EDAIC Regional Anesthesia and Pain Management 3 — Questions and Answers
Question 1: Which ultrasound finding confirms correct needle placement for an adductor canal block?
- Local anesthetic spread surrounding the femoral artery in the femoral triangle
- Local anesthetic spread surrounding the saphenous nerve between the sartorius and adductor longus muscles (Correct answer)
- Medial spread of local anesthetic around the sciatic nerve
- Posterior spread around the popliteal vessels
Correct answer: Local anesthetic spread surrounding the saphenous nerve between the sartorius and adductor longus muscles
The adductor canal contains the saphenous nerve alongside the superficial femoral artery deep to the sartorius muscle; correct placement shows LA spreading around these structures.
Question 2: What is the mechanism of action of ketamine in pain management?
- Selective mu-opioid receptor agonism
- NMDA receptor antagonism (Correct answer)
- Alpha-2 adrenergic receptor agonism
- Sodium channel blockade
Correct answer: NMDA receptor antagonism
Ketamine is an NMDA receptor antagonist that blocks central sensitization and 'wind-up' phenomena, making it effective for opioid-resistant and neuropathic pain.
Question 3: A patient has a suspected intravascular injection during an epidural test dose with epinephrine. Which response confirms intravascular placement?
- Heart rate decrease >10 bpm
- Heart rate increase >20 bpm within 60 seconds (Correct answer)
- Blood pressure drop >20 mmHg systolic
- SpO2 decrease >5%
Correct answer: Heart rate increase >20 bpm within 60 seconds
The classic epidural test dose uses 3 mL of 1.5% lidocaine with 1:200,000 epinephrine; intravascular injection causes a heart rate increase of >20 bpm within 60 seconds.
Question 4: Which nerve root primarily supplies sensation to the medial aspect of the ankle and foot?
- L4 via saphenous nerve (Correct answer)
- L5 via superficial peroneal nerve
- S1 via sural nerve
- S2 via posterior tibial nerve
Correct answer: L4 via saphenous nerve
The saphenous nerve (terminal branch of the femoral nerve, L2-L4, predominantly L4) supplies sensation to the medial leg, ankle, and foot.
Question 5: The WHO analgesic ladder for cancer pain recommends which sequence of analgesic approach?
- Opioids first, then adjuvants, then NSAIDs
- Non-opioids → weak opioids → strong opioids, with adjuvants at each step (Correct answer)
- Adjuvant analgesics first, escalating to opioids only if ineffective
- Interventional techniques before systemic opioids
Correct answer: Non-opioids → weak opioids → strong opioids, with adjuvants at each step
The WHO three-step ladder starts with non-opioids (Step 1), adds weak opioids for mild-to-moderate pain (Step 2), and escalates to strong opioids for moderate-to-severe pain (Step 3), with adjuvants at all steps.
Question 6: During a stellate ganglion block, Horner's syndrome confirms successful blockade. Which triad of signs characterizes Horner's syndrome?
- Ptosis, miosis, and anhidrosis (Correct answer)
- Mydriasis, ptosis, and facial flushing
- Exophthalmos, tachycardia, and miosis
- Ptosis, enophthalmos, and hypertension
Correct answer: Ptosis, miosis, and anhidrosis
Horner's syndrome results from sympathetic blockade and manifests as ptosis (drooping eyelid), miosis (pupillary constriction), and anhidrosis (loss of sweating) on the ipsilateral face.
Question 7: Which type of pain is best characterized by allodynia and hyperalgesia?
- Nociceptive somatic pain
- Visceral pain
- Neuropathic pain (Correct answer)
- Psychogenic pain
Correct answer: Neuropathic pain
Neuropathic pain arises from nervous system injury or dysfunction and characteristically includes allodynia (pain from non-painful stimuli) and hyperalgesia (exaggerated pain response to painful stimuli).
EDAIC Regional Anesthesia and Pain Management 3
Which ultrasound finding confirms correct needle placement for an adductor canal block?