Cortical reorganization in patients with cervical spondylotic myelopathy

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Recent investigations have demonstrated that the cerebral cortex can reorganize as a result of spinal cord injury and may play a role in preserving neurological function. Reorganization of cortical representational maps in patients with cervical spondylotic myelopathy (CSM) has not been previously described. The authors sought to determine the feasibility of using functional magnetic resonance (fMR) imaging in patients with CSM to investigate changes in the cortical representation of the wrist and ankle before and after surgical intervention.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Four patients with clinical and imaging evidence of CSM were prospectively enrolled in this study. The patients underwent preoperative neurological examination, functional assessment, cervical imaging, and brain fMR imaging. The fMR imaging activation task undertaken was either wrist extension or ankle dorsiflexion, depending on whether the patient's primary impairment was hand dysfunction or gait difficulty. The cohort then underwent further evaluations at 6 weeks and 3 and 6 months postoperatively. In addition, five healthy volunteers underwent fMR imaging at two different time points and served as controls.</jats:p> <jats:p>In the healthy volunteers fMR imaging demonstrated areas of focal cortical activation limited to the contralateral primary motor area for the assigned motor tasks; the activation patterns were stable throughout repeated imaging. In comparison, in patients with CSM fMR imaging demonstrated expansion of the cortical representation of the affected extremity. Surgical decompression resulted in improvements in neurological function and reorganization of the representational map.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>The findings of this preliminary study demonstrate the potential of fMR imaging to assess changes in cortical representation before and after surgical intervention in patients with CSM. A future study involving a larger cohort of patients as well as the stratification of patients with CSM, based on the aforementioned factors that influence cortical adaptation, will allow a more detailed quantitative analysis.</jats:p></jats:sec>

Functional cortical reorganization in cases of cervical spondylotic myelopathy and changes associated with surgery

“…1,18 In one of the earliest studies in which functional imaging was used to assess cortical reorganization in CSM, Holly et al 23 demonstrated expansion of the cortical representation of the affected extremity (involvement of adjacent motor territories, the SMA, and bilateral cortical recruitment) before surgery in 4 patients, and surgical decompression resulted in improvements in neurological function and reorganization of the representational map.…”

“…19 Some studies have shown adaptive changes in bilateral primary motor cortex (M1), supplementary motor area (SMA), premotor area (PMA), cingulate motor area, parietal cortex, and contralateral primary somatosensory cortex (S1) in cases of SCI [8][9][10][11][27][28][29]33,40 and cervical compressive myelopathy due to spondylosis. 13,14,23,38 In this study we aimed to understand the cortical changes that occur due to CSM and following CSM surgery and to correlate these changes with functional recovery by using functional MRI (fMRI). We hypothesized that the recovery of normal activation patterns might coincide with clinical improvement.…”

N-acetylaspartate in the motor and sensory cortices following functional recovery after surgery for cervical spondylotic myelopathy

“…One possible explanation is that neurons experience synaptic modification in which preexisting connections develop new circuitry to restore lost function. 12 Results from the current study demonstrate that despite successful surgical decompression and clinical recovery, NAA levels decline, suggesting not only neuronal impairment, but also, more specifically, dysfunction in neuronal mitochondria. 5,6 Although this study reveals that metabolite level changes can be detected in both the motor and sensory cortices, future studies are needed to determine whether the temporal decreases in absolute NAA levels are the trigger for the recruitment of surrounding cortex and/or if decreasing NAA levels are a consequence of decreased metabolic demand due to cortical reorganization in which adjacent neurons are now incorporated into primary circuitry.…”

“…8,12 The exact trigger of cortical reorganization in adjacent neurons remains unclear. One possible explanation is that neurons experience synaptic modification in which preexisting connections develop new circuitry to restore lost function.…”

A combination of functional magnetic resonance imaging and diffusion tensor image to explore structure&ndash;function relationship in healthy and myelopathic spinal cord

“…Moreover, expanded cortical activation was detected in patients with CSM. 48 The enhanced fMRI response of myelopathic cord might be the result of more neurons and synapses involved in performing neurological activity, corresponding to the increased area of cortical activation. Our current result also, interestingly, showed a significant linear correlation of increased BOLD signals with decreased FA and increased RD value in myelopathic cord.…”