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, 123I-FP-CIT SPECT, and 123I-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.
Keywords: Deep brain stimulation; Late stage; Parkinson’s disease.