Functional reorganization of motor cortex due to brain tumor: a case report.

We report the case of a 39-year-old man with a brain tumor and 12 years of intractable partial epilepsy with secondary generalization. After extensive noninvasive and invasive evaluation the seizure focus was localized to the right fronto-parietal region. Functional cortical mapping (FCM) was performed after craniotomy and implantation of a subdural grid with 40 electrodes covering the epileptogenic focus and the adjacent cortex. A Grass Model S12 Stimulator was used to deliver gradual increments of current and stimulus duration with fixed frequency of 10 Hz and pulse duration of 500 microsec for defining eloquent cortex next to the seizure focus. FCM demonstrated cortical representation of eye anterior to and hand posterior and inferior to expected locations on the motor cortex compared to the classical homunculus. Subsequently, he underwent resection of an oligodendroglioma. This case demonstrates that the brain undergoes reorganization of cortical motor representation as a result of pathological lesions in the brain.