Summary: Infraslow activity (ISA), direct coupled (DC), and direct current (DC) are the terms used to describe brain activity that occurs in frequencies below 0.1 Hz. Infraslow activity amplitude increase is also associated with epilepsy, traumatic brain injuries, strokes, tumors, and migraines and has been studied since the early 90s at the Henry Ford Hospital MEG Laboratory. We have used a DC-based magnetoencephalography (MEG) system to validate and characterize the ISA from animal models of cortical spreading depression thought to be the underlying mechanism of migraine and other cortical spreading depression–like events seen during ischemia, anoxia, and epilepsy. Magnetoencephalography characterizes these slow shifts easier than electroencephalography because there is no attenuation of these signals by the skull. In the current study, we report on ISA MEG signals of 12 patients with epilepsy in the preictal and postictal states. In the minutes just before the onset of a seizure, large-amplitude ISA MEG waveforms were detected, signaling the onset of the seizure. It is suggested that MEG assessment of ISA, in addition to activity in the conventional frequency band, can at times be useful in the lateralization of epileptic seizures.
Epilepsy Center, Department of Neurology, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A. Department of Neurology, Henry Ford Hospital, Detroit, Michigan, U.S.A. University of Pittsburgh Comprehensive Epilepsy Center (UPCEC), Department of Neurology, University of Pittsburgh, Pittsburgh, Pennsylvania, U.S.A.
BACKGROUND:Direct-to-consumer advertising, media, and Internet marketing to physicians and patients, as well as enticing marketing strategies, are used by the pharmaceutical industry to ensure market share growth of new drugs. Our health system adopted a strict vendor policy governing detailing and sampling activities of pharmaceutical representatives, but realized that further analysis of vendor influence in our system was needed.OBJECTIVE:An assessment of tangible benefits, ethical concerns, and financial liabilities and gains was conducted to reassess the need for further vendor restriction.CONCLUSIONS:Based on our findings, several recommendations have been made. Medical practices and health systems are encouraged to establish and enforce explicit vendor policies, measure their effectiveness, partner proactively with representatives to deliver a drug-detailing message consistent with system initiatives, monitor and regulate continuing medical education funding, and implement strategies to ensure appropriate drug use.
Summary: Purpose: In August, 2004, the Epilepsy Foundation of America convened a workshop to begin to develop an expert consensus on photosensitive seizures. Methods: Literature and data were reviewed, and consensus was derived from discussion. Results: A flash is a potential hazard if it has luminance ≥20 cd/m 2 , occurs at a frequency of ≥3 Hz, and occupies a solid visual angle of ≥0.006 steradians (∼10% of the central visual field or 25% of screen area at typical viewing distances). A transition to or from saturated red also is considered a risk. A pattern with the potential for provoking seizures contains clearly discernible stripes, numbering more than five light–dark pairs of stripes in any orientation. When the light–dark stripes of any pattern collectively subtend at the eye from the minimal‐expected viewing distance a solid angle of >0.006 steradians, the luminance of the lightest stripe is >50 cd/m 2 , and the pattern is presented for ≥0.5 s, then the pattern should display no more than five light–dark pairs of stripes, if the stripes change direction, oscillate, flash, or reverse in contrast; if the pattern is unchanging or smoothly drifting in one direction, no more than eight stripes. These principles are easier to apply in the case of fixed media, for example, a prerecorded TV show, which can be analyzed frame‐by‐frame, as compared with interactive media. Conclusions: A consensus view of stimuli likely to provoke visually evoked seizures can be developed.
