|Sciatica: Studies of symptoms, genetic factors, and treatment with periradicular infiltration|
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This is the first randomized controlled trial comparing the efficacy of periradicular steroid with that of saline for unilateral discogenic sciatica. The findings of the study indicate that both treatments had already induced clinical improvements at the 2-week follow-up. Periradicular infiltration with a combination of methylprednisolone and bupivacaine was superior to saline injection for leg pain, straight leg raising and lumbar flexion (in addition to patient satisfaction) according to findings at 2 weeks, but not at later follow-up assessments. The saline injection was more effective for back pain at the 3- and 6-month follow up assessments, and for leg pain as shown at 6 months. The economic analysis showed that the methylprednisolone treatment had produced savings in costs of therapy visits and medications at 4 weeks, but other uses of resources and their respective costs and mean duration of sick leave were more or less equal in the two groups throughout the follow-up period. The total number of operations did not differ significantly between the treatment groups. The 21 % overall rate of operations was similar to that of other studies (Dilke et al. 1973, Bush & Hillier 1991, Carette et al. 1997).
Some controlled studies suggest that epidural corticosteroids may be beneficial for sciatica (Dilke et al. 1973, Bush & Hillier 1991), but negative results also exist (Klenerman et al. 1984, Cuckler et al. 1985, Mathews et al. 1987, Carette et al. 1997). Two meta-analyses suggest some benefit of epidural steroids for sciatica (Watts & Silagy 1995, Vroomen et al. 2000). Basically, epidural steroids could be effective in sciatica because a rapid direct transport from the epidural space to the axons of the spinal nerves in pigs was observed following application of Evans-blue-labelled albumin (Byröd et al 1995). It has been found, however, that even in experienced hands up to 25 % of epidural needle placements may be incorrect (White 1983), and additionally, there is a possibility that epidural corticosteroids might be effective in a subgroup that is overlooked because of heterogeneity in the study populations, follow-up times and intervention methods (Weinstein et al. 1995).
Periradicular injections have been recommended, but unfortunately only two uncontrolled prospective series have been published (Weiner & Fraser 1997, Lutz et al. 1998). Both studies suggest that such injections might have a beneficial effect on discogenic sciatic pain. Recently, multiple periradicular infiltrations with either bupivacaine or a combination of bupivacaine and betamethasone were compared (Riew et al. 2000). The combination of steroid and anaesthetic significantly reduced the need for operative treatment during the follow-up period (13 to 28 months). Eight patients of 28 in the steroid surgery underwent surgery compared to 18 of 27 in the bupivacaine group.
Periradicular injection of a corticosteroid anaesthetic combination was found to have only a short-term, but clinically meaningful, effect compared with saline injection. This was a single-injection study, and repeated injections could possibly produce a more sustainable effect. Decisive clinical improvement had already occurred in both treatment groups at 2 weeks. Interestingly, in a rat model, thermal hyperalgesia was abated with epidural saline and abolished with a specific inhibitor of iNOS (Kawakami et al. 1998). This indicates that saline might have some clinical efficacy, maybe by blocking the NO-mediated cascade. However, the data as such does not allow any inference that saline injection has an effect superior to that of a genuine placebo.
|Phenotype of patients with the Trp3 allele (III)||Up||Subgroup analysis of periradicular infiltration (V)|