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: thirty patients with chronic (> 6 months) subcortical ischemic stroke suffering from persistent UE motor function impairment (not improved group) and twenty patients with chronic subcortical ischemic stroke and improved UE motor function (improved group). We recruited a group of (16) age-matched healthy subjects. 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 is representing the M1of hand area. UE motor function assessment is 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. 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.

Occurrence of changes in the auditory evoked potentials of smokers: systematic review of the literature

“…The number of smokers included in the studies ranged from 10 19 to 137 (19) . Regarding the country of origin of the studies, one was from Brazil (14) , two were from Turkey (20,21) , two were from India (7,22) , two were from Egypt (13,23) , and one from Germany (19) . Due to the nature of the guiding question, all included studies used convenience samples.…”

“…A summary of the characteristics of the eight included studies can be found in Chart 1. Regarding the test performed, three performed BAEP (7,14,22) , four performed P300 (19)(20)(21)23) , and one performed Mismatch Negativity (MMN) and P300 (13) .…”

“…The studies evaluated in this review present data that imply damage in the conductivity of the neural impulse along the auditory pathway in smokers. Of eight studies reviewed -observational studies -, one evidenced the relationship between smoking and the significant increase in the latencies of waves I and III and in the interpeaks I-III and III-V, as well as a decrease in the amplitudes of the BAEP waves (7,14,22) , significant increase in wave amplitude and latency of MMN in the group of smokers (13) , and also an increase in latencies and lower amplitude in the group of smokers in P300 (19)(20)(21)23) .…”

“…Studies suggest that the more significant the frequency difference between the frequent and the rare stimuli is, the more increased the amplitude of the P300, due to the greater ease of detecting the difference between them (27)(28)(29) . As it is presented by four out of five articles that used this type of AEP, there was a decrease in the amplitude of response in the group of smokers (13,19,21,23) , and only one showed absence of significant differences between the values averages between components N1, P2, N2 and P3 (20) . There was divergence between the observed latency relationship, since part of the studies reported increased latency (23) and specifically increased N1 (in FZ) for the group of smokers (21) , and results were also found in which no significant difference values were obtained between latencies (13,20) , which shows the need for further studies with this type of potential.…”

“…Kamal. (23) Egypt The P300 is an endogenous auditory evoked potential, and it is identified as the result of an internal cognitive event generated in an active and voluntary manner during the performance of a specific discriminatory task between two different sound stimuli (27,28) . In other words, one of the stimuli is often presented, while the other occurs rarely and randomly.…”