Optical imaging techniques in pediatric neocortical epilepsy
One of the most common forms of epilepsy affecting pediatric patients is neocortical (Obeid et al., 2009a, b). The majority of these pediatric patients require lengthy work-ups, which include grid arrays and strip electrodes, to localize the neocortical focus (Obeid et al., 2009a, b; Sheth, 2000). The additional monitoring for epileptogenic zone localization requires second craniotomies, with the additional risk of infection and complications. Newer imaging techniques may assist epileptologists and epilepsy surgeons in the localization of these neocortical epileptic foci (Snead and Nelson, 1993). Intraoperative techniques such as stereotactic magnetic resonance imaging (MRI) and ultrasound can localize anatomic malformations and larger neuronal migration disorders but still do not have the ability to look at the gold-standard, real-time epileptiform activity. One possible substitute for electrical recordings from the neocortical surface is optical imaging. In this chapter, we will go over the basics of optical imaging and give tangible examples of how this technique may be able to localize epileptiform activity and possibly even neocortical epileptic foci and epileptic onset zones. Basic fundamental work on the mechanisms underlying the optical intrinsic signal, and the paradigms to remove noise from the acquired images, will move this field forward to the ultimate goal of using optical imaging in real time to localize epileptic foci and allow epileptologists and epilepsy surgeons to do smaller resections and avoid unnecessary surgeries and their inherent risks.
