Evoked visual blood flow before and after deep brain stimulation in Parkinson’s disease - a fTCD study

Abstract

Besides an improvement in motor function, bilateral deep brain stimulation (DBS) of the subthalamic nucleus in Parkinson's disease (PD) patients seems also to augment perfusion in cortical motor areas. The latter finding could be a side effect of an increased cortical activity of motor areas but it was also speculated that DBS led to an improvement in vascular function. To study the effect of bilateral DBS on blood flow regulation in non-motor areas in Parkinson's disease. Five PD male patients, with a mean age of 52,4 ± 15,05 y, were selected for DBS of the subthalamic nucleus. They were evaluated with motor unified Parkinson's disease rating scale (UPDRS) and with visual functional transcranial Doppler (fTCD) test before and after the surgery (mean follow-up 4,2 ± 1,9 months). The evoked flow responses in the posterior cerebral artery were compared with 13 healthy controls. Using a control system approach the dynamic features of the flow response were evaluated with the parameters gain, rate time, attenuation and natural frequency. Implantation of the stimulators markedly improved patients motor performance, decreasing off UPDRS in 42% (43,8 ± 8,6 before and 18,3 ± 6,8 after surgery). PD patients had a lesser gain in the visual evoked blood flow response than the control group. DBS did not change blood flow regulative parameters. DBS improves motor symptoms but does not change visual cortex blood flow regulation in PD patients. Improvement of perfusion in motor areas of the brain might be explained by a higher functional activity of areas under stimulation conditions.