Regional brain stem atrophy in idiopathic Parkinson's disease detected by anatomical MRI
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Abstract(s)
Idiopathic Parkinson’s disease (PD) is a neurodegenerative disorder characterized by the dysfunction of dopaminergic
dependent cortico-basal ganglia loops and diagnosed on the basis of motor symptoms (tremors and/or rigidity and
bradykinesia). Post-mortem studies tend to show that the destruction of dopaminergic neurons in the substantia nigra
constitutes an intermediate step in a broader neurodegenerative process rather than a unique feature of Parkinson’s
disease, as a consistent pattern of progression would exist, originating from the medulla oblongata/pontine tegmentum. To
date, neuroimaging techniques have been unable to characterize the pre-symptomatic stages of PD. However, if such a
regular neurodegenerative pattern were to exist, consistent damages would be found in the brain stem, even at early stages
of the disease. We recruited 23 PD patients at Hoenn and Yahr stages I to II of the disease and 18 healthy controls (HC)
matched for age. T1-weighted anatomical scans were acquired (MPRAGE, 1 mm3 resolution) and analyzed using an
optimized VBM protocol to detect white and grey matter volume reduction without spatial a priori. When the HC group was
compared to the PD group, a single cluster exhibited statistical difference (p,0.05 corrected for false detection rate, 4287
mm3) in the brain stem, between the pons and the medulla oblongata. The present study provides in-vivo evidence that
brain stem damage may be the first identifiable stage of PD neuropathology, and that the identification of this consistent
damage along with other factors could help with earlier diagnosis in the future. This damage could also explain some nonmotor symptoms in PD that often precede diagnosis, such as autonomic dysfunction and sleep disorders.
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