ML-STIM: Machine learning for subthalamic nucleus intraoperative mapping

Objective: Deep Brain Stimulation (DBS) of the Subthalamic Nucleus (STN) is effective in alleviating motor symptoms in medication-refractory patients with Parkinson's Disease (PD). Intraoperative identification of the STN relies on MicroElectrode Recordings (MERs), typically analysed by trained operators. However, this approach is time-consuming and subject to variability. For this reason, this study proposes ML-STIM (Machine Learning for SubThalamic nucleus Intraoperative Mapping), a machine learning pipeline designed to automate STN classification from MERs, ensuring high accuracy and real-time performance. Approach: ML-STIM consists of MERs pre-processing, feature extraction, and classification using a MultiLayer Perceptron (MLP). An adaptive artifact removal algorithm was optimized to balance artifacts identification and STN signal preservation, and the features were selected among those recommended in literature through correlation analysis and ReliefF ranking. The pipeline was trained and validated on a public dataset (Dataset A, 46 patients) and tested on an independent dataset (Dataset B, 36 patients), from a different surgical center, to assess generalizability. Dataset B is made publicly available as well. Main results: ML-STIM achieved 87.8 ± 1.7% accuracy on Dataset A and 83.8 ± 1.6% accuracy on Dataset B, significantly outperforming a state-of-the-art deep learning model (ResNet-AT, p < 0.01). The artifact removal step significantly improved classification specificity (p < 0.001). ML-STIM processed raw 10-second recordings in 139.4 ± 2.1 milliseconds, demonstrating real-time feasibility. Significance: These results confirm ML-STIM as an accurate, interpretable, and computationally efficient solution for intraoperative STN identification in DBS surgeries.