Nocturnal interictal epileptic discharges in adult Lennox-Gastaut syndrome: the effect of sleep stage and time of night.

Lennox-Gastaut syndrome (LGS) is characterized by interictal epileptiform discharges (IEDs) occurring during sleep. The aim of this study was to determine whether sleep influences not only the frequency of seizures and IEDs, but also the time-dependent evolution that may support the hypothesis of homeostatic influences on epileptic threshold. Video polysomnography data from our database were reviewed to identify adult LGS patients with at least seven hours of nocturnal recording. Thirteen patients were identified and a second polysomnography was available for nine. The number, duration and index of IEDs, relative to total sleep, sleep stages, and time during the night, were calculated. The majority of IEDs occurred during non-rapid eye movement sleep, mainly in stage 2 and slow-wave sleep. Adjusting for time spent in each sleep stage, we found 45 IEDs/hour in stage 1, 123/hour in stage 2, 106/hour in slow-wave sleep, and 26/hour in rapid eye movement sleep. The temporal distribution of IEDs showed a significant rise in the first three hours of sleep, followed by a progressive decrease at the end of the night (F=85.6; p<0.0001). Interictal epileptiform discharges occurrence in adult LGS is facilitated by non-rapid eye movement sleep with an evident effect of stage 2 and slow-wave sleep. The significant IED occurrence in the first part of the night and the subsequent decline suggests a link between epileptic threshold and homeostatic sleep mechanisms. The latter should be considered regarding choice of therapy.

Epilepsy and tobacco smoking: a cross-sectional study.

There is little data concerning the prevalence of smoking in the population of people with epilepsy. The present study addresses this aspect in a sample of 429 unselected adults with epilepsy living in French-speaking Switzerland. The criterion of at least one cigarette per day for the past 6 months was used to define the status of "current" smoker. The questionnaires included questions about the type of epilepsy and tobacco consumption and were prospectively filled by attending neurologists in the presence of their patient, ensuring a reliable diagnosis of epilepsy. Data were compared with those of the "Tabakmonitoring" data collection, which gives annually detailed information about tobacco use habits in the Switzerland's population according to the different linguistic regions. Among patients suffering from epilepsy, the prevalence of current smoking was 32.1 % (28.8 % among women and 35 % among men), while the prevalence of smoking was 19.0 % in the general population in French-speaking Switzerland in the same period [OR 2.0, confidence interval (CI) 1.6-2.5, p < 0.001]. The subgroup of patients with epilepsy suffering from idiopathic (genetic) generalized epilepsy had the highest prevalence of smoking: 44.3 versus 27.8 % in the other types of epilepsy-p = 0.03. Epilepsy appears significantly correlated to smoking. The possible causal relationship, such as common genetic susceptibility to epilepsy and to nicotine addiction, indirect comorbidity through stress or depression associated with epilepsy, beneficial effect of nicotine on epilepsy, still remains unclear and deserves further studies.

Effect of deep brain stimulation of GPI on neuronal activity of the thalamic nucleus ventralis oralis in a dystonic patient.

OBJECTIVE: To record the possible effect of acute deep brain stimulation (DBS) of the globus pallidus internus (GPI) on the neuronal activity of the ventralis oralis anterior (VOA) nucleus of the thalamus. METHODS: Under general propofol anaesthesia, extracelullar single unit recordings were performed in VOA of a post-anoxic dystonic patient previously implanted with GPI located electrodes for chronic DBS. RESULTS: Neurons recorded in the VOA could be classified in two cell subpopulations: a high firing rate (16.5 Hz) and low burst index (BI; 15.6) type and a low firing rate (5.5 Hz) and high BI (35.6) type. GPI electrical stimulation reduced the frequency and increased the BI of the high firing rate cells while leaving the other cell type unchanged. CONCLUSION: These results demonstrate that pallidal DBS is able to inhibit a subpopulation of motor thalamic cells and question the pathophysiological model of dystonia based on a low firing rate of GPI cells.