Structural and functional neuroimaging in patients with Parkinson's disease and visual hallucinations: A critical review.
Patients with Parkinson's disease (PD) may develop various non-motor symptoms (NMS) during the course of the illness and psychosis is one of the common NMS of PD. Visual hallucinations (VH) are the most common manifestation of psychosis in PD. The exact pathogenesis of VH in patients with PD is not clearly understood. Presence of VH has been described to be associated with rapid cognitive decline and increased nursing home placements in PD patients. A large number of structural and functional neuroimaging studies have been conducted to understand the cerebral basis of VH in PD. Structural imaging studies (Voxel Based Morphometry) have reported grey matter atrophy in multiple regions of the brain such as primary visual cortex, visual association cortex, limbic regions, cholinergic structures such as pedunculopontine nucleus and substantia innominata, which conclude possible alterations of brain regions associated with functions such as visuospatial-perception, attention control and memory. Most functional neuroimaging studies (functional MRI, positron emission tomography and single photon emission computerized tomography) have reported altered activation, blood flow, or reduced metabolism in both dorsal and ventral visual pathways, which probably indicates an alteration in the normal bottom-top visual processing and the presence of an aberrant top-down visual processing. This review critically analyzes the published studies on the structural and functional neuroimaging in PD patients with VH.
Department of Clinical Neurosciences, National Institute of Mental Health & Neurosciences, Hosur Road, Bangalore 560029, Karnataka, India; Department of Neurology, National Institute of Mental Health & Neurosciences, Hosur Road, Bangalore 560029, Karnataka, India.
Abhishek
A
Lenka
Department of Clinical Neurosciences, National Institute of Mental Health & Neurosciences, Hosur Road, Bangalore 560029, Karnataka, India; Department of Neurology, National Institute of Mental Health & Neurosciences, Hosur Road, Bangalore 560029, Karnataka, India.
Ketan Ramakant
KR
Jhunjhunwala
Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health & Neurosciences, Hosur Road, Bangalore 560029, Karnataka, India.
Jitender
J
Saini
Department of Neurology, National Institute of Mental Health & Neurosciences, Hosur Road, Bangalore 560029, Karnataka, India. Electronic address: pal.pramod@rediffmail.com.
Pramod Kumar
PK
Pal
D059907:Functional Neuroimaging / Q000379:methods*; D006212:Hallucinations / Q000175:diagnosis* / Q000453:epidemiology* / Q000523:psychology; D006801:Humans; D010300:Parkinson Disease / Q000175:diagnosis* / Q000453:epidemiology* / Q000523:psychology; D049268:Positron-Emission Tomography / Q000379:methods
PET; Parkinson's disease; SPECT; VBM; Visual hallucinations; fMRI