Comprehensive diffusion tensor tractography of three dopaminergic pathways in advanced Parkinson’s disease: a case report

This qualitative, exploratory case report presents comprehensive diffusion tensor tractography (DTT) analysis of all three major dopaminergic pathways in advanced Parkinson’s disease (PD), which is rarely reported. We present a case demonstrating structural alterations across mesocortical, mesolimbic, and nigrostriatal pathways in a patient with severe motor and non-motor symptoms, highlighting DTT’s educational and clinical visualization value. A 77-year-old female with advanced PD presented with a complex symptom profile including severe cognitive impairment (MMSE not assessable), major depression (predating motor symptoms by 7 years), severe dysphagia with silent aspiration (PAS 8), bilateral motor weakness (MMT P- to P+), and wheelchair dependence. DTT analysis revealed marked architectural differences compared to an age-matched control subject. The mesocortical tract showed notably reduced fiber density and thinning, particularly in prefrontal cortex projections. The mesolimbic tract demonstrated diminished volume with altered trajectory patterns, especially affecting ventral tegmental area connections. The nigrostriatal tract exhibited the most pronounced degeneration with markedly reduced fiber density and widespread disruption of tract integrity. While qualitative in nature and limited by single-case design and comparison with a single age-matched control subject acquired on a different MRI system, this case illustrates comprehensive structural deterioration across three dopaminergic pathways in advanced PD, with pathway-specific structural features observed alongside the patient’s complex clinical presentation. This detailed visualization demonstrates DTT’s potential utility as a clinical tool for understanding both motor and non-motor manifestations in advanced PD. The findings highlight the educational value of comprehensive dopaminergic pathway assessment and suggest directions for future controlled studies.