Aim:Deep brain stimulation (DBS) of the subthalamic nucleus is a preferred option for the treatment of motor symptoms in patients with Parkinson\'s disease (PD). Intraoperative microelectrode recording (MER), which guides the implantation of the DBS lead, can induce a microlesion effect (MLE) that results in motor symptom improvement. Although this phenomenon is well known, its quantitative impact remains unknown. In this prospective study, we investigated MER-induced MLE on the motor symptoms of 30 patients with PD.Material and Methods:MER-induced MLE was evaluated based on the difference between tremor, rigidity, and bradykinesia scores in the preoperative off-state and intraoperative state following MER and before test stimulation.Results:MLE scores improved by 21.7% [left (L) side] and by 13.6% [right (R) side] from baseline (p < 0.05). Tremor scores improved by 31.5% (L) and by 14.2% (R) (p < 0.05), rigidity scores improved by 17.3% (L) and by 14.2% (R) (p < 0.05) and bradykinesia scores improved by 20.6% (L) and by 11.5% (R) (p < 0.05) from baseline. There was no significant difference between MLE and the number of microelectrodes used (p > 0.05).Conclusion:MER-induced MLE improved motor symptoms and was not correlated with the number of microelectrodes used during the procedure.