Epidural vs Spinal

Epidural vs Spinal Spinal (Intrathecal) Anesthesia:
• Works by even spread of local anesthetic (LA) in cerebrospinal fluid (CSF).
• Bilateral and predictable block from the highest level downward.
• A T4 block covers all pain from visceral/peritoneal manipulation (C-fiber) and T10
is needed for sharp pain from incision (A-delta fibers).
• Since LA spreads freely in CSF, assessing a spinal block just requires checking the highest sensory level.
Epidural Anesthesia:
• Works by diffusing LA through the epidural space, reaching nerve roots individually.
• Spread is not always even due to fat, vessels, and connective tissue in the epidural space.
• Patients can have "windows" of pain where certain dermatomes are not blocked.
• A T10-L1 block is needed for contraction pain, and S2-S4 is required for pudendal
nerve pain during pushing.
• High volume, low concentration boluses help improve spread by forcing LA into
channels that reach each nerve root.
Clinical Takeaways:
• Spinal anesthesia = reliable, even block.
• Epidural anesthesia = variable, needs assessment of dermatomes.
• Epidural patients may experience one-sided pain or incomplete coverage,
requiring dose adjustments and careful troubleshooting.
• Patient feedback is crucial—they will report if a dermatome isn't covered!