A prospective study of secondary degeneration following subcortical infarction using diffusion tensor imaging

Abstract

Background: Secondary degeneration of the pyramidal tract distal to the primary lesion after a stroke has been detected by some studies using diffusion tensor imaging (DTI) but its potential clinical significance and the degeneration of the fibre tract proximal to the primary lesion have received little attention. Methods: Twelve patients underwent DTI on the 1st, 4th and 12th week following a subcortical infarct involving the posterior limb of the internal capsule, and 12 age and sex matched controls underwent DTI once. The DTI parameters mean diffusivity and fractional anisotropy (FA), and the clinical scores before DTI examination, including the National Institutes of Health Stroke Scale (NIHSS), the Fugl-Meyer (FM) scale and the Barthel index (BI), were assessed. The relations between the per cent changes in DTI parameters and clinical scores were analysed. Results: From the 1st to the 12th week after stroke onset, FA values decreased (p,0.01, respectively) in the fibre tract above and below the internal capsule, and the NIHSS decreased (p,0.01) but the FM scale and BI increased (p,0.01, respectively) progressively. The per cent reductions in FA value in the fibre tract above and below the internal capsule were negatively correlated with the per cent changes in NIHSS and FM scale (p,0.05, respectively). Conclusions: Secondary degeneration of the fibre tract proximal and distal to a primary lesion can be detected by DTI clearly and quantitatively and deteriorates with time progressively, which may hamper functional recovery after a subcortical cerebral infarct.

Secondary Degeneration Detected by Combining Voxel-Based Morphometry and Tract-Based Spatial Statistics in Subcortical Strokes with Different Outcomes in Hand Function

“…1 In addition, longitudinal studies have demonstrated that a progressive decrease of FA occurs along the pyramidal tract in the cerebral peduncle below the primary lesion. 2,3 In accordance with previous studies, we found that FA of the ipsilesional brain stem significantly decreased in both CPH and PPH compared with healthy controls, and FA also significantly decreased in CPH compared with PPH. Furthermore, FA correlated positively with Fugl-Meyer Assessment scores (handϩwrist) across all patients.…”

“…A case of pontine infarction with retrograde degeneration has been detected and confirmed postmortem, 15 and the progressive reduction of FA value in the fiber tract above the initial infarction also reflects retrograde degeneration proximal to the primary lesion. 2 Two types of fiber tracts have been proposed in previous studies: 1) one is from neurons in the motor cortex, descending from the subcortex to the spinal cord and production pyramidal tract; and 2) the other is derived from relay nuclei in the thalamus that consist of basal ganglia-thalamocortical circuits. 2,[16][17][18] Moreover, Alexander et al (1986) 16 suggested that the 5 basal ganglia-thalamocortical circuits are organized in parallel and that each circuit engages specific regions of the cerebral cortex involving the motor cortex, somatosensory cortex, supplementary motor area, cingulate motor cortex, and superior temporal gyrus.…”

“…2 Two types of fiber tracts have been proposed in previous studies: 1) one is from neurons in the motor cortex, descending from the subcortex to the spinal cord and production pyramidal tract; and 2) the other is derived from relay nuclei in the thalamus that consist of basal ganglia-thalamocortical circuits. 2,[16][17][18] Moreover, Alexander et al (1986) 16 suggested that the 5 basal ganglia-thalamocortical circuits are organized in parallel and that each circuit engages specific regions of the cerebral cortex involving the motor cortex, somatosensory cortex, supplementary motor area, cingulate motor cortex, and superior temporal gyrus. It is possible that decreased FA in widespread regions of the motor system above the primary lesion may be considered retrograde degeneration of different tract pathways, which leads to motor deficits after stroke.…”

“…1 Longitudinal studies have also demonstrated a progressive decrease of FA along the pyramidal tract in the cerebral peduncle below the primary lesion. 2,3 However, these studies have mainly focused on descending degeneration at the level of the cerebral peduncle, and ROI or segment-of-corticospinal-tract analyses were often carried out based on a priori hypotheses, 4,5 which are time consuming and do not easily allow for comparisons of many brain regions or large subject groups. Therefore, secondary degeneration in more widespread regions of the motor system has rarely been studied.…”

Tract-Specific and Region of Interest Analysis of Corticospinal Tract Integrity in Subcortical Ischemic Stroke: Reliability and Correlation with Motor Function of Affected Lower Extremity

“…1,2 It has been reported that FA, which is a quantitative index of the directional anisotropy of water molecular diffusion derived from the diffusion tensor, is an effective measure of fiber integrity. 3 Decreases in FA have been found in the affected tracts at infarct regions and regions with wallerian degeneration.…”