • EMG degen of 90% within 3 weeks = poor prognosis
90
Q

How do you manage Bell’s Palsy?

A
  • Prednisone for 10 days (5 days + 5 day taper)
  • Add-on valacyclovir for: lesions, no forehead mvmt, or incomplete eye closure.
  • Lubrication drops and eye patch at night if eye can’t close

Only indicated if within 5 days of symptom onset

91
Q

When is imaging warranted in Bell’s Palsy?

A
  • Symptoms > 8 weeks
  • Progression of symptoms after 3 weeks

You should monitor until it fully resolves

MRI of brain and face
CT w/ con or MRI w/ gadolinium

Neuro (17 decks)

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