Neuromyalgia and Fibromyalgia Flashcards by Nicole Gaudreau

What are the two types of neuropathic pain?

Lesion

Disease

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What is a lesion?

Direct damage

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What is disease neuropathic pain?

Indirect damage

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What is the pathophysiology of neuropathic pain?

Neuropathic injury stimulates sensitization and induces long-term abnormal neural activity along afferent pathways
Spinal cord dorsal horn neurons show excitatory responses and decreases in firing threshold
Persistent molecular changes result in potentiated changes in the peripheral, spinal, and cortical levels

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When is neurologic pain typically the worst?

At night

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What are the 3 types of neuropathic pain?

Diabetic neuroapthy
Post-herpetic neuralgia
Trigeminal neuralgia

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What is the presentation of diabetic neuropathy?

Diffuse and symmetric length-dependent injury to peripheral nerves

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How is diabetic neuropathy diagnosed?

Diabetes

Monofilament/tuning fork test

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What is the presentation of post-herpetic neuralgia?

Burning, aching, electric shock like pain or itching associated with the outbreak of a HZV rash that continues after the resolution of the infection

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How does age correlate to post-herpetic neuralgia?

The older the patient is at shingles onset, the more likely they are to have post-herpetic neuralgia

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What can be administered w/in 72 hours of a shingles outbreak to prevent post-herpetic neuralgia?

Antiviral agents

Amitriptyline

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What is the diagnosis of post-herpetic neuraliga?

Burning pain that continues for 90 days after resolution of a herpes zoster rash

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What is the presentation of trigeminal neuralgia?

Pain that is sudden, unilateral, severe, brief, stabbing and recurrent episodes in one or more branches of the trigeminal nerve

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How is trigeminal neuralgia diagnosed?

CT scan that shows:
Compression of the 5th cranial nerve
Structural abnormality of the 5th cranial nerve

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How is fibromyalgia characterized?

Widespread musculoskeletal pain and tenderness

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What are the neuropsychological sx of fibromyalgia?

Fatigue
Nonrestorative sleep
Cognitive dysfunction
Anxiety
Depression

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What are common comorbidities of fibromyalgia?

Chronic HA
IBS
Pelvic pain syndromes

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Are men or women more likely to have fibromyalgia?

Women x9

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What is the pathophysiology of fibromyalgia?

Can be triggered by infection, metabolic/psychiatric comorbidities
Polymorphisms in the serotonin transporter gene and the enzyme that inactivates catecholamines

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What is the diagnosis of fibromyalgia?

"Pain all over"
Typically above and below the waist on both sides of the body
Poorly localized
Difficult to ignore
Severe in intensity
Present most of the day on most days for 3+ months
Fatigue, stiffness
Routine labs are normal
Diagnosis of exclusion

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What is the nonpharm treatment for neuropathic pain and fibromyalgia?

Education
Physical conditioning
Relaxation exercise
Sleep hygiene
Management of comorbidities

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What is the nonpharm treatment that is specific for neuropathic pain?

TENS

Ablation of nerve bundle (LAST LINE)

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What are the anticonvulsants used in neuropathic pain and fibromyalgia?

Pregabalin
Gabapentin
CBZ
Lamictal

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What agents must be adjusted in renal impairment?

Pregabalin
Gabapentin
SSRIs
TCAs

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What is the MOA of pregabalin?

Binds to Ca channels and modulates excitatory neurotransmitters which affects nociception

How does pregabalin relate to gabapentin?

Pregabalin is a prodrug with a higher affinity

What is the only drug that is FDA apparoved for diabetic neuropathy?

Pregabalin

What are the AEs of pregabalin and gabapentin?

Dizziness Drowsiness (Gabapentin much worse)

What is the MOA of gabapentin?

Structurally related to GABA, binds throughout the brain and may modulate the release of excitatory neurotransmitters which affect nociception

What is the MOA of CBZ in neuropathic pain and fibromyalgia?

Unknown | Modulates neurotransmitter activity at neuronal synapses and Na channels to decrease peripheral nerve excitability

What is CBZ chemically related to?

TCAs

What are DDIs of CBZ?

3A4 inducers | CNS depressants

What is FDA approved for trigeminal neuralgia?

CBZ

What is the MOA of lamictal?

Inhibits the release of glutamate and stabilizes the nueronal membranes by inhibiting sodium channels

What are the AEs of CBZ?

Somnolence Dizziness Gait disturbance

What are the AEs of lamictal?

