Relevance of Cortical Thickness of Brain Regions Associated with the Somato-Cognitive Action Network in Patients with Degenerative Cervical Myelopathy

Introduction: A new organization for the human motor cortex (M1) has been recently proposed. Proper motor effector areas were found to be interrupted by inter-effector regions which showed strong functional connectivity to the cingulo-opercular network (CON). These regions were suggested to be critical for action planning, coordination, and axial body movements whose disruption is constantly reported by patients with degenerative cervical myelopathy (DCM). We hypothesized that patients with DCM might show signs of cortical reorganization in these areas, with clinical relevance for their functional recovery.

Methods: Three-dimensional T1-weighted MRI was performed in 31 DCM patients and 43 healthy controls (HC). Clinical evaluation of DCM patients was conducted using the modified Japanese Orthopedic Association scale (mJOA). Cortical thickness estimation and between-groups (HC vs. DCM t-test) analysis were performed using FreeSurfer. Further, cortical thickness of the identified significant regions was compared between DCM patients who did and did not show functional improvement one year after surgery.

Results: For DCM patients, cortical thinning was observed in the right and left anterior prefrontal cortex (aPFC), insula, pre-supplementary motor area (pre-SMA), dorsal anterior cingulate cortex (dACC), and left SMA. Patients with DCM and improved neurological function at follow-up had significantly greater mean preoperative cortical thickness in the right and left aPFC, right superior frontal gyrus (SFG) and insula, with a statistical trend being also shown in both the left insula and SFG.

Conclusion : Patients with DCM present signs of cortical atrophy in regions of the CON which has been recently described to have critical implications for the human motor network. The preoperative cortical thickness of these regions may be of clinical prognostic value as patients who showed neurological improvement one year after surgery exhibited less atrophy in these cortical areas.