EXAM 3 Chronic Pain Part 2 Dr. Thomason

Question 1

What is Neuropathic pain?

Answer 1

Pain of a lesion of disease affecting the somatosensory system

Question 2

What are the most common causes of peripheral Neuropathy?

Answer 2

-Diabetic peripheral neuropathy (DPN)
-Postherpetic neuralgia (PHN)

also
-chemotherapy-induced
-HIV
-Phantom limb pain
-Postmastectomy pain
-Complex regional pain
-Trigeminal neuralgia

Question 3

What are the most common causes of central Neuropathy?

Answer 3

-Multiple sclerosis
-Spinal cord injury
-Central post-stroke pain
-Parkinson disease

Question 4

What are the first-line treatment options?

Answer 4

-TCA: nortriptyline, desipramine (secondary amine - not as sedating)
(amitriptyline and imipramine are tertiary amine -> amitriptyline metabolized to nortriptyline)

-duloxetine (SNRI, norepinephrine part helps with the pain), venlafaxine?

-gabapentin
-pregabalin

2nd line: combination of the first-line drugs

Question 5

What is the dose of duloxetine that is helpful for neuropathic pain?

Answer 5

60 mg
above that is not helpful for neuropathic pain but seen for depression therapy

for venlafaxine = 225 mg

Question 6

Which opioids might be used for neuropathic pain?

Answer 6

Methadone!!! in small doses

may be Tramadol

-> should not use opioids in neuropathy

Question 7

When to consider Lidocaine for neuropathy?

Answer 7

peripheral neuropathy

also:
Topical Analgesics
Anticonvulsants
Tricyclic Antidepressants
Opioids

Question 8

Which anticonvulsants are preferred in postherpetic neuralgia

Answer 8

pregabalin
gabapentin

Question 9

Which anticonvulsants are preferred for diabetic neuropathy?

Answer 9

-carbamazepine
-phenytoin
-gabapentin
-lamotrigine
-pregabalin !!!

Question 10

Which anticonvulsants are preferred for HIV-associated neuropathy and Central poststroke pain?

Answer 10

lamotrigine

Question 11

Which anticonvulsants are preferred for trigeminal neuralgia?

Answer 11

-carbamazepine !!!
-lamotrigine
-oxcarbazepine

Question 12

Non-pharmacolig treatment for neuropathic pain

Answer 12

-Neural blockade
-Neurolytic (kill the nerve)
-Stimulatory techniques
-medication pumps

Question 13

What is the first approach in diabetic neuropathy?

Answer 13

control of the blood glucose level

Question 14

What is the minimum dose of gabapentin to be effective for neuropathic pain?

Answer 14

1600 mg

Question 15

Why may Tramadol not be the best choice?

Answer 15

because it needs to be metabolized in its active form by CYP2D6

patients who cant convert efficiently end up with an excess of the parent form (tramadol) -> more serotoninergic activity VS norepinephrine activity
serotonin side effects

-also seizure risk

Question 16

What is the best way to prevent postherpatic neuropathy?

Answer 16

prevent herpes zoster infection with vaccines in patients over 50 (2 injections)

Question 17

First-line treatment for postherpetic neuropathy

Answer 17

-TCA: nortriptyline
-Licoderm patch (local anesthetic)

2nd line:
-SNRI: duloxetine
-Anticonvulsants: Pregabalin and Gabapentin first -> Carbamazepine

Question 18

What are the common side effects of gabapentin and pregabalin?

Answer 18

-weight gain
-peripheral edema (swelling in the legs)

-dose adjust if renal impaired

Question 19

Clinical presentation in Fibromyalgia

Answer 19

PAIN:
-Allodynia: pain due to stimuli that should not cause pain
-Hyperalgesia: increased pain with an increase in the dose

-fatigue
-cognitive impairment (fibro fog)

-stiffness
-IBS, diarrhea
-cant do exercise, balance problems
-Restless leg syndrome (RLS)
-Hyperactive senses (noises, odor)

Question 20

How is Fibromyalgia diagnosed?

Answer 20

-Widespread pain index WPI (0-19)
-Symptom severity scale SS (0-12)

WPI >7 and SS >5
or
WPI 3-6 and SS >9

Question 21

Pharmacotherapy of Fibromyalgia

Answer 21

1st line: Antidepressant or Cyclobenzaprine (similar structure as TCA)
SNRI: duloxetine 20 -> 30 -> 60 mg
SSRI
TCA (more side effects)

2nd line: Anticonvulsant
Gabapentin and Pregabalin

muscle relaxant (helps with sleep)
dopamine agonist

do not use opioids (may make things worse)

Question 22

Which drugs help for Restless leg syndrome in Fibromyalgia?

Answer 22

Dopamine agonist

Question 23

Non-pharmacology treatment in fibromyalgia

Answer 23

-Not pacing activites when they dont have pain -> it may cause flair of pain at the next day
-exercise (if possible)
-sleep and eat well
-Cognitive Behavioral Therapy

Question 24

How should Lidocaine patches be used

Answer 24

-can apply up to 3 patches per day (may use up to 4)
-direct over painful site
-12h on 12h off

Question 25

Patient education with Capsaicin (topical anesthetic)

Answer 25

• for PHN or DPH
  -onset at 14-28 days -> due to local depletion of substance P
  -3-4x daily dosing

-Burning and local skin irritation -> correlates with to degree of subsequent anesthesia

Question 26

How should Gabapentin and Pregabalin be discontinued?

Answer 26

taper off

-Pregabalin for at least a week
-Gabapentin may take longer to taper
-> to prevent withdrawal

Renal dosing required in CrCl < 30 mL/min!!!

Question 27

What to monitor for Carbamazepine

Answer 27

-Na level
-WBC count
-LFT
-rash

Question 28

Patient popualtion to avoid TCAs

Answer 28

patients over 65
bc of the side effects

-DO NOT USE within 14 days of MAOI use
-Acute recovery from MI - Cardiotoxic !!!
-suicidal ideation risk

Question 29

Monitor TCAs

Answer 29

-get an EKG in patients over 40
-check BP
-it causes weight gain

Question 30

Which TCAs have the least anticholinergic effects?

Answer 30

-Desipramine
-Nortriptyline

highest with Amitriptyline

Question 31

Patient population to avoid with Venlafaxine

Answer 31

uncontrolled HTN
-need dose of 225 mg to be active -> not favorable bc it is not easy to come off the drug (discontinuation effects)

Question 32

Cyclobenzaprine

Answer 32

used for Fibromyalgia if amitriptyline or nortriptyline is not tolerated

-not within 14 days of another MAOI
-helps with sleep -> give at night (sedation)

Question 33

If an opioid is used for neuropathic, which one to pick?

Answer 33

Methadone