Cervical nerve root blocks: indications and role of MR imaging

To examine whether magnetic resonance (MR) imaging findings of the cervical spine can predict pain relief after selective computed tomography (CT)-guided nerve root block and thus assist in the appropriate selection of patients who are suitable for this procedure.

Sixty consecutive patients with cervical radicular pain were examined with MR imaging and then treated with CT-guided cervical nerve root blocks (CNRBs). Various MR imaging findings were assessed and compared in terms of associated pain relief after CNRB. Pain relief was graded (0%-100%) by using a visual analogue scale (VAS). The relationship between MR imaging findings and level of pain relief was tested by using Mann-Whitney U and Kruskal-Wallis tests.

The mean percentage of pain reduction at VAS grading was 46%. There was a significant relationship between pain relief level and both location of disk herniation (mean pain reductions of 41% at median or mediolateral locations and 64% at foraminal locations, P =.034) and location of nerve root compromise (mean pain reductions of 19% at intraspinal, 45% at foraminal entrance, and 58% at foraminal locations; P =.019). There was an inverse relationship between pain relief level and absence or presence of spinal canal stenosis (mean pain reductions of 29% when stenosis present and 53% when stenosis absent, P =.013). Other parameters were not significantly related to pain relief.

MR imaging of the cervical spine assists in the appropriate selection of patients suitable for CNRB. Patients with foraminal disk herniation, foraminal nerve root compromise, and no spinal canal stenosis appear to have the greatest pain relief after this procedure.