Homotopic Connectivity in Early Pontine Infarction Predicts Late Motor Recovery

Abstract

Connectivity-based methods are essential to explore brain reorganization after a stroke and to provide meaningful predictors for late motor recovery. We aim to investigate the homotopic connectivity alterations during a 180-day follow-up of patients with pontine infarction to find an early biomarker for late motor recovery prediction. In our study, resting-state functional MRI was performed in 15 patients (11 males, 4 females, age: 57.87 ± 6.50) with unilateral pontine infarction and impaired motor function during a period of 6 months (7, 14, 30, 90, and 180 days after stroke onset). Clinical neurological assessments were performed using the Fugl-Meyer scale (FM).15 matched healthy volunteers were also recruited. Whole-brain functional homotopy in each individual scan was measured by voxel-mirrored homotopic connectivity (VMHC) values. Group-level analysis was performed between stroke patients and normal controls. A Pearson correlation was performed to evaluate correlations between early VMHC and the subsequent 4 visits for behavioral measures during day 14 to day 180. We found in early stroke (within 7 days after onset), decreased VMHC was detected in the bilateral precentral and postcentral gyrus and precuneus/posterior cingulate cortex (PCC), while increased VMHC was found in the hippocampus/amygdala and frontal pole (<i>P</i> < 0.01). During follow-up, VMHC in the precentral and postcentral gyrus increased to the normal level from day 90, while VMHC in the precuneus/PCC presented decreased intensity during all time points (<i>P</i> < 0.05). The hippocampus/amygdala and frontal pole presented a higher level of VMHC during all time points (<i>P</i> < 0.05). Negative correlation was found between early VMHC in the hippocampus/amygdala with FM on day 14 (<i>r</i> = -0.59, <i>p</i> = 0.021), day 30 (<i>r</i> = -0.643, <i>p</i> = 0.01), day 90 (<i>r</i> = -0.693, <i>p</i> = 0.004), and day 180 (<i>r</i> = -0.668, <i>p</i> = 0.007). Furthermore, early VMHC in the frontal pole was negatively correlated with FM scores on day 30 (<i>r</i> = -0.662, <i>p</i> = 0.013), day 90 (<i>r</i> = -0.606, <i>p</i> = 0.017), and day 180 (<i>r</i> = -0.552, <i>p</i> = 0.033). Our study demonstrated the potential utility of early homotopic connectivity for prediction of late motor recovery in pontine infarction.