Interventional Pain Rotation Notes (Creighton)

Question 1

What is pain?

What is the duration that defines chronic pain

Answer 1

Pain is the unpleasant sensation or emotion associated with actual or potential tissue damage

Pain lasting beyond 3 months which is the extent of normal tissue repair

Overall function is affected from sources including social/cognitive/behavioral/biological

Question 2

what is neuropathic pain vs nociceptive pain

Answer 2

neuropathic: abnormal function of nerves (ie herpetic neuralgia or diabetic peripheral neuropathy)

nociceptive (physiologic): ongoing tissue injury stimulating peripheral sensory neurons (osteoarthritis)

Question 3

What is the anatomy of a spinal unit

Answer 3

Spinal unit includes:
- Upper and lower vertebral column
- Intervertebral disc
- Facet joints that connect the superior articular process of the lower vertebra to the inferior articular process of the upper vertebra

Question 4

How does intervertebral disc disruption occur

Answer 4

dehydration of the nucleus pulposus leads to tearing of the annulus fibrosis

nucleus pulposus can then herniate (ie herniated disc) and cause local inflammation to adjacent spinal nerves resulting in radicular pain

Question 5

What are the tissue layers from skin to spine?

Answer 5

• Skin
• Subcutaneous fat
• Muscle
• Supraspinous ligament
• Interspinous ligament
• Ligamentum flavum
• Dura mater
• Arachnoid mater
• Pia mater

Question 6

Red Flags when diagnosing new low back pain

Answer 6

new onset after recent trauma, infection or cancer diagnosis (concerns for seeding)

progressively worsening neurologic symptoms (ie bladder dysfunction/numbness, concerns for compression lesions)

Question 7

How long should the following med be held prior to Regional LA/Steroid injection or neuraxial procedure?

• warfarin
• clopidogrel
• apixaban

Answer 7

Plavix (clopidogrel) – off for 7days prior
Eliquis(apixaban) – off for 4 days
Coumadin (warfarin) off for 4 days with INR < 1.5

Question 8

What are short and long term side effects to administering steroids?

Answer 8

hyperglycemia (risk of DKA, DM pt needs BG <250)
water retention/swelling > inc blood pressure
leukocytosis
osteoporosis
skin atrophy
avascular necrosis
steroid induced psychosis

Question 9

What combinations/brand names of meds are the following:

Norco
Roxycodone
Percocet
Vicodin
Oxycontin
Dilaudid
Dolophine
Suboxone
Roxanol

Answer 9

Norco/Vicodin = hydrocodone + acetaminophen (dif strengths)
Roxycodone/Oxycontin = oxycodone (SA vs ER)
Percocet = oxycodone + acetaminophen
Dilaudid = hydromorphone (avail oral)
Dolophine = methadone (for addiction)
Suboxone = buprenorphine
Roxanol = oral morphine (Cancer pain)

Question 10

What are different types of muscle relaxants and which drugs do these brand names represent:

Lioresal
Zanaflex
Flexeril
Robaxin
Skelaxin

Answer 10

Baclofen (Lioresal)
Tizanidine (Zanaflex)
Metaxalone (Skelaxin)
Cyclobenzaprine (flexerill)
Methocarbamol (Robaxin)

Question 11

Maximum daily dose of ibuprofen

Answer 11

3200mg

Question 12

Maximum daily dose of acetaminophen

Answer 12

4000mg

Question 13

What are pin prick sites for the lower body dermatomes?

L1
L2
L3
L4
L5
S1

Answer 13

L1 fem cleft
L2 upper anterior thigh
L3 medial femoral condyle, mid-thigh
L4 medial malleolus, knee
L5 great toe dorsum of foot, Digits 1-4
S1 lateral foot, fifth digit

Question 14

How long should patient be off heparin ppx prior to epidural or other neuraxial procedure (ie Heparin 5000u TID)?

Answer 14

Hold for 4-6hrs with normalization of PTT (25-35sec) prior to procedure

Therapeutic PTT range for heparin can be 60-100sec

Question 15

How long should you wait to do neuraxial procedure if a patient is taking LMWH for dvt prophylaxis

Answer 15

Should wait 12 hours after last LMWH prophylaxis dose

Question 16

When can neuraxial procedure be done if patient is on warfarin?

Answer 16

Should wait 5 days with normalization of INR (1.0)

therapeutic INR (2.0-2.5)

Question 17

Patient took aspirin, can neuraxial procedure be done the same day?

Answer 17

Yes, studies have shown that NSAIDs including aspirin have not been shown to increase risk of spinal hematoma during epidural or spinal anesthesia

CLASP trial involved 1400 pts receiving epidurals, half on 60mg asa and half not.

Question 18

Max dose of the following local anesthetics:

Lidocaine
Lidocaine + epi
Bupivicaine
Bupivicaine + epi
Mepivicaine
Mepivicaine + epi
Ropivicaine

Answer 18

Lidocaine 5mg/kg
Lidocaine + epi 7mg/kh
Bupivicaine 2.5mg/kg
Bupivicaine + epi 3mg/kg
Mepivicaine 7mg/kg
Mepivicaine + epi 8mg/kg
Ropivicaine 3mg/kg

Question 19

Duration of action for following LA:

Lidocaine
Bupivicaine
Ropivicaine
Mepivicaine

Answer 19

Lidocaine 4 hr
Bupivicaine 8-10hr
Ropivicaine 8-10hr
Mepivocaine 4hr

Question 20

How do you test for L5 muscle weakness?

Answer 20

Extensor hallucis longus (big toe extension)

Question 21

Range of post op pain opioid medication addition in a chronic pain patient who is already on opioids

Answer 21

20-30% added MME for post op period

Question 22

How does spinal cord injury lead to spasticity?

Answer 22

Brain and spinal cord sends inhibitory signals (from upper motor neuron), central lesion will lead to uncoordinated muscle activation and relaxation at the lower motor neurons

Therefore if you have LMN injury you will have too much central inhibitory signal (ie foot drop)

Question 23

What is the generic of flexeril and what is the MOA?

Answer 23

Cyclobenzaprine

5HT2 antagonist (causes sedation)

Question 24

What is the mechanism of baclofen?

Answer 24

GabaB agonist

(Benzos are gaba A agonism)

Question 25

What are symptoms of baclofen withdrawal?

Answer 25

“Itchy, bitchy, twitchy”

Pruritis, mood change, seizures

Question 26

What is the generic of Zanaflex and what is the MOA?

Answer 26

Tizanidine
Alpha2 agonist (similar to clonidine)