Abstracts

Rationale: To study cortical representation of upper and lower extremity-muscles in a 16 year old boy to optimize planning of epilepsy surgery. Methods: The boy was born with a transposition of the great arteries. At 2 days, he suffered massive left sided ischemic cerebral damage. This lead to a right hemiparesis. From six years of age he suffered from therapy-resistant epilepsy. Preoperative investigations (v-scalpEEG, dipoleanalysis and SPECT) indicated a right frontal focus. fMRI could not produce any activity in the left hemisphere. Due to widespread damage on the left side, findings were interpreted as rapid spread from left to right and a left mesial frontal resection was performed. Six months postoperative seizures reappeared. Navigated transcranial magnetic study (NBS) was performed to decide if another left sided resection was possible. Using NBS (Eximia, Nexstim Ltd), the cortical representation of upper and lower extremity muscles was investigated. Results: The NBS investigation could define cortical representation of extremity muscles. Hand and upper arm muscles of left side had normal somatotopic localisation in right primary motor area (M1). Control of the right hand muscles was shifted to corresponding area in the right hemisphere. Right forearm muscles were governed bilaterally from M1. Control of the right leg was unaltered in the left M1. Conclusions: Using NBS, localisation of the cortical control of different muscles can be investigated with high precision. In this case, a partial contralateral transfer of motor function of a forearm muscle was demonstrated.