Photosensitivity in Dravet syndrome is under-recognized and related to prognosis.

OBJECTIVE: To detect determinants for photoparoxysmal EEG response (PPR) in SCN1A-related Dravet syndrome (DS). METHODS: Data were studied from nationwide medical histories and EEGs of DS-patients (n=53; 31 males, age 2-19years). Detailed questionnaires on visual stimuli were completed by parents (n=49). RESULTS: PPR was found in 22 patients (42%; median age 1.25yr), and repeatedly in 17%. PPR (17% of 249 intermittent photic stimulation (IPS)-EEGs) occurred more often with optimal IPS protocols (OR 2.11 [95%CI 1.09-4.13]) and in EEGs showing spontaneous epileptiform abnormalities (OR 5.08 [95%CI 2.05-12.55]). PPR-positive patients tended to be younger at first (p=0.072) and second seizure (p=0.049), showed severe intellectual disability (p=0.042), and had more often spontaneous occipital epileptiform abnormalities (p<0.001). Clinical sensitivity was reported in medical files in 22% of patients and by parents in 43% (self-induction 24%). Clinical or EEG proven visual sensitivity was detected in 65% of cases. CONCLUSIONS: Sensitivity to visual stimuli is very common in DS and more often noticed by parents than confirmed by EEG. Detection of PPR improves with repetitive tests using accurate IPS protocols. SIGNIFICANCE: Photosensitivity is an important feature in DS and seems to be a marker of the severity of the disorder. Therefore repeated standardized IPS should be encouraged.

Identification of the epileptogenic zone in patients with tuberous sclerosis: concordance of interictal and ictal epileptiform activity.

OBJECTIVE: In the majority of patients with tuberous sclerosis complex (TSC) multifocal epileptiform activity is present interictally. Therefore, its value in identifying epilepsy surgery candidates has been doubted. We hypothesize that dominant interictal epileptiform foci are concordant with the ictal onset zone in TSC patients. METHODS: Consistency and dominance of focal interictal epileptiform activity was assessed in 19 patients with a clinical definite diagnosis of TSC. The ictal onset zone was identified. Concordance between interictal en ictal findings was analyzed. If concordance was found epilepsy surgery was proposed. RESULTS: We found dominant, consistently present, focal interictal epileptiform activity in 14 of the 19 patients. Concordance between the dominant interictal focus and the ictal onset zone was found in 11 of the 14 patients (79%). In one patient the ictal onset zone could not be identified and discordance was present in two patients. Epilepsy surgery was performed in six patients rendering three of them seizure free, and one had a seizure reduction >90%. In these patients local concordance was found whereas regional concordance was found in the two patients who did not benefit from epilepsy surgery. CONCLUSIONS: A dominant as well as a consistent interictal focus is concordant with the ictal onset zone in the majority of TSC patients. SIGNIFICANCE: Future studies of TSC patients addressing the value of interictal foci in the consideration of epilepsy surgery, in absence of clear ictal onset zone, are necessary.

Diurnal rhythms in seizures detected by intracranial electrocorticographic monitoring: an observational study.

Few studies have evaluated human seizure occurrence over the 24-hour day, and only one group has employed intracranial electrocorticography monitoring to record seizures. Circadian patterns in seizures may have important implications in diagnosis and therapy and provide opportunities in research. We have analyzed spontaneous seizures in 33 consecutive patients with long-term intracranial EEG and video monitoring. Several aspects of seizures were noted, including time of day, origin, type, and behavioral state (sleeping/awake). We recorded 450 seizures that showed an uneven distribution over the day, depending on lobe of origin: temporal lobe seizures occurred preferentially between 1100 and 1700 hours, frontal seizures between 2300 and 0500 hours, and parietal seizures between 1700 and 2300 hours. In the awake state, larger proportions of clinical seizures were seen from 0500 to 1100 hours and from 1700 to 2300 hours. During sleep, larger proportions occurred from 1100 to 1700 hours and from 2300 to 0500 hours. Our results suggest that seizures from different brain regions have a strong tendency to occur in different diurnal patterns.

Detection of temporal lobe spikes: comparing nasopharyngeal, cheek and anterior temporal electrodes to simultaneous subdural recordings.

OBJECTIVE: To compare nasopharyngeal (NP), cheek and anterior temporal (AT) electrodes for the detection yield and localization of interictal spikes in temporal lobe epilepsy. METHODS: In patients evaluated for epilepsy surgery with subdural electrocorticography electrodes, we simultaneously recorded NP, cheek and AT electrodes. Two observers identified spikes in EEG traces and marked in which channels they occurred. Interobserver agreement was calculated using Cohen's kappa. For localization, data-sets with high interobserver agreement (kappa-value 0.4) were evaluated. The subdural distribution of NP and AT spikes was mapped. RESULTS: Seven patients were included, six were analyzed for localization. Only 1.5% of spikes recorded by cheek electrodes were not seen on temporal leads, while 25% of NP spikes were not seen on either. Spikes only recorded by NP electrodes had mesiobasal, while AT spikes had lateral temporal distribution. CONCLUSIONS: NP electrodes can increase EEG spike detection rate in temporal lobe epilepsy and are more useful than cheek electrodes. Spikes that are seen only on NP electrodes tend to be mesiobasal temporal lobe spikes. SIGNIFICANCE: Adding NP electrodes to scalp EEG can aid interictal spike detection and source localization, especially in short recordings like MEG-EEG.

Figuring out drawing-induced epilepsy.

Rare reflex epilepsies are a clinical curiosity but may also give insight into neurocognitive processes. The authors present a patient whose seizures were precipitated by drawing but not by writing. This dissociation complements previous reports on selective impairment of writing. EEG revealed a focus in the right frontal lobe with parietal spread. This is in accord with current cognitive and neural network models of drawing.