Gastroparesis in Parkinson's disease: Diagnostic and clinical implications for optimizing pharmacological treatment.

Gastroparesis (GP), defined as delayed gastric emptying (GE) without mechanical obstruction, is an underdiagnosed non-motor symptom of Parkinson's disease (PD) that may affect levodopa pharmacokinetics and contribute to motor fluctuations. In PD, GP pathophysiology involves Lewy pathology in the enteric nervous system, neurohormonal dysregulation, gut microbiota alterations, and adverse effects of medications, including levodopa. Disruption of the gut-brain axis further exacerbates gastrointestinal dysmotility, leading to malnutrition, reduced quality of life, and increased hospitalization rates. Clinically, GP delays GE, resulting in erratic levodopa absorption and unpredictable ON/OFF responses. Diagnosis is challenging due to symptom overlap with other gastrointestinal disorders and the lack of validated scales specific to GP in PD. Gastric scintigraphy remains the reference method for assessing GE, although its use is limited by methodological variability and interference from ongoing PD treatments.This review critically examines the epidemiology, pathophysiology, and clinical consequences of GP in PD, and highlights its bidirectional relationship with levodopa pharmacokinetics, particularly its contribution to motor fluctuations. We discuss current pharmacological management strategies, with a focus on the efficacy and safety profile of domperidone. Finally, we propose the hypothesis that the future integration of digestive biomarkers and longitudinal clinical data could contribute to a more individualized treatment approach.