Evaluation of Erector Spina Plane Block(ESPB)'s Effectiveness on Patients With Lumbar Radiculopathy

Overview

A new regional anaesthetic block technique is described in this issue of Anaesthesia by Chin et al. whereby local anaesthetic is injected within a plane beneath the erector spinae muscle to achieve analgesia for abdominal surgery. After this the block has been used successfully for many implications such as post-herpetic neuralgia, thoracic and abdominal chronic or acute pain management, rib fractures, breast surgery, chronic cancer pain and etc. Cadaveric and radiologic data showed that contrast injected into the tissue plane deep to erector spinae muscle and superficial to the transverse processes and intertransverse connective tissues penetrates anteriorly to anesthetize the spinal nerves. And some cadeveric studies resulted with where both the dorsal and ventral rami of the thoracic spinal nerves were marked with dye after ESPB. Some studies even showed that dye reached to the epidural space. In this manner we we hypothesize that ESPB could be effective with radiculopathy pain.

Forero et al. proposed in 2016 an interfascial block to provide analgesia to patients suffering from thoracic chronic pain consisting of an injection of local anesthetic inside the erector spinae plane (ESP). As stated by the authors in their original work, the discovery of this technique was casual, but subsequent observations showed that this "casual" technique had a wide range of possible indications not only to thoracic area but varying from chronic to acute traumatic pain, from thoracic to orthopedic surgery, from children to elderly patients. There are three groups of muscles involved in this block: erector spinae muscles group, transverso-spinal muscles group and levatores rostrum. Erector spinae muscles are not a single muscle, but a really complex muscular group formed by ileocostalis muscles, longissimus muscles and spinalis muscles. These muscles link bone components of the back to each other: the spinous process to spinous process, rib to rib and transverse process to transverse process.Deep to this group of muscles, we find the transverso-spinal group of muscles connecting the transverse processes to the spinous processes (semispinalis, multifidus, rotatores), and deeper still are the levatores rostrum, originating from the transverse processes and inserting into the ribs. Together, all these muscles act as a geometrical structure that would facilitate the spread of local anesthetic. The ESP block's therapeutic effect is attributed to the cranial-caudal spread of local anesthetic over multiple vertebral levels in the musculofascial plane deep to the erector spinae muscle, accompanied by diffusion anteriorly into the contiguous paravertebral and intercostal spaces, where the local anesthetic then acts on the ventral and dorsal rami of spinal nerves. The subsequent realization that the erector spinae muscle extends from the lumbar spine to cervical spine led to extrapolation of the ESP block for many different indications in different regions of the body. Since after Forero's proposition in 2016 many researchers successfully tried ESPB primarily in post-operative pain and acute trauma pain management. More recently there have been some studies focusing on musculoskeletal originated pain such as myofascial pain syndrome, chronic shoulder pain/frozen shoulder etc. In this manner we hypothesize that ESPB could be effective for reducing pain effectively in a short treatment time. And considering other spinal interventions for radiculopathy pain such as transforaminal/epidural blocks require more skilled stuff, scopy device and a special place for it. Since ESPB can be done via ultrasonography and needs less stuff we also think that it can be a more cost efficient treatment choice for radiculopathy pain.