Short-Term Effects of Selective Nerve Root Block in Spinal Stenosis Patients According to Spinal Canal Dimensions

ABSTRACT

STUDY DESIGN: Prospective study. OBJECTIVES: To assess the correlation between symptom improvement and spinal canal dimensions in patients who underwent selective nerve root block for lumbar spinal stenosis. SUMMARY OF LITERATURE REVIEW: When the canal size is relatively small, the pressure on the nerve root increases. Decompressive surgery relieves more pain in such patients. MATERIALS AND METHODS: From July 2009 to March 2011, 141 patients received selective nerve root block for 1-level central lumbar spinal stenosis in our hospital. We evaluated the patients using a visual analog scale (VAS) before the procedure and 1 hour, 1 month, and 3 months following the procedure. We measured the spinal canal using magnetic resonance imaging. RESULTS: There was no significant correlation between spinal canal dimensions and the pre-procedure VAS. We divided the patients into 3 groups using the average and the standard deviation of the patients' spinal canal dimensions (172.5 mm²) (p<0.01). One hour after the procedure, the VAS scores changed by 1.43±1.8, 1.62±1.7, and 1.53±1.5, respectively, with no significant differences among the 3 groups. However there were significant differences in the VAS changes 1 month and 3 months following the procedure, with results of 2.39±1.7 and 1.39±1.5, 4.65±2.1 and 4.28±2.3, and 4.97±2.2 and 6.83±1.9 (p<0.01), respectively. CONCLUSIONS: The smaller the area of the spinal canal, the less likely symptoms were to improve after selective nerve root block. The results of this study will help predict the effects of selective nerve root block in spinal stenosis patients.