Chronic Pain Management (Hayek)

Question 1

How is neuropathic pain different from nociceptive pain?

Answer 1

It does not require activation of periphreal nociceptors to experience it.

It is also caused by lesions in the somatosensory system (neural) rather than tissue insult at sites of peripheral nociceptors.

Question 2

What cells mantain the sensation of pain?

Answer 2

Cells supportive of the nerve fiber cells

Direct nerve fiber damage may also cause increased pain (release of bradykinins, etc..)

Question 3

What is the definition of chronic pain?

Answer 3

Pain that persists beyond 3-6 months or significantly beyond normal healing time

Question 4

What sort of pain are opiates great for? Not so great for?

Answer 4

Acute pain and end-of-life chronic pain

Not so good for chonic pain in younger pts (high addiction risk)

Question 5

Between acute and chronic pain, which serves a purpose?

Answer 5

Acute pain lets us respond to the painful stimuli appropriately

Chronic pain has no physiological purpose

Question 6

What does Substance P cause?

Answer 6

Neurogenic inflammation (heat, redness, swelling)

Question 7

How does Substance P promote inflammation?

Answer 7

It induces the release of histamine by mast cells and causes local edema

Question 8

Where does the first synapse between nociceptors and the CNS occur and what happens here (think transmitters)?

Answer 8

First synapse occurs at the dorsal horn of the spinal cord

Substance P and glutamate activate post-synaptic glutamatergic and NMDA receptors

Question 9

Difference between central sensitization and peripheral sensitization

Answer 9

Both make the wound site and sites around the wound more painful (in a persistant manner)

However, peripheral sensitization is immediate while central sensitization is delayed by minutes

Question 10

Describe secondary hyperplagia.

Answer 10

Phenomenon in which localized damage increases the local pain receptor field due to central sensitization

It explains the exagerrated nociceptor response after initial injury

Question 11

What are the key features of neuropathic pain?

Answer 11

Sensory loss + paradoxical hypersensitivity

Characterized by spontaneous pain, dysesthesia, hypersenstivity

Question 12

What is a neuroma?

Answer 12

An entanglement of nerve fibers that result from a cut nerve

The truncated nerve will try to regenerate itself, but due to lack of direction, this results in a neuroma.

Fibers in the neuroma have abberrant sodium channels that are more likely to fire! (hyperalgesia)

Question 13

What signs are seen in neuropathic pain but rarely or never in inflammatory pain?

Answer 13

Cold allodynia (cold sensation causes pain)

Aftersensations

Paroxysms (same stimulus produces increasing amount of pain)

Burning pain

Sensory or motor deficits in damaged nerve territory

Question 14

There is no simple continuum from acute to chronic pain that correlates with duration or intensity of peripheral injury. T/F?

Answer 14

True

Question 15

What happens when there is a prolonged interruption of the nerve contact point with its target?

Answer 15

Death of small unmyelinated neurons (excitotoxicity)

Death of inhibitory interneurons

Cortical changes in gray matter

Question 16

Who are the main prescibers of opioid analgesics? (Top 3)

Answer 16

Primary Care Providers (PCP)

Dentists (top for ages 10-19)

Orthopedic surgeons

Question 17

America uses how much of the world’s production of opiates? hydrocodone? illicit drugs?

Answer 17

80%, 99%, 66%

Question 18

Are opioids effective for treating chronic pain?

Answer 18

Not according to many studies presented by Dr. Hayek (Excludes tramadol)

Question 19

Physical dependence in opiates only occurs with high doses over months. T/F?

Answer 19

False

Question 20

What is the most common side effect, occurring in 40-95% of all patients on opiates?

Answer 20

Constipation!

Question 21

Does opioids help sleep?

Answer 21

No, they decrease total sleep time, REM sleep, delta sleep, etc..

Question 22

Opioids have been shown to be immunosuppressive except for these two exceptions:

Answer 22

Methadone

Tramadol

Question 23

How does opiates induce hypogonadism?

What is hypogonadism characterized by?

Answer 23

Opioids bind in the hypothalamus and ultimately decreases release of LH and FSH.

Signs/symptoms: decreased libido, fatigue, depression, loss of muscle mass, infertility, erectile dysfunction, abnormal menses, osteoperosis

Question 24

How do opioids exert its addicting qualities in the brain?

Answer 24

They inhibit release of GABA (in VTA/ventral tegmental area of midbrain)

This disinhibits dopaminergic neurons, flooding the nucleus accumbens with dopamine (reinforcement of rewards system)

Question 25

Withdrawal symptoms indicate tolerance and addiction. T/F/partially T?

Answer 25

False

Question 26

What are the ABCDE signs of addiction?

Answer 26

Unable to Abstain

Unable to control Behavior

Craving

Diminished recognition of problems

Emotionally dysfunctional

Question 27

What are the 4 C’s of addiction?

Answer 27

loss of control

ignoring negative consequences

compulsive use

craving

Question 28

Pseudo-addiction definition

Answer 28

State in which pt displays drug-seeking behavior due to untreated/poorly treated condition (resolves when treated)

Question 29

Risk factors for opioid abuse include..

Answer 29

Fam hx of drug abuse

Hx of sexual abuse

Hx of mental illness

Legal/arrest hx

Chronic stress

Tobacco use

Youth

Unrealistic expectations of opioid treatment

Question 30

What does current research suggest about the efficacy of NSAIDs in treating neuropathic pain?

Answer 30

There is little evidence to show its efficacy in neuropathic pain.

Some efficacy was shown, however, in diabetic neuropathy and post-herpes neuralgia.

Question 31

Which kinds of antidepressants were found to be consistently more effective than placebo in treating neuropathic pain?

Answer 31

Serotonergic-Noradrenergic TCAs

Noradrenergic TCAs

(they inhibit reuptake of NTs)

Results tempered by numerous side effects though

Question 32

Tramadol is a cross between…

Tramadol is great for….

What side effects does tramadol not have that makes it a good treatment option?

Answer 32

• Morphine and Serotonin+NE inhibitor
• Neuropathic pain + good for nociceptive pain
• Tramadol does not cause end-organ damage AND is low risk for abuse

Question 33

There is a strong correlation between plasma levels of antidepressants and pain relief. T/F?

Answer 33

False

Question 34

How is Tramadol’s affinity for mu receptors compared to morphine?

This results in a relative potency of \_(Fraction)_ that of morphine

Answer 34

6000x less

1/20 to 1/5

Question 35

The enhanced analgesic effect of tramadol is most likely due to..

Answer 35

Inhibition of NE and 5HT reuptake in the CNS

Question 36

Usual dose of tramadol is..

Answer 36

200-400 mg PO

Question 37

Lidoderm patches. What’s in it and what kind of patients are most likely to benefit from it the most?

Answer 37

5% Lidocaine, 700 mg

Pts experiencing allodynia (pain from non-pain sensations)

Note: almost no side effects

Question 38

Which anticonvulsants have some efficacy in pain relief?

Answer 38

Topirimate, Gabapentin, Pregabalin

Note: gabapentin and pregabalin have very similar action mechanisms - Ca channel mod (gabapentin is more gradually release, pregabalin is more linear release)

Question 39

What is Dr. Hayek’s suggested algorithm for treating chronic pain?

Answer 39

Pregabalin/Gabapentin/Lidocain Patch (1st line)

Antidepressants (2nd line)

Opioids (3rd line)

Question 40

What is the best kind of therapy for neuropathic pain management?

Answer 40

Combination therapy tailored to each individual pt