Neuropathic Pain - Block 2 Flashcards

1
Q

What are the types of PNS neuropathic pain?

A
  1. DIabetic peripheral neuropathy
  2. Trigeminal neuralgia
  3. Postherpetic neuralgia
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2
Q

Types of neuropathic pain in the CNS?

A

Fibromyalgia

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3
Q

What is the most common neurologic complication of diabetes?

A

Diabetic Peripheral Neuropathy

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4
Q

What is Diabetic Peripheral Neuropathy?

A

Gradual loss of integrity of the longest nerve fibers -> sensory loss and risk of foot ulcers

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5
Q

What are the risk factors of DPN?

A
  1. Advanced age
  2. HTN
  3. PVD
  4. SMoking
  5. DLD
  6. Poor glucose control
  7. Long duration of diabetes
  8. Heavy intake of alcohol
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6
Q

What is the cause of DPN?

A

Uncontrolled hypergycemia damages nerves and capillaries -> loss of nerve fibers due to impaired blood flow -> impaired nerve sensitivity or pain

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7
Q

What are the presentations of DPN?

A
  1. Numbness, tingling, burning
  2. Affects feet/legs first, then hards/arms
  3. Sx often worse at night
  4. Foot ulcers/infections
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8
Q

How do you diagnose DPN?

A
  1. Physical exam
  2. Review med hx
  3. Review of sx
  4. Monofilament: test sensitivity to touch
  5. Sensory testing: response to vibration, temp changes
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9
Q

Preventive care for DPN?

A
  1. Glycemic control
  2. Risk factor mod
  3. Foot care
  4. Safety and falls precautions
  5. B12 def correction
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10
Q

How long should trial duration of DPN tx last?

A

2-3 months

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11
Q

What are your first line tx for DPN?

A

SNRIs: duloxetine, venlafaxine
TCAs: amitriptyline, desipramine, nortriptyline
Topical: capsaicn 8% patch

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12
Q

What are the first line alts for DPN tx?

A

Gabapentinoids: Gabapentin, pregabalin

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13
Q

What to do in inadequate response to initial DPN therapy?

A

Add a second first-line drug from a different medication class (pregabalin + duloxetine)

OR

Switch to an alternative medication among the first line options

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14
Q

What combo must you avoid for DPN?

A

SNRI + TCA -> serotonin syndrome

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15
Q

What are topical tx for DPN?

A

Capsaicin cream 0.075%
Lidocaine patch
Transcutaneous nerve stimulation
Spinal cord stimulation
Acupuncture

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16
Q

What is not recommended for DPN?

A

Opioids and topiramate

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17
Q

What is trigeminal neuralgia?

A

Recurrent brief episodes of unilateral electric shock like pains
* Pain is abrupt in onset and termination located in the distribution of one or more divisions of the trigeminal nerve
* Triggered by innocuous stimuli

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18
Q

What are the RF of TN?

A

HTN and migraine

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19
Q

What is the cause of TN?

A

Compression of the trigeminal nerve at its root by an aberrant loop of an intracranial artery:
1. Tumor
2. AV malformation
3. Aneurysm
4. MS plaque

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20
Q

What are the clinical presentation of TN?

A
  1. Attacks may recurr, 100 times a day
  2. Lancinating, stabbing, excruciating, electric
  3. Chewing, brushing the teeth, smiling, or even wind blowing up against face
  4. Unilateral
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21
Q

How do you diagnose TN?

A
  1. Primarily paroxysms of pain in the distribution of the trigeminal nerve
  2. Differentiate from other disorders that cause facial pain
  3. MRI enables visualization of trigeminal nerve and small adjacent lesions
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22
Q

What is the initial tx for TN?

A

First line: Carbamazepine, oxcarbazepine

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23
Q

What is something to be aware about when using carbamazepine oxcarbazepine?

A

HLA-B*1502 in Asian ancestry postive should avoid

24
Q

What are the alternatives for TN?

A
  1. Gabapentin
  2. Lamotrigine
  3. Baclofen
25
Q

What are the rescue agents for TN?

A

The following may provide analgesia while PO meds are titrated or during acute relapses/attacks:
1. Lidocaine (nasal spray, local nerve block, IV infusion)
1. Sumatriptan subcutaneous
1. Botulinum toxin
1. Phenytoin/fosphenytoin IV

26
Q

When can you start tapering medication for TN?

A

attempting a gradual wean is a sustained pain-free interval of at least six to eight weeks on medication (some say 6 months)

27
Q

What are the non-pharms for TN?

A
  1. Surgery for cases refractory to pharm therapy
  2. Microvscular decompression
28
Q

What is microvscular decompression?

A

Pressure is relieved by placing a sponge between the trigeminal nerve and the compressing artery

29
Q

What is Postherpetic Neuralgia (PHN)?

A

Neuropathic pain syndrome characterized by pain that persists for months to years after resolution of the herpes zoster

30
Q

What are the RF of PHN?

A
  1. Age > 60 y/o
  2. Severe rash (>50 lesions) with HZ
  3. Severe or incapacitating pain during acute HZ
31
Q

What is the cause of PHN?

A

Damage to peripheral and central neurons that may be a byproduct of the immune/inflammatory response that accompanied VZV reactivation and migration -> When damaged, peripheral and central nerve fibers develop a lower threshold for APs, discharge spontaneously, and exhibit disproportionate responses to stimuli (allodynia)

32
Q

What is the sx of PHN?

