Biochemical and Structural Magnetic Resonance Imaging in Chronic Stroke and the Relationship with Upper Extremity Motor Function

Abstract

Background: Recovery of upper extremity (UE) motor function after stroke is variable from one to another due to heterogeneity of stroke pathology. Structural and biochemical magnetic resonance imaging of the primary motor cortex (M1) have been used to document reorganization of neural activity after stroke. Objective: To assess cortical biochemical and structural causes of delayed recovery of UE motor function impairment in chronic subcortical ischemic stroke patients. Methodology: A cross sectional study with fifty patients were enrolled, (30) Patients with chronic (> 6 months) subcortical ischemic stroke suffering from persistent UE motor function impairment (not improved group). (20) Patients with chronic subcortical ischemic stroke and improved UE motor function (improved group). (16) age matched Healthy subjects group. Single voxel proton magnetic resonance spectroscopy (1H-MRS) was performed to measure N-acetylaspartate (NAA) and glutamate+glutamine (Glx) ratios relative to creatine (Cr) in the precentral gyrus which represent M1of hand area in both ipsilesional and contralesional hemispheres. Brain magnetic resonance imaging (MRI) to measure precentral gyral thickness representing the M1of hand area. UE motor function assessment using the Fugl Meyer Assessment (FMA-UE) Scale. Results: The current study found that ipslesional cortical thickness was significantly lower than contralesional cortical thickness among all stroke patients. Our study found that ipsilesional NAA/Cr ratio was lower than contralesional NAA/Cr among stroke patients. As regards UE and hand motor function by FMA-UE showed highly statistically significant correlation with ipsilesional cortical thickness and ipsilesional NAA/Cr ratio, more powerful with NAA/Cr ratio. Conclusion: We concluded that persistent motor impairment in individuals with chronic subcortical stroke may be at least in part related to ipsilesional structural and biochemical changes in motor areas remote from infarction in form of decreased cortical thickness and NAA/Cr ratio which had the strongest relationship with that impairment