Disruption of Inferior Longitudinal Fasciculus Microstructure in Parkinson's Disease: A Systematic Review of Diffusion Tensor Imaging Studies

Abstract

Parkinson's disease (PD) is a neurodegenerative disorder accompanied by a series of pathological mechanisms which contribute to a variety of motor and non-motor symptoms. Recently, there has been an increasing interest in structural diffusion tensor imaging (DTI) in PD which has shed light on our understanding of structural abnormalities underlying PD symptoms or its associations with pathological mechanisms. One of the white matter tracts shown to be disrupted in PD with a possible contribution to some PD symptoms is the inferior longitudinal fasciculus (ILF). On the whole, lower ILF integrity contributes to thought disorders, impaired visual emotions, cognitive impairments such as semantic fluency deficits, and mood disorders. This review outlines the microstructural changes in ILF associated with systemic inflammation and various PD symptoms like cognitive decline, facial emotion recognition deficit, depression, color discrimination deficit, olfactory dysfunction, and tremor genesis. However, few studies have investigated DTI correlates of each symptom and larger studies with standardized imaging protocols are required to extend these preliminary findings and lead to more promising results.

Brain Metabolic Correlates of Persistent Olfactory Dysfunction after SARS-Cov2 Infection

“…Regarding the connectivity data, the involvement of the ILF is in line with observations of its role in hyposmia in Parkinson’s Disease [ 31 ]. Interestingly, the ILF has been shown to be affected early on in viral infections, such as in HIV [ 32 ] and hepatitis C virus (HCV) [ 33 ].…”

White Matter Microstructure Changes and Cognitive Impairment in the Progression of Chronic Kidney Disease

“…The inferior longitudinal fasciculus is a critical connection from the inferior occipital gyrus to the temporal lobe ( Gold et al, 2012 ). Damaged inferior longitudinal fasciculus and superior longitudinal fasciculus integrity are associated with thought disorders and cognitive impairments ( Makris et al, 2005 ; Haghshomar et al, 2018 ). We also found reduced FA values in the anterior thalamic radiation when we compared the CKD4 group with HCs, consistent with the results of previous studies.…”

Visual hallucinations and inferior longitudinal fasciculus in Parkinson's disease

“…The inferior longitudinal fasciculus (ILF) is a major associative tract that connects the occipital and anterior temporal lobes and is topographically well located to subserve the ventral visual pathway (Catani et al., 2003; Herbet et al., 2018). The ILF has multiple functions, including visual‐related processes such as objective and facial recognition, reading, regulation of lexical and semantic processes, and emotional regulation (Haghshomar et al., 2018; Herbet et al., 2018). One diffusion tensor imaging (DTI) study reported that the disruption of white matter integrity in the ILF was associated with VH in patients with dementia with Lewy bodies (DLB) (Kantarci et al., 2010).…”

“…One diffusion tensor imaging (DTI) study reported that the disruption of white matter integrity in the ILF was associated with VH in patients with dementia with Lewy bodies (DLB) (Kantarci et al., 2010). In patients with PD, it has been reported that the disruption of the integrity of the ILF was associated with cognitive impairment, color discrimination deficits, mood disorders, and tremor‐dominant motor symptoms (Haghshomar et al., 2018). However, the involvement of the ILF in patients with PD with VH has not yet been investigated.…”