Early histopathological changes of secondary degeneration in the spinal cord after total MCA territory stroke

Abstract

Previous research has not demonstrated secondary degeneration of the spinal cord (SpC) motoneurons after cerebral infarct. The aim of the present study is to investigate the involvement of the anterior horn cells (AHC) in the early post-stroke period using histomorphological and immunohistochemical methods. Post-mortem analysis of the 6th cervical segment was performed in 7 patients who had total MCA stroke within 1 month before death. Nissl-stained sections were used for morphometry, while CD68 and synaptophysin (SYP) immunohistochemistry to monitor microglial activation and synaptic changes in the anterior horn (AH), respectively. Contralateral to the cerebral lesion (contralesional side), cells were smaller after 3 days and larger after 1 week of stroke, especially regarding the large alpha motoneurons. CD68 density increased mainly on the contralesional Rexed’s IX lamina of the SpC. SYP coverage of the large motoneurons was reduced on the contralesional side. Early microglial activation in the AH and electrophysiological signs has suggested the possibility of impairment of anterior horn cells (AHC-s). Our study supported that early microglial activation in the contralesional side of the SpC may primarily affect the area corresponding to the location of large motoneurons, and is accompanied by a transient shrinkage followed by increase in size of the large AHC-s with a reduction of their synaptic coverage. After MCA stroke, early involvement of the SpC motoneurons may be suspected by their morphological and synaptic changes and by the pattern of microglial activation.