Background Deep brain stimulation (DBS) is now a widely accepted surgical treatment for Parkinson's disease (PD). Electrodes are implanted in the patient's brain after intraoperative test stimulation. Changes in parkinsonian rigidity during test stimulation are detected by an evaluator, usually a neurologist, by identifying changes in the resistance of the patient's arm to a passive movement. We hypothesised that at the moment of reduction in rigidity, the speed with which the evaluator moves the patient's arms increases and that this change and its amplitude can be detected with an acceleration sensor. The aim of the present study was to test this hypothesis by collecting data during DBS surgery. Furthermore, to know more about the optimal stimulation target, these quantitative data were categorized based on the anatomical location of the electrode during test stimulation. Discussion: The additional acceleration measurements during the surgery did not increase operation time or the patient's discomfort. Higher sensitivity when using the accelerometer recording system; effective stimulation amplitudes were found for 33 additional test stimulations. Conventionally targeted STN requires the lowest stimulation amplitude to reduce rigidity, but has significantly higher chances of side effect occurrence. The Fields of Forel have slightly higher stimulation amplitudes but have much lower change of causing side effects. Sufficient baseline data is necessary for proper identification of BQAs. There is an inherent subjective component in the acceleration analysis because the evaluation is done by the neurologist. Conclusion • Changes in rigidity of PD patients can be quantified during passive movements by measuring data from the evaluator. • Acceleration measurements confirm the subjective evaluation, but they seem to be more sensitive (Fig 4). • STN may not be the most efficacious target structure. The patient may benefit from an electrode placed closer to the Fields of Forel.