Beyond 35 years of Parkinson's disease: a comprehensive clinical and instrumental assessment

Background We sought to characterize the clinical, neuropsychological, electrophysiological, and neuroimaging features of Parkinson's disease (PD) after over 35 years since the onset of motor symptoms. Methods Five consecutively consenting PD patients treated with subthalamic nucleus deep brain stimulation (STN-DBS) were recruited in a cross-sectional study of motor (Unified PD Rating Scale section-III), non-motor (Non-Motor Symptoms Scale), autonomic (Scale for Outcome in PD-Autonomic), and neuropsychological features associated with the very advanced phase of PD. In addition, patients underwent neurophysiological (autonomic tests and nerve conduction studies) and neuroimaging (brain MRI, I-123-FP-CIT SPECT, and I-123-MIBG myocardial scintigraphy) studies, as well as a genetic analysis of 34 genes and single nucleotide polymorphisms associated with PD. Results There was a sustained motor response to L-dopa (range 14.4-35.6%), STN-DBS (23.3-38.4%), and L-dopa plus STN-DBS (37.8-63.0%). There were mild-to-moderate non-motor symptoms (range 19-83 on a scale of 0 to 360) and autonomic dysfunction (8-28 on a scale of 0-69). Two patients were demented, one had mild cognitive impairment, and two were cognitively preserved. Three patients had a sensory-axonal peripheral neuropathy and two a moderate-to-severe autonomic neuropathy. All cases showed a complete nigro-striatal dopaminergic denervation and a severe cardiovascular noradrenergic denervation. The brain MRI revealed only moderate frontal atrophy. The genetic tests were unremarkable. Conclusions Even after more than 35 years of disease, L-dopa and STN-DBS remain effective on PD cardinal symptoms. Although axial, autonomic, and neuropsychological features may become key determinants of disability, some patients maintain a satisfactory quality of life, without significant motor and non-motor impairment.