Erector Spinae Plane Block Versus Conventional Analgesia in Complex Spine Surgery

Enhanced recovery pathways (ERPs) emphasize evidence-based, multimodal anesthetic and analgesic choices to minimize opioid consumption while providing adequate pain control after surgery. Although ERPs for spine surgery are now being described, few pathways include regional analgesia. The Erector Spinae Plane Block (ESPB) may represent a novel opportunity to incorporate regional analgesia into ERPs for spine surgery. To date, there is minimal data to support the utility of ESPB in spine surgery, and this block has not yet been evaluated in complex spine surgery.

This study seeks to see whether ESPB will reduce opioid consumption and pain scores, and improve patient recovery during the first 24 hours after complex spine surgery when included in a comprehensive ERP.

Lumbar spinal fusion with posterior approach is a moderate-severely painful procedure requiring significant postoperative opioid analgesia (Mathiesen, 2013). There are limited opportunities to use multimodal analgesia (MMA) and regional analgesia after spine surgery. For example, non-steroidal anti-inflammatory drugs are not universally provided, due to concerns regarding bleeding and impaired fusion (Sivaganasan, 2017). Likewise, local anesthetic-based techniques may cause motor weakness and sensory changes which interfere with interpretation of the early postoperative neurological examination.

As in other orthopedic subspecialty surgeries, enhanced recovery pathways (ERPs) are now being described in spine surgery (Wang 2017; Soffin 2018; Soffin 2019a; Ali 2019). Published data emphasizes the importance of opioid-sparing MMA to achieve analgesia and minimize opioid-related side effects. However, with the exception of a report from our group, none include regional analgesia or field blocks as an element of care (Soffin 2019b). Further, comparative research regarding the benefits of regional analgesia within standardized ERPs is lacking for other surgical modalities - even within subspecialties where the evidence base to support such trials is more advanced. These deficits highlight an opportunity to demonstrate the unique advantages of regional analgesia over and above that which can be provided by conventional oral and/or intravenous MMA.

Ultrasound-guided erector spinae plane block (ESPB) may represent a novel opportunity to apply regional analgesia to patients undergoing spine surgery. First described in 2016, ESPB provides analgesia by depositing local anesthetic deep to the erector spinae muscles (Forero 2016). Studies have not completely defined the mechanism of the block, but the target of the local anesthetic has been proposed to be unmyelinated C fibers / sensory cell bodies within the dorsal root ganglia (Ivanusic 2018).

Since its introduction, hundreds of case reports with a wide spectrum of indications have described ESPB as a useful analgesic adjunct for a wide range of indications (Tsui 2019). The feasibility of ESPBs in spine surgery has likewise been suggested in case reports (Almeida 2019; Chin 2019), case series (Melvin 2018; Singh 2018) and retrospective cohort studies (Ueshima 2019). Each conclude significant opioid-sparing capacity and improved NRS pain scores in patients who receive ESPB for a variety of spine surgery procedures.

More recently, results from 2 RCTs describing outcomes after ESPB for lumbar decompression have been reported. In the first, 60 patients were randomized to receive bilateral ESPB or no intervention (Yayik 2019). NRS scores and tramadol consumption were significantly lower in the first 24 hours after surgery, and the time to requesting opioid analgesia was significantly longer in patients were received ESPB. In the second RCT, postoperative morphine consumption was lower in patients who received ESPB compared to patients who did not receive ESPB (Singh, 2019). NRS scores were lower up to 6 hours after surgery in the ESPB group, and patient satisfaction scores were higher.

These preliminary RCTs are promising; however, both suffer from methodological flaws, including lack of power, inadequate blinding, and incomplete standardization of other intra- and post-operative analgesics.

Eligibility Criteria:
Inclusion Criteria:

* Age 18-80
* Planned primary complex spine surgery: \>2 level- lumbar and/or thoraco-lumbar spine fusion with or without decompression
* Planned stand-alone posterior surgical approach
* Able to follow study protocol
* Able to communicate in English (outcome questionnaires validated in English)

Exclusion Criteria:

* Age \<18 or \>80
* Revision surgery
* BMI \> 35
* planned prolonged intubation/intubation overnight on night of surgery
* Unable to communicate in English
* History of chronic pain condition requiring gabapentin/pregabalin/antidepressant medication longer than 3 months
* Opioid tolerance (\>60 OME daily for \>2 weeks)
* Allergy, intolerance or contraindication to any protocol component/study medication/technique
* Patient refusal of regional analgesia (ESPB)