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Spread of local anesthetics after erector spinae plane block: an MRI study in healthy volunteers
  1. Marie Sørenstua1,2,
  2. Nikolaos Zantalis3,
  3. Johan Raeder2,
  4. Jan Sverre Vamnes4 and
  5. Ann-Chatrin Linqvist Leonardsen5,6
  1. 1Department of Anesthesia, Sykehuset Østfold HF, Gralum, Norway
  2. 2Faculty of Medicine, University of Oslo, Oslo, Norway
  3. 3Departement of Radiology, Ostfold Hospital Trust, Sarpsborg, Norway
  4. 4Department of Anesthesia, Ostfold Hospital Trust, Moss, Norway
  5. 5Health and Welfare, Ostfold University College, Fredrikstad, Norway
  6. 6Surgery, Osfold Hospital Trust, Sarpsborg, Norway
  1. Correspondence to Dr Marie Sørenstua, Department of Anesthesia, Sykehuset Østfold HF, Grålum 1714, Norway; mbergemohr{at}


Background Erector 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.

Methods Ten 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.

Results All 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.

Conclusion We 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 number NCT05012332.

  • regional anesthesia
  • pain, postoperative
  • multimodal imaging

Data availability statement

Data are available on reasonable request.

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Data availability statement

Data are available on reasonable request.

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  • Contributors MS stands as guarantor for the overall content. MS, NZ, JR, JSV and A-CLL conceived and designed the study. MS performed the blocks. NZ reviewed and analyzed the MRI results. All authors participated in the manuscript writing and reviewed all references. MS, NZ, JR, JSV and A-CLL approved the final manuscript.

  • Funding Funding was provided by institutional and/or departmental sources in Ostfold Hospital Trust.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.