Nausea Edema Dizziness

What are the DDIs of lamictal?

VPA (SJS) | CNS depressants

What can lamictal be used for?

Trigeminal pain | Neuropathy related to HIV pain

What are the MOA of TCAs?

Modulate neurotransmitter activity at neuronal synapse at descending inhibitory spinal pathways

How does Amitripyline and imipramine work?

Inhibit presynaptic reuptake of NE and serotonin

How does despiramine work?

Inhibits presynpatic reuptake of NE

Does mood elevating properties of TCAs affect pain relief?

No, indeoendent

What are AEs of TCAs?

``` Dry mouth Constipation Orthostaic hypotension Sedation QTc prolongation ```

When should TCAs be given?

At bedtime

What is the MOA of SSRIs?

Decrease serotonin reuptake at the neuronal synapse at descending inhibitory spinal pathways

What are AEs of SSRIs?

``` Somnolence Dizziness Nausea Sexual dysfunction Sweating WEakness ```

What is the MOA of SNRIs?

Inhibits serotonin and NE reuptake at the neuronal synapse at descending inhibitory pathways in the CNS

Are SNRIs or SSRIs more effective for neuropathic pain?

SNRIs

What are AEs of SNRIs?

``` GI distress HA Somnolence Fatigue Nausea Increased bleeding risk CNS depression HYPERGLYCEMIA ```

What is the MOA of capsaicin?

Works on the vanilloid 1 receptor (TRPV1) to cause local damage and defunctionalize pain sensory receptors' ability to send pain signals Desensitizes sensory axons and inhibition of pain transmission initiation Repeated application depletes the neuron of substance P and prevents re-accumulation

How is the capsaicin patch applied?

Applied in physicians office for 60 minutes

How many patches of capsaicin can be applied at one time?

4 patches

How often can capsaicin treatment be repeated?

Every 3 months

How do we pretreat for capsaicin patches?

Lidocaine

What are AEs of capsaicin?

Short term increases in BP and HR | Local erythema and pain

What is the MOA of topical lidocaine?

Interrupts peripheral nerve impulses

How many patches of lidocaine can be applied at the same time?

Which opioid has modest efficacy for fibromyalgia and neuropathy?

Tramadol

Which opioid can be used last line in diabetic neuropathy?

Oxycodone ER

What can cyclobenzaprine be used for?

Fibromyalgia

How does botulinum toxin work in pain?

Serotype A inhibits the secretion of substance P and calcitonin

How does alpha-lipoic acid work?

Antioxidant effect that causes improved nerve blood flow

When would alpha-lipoic acid be administered?

For use at the beginning to slow progression

What is benfotiamine?

Fat soluble vitamin B1

What are first line agents for diabetic neuropathy?

Pregabalin SNRIs TCAs Gabapentin

What are the second line agents for diabetic neuropathy?

CBZ Tramadol Capsaicin Lidocaine

What are third line agents for diabetic neuropathy?

Oxycodone ER

What should not be used in diabetic neuropathy?

Cyclobenzaprine | Opioids

What are first line agents for post-herpetic neuralgia?

``` Gabapentin Pregabalin Lidocaine patch TCAs Tramadol ```

What is the second line agents for post-herpetic neuralgia?

Capsaicin

What are first line agents for trigeminal neuralgia?

Duloxetine TCAs CBZ OxCBZ

What are second line agents for trigeminal neuralgia?

Lamictal

How do we treat fibromyalgia?

Treatment is symptom specific

If the patient has fibromyalgia and difficulty sleeping, what medications should be given?

Amitriptyline | Cyclobenzaprine

If the patient has fibromyalgia and depression/anxiety, what medication should be given?

Duloxetine

What are second line agents for fibromyalgia?

Anticonvulsants

What medications should be avoided in fibromyalgia?

Opioids and NSAIDs

What is the treatment for acute/subacute lower back pain?

Non-pharm treatment (heat, massage, acupuncture, spinal manipulation) If pharm treatment is desired, NSAIDs and skeletal muscle relaxants are preferred

What is the initial treatment for chronic lower back pain?

Exercise, multidisciplinary rehabilitation, acupuncture, mindfulness-based stress reduction, tai chi, yoga, motor control exercise, low-level laser therapy, cognitive behavioral therapy, or spinal manipulation

If the initial treatment of chronic lower back pain is inadequate, what are the other treatments?

NSAIDs 1st line Tramadol and duloxetine 2nd line Opioids after failure of others and consideration of potential risk