Researchers discovered that preserving surface-based homologous interhemispheric connectivity (sHIC) in the cortex of the brain can help prevent physical and cognitive decline in multiple sclerosis (MS). The study findings were reported in Springer Nature.
The corpus callosum is particularly vulnerable to damage in MS due to its role as the primary interhemispheric tract of the brain. Medical researchers in the past have studied the implication of this damage on the clinical course of MS.
The authors of the current study hypothesized that microstructural damage to the corpus callosum disrupts homologous connectivity and contributes to clinical disability, impeding the completion of motor tasks that depend upon interhemispheric connection.
“The purpose of this study is to investigate the interactions between [corpus callosum] damage, resting-state functional connectivity, and clinical disability using novel measures of microstructural integrity and inter-hemispheric connectivity,” Russo and colleagues wrote.
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The research team recruited 36 patients from the Massachusetts General Hospital Multiple Sclerosis Clinic in Boston. The participants consisted of patients with relapsing-remitting MS, secondary progressive MS, and primary progressive MS. A total of 42 healthy individuals were recruited to be in the control group. All participants underwent magnetic resonance imaging (MRI) scans. Patients with MS also underwent neurological disability testing.
The results showed that the group of patients with MS demonstrated reduced sHIC compared to the control. Russo et al wrote, “Average sHIC correlation maps for MS and [healthy control] groups show that [interhemispheric] connectivity was highest in primary motor, somatosensory, and visual cortices.”
The research team also reported that lower sHIC correlated with cognitive impairment and higher disability scores, suggesting that a decline in sHIC plays a role in the cognitive and physical decline in patients with MS.
A previous study found that atrophy of the corpus callosum resulted in less interhemispheric coherence in patients with relapsing-remitting MS. Other past studies have likewise confirmed that damage to the corpus callosum and the resulting disruption in interhemispheric connectivity can result in MS disease progression.
Russo AW, Stockel KE, Tobyne SM, et al. Associations between corpus callosum damage, clinical disability, and surface-based homologous inter-hemispheric connectivity in multiple sclerosis. Brain Struct Funct. Published online May 10, 2022. doi:10.1007/s00429-022-02498-7