Seizure onset from periventricular nodular heterotopias

Abstract

The association between gray matter heterotopias and seizures is well established; whether seizures originate from these lesions is not known. We evaluated three patients with intractable complex partial seizures and periventricular nodular heterotopias (PNHs) with video-EEG monitoring with multiple depth electrodes, including placement in the PNH, to determine whether seizures originate from the PNH. In two of the three patients, all seizures arose from the PNH as low-voltage beta activity. In the third patient, 80% arose from the hippocampi and 20% from the heterotopia. PNHs may serve as an epileptogenic focus in patients with intractable epilepsy.

Distribution and Initiation of Seizure Activity in a Rat Brain with Subcortical Band Heterotopia

“…This finding is consistent with clinical studies of patients with SBH, in which both normotopic and heterotopic areas exhibit epileptiform discharges (46). It is also consistent with studies of other types of cortical heterotopia, in which both normotopic and heterotopic neurons have been implicated in seizure generation (15,22,47,48). However, the precise origin of seizure activity in patients with SBH remains controversial because it is unclear whether heterotopic and/or normotopic neurons are responsible for initiating discharge activity.…”

Stereo-EEG-guided radio-frequency thermocoagulations of epileptogenic grey-matter nodular heterotopy

“…Surgery may provide excellent results when resection of the nodules and of the overlying cortex is performed according to intracerebral seizure recordings 3 5. In a subset of patients, the nodule may play a leading role at ictal onset, as previously shown by depth recording 22. In such instances, it has also been reported that surgical selective resection of a unilateral single-nodule heterotopy may result in seizure control 8.…”

“…EEG/functional MRI studies have suggested that while interictal epileptiform activity arises from the nodule, ictal electrical modifications originate from the surrounding cortex 20 21. On the other hand, SEEG studies have demonstrated that ictal onset may occur either simultaneously in the nodule and in the overlying cortex and hippocampus, or in the overlying cortex with no contribution of the heterotopy 3 5 22. Surgery may provide excellent results when resection of the nodules and of the overlying cortex is performed according to intracerebral seizure recordings 3 5.…”

Independent component analysis reveals dynamic ictal BOLD responses in EEG-fMRI data from focal epilepsy patients

“…For patients without intracranial electrodes, the results can still be compared to other patients with similar characteristics in the literature. SEEG studies in patients with nodular heterotopia have shown that the nodules may be epileptogenic (Kothare et al, 1998), but almost never exclusively. Seizures usually start in the mesial temporal structures or in the cortex overlying the nodules, with only occasional involvement of the nodules themselves Battaglia et al, 2006;Tassi et al, 2005).…”