Lecture 10: Peripheral Neuropathy Part 1 Flashcards
1
Q
What are the 3 general types of PNS disorders and their characteristics?
A
- Nerve cell body: motor or sensory. rarely both at the same time
- Axonal: metabolic, distal to proximal symptoms, small fibers usually, causing burning or sharp pain
- Myelin sheath: Large fibers, causing slowed conduction, buzzing, and tingling
2
Q
If vasa nervorum is present, what part of the limb is affected?
A
Distal 2/3
3
Q
What is the MC mononeuropathy?
A
Carpal Tunnel Syndrome (CTS)
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
5
Q
How does polyneuropathy present?
A
- Multiple nerves affected
- Multifocal disease process
- Symmetric deficits
- Seen more distally
Example: Diabetic peripheral neuropathy
6
Q
What is a plexopathy and the 2 MC types?
A
- Damage or irritation to a nerve plexus
- Brachial and lumbosacral
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
8
Q
What qualifies as acute, subacute, and chronic peripheral neuropathy?
A
- Acute: days to 4 weeks
- Subacute: 4-8 weeks
- Chronic: > 8 weeks
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.
10
Q
What electrodiagnostic studies should be performed in initial evaluation of a peripheral neuropathy?
A
- Nerve conduction study (NCS)
- Electromyography (EMG)
Perform both
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
12
Q
What is the primary contraindication to NCS?
A
External pacemaker wires
For ICDs or internal pacemakers, consult cardio!
13
Q
What slows nerve conduction speeds?
A
- Slower in infants and children
- Slower in men
- Slower in cold temperatures
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
15
Q
What does electromyography (EMG) measure?
A
- Electrical activity in the skeletal muscle fibers
- Insertion of needles into muscles
16
Q
What is an interfering factor with EMG?
A
Deep brain stimulators will cause electrical artifacts
17
Q
What nerve is compressed in CTS?
A
Median nerve
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
19
Q
Who is CTS MC in?
A
Women
20
Q
What is the pathophysiology of CTS?
A
Increased pressure in the intracarpal canal
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
22
Q
How does CTS typically present?
A
- Median nerve distribution
- Dull, aching
- Paresthesias
- Weakness/clumsiness of the hand
23
Q
What aggravates CTS?
A
- Sleep
- Sustained hand or arm positions
- Repetitive movements
24
Q
What are alleviating factors for CTS?
A
- Changing hand posture (only works early on)
- Shaking/ringing of hands
25
When is atrophy of the thenar eminence seen in CTS?
Late
26
What are the **late neurovascular findings** seen in CTS?
* Sensory changes **only along median nerve**
* **Weak thumb abduction and opposition**
27
What is the median nerve distribution?
28
What is SEADS?
* Swelling
* Erythema
* Atrophy
* Deformity
* Scars (surgical)
| Inspection of the hand/wrist
29
What are the signs/tests associated with CTS?
* 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**
30
What is the most sensitive and specific CTS PE test?
Hand Elevation Test
31
What is the MC DDx for CTS?
Cervical radiculopathy
32
What are the first-line **diagnostics** for CTS?
NCS/EMG to **confirm Dx and assess severity**
33
What is considered mild CTS based on NCS/EMG? Mod/Sev?
* Mild: **sensory** conduction delay only
* Mod: **sensory and motor**
* Sev: **Axon loss = amplitude decrease**
34
When is US or MRI indicated for CTS?
Only if we suspect **structural abnormalities**
35
What are the **nonsurgical options** for helping CTS?
* Modifying activities
* Cock-up wrist splints
* Glucocorticoid/anesthetic injections
* OT/PT
36
What is the surgery for CTS?
Surgical decompression
37
For mild-mod CTS or pregnant, what is the treatment recommendation? Sev?
* Mild-Mod: Conservative therapy or surgery for non-pregnant once conservative failed.
* Sev: Conservative while awaiting surgery
38
What is tarsal tunnel syndrome?
Compression of tibial nerve through the **tarsal tunnel underneath the flexor retinaculum** at the level of the **medial ankle**, affecting the **plantar flexors**
39
What is the MCC of tarsal tunnel syndrome?
Fx or dislocation
| MC in **athletes**
40
How does tarsal tunnel syndrome present?
* 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
What worsens tarsal tunnel syndrome?
* Nighttime
* Walking
* Prolonged standing
* Dorsiflexion
* Eversion
42
If NCS is positive for tarsal tunnel syndrome, what would be seen?
Prolonged tibial motor latencies and **slowing of conduction velocity**
43
When are XRAY and MRI used for tarsal tunnel syndrome?
* XRAY only if fx suspected
* MRI only if soft tissue mass or tumor suspected
44
How do we treat tarsal tunnel syndrome?
* Conservative with NSAIDs, shoe mods, and orthotics
* **Steroid injection after failure of conservative**
* Surgical decomp **not as effective as with CTS**
45
When is referral indicated for tarsal tunnel syndrome?
* No response to conservative tx
* **Significant discomfort/impairment in ADLs**
* **Noted muscle weakness or atrophy**
46
What are the two possible locations for ulnar nerve palsy?
* Cubital Tunnel (Elbow)
* Guyons' canal (Wrist)
47
What can damage the cubital tunnel?
