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To the editor,
Lumbar epidural steroid injections are one of the most commonly performed pain management procedures. Despite being defined in the 1950s, the procedure has not undergone significant change and has only been used for low back pain caused by lumbosacral disc herniation or radicular pain.1 Caudal, interlaminar and transforaminal epidural injections are commonly used for this purpose. The expectation from these injections is for the injectate to spread to the anterolateral epidural space, blocking the structures causing pain. Low back pain or radicular pain generally arises from the sinuvertebral nerves in the ventral epidural space, the nerve root sheath, and the dorsal root ganglion.2 3
Transforaminal injection is advantageous over the two other methods as lower volume of injectate is applied close to the source of pain. Despite this advantage, the need for CT or fluoroscopy, exposure to radiation, and some reported neurologic complications (paraplegia, vascular injury, vasospasm, dural puncture, spinal-epidural abscess) have encouraged the search for safer methods. With the use of ultrasonography in regional anesthesia practice in the last decade, ultrasound-guided techniques are being used in chronic pain management in the field of algology.
Ultrasound-guided erector spinae plane block (ESPB) was first described in 2016 and has since been used for many indications when performed in the thoracic and lumbar spinal segments. Apart from postoperative analgesia, ESPB has been used for failed back surgery syndrome, as well as cervical and interscapular myofascial pain.4 5
There are some differences between thoracic and lumbar ESPB.6 7 It has been reported that when performed from the fourth lumbar segment with high volume, the injectate spreads in toward the psoas muscle and leads to an effect similar to lumbar plexus block, as well as partially to the neural foraminae.8 We hypothesized that ESPB would lead to similar effect as transforaminal injection.
The MRI of a 44-year-old male patient with left lower back and left leg pain demonstrated L3–L4 and L4–L5 intervertebral disc herniation. The patient described lower limb pain and slight paresthesia in the L4 and L5 dermatomes on the left side. Lumbar spine flexion and paravertebral muscle spasm were present. Left straight leg lift test was positive, with increased left-sided leg pain at 40° in supine position. Deep tendon reflexes and lower extremity motor tests were normal on both sides. The patient had a history of two-level transforaminal steroid injection 9 months previously. The patient presented to our clinic with pain during the last 3 months. Because the epidural access was difficult and painful during the previous transforaminal injection, the patient requested a less invasive technique to be performed. Ultrasound-guided high volume lumbar ESPB (40 mL local anesthetic + steroid) was administered. The patient’s visual analogue scales (VAS) score was 0 after the fourth hour and remained <4 for 3 months. On the return of pain, lumbar ESPB was scheduled again. After special written informed consent was taken from the patient for MRI, lumbar ESPB was performed from L4 using 40 mL of injectate that included 20 mL bupivacaine, 10 mL lidocaine, 8.6 mL saline, 40 mg/mL methylprednisolone 1 mL, and 0.4 mL gadobutrol (a contrast agent). The patient’s VAS was 9/10 before the procedure and decreased to 0 at the first hour. MRI was taken at the 45th and 60th minutes.
In the patient’s first 8-week follow-up, the VAS score was ≤3/10, and after the second ESPB injection he was able to walk and work full time without any pain. The patient reported generally more than 70% relief of his pain and symptoms. Physical therapy continued with low-dose tramadol (37.5 mg) and paracetamol (375 mg) medication.
MRI demonstrated contrast distribution between the L1 and S4 vertebrae. Contrast was observed in the left facial spina muscle (medial tract) and in the surrounding fascias, as well as in the erector spinae muscle (lateral tract). On the left, there were extensions to the L1/L2, L2/L3, L3/L4 and L4/L5 neural foramina, and to the left anterior and posterior epidural space. The contrast agent had the following borders on the left: facet joints and erector spinae muscles (medial and partially lateral tract) (figure 1).
When performed in high volumes, the injectate used in plane block can show a wide range of distribution. We previously reported dermatomal coverage from T10 to S2 when ESPB was performed from L4 using 40 mL of volume.9 In this report we have shown even further spread using MRIs.
To conclude, high volume lumbar ESPB can be used in select cases as a less invasive procedure with an effect similar to other interventional pain procedures. We believe that ESPB is an alternative and safer method that will find place in pain practice due to the requirement for non-radiation including radiologic modality. Further studies, including randomized clinical studies, are required to determine the generalizability of our findings.
Footnotes
Contributors Study conception and design: AA, ST, MC. Acquisition of data: AA, ST, MC. Analysis and interpretation of data: FA. Drafting of the manuscript: AA, ST, MC. Critical revision: AA, FA.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.