Abstract
Aim
To identify a means to reduce the duration and radiation dose coupled with fluoroscopic guided nerve root blocks (NRB).
Method
Consecutive prospective two cohort comparative study. A similar method performed during CT guided NRBs was employed to guide needle placement for transforaminal nerve root injections with the aid of static MR images and fluoroscopy.
Axial MR images at the level of the target nerve root were used. An angle of inclination of 60 degrees was created from the nerve root to the skin of the back, the apex of this to represent the site of needle introduction. Triangulation on the MRI enabled the lateral entry point to be determined.
The transforaminal injections were then performed with the simple expedient of a skin marker line at the appropriate lateral distance from the midline for needle entry. The radiation dose and fluoroscopic time as measured by the image intensifier were recorded. This method was performed for 20 patients and compared to the same parameters for 23 previous patients in whom the transforaminal injections were performed without such a technique.
Results
20 patients in the navigated arm (group 1) and 23 in the non-navigated (group 2). Average fluoroscopic time (seconds) was 17.7 seconds (range 8-40) for group 1 and 16.4 seconds (range 6-45) for group 2 (P value 0.625). Radiation dose measured was 79.76 cgycm2 (range 8-212) for group 1 and 63.05 cgycm2 (range 8-260) for group 2 (P value 0.247).
Conclusion
This method of navigating nerve root blocks via fluoroscopy did not appear to reduce the duration of the procedure or radiation dose involved on objective data. Subjectively it was found to be a useful training aid for triangulation for those new to the technique but the available objective evidence was not obtained.
