Regional Anesthesia in Minimally Invasive Lumbar Spine Surgery

Opioid abuse and misuse remain a public health crisis in the United States, notably in patients with chronic pain from degenerative spine disease. Perioperative pain management for patients undergoing spinal surgery remains largely reliant on opioid medications, with several known adverse effects including, but not limited to delirium, postoperative urinary retention (POUR), constipation and nausea. These side effects contribute to increased hospital length of stay (LOS) with increased incidence of overall in-hospital complications, perioperative costs, and increased rates of opioid habituation and addiction.

Dependence on prescription opioids has been associated with wide-ranging social and economic consequences including increased opioid overdose resulting in death, growing opioid-related incarcerations, and spiraling opioid-related healthcare cost from treatment of addiction, opioid-related mental health issues, and debilitating chronic pain. Long-term requirements for opioid medications may be associated with the use of higher doses of opioids in the perioperative period for patients undergoing invasive surgery for spinal degenerative conditions. Studies have demonstrated that patients who consume fewer opioids for 30 days after surgery are less likely to progress to become chronic opioid users. Regional analgesic techniques have shown promise in decreasing post-operative pain and opioid requirements in thoracic and abdominal surgery but difficulties with post-operative neurological assessments have limited their use in spinal surgery. Inter-fascial plane blocks, however, have emerged as a safe and potentially useful regional analgesic technique to mitigate the pain-inducing effects of posterior spine surgery.

Erector Spinae Plane Blocks (ESPBs), specifically, involve ultra-sound guided injection of local anesthetic (LA) posteriorly beneath the erector spinae muscles resulting in longitudinal and ventrolateral spread of the anesthetic into the paravertebral space where the ventral and dorsal rami of the spinal nerves are located thereby inducing a multi-level analgesic effect. Depending upon the LA used, this effect may last for 4 to 36 hours.

The proposed study will examine the efficacy of preoperative ESPBs in reducing post-operative opioid utilization and its associated complications specifically after minimally invasive (MIS) lumbar spine surgery including both decompressive and instrumented fusion procedures. The guiding principle of MIS spine surgery is reduction of iatrogenic injury by utilizing muscle dilating approaches and tubular retractors rather than conventional open, subperiosteal muscle stripping techniques. The latter typically results in muscle denervation and devascularization as well as postoperative muscle atrophy and dead space creation that increase postoperative pain, muscle dysfunction, prolonged recovery times and complications. Since MIS spinal surgical procedures preserve normal paraspinal musculature compared to open surgery, the magnitude of effect of ESPBs may actually be more pronounced in this population.

The investigators hypothesize that by conducting this investigation within the rigor of a double-blinded, randomized placebo-controlled clinical trial, the results will definitively demonstrate that the addition of regional analgesia in the form of ESPB during MIS lumbar spine surgery will 1) reduce post-operative opioid consumption and 2) reduce opioid-related complications and hospital LOS but 3) have no adverse effects on postoperative pain control.

Inclusion criteria

• Age 18-80
• Undergoing one of 3 procedure types: 1) 2 or more levels of MIS decompression (e.g., discectomy, foraminotomy, laminectomy); 2) 1-3 levels of MIS transforaminal lumbar interbody fusion (TLIF) (with or without additional levels of MIS decompression for no greater than 3 total operative levels); 3) 1-3 levels of anterior lumbar interbody fusion (ALIF) or MIS lateral lumbar interbody fusion (LLIF) accompanied by posterior percutaneous instrumentation at the same levels
• Willing and able to give consent

Exclusion criteria

• Opioid tolerant at the time of the surgical procedure--defined as consuming greater than 30mg of morphine milligram equivalents (MME) daily (https://www.cdc.gov/drugoverdose/prescribing/guideline.html)
• Presence of an indwelling pain device (e.g., intrathecal opioid pump, spinal cord stimulator, dorsal root ganglion stimulator)
• Known allergy to bupivacaine, clonidine or similar local anesthetics
• Indication for surgery other than degenerative disease (e.g., neoplasm, infection, trauma)
• Chronic kidney disease (stage 3 or greater), or hepatic failure
• Active pregnancy
• Disease process or mental illness that would preclude accurate evaluation of pain in the perioperative period
• Active Worker's Compensation litigation