Cortical Damage and Disability in Multiple Sclerosis: Relation to Intracortical Inhibition and Facilitation

Publication date: Available online 21 January 2016
Source:Brain Stimulation
Author(s): Julia C. Nantes, Jidan Zhong, Scott A. Holmes, Sridar Narayanan, Yves LaPierre, Lisa Koski
BackgroundMultimodal research combining biomarkers of intracortical activity and cortical damage could shed light on pathophysiological and adaptive neural processes related to the clinical severity of neurological conditions such as multiple sclerosis (MS).ObjectiveAmong people with relapsing-remitting and progressive forms of MS, we assessed the extent to which transcranial magnetic stimulation (TMS)-based biomarkers of excitatory and inhibitory cortical activity are related to cortical damage and clinical impairment.MethodsParticipants included 18 healthy individuals and 36 people with MS who had a relapsing-remitting or progressive clinical course. Using TMS, intracortical facilitation (ICF), short-interval intracortical inhibition (SICI), long-interval intracortical inhibition (LICI), and cortical silent period (CSP) were obtained. Cortical volume and cortical magnetization transfer ratio (MTR) were quantified. Disability was assessed with Multiple Sclerosis Functional Composite (MSFC).ResultsLower mean MTR within the cerebral cortex correlated with shorter CSP among MS participants with a progressive, but not a relapsing-remitting, clinical course. Within the cortical hand knob region targeted with the TMS, lower MTR was correlated with lower SICI only among individuals with relapsing-remitting MS. Longer CSP, higher ICF, lower cortical MTR, and sex were all independent significant predictors of poor upper extremity motor performance, while only cortical MTR was a significant independent predictor of total MSFC score among people with MS.ConclusionsCortical damage and cortical activity (both inhibitory and excitatory) may contribute to the severity of motor disability experienced by people with MS. When interpreting TMS-based outcomes, cortical integrity, clinical course, and symptom type should be considered.



from #MedicinebyAlexandrosSfakianakis via xlomafota13 on Inoreader http://ift.tt/1RD4Tf9
via IFTTT