Editor in Chief
DNETs were first identified in 1988 by Daumas-Duport and colleagues (11), who distinguished these slow-growing tumors from other gliomas. Initially, DNETs were found in young patients with long-standing intractable partial epilepsy treated in epilepsy surgery centers (11, 16, 21, 25, 32). In the most recent WHO classification (2007), DNET is a grade I glioneuronal tumor. During the last two decades, it has become clear that DNETs occur not only in the context of intractable epilepsy but also in patients with few seizures or even a single seizure. DNETs are slow-growing lesions, but regrowth of residual tumors and recurrences after apparent complete resection may occur.
- Associated dysplasia: DNET is a glioneuronal tumor that is associated with adjacent focal cortical dysplasia.
- Surgical goal to remove tumor plus seizure foci: There are twin surgical goals for DNETs. The oncological goal is a gross total resection, while the neurological or functional goal is for the resection of the epileptic focus with resultant seizure control. Image guidance is of great benefit; and in cases of intractable epilepsy, the ability for intraoperative cortical mapping should be available.
- Preoperative need to map epilepsy foci: Preoperative evaluation of suspected DNET (and other low-grade tumors like gangliogliomas) associated with poorly controlled epilepsy should not only consist of routine imaging but also include 24-hour video-EEG monitoring, functional imaging to detect the epileptic foci (SPECT, PET, SISCOM), and fMRI for sensorimotor and language mapping in selected cases. Invasive monitoring with surgically implanted subdural or depth electrodes is reserved for incongruent cases after noninvasive monitoring or in cases of persistent epilepsy after resection of the tumoral lesion.