Mesial temporal resection following long-term ambulatory intracranial EEG monitoring with a direct brain-responsive neurostimulation system.

OBJECTIVE: To describe seizure outcomes in patients with medically refractory epilepsy who had evidence of bilateral mesial temporal lobe (MTL) seizure onsets and underwent MTL resection based on chronic ambulatory intracranial EEG (ICEEG) data from a direct brain-responsive neurostimulator (RNS) system. METHODS: We retrospectively identified all patients at 17 epilepsy centers with MTL epilepsy who were treated with the RNS System using bilateral MTL leads, and in whom an MTL resection was subsequently performed. Presumed lateralization based on routine presurgical approaches was compared to lateralization determined by RNS System chronic ambulatory ICEEG recordings. The primary outcome was frequency of disabling seizures at last 3-month follow-up after MTL resection compared to seizure frequency 3 months before MTL resection. RESULTS: We identified 157 patients treated with the RNS System with bilateral MTL leads due to presumed bitemporal epilepsy. Twenty-five patients (16%) subsequently had an MTL resection informed by chronic ambulatory ICEEG (mean = 42 months ICEEG); follow-up was available for 24 patients. After MTL resection, the median reduction in disabling seizures at last follow-up was 100% (mean: 94%; range: 50%-100%). Nine patients (38%) had exclusively unilateral electrographic seizures recorded by chronic ambulatory ICEEG and all were seizure-free at last follow-up after MTL resection; eight of nine continued RNS System treatment. Fifteen patients (62%) had bilateral MTL electrographic seizures, had an MTL resection on the more active side, continued RNS System treatment, and achieved a median clinical seizure reduction of 100% (mean: 90%; range: 50%-100%) at last follow-up, with eight of fifteen seizure-free. For those with more than 1 year of follow-up (N = 21), 15 patients (71%) were seizure-free during the most recent year, including all eight patients with unilateral onsets and 7 of 13 patients (54%) with bilateral onsets. SIGNIFICANCE: Chronic ambulatory ICEEG data provide information about lateralization of MTL seizures and can identify additional patients who may benefit from MTL resection.

Evidence of charge-transfer ferromagnetism in transparent diluted magnetic oxide nanocrystals: switching the mechanism of magnetic interactions.

We report the experimental evidence of a new form of room-temperature ferromagnetism in high surface area nanocrystalline manganese-doped In2O3, prepared from colloidal nanocrystals as building blocks. The nanocrystal structure (bixbyite or corundum) and assembly were controlled by their size, and the type and concentration of dopant precursors. The existence of substitutional paramagnetic Mn dopant ions in mixed valence states (Mn(2+) and Mn(3+)) was confirmed and quantified by different spectroscopic methods, including X-ray absorption and magnetic circular dichroism. The presence of different oxidation states is the basis of ferromagnetism induced by Stoner splitting of the local density of states associated with extended structural defects, due to charge transfer from the Mn dopants. The extent of this charge transfer can be controlled by the relationship between the electronic structures of the nanocrystal host lattice and dopant ions, rendering a higher magnetic moment in bixbyite relative to corundum Mn-doped In2O3. Charge-transfer ferromagnetism assumes no essential role of dopant as a carrier of the magnetic moment, which was directly confirmed by X-ray magnetic circular dichroism, as an element-specific probe of the origin of ferromagnetism. At doping concentrations approaching the percolation limit, charge-transfer ferromagnetism can switch to a double exchange mechanism, given the mixed oxidation states of Mn dopants. The results of this work enable the investigations of the new mechanisms of magnetic ordering in solid state and contribute to the design of new unconventional magnetic and multifunctional materials.

Seizure exacerbation in two patients with focal epilepsy following marijuana cessation.

While animal models of epilepsy suggest that exogenous cannabinoids may have anticonvulsant properties, scant evidence exists for these compounds' efficacy in humans. Here, we report on two patients whose focal epilepsy was nearly controlled through regular outpatient marijuana use. Both stopped marijuana upon admission to our epilepsy monitoring unit (EMU) and developed a dramatic increase in seizure frequency documented by video-EEG telemetry. These seizures occurred in the absence of other provocative procedures, including changes to anticonvulsant medications. We review these cases and discuss mechanisms for the potentially anticonvulsant properties of cannabis, based on a review of the literature.