A Convolutional Neural Network Model for Classifying Resting Tremor Amplitude in Parkinson’s Disease

Resting tremor (RT) is one of the most common and debilitating symptoms of Parkinson's Disease (PD), characterized by involuntary rhythmic muscle contractions. The Unified Parkinson's Disease Rating Scale (UPDRS) 3.17 is a clinical assessment used to evaluate the amplitude of RTs, providing critical insights into the severity of this condition. However, it relies on subjective evaluation which may introduce intra- and inter-individual biases in tremor assessment. The present study evaluates the effectiveness of a Convolutional Neural Network (CNN) model for the multiclass classification of RT amplitude in PD patients and compares its performance with traditional machine learning models. A publicly available dataset containing data from 3-axis accelerometers placed on arms of 13 PD patients and 11 healthy subjects over approximately two days, including in-clinic and daily living activities (ADLs), was used. Resting data recorded during the UPDRS assessment were extracted and used to identify additional resting periods within the recordings through an automatic segmentation algorithm. At the end, for each of the selected arms, 90,000 data points were labeled based on the respective UPDRS 3.17 scores. A CNN structured into 7 layers was developed, and a 5-fold cross-validation method was employed to test the robustness of the model. Results from the best run of the most efficient combination of hyperparameters indicate that the CNN model achieves an average accuracy of 95.94% across the validation folds. The proposed model outperformed traditional machine learning techniques as Random Forest, Support Vector Machine (SVM) and Decision Trees, demonstrating superior accuracy in tremor classification. Our method exploited the ability of CNNs to classify RT amplitude efficiently, aiming at simplify diagnostic processes, enhancing the accuracy of the RT assessment in clinical settings.