Date Added: 2008-07-25 06:30:08

Pain & Central Nervous System Week via NewsEdge :

2008 JUL 28 - (NewsRx.com) -- "The aim of this study was to determine whether seizure occurrence in partial epilepsy is under the influence of circadian rhythms and rhythmic exogenous factors, and how this influence varies according to cortical brain region (see also Epilepsy). For these ends, we determined and analyzed detailed temporal distributions of seizures arising from the frontal, parietal, occipital, neocortical temporal, and mesial temporal lobes," investigators in the United States report.

"We retrospectively analyzed intracranial EEG recordings from 131 consecutive adult subjects whose partial epilepsy was sufficiently localized for surgical resection. In all, 669 seizures were analyzed: 132 frontal, 77 parietal, 83 occipital, 217 mesial temporal, and 160 neocortical temporal. Seizure distribution was dependent on brain region (p < 10(-9)). Nonuniform seizure distributions were observed in the parietal (p < 10(-4)), occipital (p < 10(-7)), mesial temporal (p < 0.02), and neocortical temporal lobes (p < 0.04). Occipital and parietal seizures occurred in strong gaussian-like distributions, 180 degrees out of phase relative to each other; occipital seizure occurrence peaked between 16:00 and 19:00, whereas parietal seizures peaked between 4:00 and 7:00. Frontal lobe seizures followed a unimodal distribution, peaking between 4:00 and 7:00. Seizures from the mesial temporal lobe were distributed bimodally, with the primary peak in the late afternoon between 16:00 and 19:00 and secondary peak in the morning between 7:00 and 10:00. Neocortical temporal seizures peaked slightly before the primary peak observed in the mesial temporal lobe; however, these distributions did not differ significantly. Seizure occurrence in partial epilepsy is not random. Endogenous circadian rhythms and rhythmic exogenous factors likely play substantial roles in seizure occurrence. These roles vary considerably according to brain region," wrote T.S. Durazzo and colleagues, Yale University.

The researchers concluded: "Frontal and parietal lobe seizures seem most likely to occur nocturnally, whereas occipital and temporal lobe seizures seem to have strong afternoon preferences."

Durazzo and colleagues published their study in Neurology (Temporal distributions of seizure occurrence from various epileptogenic regions. Neurology, 2008;70(15):1265-1271).

For additional information, contact H.P. Zaveri, Yale University, Dept. of Neurology, 333 Cedar St., New Haven, CT 06520, USA.

The publisher of the journal Neurology can be contacted at: Lippincott Williams & Wilkins, 530 Walnut St., Philadelphia, PA 19106-3621, USA.

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