PURPOSE: In patients with reflex epilepsy, it is sometimes possible to evoke interictal spikes predictably, thus providing an uncommon but important experimental paradigm for examining the physiological changes produced by epileptiform discharges. METHODS: To examine the changes in regional cerebral blood flow (rCBF) and glucose consumption (rCMRglc) produced by interictal spikes, we performed positron emission tomography (PET) scans with the blood-flow tracer [15O]H20 and with [18F]fluorodeoxyglucose in a patient with fixation-off epilepsy. The scans were performed in states of high and low spike frequency produced by eye closure and opening, respectively. RESULTS: The rCBF study revealed a focal increase in blood flow associated with the state of increased interictal spiking. The focus was in the posterior portion of the left superior parietal lobule (Talairach coordinates: x: -36, y: -71, z: 39; t = 4.5; p<0.05) and corresponded to the site of maximal ictal EEG abnormality recorded with implanted electrodes. In a volume of interest of 10-mm diameter centered on the t statistic peak in the rCBF study, the mean rCMRglc was 39.1 micromol/100 g/min with eyes open and 44.1 micromol/100 g/min (13% increase) with eyes closed. An identical activation paradigm was used in six normal subjects studied with functional magnetic resonance imaging. In the normal subjects, no significant activation was observed in the parieto-occipital region, indicating that the changes observed in the patient were due to interictal spiking rather than to task performance alone. CONCLUSIONS: Interictal spiking produces focal increases in cerebral blood flow and glucose metabolism.
PURPOSE: In patients with reflex epilepsy, it is sometimes possible to evoke interictal spikes predictably, thus providing an uncommon but important experimental paradigm for examining the physiological changes produced by epileptiform discharges. METHODS: To examine the changes in regional cerebral blood flow (rCBF) and glucose consumption (rCMRglc) produced by interictal spikes, we performed positron emission tomography (PET) scans with the blood-flow tracer [15O]H20 and with [18F]fluorodeoxyglucose in a patient with fixation-off epilepsy. The scans were performed in states of high and low spike frequency produced by eye closure and opening, respectively. RESULTS: The rCBF study revealed a focal increase in blood flow associated with the state of increased interictal spiking. The focus was in the posterior portion of the left superior parietal lobule (Talairach coordinates: x: -36, y: -71, z: 39; t = 4.5; p<0.05) and corresponded to the site of maximal ictal EEG abnormality recorded with implanted electrodes. In a volume of interest of 10-mm diameter centered on the t statistic peak in the rCBF study, the mean rCMRglc was 39.1 micromol/100 g/min with eyes open and 44.1 micromol/100 g/min (13% increase) with eyes closed. An identical activation paradigm was used in six normal subjects studied with functional magnetic resonance imaging. In the normal subjects, no significant activation was observed in the parieto-occipital region, indicating that the changes observed in the patient were due to interictal spiking rather than to task performance alone. CONCLUSIONS: Interictal spiking produces focal increases in cerebral blood flow and glucose metabolism.
Authors: Amir Omidvarnia; Mangor Pedersen; David N Vaughan; Jennifer M Walz; David F Abbott; Andrew Zalesky; Graeme D Jackson Journal: Hum Brain Mapp Date: 2017-07-24 Impact factor: 5.038
Authors: Allison C Nugent; Ashley Martinez; Alana D'Alfonso; Carlos A Zarate; William H Theodore Journal: J Cereb Blood Flow Metab Date: 2015-03-31 Impact factor: 6.200
Authors: M R Patel; A Blum; J D Pearlman; N Yousuf; J R Ives; S Saeteng; D L Schomer; R R Edelman Journal: AJNR Am J Neuroradiol Date: 1999 Nov-Dec Impact factor: 3.825
Authors: Tatjana Traub-Weidinger; Otto Muzik; Lalith Kumar Shiyam Sundar; Susanne Aull-Watschinger; Thomas Beyer; Marcus Hacker; Andreas Hahn; Gregor Kasprian; Eva-Maria Klebermass; Rupert Lanzenberger; Markus Mitterhauser; Magdalena Pilz; Ivo Rausch; Lucas Rischka; Wolfgang Wadsak; Ekaterina Pataraia Journal: Front Neurol Date: 2020-01-31 Impact factor: 4.003