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Erector Spinae Plane (ESP) Block - Detailed Notes

1. Historical Background

• First described in 2016 as an analgesic technique for neuropathic chest wall pain
• Rapidly gained popularity as an alternative to paravertebral block (PVB) and neuraxial techniques
• Considered a fascial plane block - a category of ultrasound-guided regional techniques

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2. Anatomy

Erector Spinae Muscle Group

• Iliocostalis (most lateral)
• Longissimus (intermediate)
• Spinalis (most medial)

• High thoracic: muscles lie deep to the trapezius and rhomboid muscles
• Low thoracic: lie deep to the latissimus dorsi

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3. Mechanism of Action

1. Local anesthetic diffusion - Injectate spreads cranially and caudally within the continuous ESP fascial plane
2. Paravertebral space diffusion - LA may track anteriorly into the paravertebral space (some authors consider the ESP block a variant of the PVB)
3. Blockade of dorsal and ventral rami of thoracic spinal nerves
4. Sympathetic nerve fiber blockade - contributing to visceral pain control
5. A 20 mL injection at T5 can result in spread from C7 to T8 levels

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4. Indications

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5. Advantages Over Other Blocks

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6. Patient Positioning

• Sitting, or
• Lateral decubitus (block-side up)

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7. Ultrasound-Guided Technique

Probe Selection & Placement

• Linear probe (13-6 MHz) - standard for average adult
• Curvilinear probe (8-3 MHz) - for larger patients with deep structures
• Probe placed in parasagittal orientation over the paraspinal skin at the target thoracic or lumbar level
• Slide the probe laterally from the spinous process until the transverse processes are clearly visible (rectangular hyperechoic structures with acoustic shadowing) without pleura interposed between the transverse process and probe

Sonoanatomy to Identify

1. Trapezius (upper thoracic) / Latissimus dorsi (lower thoracic)
2. Rhomboid muscles (upper thoracic)
3. Erector spinae muscle group (large, fusiform)
4. Transverse processes - rectangular hyperechoic, with acoustic shadow below
5. Ribs appear as overlapping curved lines
6. Pleura - hyperechoic line between rib shadows (deeper and more lateral)

Needle Technique (In-Plane)

• Insert the needle either:
  • Caudal to the probe, directing cranially (caudal-to-cephalad)
  • Cephalad to the probe, directing caudally (cephalad-to-caudad)
• Advance in-plane until the tip contacts the transverse process
• Administer a saline bolus (hydrodissection) first to open the collapsible ESP plane - the erector spinae muscle should visibly lift/detach from the transverse process
• If resistance is encountered, withdraw the needle slightly (while keeping it beneath the erector spinae) and re-attempt
• After confirming correct plane (linear spread of LA deep to ESM), inject in 5 mL aliquots after each aspiration

Confirmation of Correct Plane

• Spread of LA visible deep to the erector spinae muscle, superficial to the transverse process
• Cranial and caudal spread spanning multiple vertebral levels
• Muscle visibly lifting off the transverse process

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8. Local Anesthetic Dosing

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9. Catheter Technique

• After hydrodissection opens the plane, pass catheter 5 cm beyond needle tip
• Programmed intermittent bolus, continuous infusion, or patient-controlled options
• Particularly valuable for thoracotomy, rib fractures, and spine surgery
• Case reports include use in neonates and infants for thoracotomy analgesia

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10. Landmark Technique (Non-Ultrasound)

• Transverse processes are located 1-2.5 cm lateral to the spinous processes
• Insert needle perpendicularly until transverse process is contacted
• Inject after aspiration; withdraw slightly if resistance is high
• Ultrasound is strongly recommended over landmark technique for safety

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11. Complications and Safety Profile

• Transverse process acts as an osseous backstop - the needle does not need to go "past" it
• Location is more superficial and posterior, away from pleura, major vessels, and neuraxial structures

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12. Special Populations

• Anticoagulated patients (e.g., cardiac surgery with cardiopulmonary bypass): ESP block is a preferred analgesic option given lower bleeding risk
• Pediatric / neonatal patients: Case reports of successful use for thoracotomy analgesia, including pre-term infants
• High-risk patients: The more superficial posterior location makes this safer than neuraxial or PVB

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13. Comparison with Retrolaminar Block

• The US probe is slid medially from the ESP position until vertebral laminae (diagonal sawtooth structures) are visualized
• LA is deposited on the periosteum of the lamina rather than the transverse process
• Considered an alternative to the ESP block, sometimes used for cardiac and noncardiac pediatric procedures

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14. Current Evidence (2023 Cochrane Review)

• vs. No block: Moderate-certainty evidence of a slight but not clinically meaningful reduction in 24-hour pain at rest (MD -0.77 VAS points, 95% CI -1.08 to -0.46)
• vs. Placebo block: Moderate-certainty evidence of no significant difference (MD -0.14, 95% CI -0.29 to 0.00)
• vs. Paravertebral block: Low-certainty evidence - no significant difference in 24-hour pain at rest (MD 0.23)
• Block-related adverse events: No events reported across multiple trials
• Conclusion: ESPB is safe, but the analgesic benefit over placebo is uncertain and may be inferior to PVB in expert hands

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15. Key Clinical Pearls

1. Inject deep to the erector spinae muscle, superficial to the transverse process - do not inject into the muscle itself
2. Hydrodissect first with saline to open the plane before injecting LA
3. Large volumes (20-50 mL) are needed to spread across multiple dermatomes - vigilance for LAST is required
4. The clear osseous endpoint (transverse process contact) makes this technically simpler than PVB
5. It may be inferior to PVB in expert hands but preferred in lower-volume centers or when PVB complications are a concern
6. For bilateral blockade, reduce volumes per side to avoid exceeding toxic LA thresholds
7. Spread from C7 to T8 is possible from a single T5 injection - plan level selection based on surgical site
8. Can be used as rescue analgesia when thoracic epidural fails or is contraindicated

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• Morgan and Mikhail's Clinical Anesthesiology, 7e, p. 1951-1952
• Barash, Cullen, and Stoelting's Clinical Anesthesia, 9e, p. 2979-2983
• Miller's Anesthesia, 10e, p. 7344-7345, p. 11082-11083
• Schnabel A et al. Erector spinae plane block for postoperative pain. Cochrane Database Syst Rev. 2023 (PMID 37811665)
• Zhang L et al. Impact of ESPB on postoperative recovery quality in spinal surgery. Eur Spine J. 2025 (PMID 40175641)