title: Brain control of volitional ankle tasks in people with chronic stroke and in healthy individuals.
abstract: This study explored the relationships between motor cortical control of ankle dorsiflexors and clinical impairments of volitional ankle dorsiflexion in people with chronic stroke. Eighteen persons with stroke and 14 controls were evaluated. Clinical tools were used to assess ankle dorsiflexion amplitude and isometric strength. Transcranial magnetic stimulation (TMS) of the primary motor cortex (M1) tested the functional integrity of cortical circuits controlling the tibialis anterior (TA). All clinical scores and most TMS outcomes were impaired in people with chronic stroke. The lower clinical scores were related to the reduction of the strength of corticospinal projections onto spinal motoneurons. Concurrent TMS and clinical testing in chronic stroke provided original data demonstrating relationships between the integrity of cortical and corticospinal components of TA motor control and volitional ankle tasks. Our study proposes that volitional ankle mobilization in chronic stroke may be explained by the residual abnormal M1 circuits which may be responsive for rehabilitation intervention. This should be confirmed in longitudinal studies with larger samples to determine whether TMS outcomes associated with lower limb muscles are predictive of clinical changes or vice versa.
authors.affiliation: Axe neurosciences du Centre de recherche du CHU de Québec, Québec, QC, Canada.
authors.forename: L D
authors.initials: LD
authors.lastname: Beaulieu
authors.affiliation: Axe neurosciences du Centre de recherche du CHU de Québec, Québec, QC, Canada.
authors.forename: H
authors.initials: H
authors.lastname: Massé-Alarie
authors.affiliation: School of Rehabilitation Therapy, Faculty of Health Sciences, Queen's University, ONT, Canada.
authors.forename: B
authors.initials: B
authors.lastname: Brouwer
authors.affiliation: Axe neurosciences du Centre de recherche du CHU de Québec, Québec, QC, Canada; Department of Rehabilitation, Faculty of Medicine, Université Laval, Québec, QC, Canada. Electronic address: Cyril.Schneider@rea.ulaval.ca.
authors.forename: C
authors.initials: C
authors.lastname: Schneider
mesh_terms: D000328:Adult; D000842:Ankle / Q000503:physiopathology*; D002908:Chronic Disease; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009431:Neural Conduction / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012018:Reflex / Q000502:physiology*; D012720:Severity of Illness Index; D020521:Stroke / Q000473:pathology* / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed; D050781:Transcranial Magnetic Stimulation
keywords: Ankle function; Central conduction time; Chronic stroke; Clinical assessment; Intracortical excitability; Motor evoked potential; Neural reorganization; Primary motor cortex