This paper was presented at the International Society for Pediatric Neurosurgery Meeting in Cape Town in October 2008 during the post-meeting Focus Session on Intraoperative Neurophysiology. It reflects the personal views of the author and is intended as a pragmatic approach to cases where a non-invasive pre-surgical evaluation has not been successful in localising the epileptogenic zone. It is based on the experience of the multi-disciplinary team at Great Ormond Street Hospital without whose support none of the surgical work would be possible. [ABSTRACT FROM AUTHOR]