Deep brain stimulation of subthalamic nucleus helps in improving late phase motor planning in Parkinson's disease

- Bilateral stimulation of subthalamic nucleus (DBS-STN) along with medications improves bereitschaftspotentials (BP) in PD.
- The chronic and acute effects of switching DBS-STN ON or OFF do have different effects on BP.
- Acute effect of switching DBS-STN OFF results in reduction of later part of motor planning.
- Re-switching DBS-STN ON did not return the potentials to normal at Cz site even after 15 min.
- These findings must be considered in future to study the structural and neurotransmitter changes after DBS-STN.

ObjectiveDeep brain stimulation of subthalamic nucleus (DBS-STN) is a well-accepted treatment for Parkinson's disease (PD) but its effect on motor planning in the disease is yet unclear. This study examines the effect of switching the stimulation ON and OFF on components of bereitschaftspotentials in PD.Patients and methodsScalp bereitschaftspotentials were recorded during self-paced right wrist extensions at Fz, Cz, Pz, C3 and C4 sites in patients on DBS-STN plus medications (DBS-STN group) as treatment modality or on medications only (Med group) and compared with age matched healthy controls. In DBS-STN group, the potentials were recorded in stimulation ON, stimulation OFF, and again after re-switching stimulation ON-2. Offline analysis of potentials was done to calculate peak amplitude, late slope (−500 to 0 ms) and early slope (−1500 to −500 ms).ResultsWe observed that the two components of bereitschaftspotentials in stimulation ON state were comparable to those in age matched controls. The late slope was found to be significantly reduced during stimulation OFF as compared to stimulation ON at Cz (p < 0.001), C3 (p < 0.001) and C4 (p < 0.01) electrode sites. This parameter failed to improve on re-switching stimulation ON at Cz (p < 0.01). No significant change was observed in early part of bereitschaftspotentials among any of the conditions.ConclusionOur study shows that DBS-STN along with anti-parkinsonian medications helps in improving both components of bereitschaftspotentials in PD. Switching stimulation OFF for fifteen minutes principally affects the late component i.e. the execution part of motor planning; which cannot be reversed by re-switching ON. Thus the chronic and acute effects of switching DBS-STN ON are different and principally affect the later part of motor planning.