Spread of local anesthetics after erector spinae plane block: an MRI study in healthy volunteers

Abstract

BackgroundErector spinae plane block (ESPB) is a truncal fascial block with a disputed mechanism and anatomical site of effect. This study aimed to perform a one-sided ESPB and use MRI to investigate the spread of the local anesthetic (LA) and the corresponding cutaneous loss of sensation to pinprick and cold.MethodsTen volunteers received a right-sided ESPB at the level of the seventh thoracic vertebra (Th7), consisting of 30 mL 2.5 mg/mL ropivacaine with 0.3 mL gadolinium. The primary outcome was the evaluation of the spread of LA on MRI 1-hour postblock. The secondary outcome was the loss of sensation to cold and pinprick 30–50 min after the block was performed.ResultsAll volunteers had a spread of LA on MRI in the erector spinae muscles and to the intercostal space. 9/10 had spread to the paravertebral space and 8/10 had spread to the neural foramina. 4/10 volunteers had spread to the epidural space. One volunteer had extensive epidural spread as well as contralateral epidural and foraminal spread. Four volunteers had a loss of sensation both posterior and anterior to the midaxillary line, while six volunteers had a loss of sensation only on the posterior side.ConclusionWe found that LA consistently spreads to the intercostal space, the paravertebral space, and the neural foramina after an ESPB. Epidural spread was evident in four volunteers. Sensory testing 30–50 min after an ESPB shows highly variable results, and generally under-represents what could be expected from the visualized spread on MRI 60 min after block performance.Trial registration numberNCT05012332.

Population pharmacokinetic and safety analysis of ropivacaine used for erector spinae plane blocks

“…Because of toxicity concerns and inconsistent efficacy, we have subsequently lowered our doses and are no longer routinely performing ESP blocks for thoracic surgery. This may have been a result of inconsistent paravertebral spread reported in anatomical studies28 29 as well as inconsistent epidural spread and resulting sensory changes in a volunteer study 30…”

Insignificant influence of the intertransverse process block for major breast cancer surgery: a randomized, blinded, placebo-controlled, clinical trial

“…To our knowledge, no MRI study concerning the spread of ITP blocks exists. In close ‘paraspinal’ comparison, a novel in vivo MRI study21 with the erector spinae plane block (ESPB) shows epidural spread of LA in 4/10 cases; of these, 1 extensively. Another ESPB MRI study22 reveals epidural spread in 2/6, and a thoracic paravertebral block MRI study20 shows epidural spread in 5/20.…”

Quest for the Elusive Mechanism of Action for the Thoracic Paraspinal Nerve Block Techniques. Are We Ignoring the Anatomy of the “Retro Superior Costotransverse Ligament Space?”

“…There is paucity of data documenting the spread of an injectate after the TPSBs in the living human. 12,31,32 Magnetic resonance imaging (MRI), after an ESPB, has demonstrated spread of radiocontrast medium to the erector spinae plane (ESP), 12,31,32 intervertebral foramina, 12,31,32 ES, 12,31,32 TPVS, 12,31,32 and intercostal space, 12,31,32 across multiple vertebral levels. 12,31,32 There are also clinical data demonstrating that an ESPB can affect both the ventral 1,3,4,33 and dorsal 17,31,34 rami of the thoracic spinal nerves.…”