Diametral measurements of the upper spinal cord for stereotactic pain procedures: experimental and clinical study.

BACKGROUND

Stereotactic percutaneous pain procedures, percutaneous cordotomy, trigeminal tractotomy, and extralemniscal myelotomy are routinely performed with computed tomography (CT) guidance. This new imaging technique enables one to measure the spinal cord diameters for each patient uniquely. Significant differences have been recognized between the measurements obtained with CT and the reference values given for such procedures.

METHODS

To confirm the reliability of CT measurements, two experimental models were used. In the first stage, an artificial neck and spinal cord model was set up and diameters of the spinal cord were remeasured with CT. In the second stage, spinal cord diameters of the upper cervical region on 10 mongrel dogs were initially taken with CT, then standard laminectomy was performed and diameters of the same region were measured under the operating microscope.

RESULTS

The experimental studies confirmed that CT measurements of the upper cervical cord are reliable. In clinical application, diametral measurements of the spinal cord at occiput C-1 level were carried out in 30 patients who underwent percutaneous trigeminal tractotomy and extralemniscal myelotomy. The anteroposterior diameter at this level was measured at 7.0-12.8 mm and the transverse diameter ranges between 9.3-14 mm. At the level of C-1-C-2, these measurements were performed over 63 patients who experienced percutaneous cordotomy. In this group the anteroposterior (A-P) diameter was measured as 7.0-11.4 mm, and the transverse diameter as 9.0-14.0 mm.

CONCLUSIONS

Our clinical experiences and the results of the experimental measurements demonstrate that CT imaging gives accurate diametral values that would favorably influence the surgical procedures, and thus, with CT imaging it is possible to perform main stereotactic destructive pain procedures safely, effectively and selectively.