Ex vivo 1H MR spectroscopy and histology after experimental chronic spinal cord compression

Proton magnetic resonance imaging (MRS) is used increasingly to image the spinal cord in compressive cervical myelopathy (CSM). However, detailed analyses of the underlying histomorphological changes leading to MRS alterations are still lacking. The aim of our study was to correlate neuroimaging and neuropathologic alterations in a rabbit myelopathy model.

Chronic spinal cord compression was induced in a rabbit model (n=16) allowing for a gradual 270° compression of the spinal cord. Spinal cord compression core areas were divided into two samples for (A) 1H MRS and (B) histopathological analyses. Postoperatively the animals underwent a neurological examination twice a day and outcome was categorized in pattern of injury and amount of recovery.

Three groups were observed and categorized: (I) animals with severe deficits and no or minimal recovery; (II) animals with severe deficits and complete or almost complete recovery; (III) animals with mild to moderate deficits and a complete recovery. Significant differences in the lesioned spinal cords between the different recovery groups were found for N-acetyl-aspartate and choline. NAA/Cr was detected significantly (P<0.001, ANOVA) less in the group that did show permanent neurological deficits. To the contrary, choline was detected significantly (P<0.001, ANOVA) more in the group that did show permanent neurological deficits. Histologically the first group showed more apoptosis and necrosis than the second and third group.

MR spectroscopy (MRS) may be helpful for clinicians in improving the prognostic accuracy in cervical myelopathies since this method nicely reflects the extent and severity of spinal cord damage.