The value of nerve root infiltration for leg pain when used with a nerve stimulator

Randomized comparative study of the efficacy of nerve root infiltration (NRI) guided by neurostimulator to find the value of nerve stimulators in nerve root infiltration was undertaken. The response to nerve root infiltration using local anaesthetics and steroid is unpredictable, partly because the exact nerve root giving rise to pain may not be truly infiltrated. The nerve stimulator is advocated to identify the nerve root of concern prior to infiltration. The current study assessed the results of NRI with and without the nerve stimulator. Ninety-six patients with leg pain awaiting selective nerve root infiltration using long acting local aesthetic, were prospectively randomized into two groups, in the first one, the nerve root block was carried out without nerve stimulator (n = 39) and in the second group the block was carried out with the guidance of a nerve root stimulator (n = 57). Seventy-seven of the patients who had lateral canal stenosis (a total 81) responded to NRI; within this group nerve stimulator was used for 50 patients. Nerve root infiltration was used to relieve post-discetomy leg pain (ten), post-disc prolapse (four) and in one patient post-nucleotomy leg pain. Overall 89% of the patients were responders of NRI. Responders of around 65% had the NRI performed with the aid of stimulator. The response rate to pain was 96% when NRI was guided by a neurostimulator and 79% when no neurostimulator was used. When responded there was no significant statistical difference using the Oswestry disability score between both groups. After excluding disc bulge in patients who respond partially to NRI, it is worthwhile repeating the injection. There was a significant difference in response rate when NRI was done under guidance of a nerve stimulator, the stimulator is safe to use and increases the specificity of the block.