Biomarkers for assessing motor dysfunction after stroke

Abstract

Objective To investigate whether diffusion tensor imaging (DTI) and motor evoked potentials (MEP) can be used as biomarkers to assess the degree of motor dysfunction of stroke survivors. Methods Sixty partially-paralyzed stroke survivors were given Fugl-Meyer assessments (FMAs) and MEP tests and assessed using DTI seeking any correlations among the results. The receiver operating characteristics curves (ROCs) were prepared to determine the tests′ efficacy in assessing severe motor dysfunction. Results ① Asymmetry in the fractional anisotropy (aFA) of the peduncles cerebra as measured by DTI was negatively correlated with the FMA scores of the upper and lower limbs on the affected side. The aFA values of the posterior limb of the internal capsule (PLIC) were negatively correlated with the FMA scores of the affected upper limb, but not with the FMA scores of the affected lower limbs. The abnormalities in central motor conduction time and motor threshold, which are MEP parameters, were negatively correlated with the FMA scores of the affected limbs. ② The ROCs showed that the aFA value of the PLIC was the best indicator for assessing severe upper limb motor dysfunction, with a cut-off value of 0.167 giving the best discrimination. MEP waveform loss could also be used. It has high sensitivity but low specificity. ③ A combination of DTI and MEP can improve specificity in assessing severe motor dysfunction in the upper limbs. Conclusion DTI and MEP can both be used to evaluate motor dysfunction in stroke survivors. They have high clinical value for assessing severe motor dysfunction of the upper limbs. Key words: Stroke; Motor dysfunction; Diffusion tensor imaging; Motor evoked potentials