CT-guided cervical selective nerve root block with a dorsal approach

Abstract

Background and purpose: Cervical transforaminal blocks are frequently performed to treat cervical radicular pain. These blocks are performed mostly under fluoroscopy, but a CT-guided technique has also been described. The aim of this study was to review the results of CT-guided CSNRB by using a dorsal approach, to describe the contrast patterns achieved with this injection technique, and to estimate the degree of specificity and sensitivity.

Materials and methods: We used a CT-guided technique with a dorsal approach leading to a more extra-than transforaminal but a selective nerve root block as well. Of 53 blocks, we performed 38 for diagnostic and 15 for therapeutic indications. Pain relief was measured hourly on a VAS. The distribution of contrast and the angle of the trajectory of the injection needle were analyzed as well as the degree of pain relief.

Results: Contrast was found in the intraforaminal region in 8 (15%) blocks, extraforaminally in 40 (78%) blocks, and intraspinally in 3 (6%) blocks. The mean angle between the needle and the sagittal plane was 26.6° (range, from 1° to 50°). The mean distance between needle tip and nerve root was 4.43 mm (range, 0-20 mm). Twenty-six (68.4%) of the 38 diagnostic blocks led to a decrease in the pain rating of >50%. There were no complications or unintended side effects, apart from occasional local puncture pain.

Conclusions: We conclude that CT-guided CSNRBs using a dorsal approach are feasible and that they are sensitive and specific.

Fig 1.

Extraforaminal contrast distribution after CSNRB of the right C6 nerve root.

Fig 2.

Extra- and intraforaminal contrast distribution after CSNRB of the right C6 nerve root.

Fig 3.

Schematic illustration of the needle tip and entrance of the foramen. 1 indicates the facet joint; 2, the uncinate process; 3, the line reaching from the anterior part of the uncinate process to the anterior part of the zygapophyseal joint; 4, the area in which the needle tip in the dorsal-approach technique is expected; and 5, the area in which the nerve root and nerve supplying the artery are expected.