Prevention of Postoperative Pain and of Epidural Fibrosis After Lumbar Microdiscectomy

Abstract

At the end of lumbar microdiscectomy, we administered an emulsion of low-dose epidural morphine and vaseline sterile-oil as carrier for morphine delivery. To evaluate safety and analgesic efficacy of this compound and the impact on long-term epidural scar production. Epidural analgesia has been used with lumbar microdiscectomy for facilitating management of postoperative pain, shortening patients' hospital stay and recovery time, and increasing the satisfaction rate. Several products have been used as barrier against the development of epidural fibrosis after lumbar procedures, to improve long-term outcome. Two milligrams of morphine mixed with 2 mL of vaseline sterile-oil have been epidurally administered to 40 consecutive patients undergoing lumbar microdiscectomy, evaluating safety and analgesic effectiveness of the compound and the incidence of epidural fibrosis at clinical and magnetic resonance imaging or computed tomography scan follow-up. Outcome measures included (1) visual analog scale (VAS) to assess the intensity of spontaneous low back and radicular pain, (2) straight-leg-raising maneuver to assess the degrees of leg elevation in relation to evoked-sciatic pain, (3) postoperative time to comfortable ambulation, (4) duration of postoperative hospitalization, (5) required amount of postoperative analgesics, (6) postoperative work time loss, and (7) follow-up lumbar magnetic resonance imaging or segmental computed tomography with contrast medium for quantitative evaluation of postoperative epidural fibrosis. Neither intraoperative nor postoperative clinically relevant adverse events, such as urinary retention, respiratory disturbances, or wound infections, were observed. At hospital discharge, patients showed a low pain intensity score (mean VAS 11.3 mm +/- 0.88; mean straight-leg-raising 64.9 degrees +/- 14.6), with low consumption of analgesics (31.2% in hospital, 35% at home). Mean hospital stay was 1.21 +/- 0.17 days; mean postoperative work time loss was 22.23 +/- 1.97 days. At 1-week and 2-week control, mean pain intensity score was 10.7 +/- 2.3 and 9.3 mm +/- 1.3, respectively. After a mean follow-up of 34.3 months (range, 24-48) 12 patients episodes of transient lumbar and/or sciatic pain. At the last neuroradiological control, according to the 5-grade scale of Ross et al (Neurol Res 1999), epidural fibrosis scored 0 in 8 cases and 1 in 32 cases. Epidural application of morphine-vaseline sterile-oil compound after lumbar microdiscectomy proved to be safe and effective, improving postoperative pain control and return to function. At clinical and neuroradiological follow-up epidural fibrosis was acceptable. To confirm the efficacy of the compound, large prospective studies are warranted.