Article

Abnormal brain excitability influences recovery after stroke at which
time a prolonged transcranial magnetic stimulation (TMS)-induced
electromyographic silent period is thought to reflect abnormal inhibitory
interneuron excitability. Cortical excitability can be probed directly during the
silent period using concurrent electroencephalography (EEG) of TMS-evoked
responses. OBJECTIVE: The primary study objectives were to characterize
TMS-evoked cortical potentials (TEPs) using EEG and to investigate associations
with persistent hand and arm motor dysfunction in individuals with chronic
stroke. METHODS: Thirteen participants with chronic stroke-related mild-moderate
arm motor impairment and 12 matched controls completed a single TMS-EEG cortical
excitability assessment. TEPs recorded from the vertex during cortical silent
period (CSP) assessment and while at rest were used to evaluate differences in
cortical excitability between stroke and control participants. Associations
between TEPs and CSP duration with measures of upper extremity motor behavior
were investigated. RESULTS: Significantly increased TEP component peak amplitudes
and delayed latencies were observed for stroke participants compared with
controls during CSP assessment and while at rest. Delayed early TEP component
(P30) peak latencies during CSP assessment were associated with less manual
dexterity. CSP duration was prolonged in stroke participants, and correlated with
P30 peak latency and paretic arm dysfunction. CONCLUSIONS: Abnormal cortical
excitability directly measured by early TMS-evoked EEG responses during CSP
assessment suggests abnormal cortical inhibition is associated with hand
dysfunction in chronic stroke. Further investigation of abnormal cortical
inhibition in specific brain networks is necessary to characterize the salient
neurophysiologic mechanisms contributing to persistent motor dysfunction after
stroke.

Langue : ANGLAIS