title: Functional and structural cortical characteristics after restricted focal motor cortical infarction evaluated at chronic stage - Indications from a preliminary study.
abstract: To assess the inter-hemispheric differences in neuronal function and structure of the motor cortex in a small group of chronic stroke patients having suffered a restricted ischemic lesion affecting hand motor representation. GABAergic intracortical inhibition, known to be affected by stroke lesion, was also investigated.
  
  
  
  Eight patients exhibiting little or no motor impairment were studied using transcranial magnetic stimulation (TMS) and diffusion weighted imaging (DWI) >15months from diagnosis. Resting motor threshold (MT) for 50μV and 2mV motor evoked potentials, and short-interval intracortical inhibition (SICI) were measured from hand muscles. Apparent diffusion coefficients (ADCs) were analyzed from the DWI for the primary motor cortex (M1), the supplementary motor area (SMA) and thalamus for reflecting changes in neuronal organization.
  
  
  
  The MTs did not differ between the affected (AH) and unaffected hemisphere (UH) in 50μV responses, while the MTs for 2mV responses were higher (p=0.018) in AH. SICI was weakened in AH (p=0.008). ADCs were higher in the affected M1 compared to the unaffected M1 (p=0.018) while there were no inter-hemispheric differences in SMA or thalamus.
  
  
  
  Inter-hemispheric asymmetry and neuronal organization demonstrated abnormalities in the M1. However, no confident inference can be made whether the observed alterations in neurophysiological and imaging measures have causal role for motor rehabilitation in these patients.
  
  
  
  Neurophysiological changes persist and are detectable using TMS years after stroke even though clinical symptoms have normalized.
authors.affiliation: Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland; Department of Applied Physics, University of Eastern Finland, Kuopio, Finland. Electronic address: petro.julkunen@kuh.fi.
authors.forename: Petro
authors.initials: P
authors.lastname: Julkunen
authors.affiliation: Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland; Department of Clinical Neurophysiology, Institute of Clinical Medicine, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland.
authors.forename: Sara
authors.initials: S
authors.lastname: Määttä
authors.affiliation: Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland; Department of Clinical Neurophysiology, Institute of Clinical Medicine, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland.
authors.forename: Laura
authors.initials: L
authors.lastname: Säisänen
authors.affiliation: Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland; Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
authors.forename: Elisa
authors.initials: E
authors.lastname: Kallioniemi
authors.affiliation: Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland; Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Mervi
authors.initials: M
authors.lastname: Könönen
authors.affiliation: Department of Neurology, Kuopio University Hospital, Kuopio, Finland; Department of Neurology, Institute of Clinical Medicine, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland.
authors.forename: Pekka
authors.initials: P
authors.lastname: Jäkälä
authors.affiliation: Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland; Department of Clinical Radiology, Institute of Clinical Medicine, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland.
authors.forename: Ritva
authors.initials: R
authors.lastname: Vanninen
authors.affiliation: Department of Clinical Neurophysiology, Helsinki University Hospital, Helsinki, Finland; Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland.
authors.forename: Selja
authors.initials: S
authors.lastname: Vaalto
mesh_terms: D000368:Aged; D020520:Brain Infarction / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D038524:Diffusion Magnetic Resonance Imaging; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D009433:Neural Inhibition / Q000502:physiology; D020521:Stroke / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D013788:Thalamus / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D050781:Transcranial Magnetic Stimulation
keywords: Diffusion weighted imaging; Infarction; Motor cortex; Motor evoked potential; Navigated transcranial magnetic stimulation; Stroke