Progressive Remote Axonal Degeneration Following Spinal Cord Injury: A Histological and MRI Study

In acute human spinal cord injury (SCI), magnetic resonance imaging (MRI) reveals progressive neuroanatomical changes at the lesion site and in remote regions. Here, we aimed to elucidate the structural underpinnings of these neuroanatomical changes and to characterize their spatiotemporal distribut...

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Main Authors: Gergely David, Alice Motovylyak, Felix Schlegel, Zsofia Kovacs, Christian Kündig, Angela R. Filous, Jan M. Schwab, Matthew D. Budde, Jan Klohs, Patrick Freund
Format: Article
Language:English
Published: Mary Ann Liebert 2025-01-01
Series:Neurotrauma Reports
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Online Access:https://www.liebertpub.com/doi/10.1089/neur.2025.0011
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author Gergely David
Alice Motovylyak
Felix Schlegel
Zsofia Kovacs
Christian Kündig
Angela R. Filous
Jan M. Schwab
Matthew D. Budde
Jan Klohs
Patrick Freund
author_facet Gergely David
Alice Motovylyak
Felix Schlegel
Zsofia Kovacs
Christian Kündig
Angela R. Filous
Jan M. Schwab
Matthew D. Budde
Jan Klohs
Patrick Freund
author_sort Gergely David
collection DOAJ
description In acute human spinal cord injury (SCI), magnetic resonance imaging (MRI) reveals progressive neuroanatomical changes at the lesion site and in remote regions. Here, we aimed to elucidate the structural underpinnings of these neuroanatomical changes and to characterize their spatiotemporal distribution in a rat contusion SCI model, using both histology and MRI. First, rats subjected to a thoracic contusion SCI (T8) and sham-operated rats were sacrificed at 56 days post-injury (dpi), and SMI-32 immunohistochemistry was used to assess remote axonal degeneration at cervical segments C2–C5. Second, to evaluate the effect of severity and time since injury on axonal degeneration, rats of varying injury severity were sacrificed at 2, 30, and 90 dpi, respectively, followed by SMI-32 immunohistochemistry. Third, ex vivo structural MRI and diffusion tensor imaging were performed rostral to the injury site (C3–T6) at 90 dpi. Histological evidence of axonal degeneration emerged as early as 2 dpi rostral to the injury site, persisting at 90 dpi. Severity-dependent degeneration occurred within the fasciculus gracilis and the periphery of the medio- and ventrolateral columns. Corresponding MRI changes, including lower fractional anisotropy in these regions and smaller gray matter area, were detected. In contrast, the dorsal corticospinal tract exhibited lower fractional anisotropy without clear histological abnormalities, potentially due to atrophy-related mislocalization. This highlights the value of correlative, multimodal approaches and the need for further methodological refinement. The number of SMI-32+ axonal profiles correlated negatively, while gray matter area and fractional anisotropy correlated positively with locomotion assessed by Basso, Beattie, and Bresnahan scores. This study demonstrates in independent experiments that neuroanatomical MRI changes observed after SCI, occurring remote from the injury site, are linked to axonal degeneration. Experimental SCI offers translational insights into underlying mechanisms and potential avenues for neuroprotective or rehabilitative approaches.
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spelling doaj-art-af1a37c812dc413e9b9a4999db0d8b312025-08-20T03:24:53ZengMary Ann LiebertNeurotrauma Reports2689-288X2025-01-016144346410.1089/neur.2025.0011Progressive Remote Axonal Degeneration Following Spinal Cord Injury: A Histological and MRI StudyGergely David0Alice Motovylyak1Felix Schlegel2Zsofia Kovacs3Christian Kündig4Angela R. Filous5Jan M. Schwab6Matthew D. Budde7Jan Klohs8Patrick Freund9Spinal Cord Injury Center, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, Wisconsin, USA.Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland.Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland.Spinal Cord Injury Center, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.Belford Center for Spinal Cord Injury, The Ohio State University, Columbus, Ohio, USA.Belford Center for Spinal Cord Injury, The Ohio State University, Columbus, Ohio, USA.Department of Neurosurgery, Clement J Zablocki Veterans Affairs Medical Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland.Spinal Cord Injury Center, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.In acute human spinal cord injury (SCI), magnetic resonance imaging (MRI) reveals progressive neuroanatomical changes at the lesion site and in remote regions. Here, we aimed to elucidate the structural underpinnings of these neuroanatomical changes and to characterize their spatiotemporal distribution in a rat contusion SCI model, using both histology and MRI. First, rats subjected to a thoracic contusion SCI (T8) and sham-operated rats were sacrificed at 56 days post-injury (dpi), and SMI-32 immunohistochemistry was used to assess remote axonal degeneration at cervical segments C2–C5. Second, to evaluate the effect of severity and time since injury on axonal degeneration, rats of varying injury severity were sacrificed at 2, 30, and 90 dpi, respectively, followed by SMI-32 immunohistochemistry. Third, ex vivo structural MRI and diffusion tensor imaging were performed rostral to the injury site (C3–T6) at 90 dpi. Histological evidence of axonal degeneration emerged as early as 2 dpi rostral to the injury site, persisting at 90 dpi. Severity-dependent degeneration occurred within the fasciculus gracilis and the periphery of the medio- and ventrolateral columns. Corresponding MRI changes, including lower fractional anisotropy in these regions and smaller gray matter area, were detected. In contrast, the dorsal corticospinal tract exhibited lower fractional anisotropy without clear histological abnormalities, potentially due to atrophy-related mislocalization. This highlights the value of correlative, multimodal approaches and the need for further methodological refinement. The number of SMI-32+ axonal profiles correlated negatively, while gray matter area and fractional anisotropy correlated positively with locomotion assessed by Basso, Beattie, and Bresnahan scores. This study demonstrates in independent experiments that neuroanatomical MRI changes observed after SCI, occurring remote from the injury site, are linked to axonal degeneration. Experimental SCI offers translational insights into underlying mechanisms and potential avenues for neuroprotective or rehabilitative approaches.https://www.liebertpub.com/doi/10.1089/neur.2025.0011atrophyaxonal degenerationdiffusion tensor imagingimmunohistochemistryremote degenerationtraumatic spinal cord injury
spellingShingle Gergely David
Alice Motovylyak
Felix Schlegel
Zsofia Kovacs
Christian Kündig
Angela R. Filous
Jan M. Schwab
Matthew D. Budde
Jan Klohs
Patrick Freund
Progressive Remote Axonal Degeneration Following Spinal Cord Injury: A Histological and MRI Study
Neurotrauma Reports
atrophy
axonal degeneration
diffusion tensor imaging
immunohistochemistry
remote degeneration
traumatic spinal cord injury
title Progressive Remote Axonal Degeneration Following Spinal Cord Injury: A Histological and MRI Study
title_full Progressive Remote Axonal Degeneration Following Spinal Cord Injury: A Histological and MRI Study
title_fullStr Progressive Remote Axonal Degeneration Following Spinal Cord Injury: A Histological and MRI Study
title_full_unstemmed Progressive Remote Axonal Degeneration Following Spinal Cord Injury: A Histological and MRI Study
title_short Progressive Remote Axonal Degeneration Following Spinal Cord Injury: A Histological and MRI Study
title_sort progressive remote axonal degeneration following spinal cord injury a histological and mri study
topic atrophy
axonal degeneration
diffusion tensor imaging
immunohistochemistry
remote degeneration
traumatic spinal cord injury
url https://www.liebertpub.com/doi/10.1089/neur.2025.0011
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