Parkinson disease (PD) is a rapidly growing neurologic disorder affecting millions of people worldwide. While bradykinesia, rigidity, and tremor define its motor phenotype, gastrointestinal (GI) symptoms are highly prevalent and significantly impact quality of life. These symptoms often persist or worsen despite dopaminergic therapy and result from dysmotility involving the entire GI tract. Notably, many patients exhibit substantial objective motility disturbances despite minimal or no reported symptoms. This mismatch reflects impaired gut-brain communication and profound gut hyposensitivity, which dampen symptom perception and awareness. As such, reliance solely on patient-reported symptoms risks overlooking clinically significant dysmotility that can impair drug absorption, promote malnutrition, and increase the risk of complications such as bacterial overgrowth or aspiration. In response, diagnostic strategies are evolving to incorporate objective assessments, including videofluoroscopy, cough reflex testing, high-resolution manometry, and transit studies. These tools enhance the detection and characterization of unrecognized GI dysfunction in PD. A more nuanced, mechanism-based approach to evaluation is critical, as improved recognition of pan-gut dysmotility can guide individualized management strategies. This article reviews the underlying mechanisms of GI dysfunction in PD and provides a framework for its clinical assessment and care, emphasizing the need for proactive, objective evaluation beyond symptom reporting alone.
Keywords: Parkinson disease; constipation; dysphagia; enteric nervous system; gastrointestinal motility; gastroparesis; gut-brain axis.
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