Inhibition versus facilitation of contralesional motor cortices in stroke: Deriving a model to tailor brain stimulation
| Autor: | Kenneth Earl Sakaie, Vishwanath Sankarasubramanian, Andre G. Machado, Adriana Bastos Conforto, Kelsey A. Potter-Baker, David A. Cunningham, Ela B. Plow, Xiaofeng Wang, Nicole Varnerin |
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| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
medicine.medical_specialty
medicine.medical_treatment Stimulation 050105 experimental psychology Article Premotor cortex 03 medical and health sciences 0302 clinical medicine Physical medicine and rehabilitation Physiology (medical) Neuroplasticity medicine 0501 psychology and cognitive sciences Stroke 05 social sciences medicine.disease Sensory Systems Transcranial magnetic stimulation medicine.anatomical_structure Neurology Brain stimulation Facilitation Neurology (clinical) Psychology 030217 neurology & neurosurgery Motor cortex |
| Popis: | Objective The standard approach to brain stimulation in stroke is based on the premise that ipsilesional M1 (iM1) is important for motor function of the paretic upper limb, while contralesional cortices compete with iM1. Therefore, the approach typically advocates facilitating iM1 and/or inhibiting contralesional M1 (cM1). But, this approach fails to elicit much improvement in severely affected patients, who on account of extensive damage to ipsilesional pathways, cannot rely on iM1. These patients are believed to instead rely on the undamaged cortices, especially the contralesional dorsal premotor cortex (cPMd), for support of function of the paretic limb. Here, we tested for the first time whether facilitation of cPMd could improve paretic limb function in severely affected patients, and if a cut-off could be identified to separate responders to cPMd from responders to the standard approach to stimulation. Methods In a randomized, sham-controlled crossover study, fifteen patients received the standard approach of stimulation involving inhibition of cM1 and a new approach involving facilitation of cPMd using repetitive transcranial magnetic stimulation (rTMS). Patients also received rTMS to control areas. At baseline, impairment [Upper Extremity Fugl-Meyer (UEFM PROXIMAL , max=36)] and damage to pathways [fractional anisotropy (FA)] was measured. We measured changes in time to perform proximal paretic limb reaching, and neurophysiology using TMS. Results Facilitation of cPMd generated more improvement in severely affected patients, who had experienced greater damage and impairment than a cut-off value of FA (0.5) and UEFM PROXIMAL (26–28). The standard approach instead generated more improvement in mildly affected patients. Responders to cPMd showed alleviation of interhemispheric competition imposed on iM1, while responders to the standard approach showed gains in ipsilesional excitability in association with improvement. Conclusions A preliminary cut-off level of severity separated responders for standard approach vs. facilitation of cPMd. Significance Cut-offs identified here could help select candidates for tailored stimulation in future studies so patients in all ranges of severity could potentially achieve maximum benefit in function of the paretic upper limb. |
| Databáze: | OpenAIRE |
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