Changes in cortical motor outputs after a motor relapse of multiple sclerosis

Abstract

BackgroundMotor recovery following a multiple sclerosis (MS) relapse depends on mechanisms of tissue repair but also on the capacity of the central nervous system for compensating of permanent damage.ObjectivesWe aimed to investigate changes in corticospinal plasticity and interhemispheric connections after a relapse of MS using transcranial magnetic stimulation (TMS).MethodsTwenty healthy and 13 relapsing–remitting MS subjects with a first motor relapse were included. TMS mapping and ipsilateral silent period (iSP) were performed after relapse and at 6-month follow-up.ResultsStrength and dexterity of the paretic hand were impaired at baseline and improved over time. After relapse, mapamplitude and mapdensity were decreased for the ipsilesional-corticospinal tract (IL-CST) while expanded for the contralesional-CST (CL-CST). At follow-up, map parameters normalized for the CL-CST independently from recovery while the increase of outputs from the IL-CST was associated with straight and dexterity improvement. iSP measurements were impaired in MS irrespective of the phase of the disease. Prolonged iSPduration at baseline was associated with less dexterity recovery.ConclusionsAfter a motor relapse, TMS mapping shows acute changes in corticospinal excitability and rearrangements of motor outputs. iSP is less influenced by the phase of disease but may better predict recovery, possibly reflecting the integrity of interhemispheric motor networks.

Exercise in the management of multiple sclerosis relapses: current evidence and future perspectives

“…Neuroplasticity refers to the ability of the CNS to structurally and functionally adapt in response to damage (i.e. MS relapses) [69], and can therefore contribute to the recovery of CNS function in people with MS after a relapse by facilitating re-organisation of neural networks [70,71]. As plasticity of the CNS is task-dependent [72], any changes in the CNS that occur following exercise are more likely to occur in neural pathways involved in the planning and execution of movement.…”