This double-blind study of 225 patients at a single center undergoing posterior cervical or lumbar surgery by the same surgeon demonstrated improved postoperative pain control when 150 ug clonidine was added to 20mL of bupivacaine for pre-incisional field block compared with using bupivacaine alone. This effect was noted especially in patients without preoperative back pain. Patients were grouped by surgical procedure: lumbar spinal fusion (n = 80), lumbar laminectomy (n = 25), lumbar microdiscectomy (n = 94), or cervical laminectomy (n = 26). Within each group, enrolled patients were randomized to the control (bupivacaine only) or clonidine + bupivacaine (C+B) group. Patients received a standard general anesthetic and postoperative analgesic protocol. Diary of pain scores in the first eight days and quantity of rescue morphine consumption in the first three postoperative days were tracked. The primary outcome measure was the calculated area under the curve (AUC) of pain tabulated from the pain diary values recorded at regular intervals in the first postoperative week. The AUC was significantly lower for the C+B subgroups in all procedure groups except cervical stenosis as well as overall. Rescue morphine consumption was also reduced in C+B group for lumbar fusion and lumbar laminectomy, although not statistically significantly lower for cervical surgery or microdiscectomy. The least difference in AUC was noted in the cervical laminectomy group. Patients with prior low back pain experienced lower benefit from clonidine addition. Local pre-incisional C+B field blocks resulted in better, more prolonged postoperative analgesia in posterior lumbar spine surgeries. This well-designed prospective randomized study supports the approach of a multimodal analgesia strategy for postoperative pain control.
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