DIAMETRAL MEASUREMENTS OF THE UPPER SPINAL-CORD FOR STEREOTAXIC PAIN PROCEDURES - EXPERIMENTAL AND CLINICAL-STUDY

BACKGROUND Stereotactic percutaneous pain procedures, percutaneous cor dotomy, trigeminal tractotomy, and extralemniscal myelotomy are routin ely performed with computed tomography (CT) guidance. This new imaging technique enables one to measure the spinal cord diameters for each p atient uniquely. Significant differences have been recognized between the measurements obtained with CT and the reference values given for s uch 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 o f the upper cervical region on 10 mongrel dogs were initially taken wi th CT, then standard laminectomy was performed and diameters of the sa me region were measured under the operating microscope. RESULTS The ex perimental studies confirmed that CT measurements of the upper cervica l cord are reliable. In clinical application, diametral measurements o f the spinal cord at occiput C-1 level were carried out in 30 patients who underwent percutaneous trigeminal tractotomy and extralemniscal m yelotomy. 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 th e level of C-1-C-2, these measurements were performed over 63 patients who experienced percutaneous cordotomy. In this group the anteroposte rior (A-P) diameter was measured as 7.0-11.4 mm, and the transverse di ameter as 9.0-14.0 mm. CONCLUSIONS Our clinical experiences and the re sults of the experimental measurements demonstrate that CT imaging giv es accurate diametral values that would favorably influence the surgic al procedures, and thus, with CT imaging it is possible to perform mai n stereotactic destructive pain procedures safely, effectively and sel ectively.