Compensatory cerebral adaptations before and evolving changes after surgical decompression in cervical spondylotic myelopathy

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>The goal of this study was to compare cortical sensorimotor adaptations associated with neurological deterioration and then recovery following surgical decompression for cervical spondylotic myelopathy (CSM).</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Eight patients with CSM underwent functional MR (fMR) imaging during wrist extension and the 3-finger pinch task, along with behavioral assessments before and 3 and 6 months after surgery. Six healthy control volunteers were scanned twice.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Cervical spine MR imaging demonstrated successful cord decompression. The patients improved after surgery on the modified Japanese Orthopaedic Association score for the upper extremity, which correlated with the changes in task-associated activation in specific sensorimotor regions of interest. Pinch-related activation in sensorimotor cortex contralateral to the movement paradigm was reduced before surgery then increased toward the extent of healthy controls after surgery. Before surgery, patients showed broader activation in ipsilateral sensorimotor cortex during wrist extension than during pinch, but activations became similar to those of healthy controls after surgery. Pinch-related activation volume in the ipsilateral sensorimotor cortex and the magnitude of activation in the contralateral dorsal premotor cortex evolved linearly across time after surgery, along with wrist extension–related activation magnitude in the contralateral supplementary motor area.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Serial fMR imaging studies in CSM can capture the adaptations in specific sensorimotor cortices that accompany clinical deterioration and postsurgical improvement in sensorimotor function associated with damage and partial recovery of conduction in corticospinal pathways. These adaptive regions can be monitored by serial fMR imaging to detect a critical loss of supraspinal reserve in compensatory plasticity, which might augment clinical information about the need for surgical decompression.</jats:p></jats:sec>

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

“…In a larger study by Dong et al, 13 which included 8 patients with CSM and 6 healthy control volunteers, the authors quantitatively captured reduced activation in the contralateral M1, S1, and dorsal PMA for dexterous fin- ger movements-though not for less complex wrist movements before surgery-followed by a progressive increase toward the activation pattern of healthy controls, as functional gains in the upper extremity proceeded after surgical decompression. The reduced pinch-related activation and the normal amount of wrist extension-related activation in contralateral M1 and S1 before surgery suggest that the coordinated finger pinch task demands greater integrity of the corticospinal tract.…”

“…Two of the most commonly discussed mechanisms by which functional recovery occurs after decompression are synaptic changes and dendritic sprouting in the cortical and spinal cord neurons. 12,13 Rapid cortical and subcortical changes occurring after spinal cord injury (SCI) or myelitis have been demonstrated on functional imaging. 1 Cortical reorganization as well as improvement in corticospinal conduction happens during motor recovery after stroke, and this has been proved by studies using transcranial magnetic stimulation (TMS).…”

“…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.…”

Insights into Adult Postlesional Language Cortical Plasticity Provided by Cerebral Blood Oxygen Level–Dependent Functional MR Imaging

“…Duffau et al 46 studied 77 patients with brain tumors without preoperative significant neurologic deficit and suggested, on the basis of their results with intraoperative cortical stimulation mapping, that recruitment of functionally compensatory brain regions adjacent to the tumor margins may account for the absence of preoperative deficits. In 4 patients with low-grade gliomas that infiltrated Broca area (Brodmann areas 44,45 ), they noted recruitment of the middle frontal gyrus and precentral gyrus, as well as the pars orbitalis of the inferior frontal gyrus as determined by speech arrest in these areas during intraoperative DECS. They also noted that eloquent structures may be present even within an area of brain tissue infiltrated by a low-grade glioma; they cite examples of 6 patients with gliomas infiltrating the insular cortex in which DECS of the insula resulted in speech arrest.…”

“…For example, Meunier et al 44 showed by using magnetoencephalography that resections of the somatosensory cortex have caused recruitment of perilesional sites adjacent to the resection cavity within the postcentral gyrus. In addition, Dong et al 45 studied the effects of decompression for cervical spondylotic myelopathy on primary somatosensory activation.…”