Neuropathic pain+ Fibromyalgia- Dart

1 hr

Describe the difference types of pain:

• nociceptive

• neuropathic

• nociplastic

• mixed

• nociceptive

  • most common type of pain

  • pain due to actual or threatened damage to non-neural tissue activating nociceptors

  • adaptive

  • 2 subtypes (somatic, visceral)

• neuropathic

  • pain due to lesion or disease affecting the somatosensory system

  • damage to peripheral or central nerves

  • often chronic

  • maladaptive

• nociplastic

  • idiopathic pain that has no clear evidence of tissue damage or damage to the somatosensory system

  • fibromyalgia

  • IBS

• mixed

  • overlap of nociceptive and neuropathic sx

  • ex: cancer, OA

What NTs are associated with neuropathic pain?

• GABA—> primary inhibitory NT, decreasing release of glutamate, aspartate, and sub P

• NE

• Serotonin

What are the 4 neuropathic types?

• motor—> damage to nerve cells controlling muscles= loss of control/coordination

• sensory—> damage to sensory nerves= loss of pain/touch

• autonomic nerve—> damage to nerve cells controlling unconscious bodily functions

• combo

What are the 6 different neuropathic sensations a pt. can experience?

• paresthesias- abnormal skin sensation (tingle, prick)

• dysesthesias- abnormal painful sensation

• allodynia- non-painful stimulus can elicit pain like light or cold temp

• hyperalgesia- increased sensitivity to mild pain stimulus

• hyperpathia- exaggerated response to stimuli often delayed or prolonged

• hyperesthesia- increased sensitivity to both non-painful and painful stimulus

How is neuropathic pain diagnosed?

combo of a lot of things: physical, pain interview, PMH, blood tests, DM, electrodiagnostic tests, quantitative sensory testing

List examples of neuropathic syndromes:

• do not memorize, just an overview

• painful diabetic neuropathy (PDN)- most common

• postherpetic neuralgia

• chemotherapy induced neuropathy

• guillain-barre syndrome

• chronic inflammatory demyelinating polyneuropathy

• trigeminal neuralgia

• phantom limb pain

• spinal cord injury pain

WHAT ARE THE FIRST LINE AND ALTERNATIVES TX FOR PDN?

• 1st line: PREGABALIN or DULOXETINE

• alt 1st line: gabapentin, TCAs

• last line: opioids

• nonpharm: glucose control

postherpetic neuralgia (PHN) is a pain syndrome after nerves have been damaged due to WHAT INFECTION?

varicella zoster virus infection aka SHINGLES

Shingles follows what to produce a rash and pain on that area of the body? What are they?

DERMATOMES—> aka areas/pathways on the body that rely on a specific spinal nerve for fxn

What is 97% effective at preventing the formation of shingles and technically PHN?

Herpes Zoster vaccination—> SHINGRIX

Indication for Shingrix?

recommended for pts. 50+ with a history of shingles, previously vaccinated with Zostavax, or who previously received the varicella vaccine

What are the topical and systemic tx options for PHN?

• which is 1st line?

• topical: Lidocaine 5% patch (1st line), capsaicin cream

• systemic:

  • APAP, NSAIDs

  • GABA Analogs

  • TCAs

  • opioids—> last line

What are the names of the GABA Analogs? MOA?

• names: Gabapentin, Pregabalin

• MOA: mimic the action of the GABA a-2-d subunit decreasing the release of NTs

Which GABA analog is a controlled med? which isn’t?

• Pregabalin—> CV

• Gabapentin—> not a CS, but some states elected it as one

GABA Analog ADRs:

• idk how imp

• both: CNS/respiratory depression, dizzy, somnolence, dry mouth

• gabapentin: n, ataxia, fatigue, neuropsych effects

• pregabalin: blurred vision, weight gain, peri edema, difficulty concentrating

Pregabalin ER not recommended if CrCl <___ ml.min

30

What are the names of the TCAs? MOA?

• names: desipramine, nortriptyline, amitriptyline, impramine

• MOA: block Na+ channels, impact NE and 5-HT

When should TCAs be avoided and used in caution?

• avoid:

  • pts. with 2’ or 3’ heart block

  • arrhythmias

  • QT prolongation

  • recent MI

  • severe liver disease

• caution:

  • closed-angle glaucoma

  • BPH

  • CV disease

  • urinary retention

  • constipation

  • liver dysfunction

TCA ADRs:

• idk how imp

• constipation

• dry mouth

• blurred vision

• urinary hesistency

• tachycardia

• mental status changes

• orthostatic hypotension

• sedation

• weight gain

• falls

Duloxetine belongs to what class of drugs?

SNRI (selective serotonin and NE reuptake inhibitor)

BBW of Duloxetine

Suicidality

C/I of Duloxetine

with concurrent or recent MAOI use or closed-angle glaucoma

ADRs of Duloxetine:

• idk how imp

• n

• dizzy

• HA

• somnolence

• constipation

• dry mouth

• hyperhidrosis

Precautions of Duloxetine

• serotonin syndrome

• may increase HR or BP

• may increase glucose

• bleeding risk

• hepatotoxicity

• should be tapered off

What is the place of Tramadol in therapy of neuropathy?

for acute pain management until neuro agents reach effect

ADRs of Tramadol:

• idk how imp

• addiction risk

• CNS depression

• constipation

• serotonin syndrome

For lidocaine transdermal patches how many patches can you wear at once? for how long?

can the patches be cut?

• 1-3 patches for up to 12 hours daily

• patches CAN be cut

What is the name of the irritant derived from hot chili peppers and used topically for PHN, arthritis pain, and post-op pain?

capsaicin

Is Capsaicin a good option for immediate relief?

no! takes 2-4 weeks for onset and 4-6 weeks till max effects

What antiepileptics can be used for PHN?

• idk how imp

• carbamazepine

• lamotrigine

• oxcarbazepine

• phenytoin

• topiramate

• valproic acid

• zonisamide

What is fibromyalgia? cure?

• musculoskeletal connective tissue disorder with chronic widespread pain and fatigue which can be difficult to localize

• no cure

What is the pathophys behind fibromyalgia?

• exact mechanism not known—> thought to deal with serotonin and NE imbalances

Symptoms of fibromyalgia:

• most common—> widespread pain in joints with fatigue and sleep problems

  • generally hurts all over

• other sx:

  • numb, tingle, burning sensations

  • memory problems “fibro fog”

  • depression/anxiety

  • HA

  • digestion problems

  • urinary issues

  • pelvic pain

How is fibromyalgia diagnosed?

• not one formal diagnostic test

• look for:

  • presence of pain in 6+ body sites with other common fts.

  • identify common comorbidities like IBS, chronic HA, or depression

• ACR criteria—> assigns a widespread pain index (WPI) score

• SS score

• clinical diagnosis from WPI or SS score

Nonpharm for fibromyalgia:

• lifestyle: exercise, stress management, sleep hygiene

• alt therapies: acupuncture, massages, and other bs like that

What is the pharm tx for fibromyalgia?

• analgesics—> APAP

• anticonvulsants—> pregabalin, gabapentin

• muscle relaxers—> cyclobenzaprine

• opioids—> strongly discouraged, but maybe tramadol

• SNRIs—> duloxetine, milnacipran

• TCAs—> amitrptyline

What is the only class of drugs for fibromyalgia helps with pain, sleep, fatigue, and QOL?

anticonvulsants (gabapentin, pregabalin)

What selective SNRI is only currently approved for fibromyalgia pain in adults?

What’s the boxed warning?

Milnacipran—> BBW for suicide