An assessment of the correlation between early postinfarction pyramidal tract Wallerian degeneration and nerve function recovery using diffusion tensor imaging

Abstract

ABSTRACT. This study aimed to evaluate the clinical significance of diffusion tensor imaging (DTI) in the early diagnosis of pyramidal tract Wallerian degeneration (WD) and assessment of neurological recovery following cerebral infarction. This study included 23 patients with acute cerebral infarction and 10 healthy adult controls. All participants underwent both magnetic resonance imaging (MRI) and DTI scans. DTI images were analyzed using the Functional MRI of the Brain Software Library to determine the regions of interest (ROI) and obtain the mean diffusivity (MD) and fractional anisotropy (FA) value for each ROI. The correlation between FA or MD and postinfarction functional recovery of the nervous system was further analyzed to assess the feasibility of using a DTI scan in the evaluation of functional recovery of the nervous system in patients with cerebral infarction. DTI may be useful in detecting signals of early postinfarction pyramidal tract WD and is useful for the evaluation of postinfarction neurological recovery. Cerebral lesions were detected using MRI in all patients. It was found that in some patients, the FA value of the ipsilateral pyramidal tract on DTI was decreased as early as day 3 after the onset of infarction and in all patients by day 7. Subsequent correlation studies showed that the FA value of the ipsilateral pyramidal tract on day 13 was negatively correlated with the National Institutes of Health Stroke Scale score, but positively correlated with the Barthel Index, motricity index, and modified Rankin Scale scores.

Corticosterone Administration Alters White Matter Tract Structure and Reduces Gliosis in the Sub-Acute Phase of Experimental Stroke

“…Our research showed some effect of CORT administration on WMT after stroke; however, it is not clear whether this effect is strictly negative. Clinically, WMT reorganization and microstructure have been proven to be associated with cognitive decline and functional recovery after stroke [11][12][13]40,41]. Similar effects after stroke have been observed in patients experiencing chronic stress and elevated cortisol levels [16,21,42].…”

“…The association between stroke and secondary Wallerian degeneration of white matter has been explored in a number of preclinical [2,[5][6][7][8] and clinical studies [9,10]. Neuroimaging studies suggest that these changes are associated with neurological deficits and poorer functional outcomes post-stroke [11][12][13]. A study by Jokinen et al (2005) found that WMT hyperintensities on T2 diffusion-weighted images could be used as independent predictors of post-stroke cognitive impairment and were associated with poor performance in tests of mental speed, executive function, memory, and visuospatial functions [13].…”

Acute Subcortical Infarcts Cause Secondary Degeneration in the Remote Non-involved Cortex and Connecting Fiber Tracts

“…After ischemic stroke, nerve fibers disintegrate due to ischemia, hypoxia, and necrosis of the local tissue. In addition, axonal injury and demyelination occur in the remote intact tissue due to Wallerian degeneration (19, 20). Therefore, the integrity and number of nerve fibers decrease.…”

“…Consistent with previous studies (21, 22), our results showed that the TDI and FA values reduced in both the non-involved lower and upper parts of the IL CST during follow-up, indicating that the integrity and number of fibers reduced in both the proximal and distal parts of the remote non-involved IL CST. In addition to the changes in the infarct itself, the infarct lesion will cut off the nutritional supply and synaptic connection between the inferior nerve fibers and the upper cortex, leading to Wallerian degeneration of the inferior nerve fibers, which causes axonal and myelin sheath disintegration and nerve fiber atrophy (19, 20). These changes lead to a reduction in the TDI and FA values.…”

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“…Waller nominated the fragmentation of myelin, which he mentioned to as "medulla", into discreteunits of different sizes. The disintegrated axons shaped droplets that could be stained, consequently allowing studies of the development of individual nerve fibers [2].…”