2.6. Clinical outcome analysis

We conducted visits with all patients at the last follow-up after implanting the DBS electrodes. Each patient was evaluated with the UPDRS under four different conditions. The medication off condition (Med-off) was defined as when a patient had not taken antiparkinsonian medication for at least 12 hours. The DBS off condition (DBS-off) was defined as when a patient had not received DBS for 4 hours or for the time of tolerance of the patient (sometimes < 4 hours due to intolerable symptoms).

To evaluate the effectiveness of STN-DBS or medications, we compared postoperative UPDRS scores between patients with DBS on/Med off and those with DBS off/Med off. The extent to which a patient benefitted from the operation was defined as the percentage of change in the difference between UPDRS scores. Neuropsychiatric function was evaluated using the Mini-Mental Status Examination (MMSE), Cognitive Abilities Screening Instrument (CASI), and Beck Depression Inventory (BDI).