Peripheral neuropathies Flashcards by Linda Chen

define peripheral neuropathies

: group of disorders (100+) that are caused by damage of the nerves of the peripheral nervous system

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classification of peripheral neuropathies may be done according to (3)

type of affected nerves
number of affected nerves
pathology of affected nerve

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____________ means PN that affects one nerve

mononeuropathy

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____________ means PN that affects many nerves

polyneuropathy

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____________ means damage to 2 or few separate nerves at the same time asymmetrically

mononeuritis multiplex

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what pathology affects axons

axonopathy

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which pathology affects myelin

myelinopathy

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which pathology affects the cell body

ganglionopathy

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what is the most common polyneuropathy

diabetic neuropathy

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what is the most common genetic polyneuropathy

charcot-marie-tooth disease

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what is the most common mononeuropathy

carpal tunnel syndrome

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list 3 etiologies for PN

mechanical compression, entrapment
trauma
diseases
immune mediated neuronal destruction
genetics
drugs (isoniazid, cisplatin, vincristine,amiodarone, metro, statins)
toxins
unknown

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what is wallerian degeneration

trauma/ injery o a nerve that causes dysfunction of nerves and muscles distal to it = muscle atrophy

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what is segmental demyelination

demyelination of neuron but axon function maintained

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what is axonal degeneration

gradual distal dying of neuron that doesn’t reverse

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what is causalgia

burning pain due to peripheral nerve injury

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what is hyperesthesia
1. abnormal increased sensation to stimuli
2. abnormal increased sensitivity to pain
3. burning pain due to PN injury
4. painful sensation to nonpainful stimulus

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name 3 autonomic sx from PN

Due to alteration of sympathetic and/or parasympathetic nervous system function
Anhidrosis, heat intolerance, OH, diarrhea, constipation, incontinence ,ED, cardiac arrhythmias, gastroparesis, esophageal dysmotility
Morbidity due to falls, OH
Severe dysautonomia: ↑ risk for arrhythmias and sudden cardiac death

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what is considered acute PN

<4wks

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what is considered subacute PN

4-8wks

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what is considered chronic PN

> 8wks

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name the 6 ways PN may be evaluated

history
labs
electrophysiology
imaging
nerve biopsies
pain assessment scales

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what are some nonpharm managements for PN

Psych support, physio, exercise programs, rehab, surgery in some kinds of mononeuropathies

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3 ways to treat immune mediated neuropathies

intravenous immunoglobulins (IVIG)
therapeutic plasma exchange
immunomodulators

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describe IVIG

Intravenous immunoglobulins (IVIG): random antibody decoys that stear attention off bad antibodies

describe TPE

extracorporeal process where pt’s blood components (generally plasma) is removed and the rest is returned back to pt with or without replacement fluid TPE removes plasma → plasma contains plasma proteins → drugs in plasma (esp those bound to plasma proteins) are removed with plasma → drugs that are extensively distributed hide from TPE removal

which are more likely to be removed from TPE 1. drugs that are highly protein bound 2. drugs that have a high Vd

after IVIG, how soon can you do TPE

2-4wks

what immunomodulators may be used in immune med peripheral neuropathies

corticosteroids, cyclophosphmide

how to treat autonomic neuropathies

treat underlying condition - like immune med or diabetes symptomatic tx for untreatable neuropathies

nonpharm OH management

maintain fluid intake, slow cautious movements when changing body posture, sit or lie down if it happens, elevate head in sleep, compression stockings

pharm options for OH management

fludrocortisone midodrine sodium chloride tablets erythropoietin if anemic desmopressin for those with nocturnal polyuria BBs for tachycardia

what to watch out for with midodrine

beware of supine HPTN- space before pt sleeps, but if immobile = fine whenever

what can be given if a pt has anemia and OH

erythropoetin

what can be given if a pt has nocturnal polyuria and OH

desmopressin

what may be given for postural orthostatic tachycardia sx

beta blockers

how to treat a hyperactive bladder (2 drugs)

tolterodine oxybutynin

how to treat hyperhydrosis

anticholinergics

define carpal tunnel sx

: collection of sx due to pathology in median nerve of the wrist, sx confined to median nerve distribution

RF for carpal tunnel

obesity, repetitive motions, genetics

presentation of carpal tunnel

intermittent sx that are associated with spec activities numbness, tingling, pin, weakness, feeling cold/ hot hnds

nonpharm management for carpal tunnel sx

avoid/ minimize exacerbating factors, activities with repeated wrist movement, PT/OT, splint, branches surgical decompression for mod-severe cases

when should surgical decompression be recommended for carpal tunnel

if sx >2-7 wks despite other treatments

what are some pharm managements for carpal tunnel

local methylprednisone injection short course of oral CS (10-30d)

T or F: NSAIDs and gabapentin are recommended for carpal tunnel

F- no benefit compared to placebo

what is the evidence for methylprednisone injection in carpal tunnel sx

evidence of LT improvement of up to 1yr = strong recommendation

when should sx reduction be seen in using oral CS for carpal tunnel sx

2-8wks

RF for postherpetic neuralgia

>50yrs old, immunosuppression

what is first line tx for elderly post herpetic neurlgia

topical lidocaine

list the 4 options for postherpetic neuralgia

topical lidocaine topical capsacin gabapentin, pregabalin TCAs

what is sciatica

Pain across path of sciatic nerve Due to lumbar disc herniation or spinal stenosis

where is sciatica usually located? what are the characteristics?

unilateral leg pain- more leg pain than lower back pain numbness, paresthesia, radiation to lower leg

managements for sciatica

Heat therapy Continue normal activity, exercise NSAIDs- for ST pin control Opioids- ST for severe acute pain Steroids Epidural injection: ST pain control Systemic: possibly ineffective Gabapentin Muscle relaxants- weak recommendation Surgery: decompressive surgery

what is TGN

Severe, sharp, electric like, brief unilateral pain across the path of 1 or more of the trigeminal nerve divisions

RF for TGN

female, >50yrs old

1st line tx for TGN

Carbamazepine or oxcarbamazepine

name the 6 add ons/ alts for TGN

lamotrigine gabapentin/ pregabalin VA baclofen botox phenytoin

can topical ophthalmic anesthetics be used for TGN?

no, not effective

1st line meds for chronic neuropathic pain

gabapentin ,pregabalin, TCAs, venlafaxine, duloxetine

2nd line meds for chronic neuropathic pain

tramadol, opioids

3rd line meds for chronic neuropathic pain

cannabinoids

how often should you assess efficacy of neuropathic pain meds

q2-3wks

what is an adequtae trial period of meds for neuropathic pain

2-3mths