LESI LESI Pharmacology 1 — Questions and Answers
Question 1: Which corticosteroid is particulate and therefore associated with higher risk of embolic complications in transforaminal LESI?
- Dexamethasone
- Betamethasone sodium phosphate
- Methylprednisolone acetate (Depo-Medrol) (Correct answer)
- Prednisolone sodium succinate
Correct answer: Methylprednisolone acetate (Depo-Medrol)
Methylprednisolone acetate is a particulate steroid; its particles can aggregate and cause embolic occlusion of spinal arteries if inadvertently injected intravascularly.
Question 2: Which corticosteroid is recommended as the preferred agent for transforaminal LESI because it is non-particulate?
- Triamcinolone acetonide
- Methylprednisolone acetate
- Dexamethasone (Correct answer)
- Betamethasone acetate
Correct answer: Dexamethasone
Dexamethasone is a non-particulate steroid that does not form aggregates, making it the preferred and safer choice for transforaminal injections.
Question 3: What is the primary mechanism by which corticosteroids reduce radicular pain in LESI?
- Direct analgesia via opioid receptors
- Inhibition of phospholipase A2 and reduction of inflammatory mediators (Correct answer)
- Selective serotonin reuptake inhibition
- Blockade of sodium channels in nerve roots
Correct answer: Inhibition of phospholipase A2 and reduction of inflammatory mediators
Corticosteroids reduce inflammation by inhibiting phospholipase A2, thereby decreasing prostaglandins, leukotrienes, and other inflammatory mediators around compressed nerve roots.
Question 4: The local anesthetic most commonly added to corticosteroids in LESI to provide immediate pain relief is:
- Tetracaine 1%
- Bupivacaine 0.25% or lidocaine 1% (Correct answer)
- Cocaine 4%
- Ropivacaine 2%
Correct answer: Bupivacaine 0.25% or lidocaine 1%
Bupivacaine (0.25%) or lidocaine (1%) are the most commonly used local anesthetics combined with corticosteroids to provide immediate but temporary pain relief during LESI.
Question 5: The typical dose of triamcinolone acetonide used per interlaminar LESI is:
- 5-10 mg
- 20-40 mg (Correct answer)
- 80-120 mg
- 200-400 mg
Correct answer: 20-40 mg
Triamcinolone acetonide is typically used at 20-40 mg per lumbar epidural steroid injection, balancing efficacy with minimizing systemic steroid effects.
Question 6: Why is preservative-free formulation required for epidural steroid injections?
- Preservatives increase steroid potency
- Preservatives (e.g., benzyl alcohol) are neurotoxic and can cause arachnoiditis (Correct answer)
- Preservatives shorten the duration of effect
- Preservatives cause local anesthetic resistance
Correct answer: Preservatives (e.g., benzyl alcohol) are neurotoxic and can cause arachnoiditis
Preservatives such as benzyl alcohol and polyethylene glycol are neurotoxic and can cause chemical arachnoiditis or nerve damage if introduced into the epidural or intrathecal space.
LESI LESI Pharmacology 1
Which corticosteroid is particulate and therefore associated with higher risk of embolic complications in transforaminal LESI?