Peripheral neuropathies Flashcards
define peripheral neuropathies
: group of disorders (100+) that are caused by damage of the nerves of the peripheral nervous system
classification of peripheral neuropathies may be done according to (3)
type of affected nerves
number of affected nerves
pathology of affected nerve
____________ means PN that affects one nerve
mononeuropathy
____________ means PN that affects many nerves
polyneuropathy
____________ means damage to 2 or few separate nerves at the same time asymmetrically
mononeuritis multiplex
what pathology affects axons
axonopathy
which pathology affects myelin
myelinopathy
which pathology affects the cell body
ganglionopathy
what is the most common polyneuropathy
diabetic neuropathy
what is the most common genetic polyneuropathy
charcot-marie-tooth disease
what is the most common mononeuropathy
carpal tunnel syndrome
list 3 etiologies for PN
mechanical compression, entrapment
trauma
diseases
immune mediated neuronal destruction
genetics
drugs (isoniazid, cisplatin, vincristine,amiodarone, metro, statins)
toxins
unknown
what is wallerian degeneration
trauma/ injery o a nerve that causes dysfunction of nerves and muscles distal to it = muscle atrophy
what is segmental demyelination
demyelination of neuron but axon function maintained
what is axonal degeneration
gradual distal dying of neuron that doesn’t reverse
what is causalgia
burning pain due to peripheral nerve injury
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
1
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
what is considered acute PN
<4wks
what is considered subacute PN
4-8wks
what is considered chronic PN
> 8wks
name the 6 ways PN may be evaluated
history
labs
electrophysiology
imaging
nerve biopsies
pain assessment scales
what are some nonpharm managements for PN
Psych support, physio, exercise programs, rehab, surgery in some kinds of mononeuropathies
3 ways to treat immune mediated neuropathies
intravenous immunoglobulins (IVIG)
therapeutic plasma exchange
immunomodulators
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
1
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
