Unaffected motor cortex remodeling after hemispherectomy in an epileptic cerebral palsy patient. A TMS and fMRI study.

PURPOSE

Here we describe pre- and post-operative neurophysiological and functional magnetic resonance imaging (fMRI) findings in a young epileptic girl with right hemiplegic cerebral palsy. Our findings demonstrate the feasibility of transcranial magnetic stimulation (TMS) and fMRI for predicting a post-surgical outcome and for evaluating functional cortical reorganization.

METHODS

We used TMS and fMRI to evaluate the excitability of the human motor cortex and cortical map representation before and after functional hemispherectomy. TMS was performed using single- and paired-pulse stimulation protocol. Cortical silent periods (CSPs), short interval intra-cortical inhibition (SICI), volume, area and center of gravity (CoG) of cortical map representation were studied before and after surgery. fMRI was done using the blood oxygenation level dependent (BOLD) technique with block-designed protocols.

RESULTS

After surgery the patient showed an improvement of her clinical status and TMS and fMRI demonstrated a reshaping of cortical representation of motor cortex and a significant reduction of cortical silent periods.

DISCUSSION

Before surgery, the combination of a clinical, neurophysiological and neuro-radiological approach may be predictable of the neurological outcome in epileptic patients. Moreover, the patient we describe provides new pieces of information in the mechanisms of plasticity underlying motor recovery after epilepsy surgery.