title: Longitudinal study on modulated corticospinal excitability throughout recovery in supratentorial stroke.
abstract: Corticospinal excitability (CSE) is modulated by stroke-induced lesions affecting the brain. This modulation is known to be dependent on the timing of the evaluation, and strongest abnormalities are often found in the acute stage. Our study aimed to characterize changes in CSE asymmetry between the affected and the unaffected hemisphere (AH and UH) during the first month after stroke onset and at 6 month follow-up. Neuronavigated transcranial magnetic stimulation (nTMS) was used to assess the CSE of the abductor pollicis brevis (APB) muscle of the hand and tibialis anterior (TA) muscle of the leg in 16 patients over 5 time-points. AH excitability recovered significantly during 6 months, whereas interhemispheric asymmetry remained significant up to 1 month post-stroke in the APB muscle. Greater initial CSE was associated with good motor function at 6 months. The motor cortical excitatory recovery initiated within week of the stroke and was most prominent within 1 month after stroke onset. Lesion size correlated with CSE of the UH at 10 days, while overall severity of the symptoms correlated inversely with CSE of the AH. This study demonstrates the quick improvement in the CSE via estimation of interhemispheric asymmetry; however, the recovery in the asymmetry continues to normalize even after reaching the threshold for normal values in CSE.
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 Radiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Mervi
authors.initials: M
authors.lastname: Könönen
authors.affiliation: Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland; Institute of Clinical Medicine, Clinical Neurophysiology, University of Eastern Finland, Finland.
authors.forename: Sara
authors.initials: S
authors.lastname: Määttä
authors.affiliation: Department of Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Ina M
authors.initials: IM
authors.lastname: Tarkka
authors.affiliation: The Finnish Association of People with Physical Disabilities, Validia Rehabilitation, Helsinki, Finland.
authors.forename: Sinikka H
authors.initials: SH
authors.lastname: Hiekkala
authors.affiliation: Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland; Institute of Clinical Medicine, Clinical Neurophysiology, University of Eastern Finland, Finland.
authors.forename: Laura
authors.initials: L
authors.lastname: Säisänen
authors.affiliation: Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland; Institute of Clinical Medicine, Clinical Radiology, University of Eastern Finland, Kuopio, Finland.
authors.forename: Ritva
authors.initials: R
authors.lastname: Vanninen
authors.affiliation: Nexstim Plc, Helsinki, Finland.
authors.forename: Jari
authors.initials: J
authors.lastname: Karhu
authors.affiliation: Institute of Clinical Medicine, Neurology, University of Eastern Finland, Kuopio, Finland.
authors.forename: Pekka
authors.initials: P
authors.lastname: Jäkälä
mesh_terms: D000368:Aged; D001921:Brain / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D006225:Hand; D006801:Humans; D007866:Leg; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation; D011712:Pyramidal Tracts / Q000503:physiopathology*; D020521:Stroke / Q000473:pathology / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation
keywords: Corticospinal excitability; Motor evoked potential; Motor threshold; Stroke; Transcranial magnetic stimulation