* Trauma
* Funny bone trauma
* Compression/fricture
48
What two bones surround Guyons' canal?
* Hamate
* Pisiform
49
What can cause ulnar nerve palsy via Guyons' canal?
* Trauma
* Space occupying lesions
50
What is the 2nd MC focal neuropathy?
Ulnar nerve palsy
51
What are the RFs for ulnar nerve palsy?
* Occupations where you lean on your elbows
* Baseball
* Cycling
* Karate
52
How does ulnar nerve palsy present?
* Paresthesias in the **4th and 5th digit**
* **Less commonly motor changes**
53
What triggers ulnar nerve palsy?
* Sustained elbow **flexion**
* Sustained/repetitive grip
* Leaning on elbow/wrist
* Repeated pronation/supination
54
What are the 3 possible branches of Guyons' canal that can produce symptoms in ulnar nerve palsy?
* Superficial terminal branch
* Palmar cutaneous branch
* Dorsal cutaneous branch
55
How does a PE present for Ulnar nerve palsy?
* 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
When are MRI and US used for ulnar nerve palsy evaluation?
Only if electrodiagnostics are **non-confirming**
57
What is the conservative management for Ulnar nerve palsy **without wasting**?
* Avoid prolonged flexion of elbow
* Padding wrists
58
What are the surgical interventions for ulnar nerve palsies?
* Elbow: Decomp or transposition
* Wrist: Decomp
59
When is surgery indicated for ulnar nerve palsy?
* Compression due to trauma or structural abnormality
* Mod-Sev symptoms **> 6 mo**
* Refractory
* Progression
* **Muscle wasting**
* **ADL impairment**
60
What phenomenon is characteristic of radial nerve palsy?
Wrist drop
| Inability to extend the wrist, so it drops down.
61
What are the possible locations that can compress the radial nerve?
* Axilla: Crutches
* **Humerus spiral groove**: fx, injury, compression due to tourniquets or sleep
* Proximal forearm (radial tunnel): radial fx
* Wrist: fx
62
What are the RFs for radial nerve palsy?
* **Crutch use**
* Inebriation
* Improper positioning
* Frequently **tight fitting** straps or gloves
* Trauma
63
Where is sensation decreased with radial nerve palsy?
64
How is radial nerve palsy typically diagnosed?
Clinically with just H&P.
| Only need electrodiagnostics if atypical.
65
What is the conservative tx for radial nerve palsy?
* Wrist splint
* PT
* Pain management
66
What would prompt us to do surgery or follow-up EMG for radial nerve palsy?
* Surgery: If symptoms persist more than **6-8 weeks**
* Trauma: **follow up with EMG**
67
When is referral warranted in radial nerve palsy?
* 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
What are the 3 branches of the trigeminal nerve? (CN V)
* Ophthalmic
* Maxillary
* Mandibular
69
What is the typical demographic/Hx of trigeminal neuralgia (TN)?
* Women
* 40+ years with typical onset of 60-70
* HTN
* Migraines
70
What is the underlying physiology behind classic TN?
* Compression of nerve root, causing demyelination around the area.
* **MCC: Abnormally positioned artery/vein**
71
What typically precipitates secondary TN?
* MS
* Tumors
* Cysts
* Aneurysms
* AV malformations
72
How does TN present?
* 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
How does V1 TN specifically present?
* Increased lacrimation
* Conjunctival injection
* Rhinorrhea
74
What are the typical branches affected in TN?
V2 and V3
75
How does chronic TN present?
* Dull aching pain between episodes
* Reproducible by light touch of **trigger zones**
76
How does PE typically present for TN?
Normal
77
What is the diagnostic criteria for classic TN?
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
What are the 4 possible characteristics for TN pain?
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
What features would suggest **secondary TN over classic**?
* 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
What imaging is used to differentiate between secondary and classical TN?
MRI brain w/ and w/o con
81
What is the primary drug to treat TN?
Carbamazepine
82
What is the MOA and risk of carbamazepine?
* MOA: Reducing neuron excitability
* Risk: **Assess for HLA-B*15:02 allele** in **asians.** Predisposes to SJS or TEN.
83
When do you taper carbamazepine dosing?
Once pain control is achieved.
84
What two drug classes can be **added on** for breakthrough symptoms in TN?
* Neuroleptics: lamotrigine, gabapentin, topiramate
* Muscle relaxants: Tizanidine, baclofen
85
How do you treat **refractory TN**?
* Botox
* Surgery
86
What is Bell's palsy also known as?
CN VII palsy/Facial nerve palsy
87
Who is Bell's Palsy MC in?
* Colder months
* 20-40y/o who are pregnant or diabetic
88
How does Bell's palsy present?
* **Acute onset** facial weakness in 48hrs.
* **Poor eyelid closure**
* Hyperacusis
* Decreased tearing
* Tingling of cheek/mouth
* Reduced sense of taste
89
How do you workup Bell's Palsy?
* 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
How do you manage Bell's Palsy?
* **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
When is imaging warranted in Bell's Palsy?
* Symptoms > 8 weeks
* Progression of symptoms after 3 weeks
| You should **monitor until it fully resolves**
## Footnote
MRI of brain and face
CT w/ con or MRI w/ gadolinium
