Randomized Control Trial of Quadratus Lumborum Block for Lumbar Spine Decompression and Fusion Surgery

Spinal decompression is a surgical procedure that is performed to alleviate pain caused by pinched nerves (neural impingement). Surgical options for decompressing the lumbar spine vary from minimally invasive disc decompression to open laminectomy and foraminotomy. The lumbar spine decompression and fusion differs from a microdiscectomy in that the incision is longer and there is more muscle stripping. Lumbar spinal decompression is a commonly performed procedure and the conventional open techniques of decompression remain the gold standard of treatment.

During a lumbar decompression back surgery, a small portion of the bone over the nerve root and/or disc material from under the nerve root is removed to give the nerve root more space and provide a better healing environment. A lumbar spine decompression and fusion is typically performed to relieve the lumbar spinal stenosis symptoms. The goal of the surgery is to allow more space for the nerve root, thus reducing pain (and potentially any leg weakness or neurological symptoms) and restoring the patient's ability to participate in everyday activities[1].

Quadratus lumborum (QL) block was introduced in 2007 and is performed for perioperative pain management in various abdominal, pelvic, gynecological and hip procedures in all age groups[2]. Four types of QL block were described, differentiated by the exact location of the anesthetic injection. Type 1/lateral QL block is performed at the lateral border of the QL muscle, type 2/posterior QL block is performed at the medial edge of the QL muscle (at the border or the spine erector muscles and the thoraco-lumbar fascia), type 3/anterior is performed between the QL muscle and the psoas major and type 4 is intramuscular (see figure 1). In the majority of cases, these blocks are performed pre/post operatively under ultrasound guidance. There are sporadic reports of QL block performed for lumbar spinal surgery [3, 4].However, the plane for a type 2 QL block can be easily reached during open midline spinal surgery.

The importance of pain control in the postoperative period for spinal surgery has been discussed and proven extensively, with both immediate and delayed reduction in complications and improved clinical results [5, 6].

The investigators hypothesize that the type 2 QL block is an effective analgesic tool for lumbar laminectomy surgery, because in lumbar laminectomy the quadratus lumborum is already exposed and is in direct visual contact. For that reason it is imperative, in our opinion, to test its benefits of this procedure.

Study's objective:

To test the safety and efficacy of open quadratus lumborum block as an add-on postoperative analgesic technique for lumbar spine decompression and fusion.

Study design:

This is a pilot comparative study, double blind and placebo controlled . Patients scheduled for a lumbar spine decompression and fusion will be divided randomly into two groups of N=50 each. Subjects in both groups will receive an intra-operative exposure of the posterior QL block plane, with injection of long acting local anesthetic for group A and Saline for group B. Both groups will be monitored during their admission in the department for opioid dose administered, reported pain levels (NRS), narcotics side effects (delirium, urinary retention, falls) and general operative complications. Patient pain levels, satisfaction and general complications will be gathered during clinic follow up.

Methods:

Patients arriving to undergo lumbar spine decompression and fusion will be offered to participate in the study. They will receive a thorough explanation about the study and will sign an informed consent form. The division into each group will be done randomly on a one by one basis, by an operating room nurse. The scrubbed nurse will be exposed to the nature of the substance injected for its sterile preparation, however the surgeons will be blinded to it. Patients will be blinded to their study arm until the end of the study. The lumbar laminectomy (open decompression) procedure will be performed as usual:

• First, the back is approached through a two-inch to five-inch long incision in the midline of the back, and the left and right back muscles (erector spinae) are dissected off the lamina on both sides and at multiple levels.
• After the spine is approached, the lamina is removed (laminectomy), allowing visualization of the nerve roots.
• The facet joints, which are directly over the nerve roots, may then be undercut (trimmed) to give the nerve roots more room.
• Fusion will be performed with pedicular screws and rods and when indicated an interbody device.

Study group A will be given an analgesic injection into the quadratus lumborum, comprising of Marcaine 0.25% with normal saline (for a total of 20 ml per side). Study group B will receive an identical procedure, however with 20 ml normal saline alone per side. Time required to perform the block for both sides will be measured.

The postoperative regime will include a standardized pain protocol as is used in routine practice. all other operative or postoperative procedures are the same for both groups. Data will be collected from nurses and physical therapy as well as discharge notes. A standardized form for obtaining data will be used in clinic follow up at 2-3 weeks and 3-4 months.

Safety data collected:

A subjective report of each patient regarding any adverse events will be collected by the study nurse during their recovery. The surgeon will report at the end of each operation if there were any adverse events and level of difficulty administrating the injection on designated forms.