Motor cortical excitability in patients with poststroke epilepsy

Purpose: To gain insight into the mechanisms underlying poststroke epilepsy (PSE), we evaluated motor cortical function in chronic stroke patients with (N = 18) and without (N = 18) PSE. Methods: We measured resting motor threshold (RMT), motor evoked potential (MEP) amplitudes, cortical silent period (CSP), intracortical inhibition (ICI), influenced by GABAergic neurotransmission, and intracortical facilitation (ICF), influenced by glutamatergic activity, to transcranial magnetic stimulation. Results: We found (1) larger MEP amplitudes and ICF, in the affected than unaffected hemispheres of patients in the PSE group but not in patients without epilepsy, and (2) comparably higher RMT and longer CSP in the absence of differences in ICI, H-reflexes or F-waves in the affected and unaffected hemispheres of both PSE and non-PSE patients. Conclusions: Enhanced cortical excitability in the affected hemisphere, possibly related to increased glutamatergic activity, could be one of the mechanisms contributing to the development of poststroke epilepsy.