RT Journal Article
SR Electronic
T1 Diffusion Tensor Magnetic Resonance Imaging of Wallerian Degeneration in Rat Spinal Cord after Dorsal Root Axotomy
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 3160
OP 3171
DO 10.1523/JNEUROSCI.3941-08.2009
VO 29
IS 10
A1 Jiangyang Zhang
A1 Melina Jones
A1 Cynthia A. DeBoy
A1 Daniel S. Reich
A1 Jonathan A. D. Farrell
A1 Paul N. Hoffman
A1 John W. Griffin
A1 Kazim A. Sheikh
A1 Michael I. Miller
A1 Susumu Mori
A1 Peter A. Calabresi
YR 2009
UL http://www.jneurosci.org/content/29/10/3160.abstract
AB Diffusion tensor imaging (DTI) and immunohistochemistry were used to examine axon injury in the rat spinal cord after unilateral L2–L4 dorsal root axotomy at multiple time points (from 16 h to 30 d after surgery). Three days after axotomy, DTI revealed a lesion in the ipsilateral dorsal column extending from the lumbar to the cervical cord. The lesion showed significantly reduced parallel diffusivity and increased perpendicular diffusivity at day 3 compared with the contralateral unlesioned dorsal column. These findings coincided with loss of phosphorylated neurofilaments, accumulation of nonphosphorylated neurofilaments, swollen axons and formation of myelin ovoids, and no clear loss of myelin (stained by Luxol fast blue and 2′-3′-cyclic nucleotide 3′-phosphodiesterase). At day 30, DTI of the lesion continued to show significantly decreased parallel diffusivity. There was a slow but significant increase in perpendicular diffusivity between day 3 and day 30, which correlated with gradual clearance of myelin without further significant changes in neurofilament levels. These results show that parallel diffusivity can detect axon degeneration within 3 d after injury. The clearance of myelin at later stages may contribute to the late increase in perpendicular diffusivity, whereas the cause of its early increase at day 3 may be related to changes associated with primary axon injury. These data suggest that there is an early imaging signature associated with axon transections that could be used in a variety of neurological disease processes.