Enhanced Information Flow From Cerebellum to Secondary Visual Cortices Leads to Better Surgery Outcome in Degenerative Cervical Myelopathy Patients: A Stochastic Dynamic Causal Modeling Study With Functional Magnetic Resonance Imaging

Abstract

Degenerative cervical myelopathy (DCM) damages the spinal cord, resulting in long-term neurological impairment including motor and visual deficits. Given that visual feedback is crucial in guiding movements, the visual disorder may be a cause of motor deficits in patients with DCM. It has been shown that increased functional connectivity between secondary visual cortices and cerebellum, which are functionally related to the visually guided movements, was correlated with motor function in patients with DCM. One possible explanation is that the information integration between these regions was increased to compensate for impaired visual acuity in patients with DCM and resulted in better visual feedback during motor function. However, direct evidence supporting this hypothesis is lacking. To test this hypothesis and explore in more detail the information flow within the “visual-cerebellum” system, we measured the effective connectivity (EC) among the “visual-cerebellum” system via dynamic causal modeling and then tested the relationship between the EC and visual ability in patients with DCM. Furthermore, the multivariate pattern analysis was performed to detect the relationship between the pattern of EC and motor function in patients with DCM. We found (1) significant increases of the bidirectional connections between bilateral secondary visual cortices and cerebellum were observed in patients with DCM; (2) the increased self-connection of the cerebellum was positively correlated with the impaired visual acuity in patients; (3) the amplitude of effectivity from the cerebellum to secondary visual cortices was positively correlated with better visual recovery following spinal cord decompression surgery; and (4) the pattern of EC among the visual-cerebellum system could be used to predict the pre-operative motor function. In conclusion, this study provided direct evidence that the increased information integration within the “visual-cerebellum” system compensated for visual impairments, which might have importance for sustaining better motor function in patients with DCM.

Brain Structural and Functional Dissociated Patterns in Degenerative Cervical Myelopathy: A Case-Controlled Retrospective Resting-State fMRI Study

“…In this study, we first applied the voxel-wise graph theory to investigate the spatial distribution patterns of gFCD and GMV alterations in patients with DCM. According to the results, gFCD and GMV were both affected in some regions of the visual system, sensorimotor cortices, and cerebellum, which are the key regions contributing to the pathology of DCM as indicated by several lines of evidence ( 15 – 17 , 19 , 24 ). More importantly, our findings showed that decreased gFCD was found in areas primarily located in the sensorimotor cortices, while increased gFCD was observed primarily in areas located in the visual system and cerebellum.…”

“…Its utility remains controversial as the information obtained from the spinal cord area is limited, i.e., the small cross-sectional area ( 10 – 12 ). Therefore, researchers set their sights on resting-state functional MRI for exploring brain alterations in patients with DCM ( 13 – 15 ). Several studies reported that DCM is associated with significant brain structural and functional changes ( 13 – 24 ).…”

“…Notably, the frontal, sensorimotor, and occipital cortices, thalami, and cerebellum are key regions with GMV decrease in DCM patients ( 13 , 17 , 18 , 20 – 23 ). Further, results from fMRI studies indicated that functional alterations, which are characterized by reduced functional activity in subcortical regions such as the basal ganglia and some regions of the limbic system, and concurrent hyper-functional activity in cortical regions were observed in patients with DCM ( 15 , 17 – 19 , 25 , 26 ). They have also been shown to exhibit functional alterations within frontal, temporal, and parietal lobes, sensorimotor cortex, cingulate gyrus, occipital gyrus, hippocampus, and thalami regions ( 26 – 32 ).…”

Dynamic and Static Amplitude of Low-Frequency Fluctuation Is a Potential Biomarker for Predicting Prognosis of Degenerative Cervical Myelopathy Patients: A Preliminary Resting-State fMRI Study

“…Cortical functional alterations of the brain have been identified in the past decades. Widespread brain regions including sensorimotor cortices (such as M1, S1, SMA) ( 37 – 39 ), occipital cortices (such as primary visual cortices, secondary visual cortices) ( 11 , 40 , 41 ), frontal cortices (such as superior and middle parts) ( 10 , 38 , 42 ), default mode network (such as medial frontal cortices, posterior cingulate cortices, angular gyri) ( 29 ), temporal cortices (including inferior part and superior part) ( 29 ), and cerebellum (including cerebellum crus, posterior cerebellum) are implicated in DCM pathogenesis ( 40 , 41 ). However, these studies only conducted univariate analysis (such as voxel-wise independent T -test) to explore group differences between DCM patients and healthy controls.…”

“…However, its utility is controversial because information obtained from the spinal cord area is limited (only a small cross-sectional area is accessible) ( 7 , 8 ). Resting-state fMRI was recently used to establish a prognostic biomarker for DCM patients ( 9 – 11 ). The functional connectivity (FC) between the occipital lobe and the frontal lobe is highly associated with neurological recovery in DCM patients ( 9 ).…”