Primary Motor Cortex in Stroke

Abstract

Background and Purpose Our goal was to investigate whether certain metabolites, specific to neurons, glial cells, or the neuronal-glial neurotransmission system, in primary motor cortices (M1), are altered and correlated with clinical motor severity in chronic stroke. Methods Fourteen survivors of a single ischemic stroke located outside the M1 and 14 age-matched healthy control subjects were included. At >6 months after stroke, N-acetylaspartate, myo-inositol, and glutamate/glutamine were measured using proton magnetic resonance spectroscopic imaging (in-plane resolution=5×5 mm2) in radiologically normal-appearing gray matter of the hand representation area, identified by functional MRI, in each M1. Metabolite concentrations and analyses of metabolite correlations within M1 were determined. Relationships between metabolite concentrations and arm motor impairment were also evaluated. Results The stroke survivors showed lower N-acetylaspartate and higher myo-inositol across ipsilesional and contral-esional M1 compared with control subjects. Significant correlations between N-acetylaspartate and glutamate/glutamine were found in either M1. Ipsilesional N-acetylaspartate and glutamate/glutamine were positively correlated with arm motor impairment and contralesional N-acetylaspartate with time after stroke. Conclusions Our preliminary data demonstrated significant alterations of neuronal-glial interactions in spared M1 with the ipsilesional alterations related to stroke severity and contralesional alterations to stroke duration. Thus, MR spectroscopy might be a sensitive method to quantify relevant metabolite changes after stroke and consequently increase our knowledge of the factors leading from these changes in spared motor cortex to motor impairment after stroke.

Transcranial Direct Current Stimulation and Manual Asymmetries: The Effect of the Stimulation on the Manual Dexterity

“…Uma possível aplicação prática desses resultados está associada à processos de reabilitação que exijam alterações plásticas nas funções hemisféricas. Após um acidente vascular cerebral (AVC), o retorno espontâneo da função motora está associada com o retorno da atividade no M1 29 . A função manual de um paciente que tenha sofrido um AVC em região subcortical, depende predominantemente da atividade do M1 do hemisfério lesionado 30 .…”

Positive Effect of Impairment-Oriented Training on N-Acetylaspartate Levels of Ipsilesional Motor Cortex in Subcortical Stroke: A Case Study

“…A similar decrease in NAA levels was found in the ischemic core in patients and the outcome predictions based upon the residual NAA in the infarct core have proved accurate [10,11]. More importantly, our recent 1H-MRS studies established a relationship between NAA levels in spared motor areas and behaviorally-relevant neurophysiological brain changes in chronic subcortical stroke [12-14]. Specifically, we found lower levels of NAA, putatively reflecting neuronal metabolic depression [15], in the paretic hand area representation in the ipsilesional motor and premotor areas.…”

Primary Motor Cortex Ipsilateral to the Paretic Arm - A Potential Neural Substrate for Compensatory Trunk Use in Chronic Stroke

“…The MRI experimental protocol has been detailed previously [59]. Briefly, a T2-weighted MRI was acquired to confirm stroke location, exclude undiagnosed pathologies, and assess the white matter changes (hyperintensities, WMH, Fazekas visual rating scale [60]).…”

“…This is interesting because a part of the M1 output was damaged by infarction in most survivors (Table 1). One explanation is that neurons that escaped infarction but were functionally impaired [59] may recover with training. Alternatively, enhanced activity in spared fibers could lead to new growth, branching of intact fibers [74] possibly altering the anatomical connections with premotor areas and potentially enlarging the motor output zone [45,74].…”