A
  1. Unilateral
  2. Erythematous & maculopapular rash -> clear -> vesicles -> pustules -> ulceration -> scabbing -> scarring
  3. The rash most commonly appearson the trunk along a thoracic dermatome or on the face(trigeminal) and it usually does not cross the body’s midline
  4. Pain and dysesthesia
33
Q

What are the types of pain experienced in PHN?

A
  1. Constant pain without stimulus (burning, aching, throbbing)
  2. Intermittent pain without a stimulus (stabbing, shooting, electric shock like)
  3. Hyperalgesia
34
Q

How long does pain persists after healing of PHN?

A

3 months

35
Q

How do you diagnosis PHN?

A
  1. Characteristic, localized, and persisting pain consistent with PHN
  2. Localized neuropathic pain persists beyond 3 months in the same distribution as a preceding documented episode of acute HZ

Additional factors:
1. Age >60 years
2. Distribution in trigeminal or brachial plexus dermatomes
3. The presence of localized allodynia
4. Severe pain or rash with acute herpes zoster episode

36
Q

What is the tx for PHN? Alternatives?

A

First line: gabapentinoids (gabapentin or pregabalin)
Alt: TCAs (amitriptyline, nortriptyline, desipramine)

37
Q

For mild symptoms or preference for topical for PHN?

A

Capsaicin (0.025 or 0.075%, reserve higher concentration 8% patch
Alt: lidocaine patch

38
Q

When do you use alt therapies for PHN?

A
  1. If Initial Therapy choice(s) is/are intolerable, contraindication present, or no response, consider switching to an Alternative Therapy
  2. If Initial Therapy choice(s) result/s in a partial or suboptimal response, consider adding an Alternative Therapy
39
Q

What are non-gabapentinoids used for PHN? SNRIs?

A
  1. Divalproex sodium (moderate improvement reported in studies)
  2. Valproic acid
  3. Carbamazepine
  4. Oxcarbazepine
  5. Lamotrigine

SNRIs: duloxetine, venlafaxine

40
Q

When is adjuct therapy used for PHN? Types?

A

In intractable pain with inadquate responsive to initial or alternative agent(s), adjunctive options may provide additional benefit:
* PO or transdermal opioid
* Intrathecal glucocorticoid injections (Methylprednisolone)

41
Q

What are treatments for refractory sx?

A
  1. Botox
  2. Cryotherapy
  3. Neuromodulation
  4. Cognitive and behavior therapies
42
Q

What is fibromyalgia?

A

Chronic, widespread, musculoskeletal, noninflammatory pain disorder:
* generalized aching (sometimes severe)
* Widespread tenderness of muscles, tendon insertions, and adjacent soft tissues
* Muscle stiffness
* Fatigue
* Mental cloudiness
* Poor sleep
* Mood disorders
* Variety of other somatic symptoms

43
Q

What is the cause of fibromyalgia?

A

The enhanced pain sensitivity and persistence of widespread pain may be caused by changes in the central processing of sensory input and deficiencies in endogenous pain inhibition

44
Q

What are the sx of fibromyalgia?

A
  1. Chronic widespread pain (CWP) or multisite pain (MSP)
  2. FIbro fog: difficulty w/ attention or tasks that require rapid thought changes
  3. Psychiatric sx
  4. Fatigue / sleep disturbances (moderate to severe) - stiffness/unrefreshed even if 8-10 hr or more of sleep
    * minor activities aggravate pain/fatigue
45
Q

How is fibromyalgia diagnosed?

A
  1. Diagnosis of exclusion
  2. Physical exam
  3. Labs
  4. Diagnosis is symptom based:
    * CWP at multiple sites
    * > 3 months duration of pain w/o another identified cause
    * Fatigue / sleep disturbances
46
Q

Initial trial should be of adequate duration for fibromyalgia?

A

one to three months: drugs should be started at low doses, built up slowly over time, and maintained at the lowest dose possible that produces therapeutic benefit

47
Q

What are the goals of fibromyalgia tx?

A

Increase patient self-efficacy with empowerment

48
Q

How do we screen for depression?

A

Patient Health Questionnaire PHQ-9

49
Q

What is the score of PHQ-9?

A

< 5 usually absence of a depressive disorder
5-9 no depression or subthreshold
10-14 spectrum of patients, other depressive disorder
> 15 indicate major depression

50
Q

What is the non-pharm for fibromyalgia?

A
  1. Patient education
  2. Nutrition and diet
  3. Cognitive intervention
  4. Exercise (low impact aerobic)
  5. Acupuncture/massage
  6. Neuromodulation
51
Q

What are the initial tx for fibromyalgia?

A

TCAs (e.g., amitriptyline)
* Cyclobenzaprine as an alternative to amitriptyline

SNRIs (e.g., duloxetine, milnacipran)
Pregabalin and gabapentin

52
Q

What agents are use in FM , widespread pain WITHOUT major mood or sleep disturbances?

A
  1. Amitriptyline
  2. Cyclobenzaprine
53
Q

What agents are use in FM with severe fatigue and/or depression?

A
  1. Duloxetine
  2. Milnacipran as an alternative
54
Q

What agents are used in FM for prominent sleep disturbances?

A
  1. Pregabalin
  2. Gabapentin (alt)
55
Q

WHat do you do if intial tx for fibromyalgia is not working?

A
  • Changing to another agent by similar process as choosing initial therapy, evaluate AEs experienced with initial choice & prominent symptoms
  • Medications should be tapered to avoid withdrawal symptoms
  • Consider combination if no AEs reported with initial therapy & add therapy with different MoA