PointExplainer: Towards Transparent Parkinson's Disease Diagnosis

A B S T R A C T Deep neural networks have shown potential in analyzing digitized hand-drawn signals for early diagnosis of Parkinson's disease. However, the lack of clear inter-pretability in existing diagnostic methods presents a challenge to clinical trust. In this paper, we propose PointExplainer, an explainable diagnostic strategy to identify hand-drawn regions that drive model diagnosis. Specifically, PointExplainer assigns discrete attribution values to hand-drawn segments, explicitly quantifying their relative contributions to the model's decision. Its key components include: (i) a diagnosis module, which encodes hand-drawn signals into 3D point clouds to represent hand-drawn trajectories, and (ii) an explanation module, which trains an interpretable surrogate model to approximate the local behavior of the black-box diagnostic model. We also introduce consistency measures to further address the issue of faithfulness in explanations. Extensive experiments on two benchmark datasets and a newly constructed dataset show that PointExplainer can provide intuitive explanations with no diagnostic performance degradation. Introduction Parkinson's disease (PD) is one of the most prevalent neurological disorders worldwide, leading to a decrease in functional, cognitive, and behavioral abilities [1, 10]. Despite the unclear etiology and lack of a cure, evidence indicates that early diagnosis, coupled with subsequent neuroprotective interventions, can significantly delay its progression [53]. Hand drawing is a common but complex human activity, requiring fine motor control and involving a sophisticated interplay of cognitive, sensory, and perceptual-motor functions [14]. Dysgraphia is recognized as a crucial biomarker in the early stages of PD [39]. Digitized hand-drawn analysis [6, 26], as a noninvasive and easily accessible biometric technology, has emerged as a promising computer-aided approach for diagnosing PD [23, 30, 22, 72, 47, 21].