CAA CAA Regional & Neuraxial Anesthesia 1 — Questions and Answers
Question 1: At which vertebral interspace is spinal anesthesia most commonly performed in adults to avoid injury to the spinal cord?
- T10–T11
- T12–L1
- L2–L3 or L3–L4 (Correct answer)
- L5–S1
Correct answer: L2–L3 or L3–L4
The spinal cord ends at approximately L1–L2 in adults; intrathecal injection is performed below this level (L2–L3 or L3–L4) to avoid direct cord injury.
Question 2: Which baricity of local anesthetic is used for spinal anesthesia when the patient is placed in the sitting position for a 'saddle block'?
- Isobaric
- Hypobaric
- Hyperbaric (Correct answer)
- Isotonic
Correct answer: Hyperbaric
Hyperbaric local anesthetic is heavier than CSF and sinks with gravity; when the patient remains seated, it concentrates in the sacral (saddle) region.
Question 3: Post-dural puncture headache (PDPH) is caused by:
- Systemic absorption of local anesthetic
- Leakage of CSF through the dural puncture site, causing intracranial hypotension (Correct answer)
- Vasovagal reaction to needle insertion
- Epidural hematoma compressing the dura
Correct answer: Leakage of CSF through the dural puncture site, causing intracranial hypotension
CSF leaking through the dural hole lowers intracranial pressure, causing traction on pain-sensitive intracranial structures when the patient is upright.
Question 4: The DEFINITIVE treatment for a severe post-dural puncture headache is:
- IV caffeine infusion
- Epidural blood patch (Correct answer)
- Oral hydration and bed rest
- NSAID therapy
Correct answer: Epidural blood patch
An epidural blood patch—injecting 15–20 mL of the patient's autologous blood into the epidural space—seals the dural hole and provides rapid, durable relief.
Question 5: Total spinal anesthesia is a life-threatening complication characterized by:
- Unilateral sensory loss and leg weakness only
- High cephalad spread of intrathecal drug causing apnea, hypotension, and unconsciousness (Correct answer)
- Localized low back pain and urinary retention
- Prolonged motor block without hemodynamic changes
Correct answer: High cephalad spread of intrathecal drug causing apnea, hypotension, and unconsciousness
Excessive cephalad spread of intrathecal local anesthetic blocks cervical spinal roots and the brainstem, causing respiratory arrest, profound hypotension, and loss of consciousness.
Question 6: Which patient position during a spinal anesthetic MOST effectively limits cephalad spread of a hyperbaric local anesthetic solution?
- Trendelenburg (head-down)
- Reverse Trendelenburg (head-up) (Correct answer)
- Left lateral decubitus
- Prone jackknife
Correct answer: Reverse Trendelenburg (head-up)
Reverse Trendelenburg keeps the head higher than the injection site so the hyperbaric (gravity-dependent) solution pools in the lumbar region rather than spreading cephalad.
CAA CAA Regional & Neuraxial Anesthesia 1
At which vertebral interspace is spinal anesthesia most commonly performed in adults to avoid injury to the spinal cord?