Partial symptom remission in occupational pesticide-related parkinsonism: a case report

Abstract

Parkinson’s disease (PD) is a progressive neurodegenerative disorder in which environmental exposures, particularly pesticides, are increasingly recognized as relevant risk factors. Chronic occupational pesticide exposure has been associated with increased PD risk, yet clinical improvement after removal from ongoing exposure is rarely documented. This case highlights the potential role of environmental intervention in symptom modulation in selected patients and underscores the importance of occupational history-taking and preventive strategies to reduce exposure to neurotoxicants. We report the case of a white Spanish right-handed male horticultural worker in his early 50s with more than three decades of occupational exposure to pesticides and herbicides, including rotenone, organophosphates, carbamates, pyrethrins, triazoles, mancozeb, fipronil, and other compounds. At age 49, he developed progressive left-sided tremor, bradykinesia, rigidity, hypomimia, and reduced left arm swing. He reported symptom fluctuation, with partial improvement during weekends and vacation periods. Neurological evaluation classified him as Hoehn and Yahr stage 1, with preserved functional independence. Laboratory tests were largely unremarkable except for mildly elevated C-reactive protein and interleukin-6. Brain MRI was normal, while DaTscan showed bilateral presynaptic dopaminergic deficits. Genetic testing through the ROPAD III study revealed no pathogenic variants or copy number variations in major PD-related genes. His dizygotic twin, without occupational pesticide exposure, remains asymptomatic. Pharmacological treatment with rasagiline and rotigotine was initiated before occupational reassignment. Following reassignment to pesticide-free tasks, the patient reported approximately 85% subjective symptom improvement. Objective assessment showed a reduction in the MDS-UPDRS Part III motor score from 16 to 8 after three months, representing a 50% improvement. He remains clinically stable under combined neurological and environmental medicine follow-up. This case supports the clinical relevance of chronic occupational pesticide exposure as a potentially modifiable contributor to symptom burden in PD. The substantial improvement observed after removal from the exposure source suggests that environmental interventions may help reduce symptom burden and influence the symptomatic trajectory in selected patients with established PD. Routine environmental and occupational history-taking in patients with Parkinson’s disease or parkinsonism is essential for identifying modifiable risk factors. Preventive strategies to minimize neurotoxic exposures, ideally beginning in early life, represent an important public health priority. Although causality cannot be established from a single case, the temporal association between pesticide exposure cessation and partial motor improvement highlights the value of environmental intervention as an adjunct to standard neurological care.