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Probing modifications of cortical excitability during stroke recovery with navigated transcranial magnetic stimulation.

Abstract

OBJECTIVE
To follow cortical excitability changes during recovery from stroke with navigated transcranial magnetic stimulation (nTMS), in particular, to characterize changes of short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF), to correlate them with recovery of upper extremity function, and to detect possible shifts of cortical hand representations.
METHODS
Single and paired pulse nTMS were delivered to the hemisphere with infarction and to the hemisphere without infarction in 14 first-ever stroke patients at 1 (T1) and 3 months (T2) after stroke. Electromyographic responses to nTMS stimulation were recorded from the first dorsal interosseus muscles. nTMS was used to ensure an accurate coil repositioning in repeated measurements. Hand function recovery was clinically evaluated using the Action Research Arm Test (ARAT) and 9-hole peg test (9-HPT).
RESULTS
SICI and ICF were modulated in both hemispheres during recovery. Inhibition in the hemisphere without infarction correlated significantly with the affected hand performance at T2; stronger disinhibition (poor inhibition) was associated with worse hand performance. Location of hand muscle representations was shifted in 3 well-recovered patients out of 14 patients at T2.
CONCLUSIONS
In line with earlier studies, disinhibition in the hemisphere without infarction may be related to poor recovery of the affected hand. Usage of the affected hand during stroke recovery seems to influence these cortical excitability changes. nTMS is a valuable tool for tracking muscle cortical representation changes during brain reorganization.

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  • Publisher Full Text

    • Authors

    Lioumis P, Mustanoja S, Bikmullina R, Vitikainen AM, Kičić D, Salonen O, Tatlisumak T, Kaste M, Forss N, Mäkelä JP

    Institution

    Hospital District of Helsinki and Uusimaa, Helsinki, Finland.

    Source

    Topics in stroke rehabilitation 19:2 pg 182-92

    MeSH

    Aged
    Aged, 80 and over
    Brain Ischemia
    Brain Mapping
    Cerebral Cortex
    Evoked Potentials, Motor
    Female
    Functional Laterality
    Hand
    Humans
    Male
    Middle Aged
    Neural Inhibition
    Predictive Value of Tests
    Recovery of Function
    Stroke
    Transcranial Magnetic Stimulation

    Pub Type(s)

    Clinical Trial
    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    22436366