Introduction: The effectiveness of stimulating the subthalamic nucleus (DBS-STN) in advanced Parkinson's disease (PD) largely depends on the correct placement of the electrodes. Since the sensory-motor region of the STN lies beside the internal capsule (IC), we believe that the motor effectiveness of DBS-STN could be related to the stimulation threshold in which IC signs appear (IC threshold).
Patients and methods: An examination of 17 consecutive patients with advanced PD who had been submitted to bilateral DBS-STN (one case was unilateral) was carried out to determine the motor improvement on each side of the body (n = 33) and the energy consumption one year after surgery according to the IC threshold obtained during the programming.
Results: A 45% improvement was observed in the UPDRS III in off and there was a 24% reduction in the equivalent dose of levodopa with bilateral DBS-STN. When the electrodes were considered, there was a statistically significant improvement that depended on the IC threshold. Energy consumption differed significantly between electrodes with an IC threshold of 3-7 V (1.5 +/- 1.2 microW) and those with an IC threshold > 7 V (8.3 +/- 9.4 microW).
Conclusions: During the stimulation phase and following the correct location of the STN, which was achieved by neurophysiological recording, the IC threshold has prognostic implications in medium-long term motor effectiveness and in the consumption of the battery in the generator.