Complications in spinal cord stimulation for treatment of angina pectoris. Differences in unipolar and multipolar percutaneous inserted electrodes.

Spinal cord stimulation (SCS) has become a well established treatment for ischaemic nociceptive pain condition such as angina pectoris. In patients not suitable candidates for coronary bypass grafting or intraarterial invasive technique (i.e. PTCA and Stent) SCS is an alternative. The purpose was to record the complications: electrode fracture, infection, electrode migration, and technical equipment failure, which occurred during long-term spinal cord stimulation (SCS). Of 60 patients with severe angina pectoris and not candidates for angioplastic or coronary bypass surgery, 22 had monopolar and 38 had quadripolar spinal cord electrodes positioned percutaneously. The patients were followed with 1 to 4 month intervals in a 4 year period, and all complications were recorded. Infection was seen in 5% and electrode fracture was seen in 3% of the patients. The most frequent complication was electrode displacement, which required operation (23%). The incidence of this complication was statistically lower in patients with quadripolar electrodes than in patients with monopolar electrodes (p < 0.003). All displacements occurred within 1 year after implantation. The lower frequency of displacements, which required reoperations, seen among the multipolar electrodes, was due to the possibility of noninvasive changes of electrode combinations to optimize the topography of stimulation. Changes of electrode combination in connection with small migrations were necessary in 29% of the patients with multipolar electrodes. Therefore, there was no significant difference between frequency of migration for patients with monopolar or quadripolar epidural stimulation electrodes (p = 0.31). When SCS was used for treatment of anginal pain, the frequency of electrode tip migrations was high, but the use of multipolar electrodes gave the possibility to compensate for the migration, and to avoid surgical replacement.