Role of the intact hemisphere in determining the rehabilitation potential in the acute period of ischemic stroke: a diffusion and perfusion model

Abstract

The promising approaches to determining the rehabilitation potential of ischemic stroke (IS) patients include an assessment of the microstructural integrity of the brain matter by diffusion tensor imaging (DTI), the main indicator of which is fractional anisotropy (FA). The role of the intact hemisphere in the rehabilitation process after IS remains a controversial subject. The hypothesis for the investigation is that the development of a diffusion and perfusion model (DPM) based on the assessment of FA in combination with data on cerebral blood flow velocity (CBFV) and the impact of the focus will be able to predict the patients' neurological status by the end of the acute period of IS. Objective: to investigate the role of diffusion and perfusion characteristics of the intact hemisphere in determining the rehabilitation potential in the acute period of IS and to develop a prognostic DPM.Patients and methods. The investigation enrolled 100 patients with IS and 10 individuals in the control group. All the examinees underwent brain MRI. Perfusion-weighted sequence without bolus injection of a contrast agent was used to quantify CBFV in 10 areas according to the Alberta stroke program early CT score (ASPECTS). Values for FA in 10 areas of both hemispheres were calculated using DTI findings. Neurological and functional statuses were evaluated over time with the National Institute of Health Stroke Scale (NIHSS) and the modified Rankin scale.Results. The NIHSS score at discharge was associated with FA and CBFV in 4 and 6 of the 10 areas of the intact hemisphere, respectively. DPM for predicting the rehabilitation potential included the key parameters correlating with a discharge NIHSS score (in order of decreasing the significance): admission NIHSS value (r = 0.55; p < 0.001), the size of a focus (r = 0.42; p < 0.001), FA in the contralateral cingulum bundle FA (r = -0.28; p = 0.007), and CBFV in M2 white matter [r = -0.24; p = 0.025; R2 = 0.642; p(F) <0.001].Conclusion. In addition to the NIHSS score at admission, the size of a focus, DPM values (FA in the contralateral cingulum bundle and CBFV in the white matter) allow prediction of the rehabilitation potential in IS.

Keywords

• diffusion tensor imaging
• fractional anisotropy
• arterial spin labeling (asl) perfusion
• cerebral blood flow velocity
• ischemic stroke
• rehabilitation potential