Erector Spinae Block
The erector spinae plane (ESP) block was first described by Forero et al. in 2016 [[i]]. It is a novel interfascial paraspinal plane block which was initially utilized as a regional technique for thoracic neuropathic pain. Using ultrasound, local anaesthetic is deposited deep to the three columns of erector spinae muscles which run the length of the spine from the base of the skull to the medial crest of the sacrum. Cadaveric and MRI studies have demonstrated spread of dye in a craniocaudal fashion over several levels. Due to the discontinuity of intercostal muscles, local anaesthetic diffuses anteriorly to the ventral and dorsal rami of the spinal nerves, and through the intertransverse connective tissue entering the thoracic paravertebral space. In 2018, Schwartzmann [[ii]] conducted an MRI study demonstrating spread of injectate into the paravertebral space with circumferential epidural spread from T5 to T12 through the neuroforamina. The rami communicantes, including sympathetic nerve fibres, can be covered with local anaesthetic, meaning ESPBs may provide somatic and visceral analgesia. Given the recent introduction of the ESP block, evidence is mainly limited to case reports and case series. Despite this, the clinical uses described for ESP block are wide and include – Cervical (brachial plexus spread for shoulder surgery), thoracic (rib fractures, thoracic surgery, breast surgery, open cardiac surgery), abdominal (laparotomy, nephrectomy).
[i] Forero M et al. The Erector Spinae Plane Block: A Novel Analgesic Technique in Thoracic Neuropathic Pain. Reg Anesth Pain Med. 2016 Sep-Oct;41(5):621-7.
[ii] Schwartzmann A, Peng P, Maciel MA, et al. Mechanism of the erector spinae plane block: insights from a magnetic resonance imaging study. Can J Anaesth. 2018;65:1165–6.