The Influence of Climatic Factors on the Provocation of Epileptic Seizures.

Background/Objectives: Recent studies provide the first indications of the impact of climate factors on human health, especially with individuals already grappling with internal and neurological conditions being particularly vulnerable. In the face of escalating climate change, our research delves into the specific influence of a spectrum of climatic factors and seasonal variations on the hospital admissions of patients receiving treatment for epileptic seizures at our clinic in Kaiserslautern. Methods: Our study encompassed data from 9366 epilepsy patients who were admitted to hospital due to epileptic seizures. We considered seven climate parameters that Germany's National Meteorological Service made available. We employed the Kruskal-Wallis test to examine the correlation between the frequency of admittance to our hospital in the mentioned patient group and seasons. Furthermore, we used conditional Poisson regression and distributed lag linear models (DLMs) to scrutinize the coherence of the frequency of patient admittance and the investigated climate parameters. The mentioned parameters were also analyzed in a subgroup analysis regarding the gender and age of patients and the classification of seizures according to ILAE 2017. Results: Our results demonstrate that climatic factors, such as precipitation and air pressure, can increase the frequency of hospital admissions for seizures in patients with general-onset epilepsy. In contrast, patients with focal seizures are less prone to climatic changes. Consequently, admittance to the hospital for seizures is less affected by climatic factors in the latter patient group. Conclusions: The present study demonstrated that climatic factors are possible trigger factors for the provocation of seizures, particularly in patients with generalized seizures. This was determined indirectly by analyzing the frequency of seizure-related emergency admissions and their relation to prevailing climate factors. Our study is consistent with other studies showing that climate factors, such as cerebral infarcts or cerebral hemorrhages, influence patients' health.

EEG Synchronization-Parameters in Patients With Subcortical Arteriosclerotic Encephalopathy and Gait Disorder.

PURPOSE: Subcortical arteriosclerotic encephalopathy (SAE) is characterized by extensive white matter lesions in the MRI. Clinical symptoms are cognitive impairment, ranging from mild deficits to vascular dementia, impaired executive functioning, and gait disorders. In the EEG of SAE patients with vascular dementia, the lower frequencies are increased. However, it is unclear whether EEG changes also exist in SAE patients with gait disorders but without vascular dementia. METHODS: The authors analyzed the EEGs of 50 nondemented patients with SAE and gait disorders and 50 healthy controls applying pointwise transinformation as a measure of synchronization. RESULTS: Hundred seconds of waking EEG that appeared unaltered in visual analysis were sufficient to prove changes in synchronization. The authors found a decrease in the mean level of synchronization, combined with an elongation of synchronization time in all examined brain areas. These effects correlated slightly with the extent of subcortical lesions. CONCLUSIONS: Changes in EEG synchronization in patients with SAE and gait disorders seem to occur independently of cognitive function. The causal relationship of the changes in EEG synchronization and gait disorders remains to be clarified. The results of this study might point to a decrease in coupling efficiency in these patients, with the increase in synchronization duration as a possible compensatory mechanism. Because a time-efficient signal transmission particularly during gait execution is crucial, reduced efficiency might contribute to an impairment of postural stabilization. The study results might indicate a neuronal network for planning and execution of motor activity and particularly gait, extending from the frontal over the central to the parietal cortex.

Acute Symptomatic Seizures in Geriatric Patients with Multiple Risk Factors - A Diagnostic Challenge.

BACKGROUND: Acute symptomatic seizures and epileptic disorders are frequent health problems of elderly patients. An early and reliable distinction of the seizure etiology is important to ensure adequate treatment, and to prevent unwarranted diagnostic and therapeutic procedures. METHODS: We review the current literature based on a MEDLINE search, describe age-related problems in detail, with particular attention to clinical practice, discuss possible criteria and potential pitfalls for diagnostics, and provide a compilation of etiologic factors for acute symptomatic seizures. RESULTS: The most common causes of acute symptomatic seizures - acute cerebrovascular disorders, metabolic disorders, traumatic brain injury, meningo-encephalitis, cerebral tumors, and withdrawal of alcohol and other central agents - are well-defined and seem to permit straightforward diagnostic and therapeutic strategies. The current classification of seizures and epileptic syndromes apparently provides clear definitions. However, multiple age-related risk factors, as well as a reduced discriminatory power of clinical and technical diagnostic criteria can make the distinction difficult. CONCLUSION: Typical age-related problems are incomplete or missing medical history, dementia, oligosymptomatic seizures, inconclusive EEG and cerebral imaging results, multiple pathological findings and comorbidity with ambiguous significance, confounding sleep disorders, intake of proconvulsive drugs, and psychogenic seizures. All diagnostic and therapeutic decisions need to be based on an integrative and individual approach that includes diagnostic findings and risk factors, the intake of medications and other agents, and the social situation of the elderly patient.

A Recurrent Increase of Synchronization in the EEG Continues from Waking throughout NREM and REM Sleep.

Pointwise transinformation (PTI) provides a quantitative nonlinear approach to spatiotemporal synchronization patterns of the rhythms of coupled cortical oscillators. We applied PTI to the waking and sleep EEGs of 21 healthy sleepers; we calculated the mean levels and distances of synchronized episodes and estimated the dominant frequency shift from unsynchronized to synchronized EEG segments by spectral analysis. Recurrent EEG synchronization appeared and ceased abruptly in the anterior, central, and temporal derivations; in the posterior derivations it appeared more fluctuating. This temporal dynamics of synchronization remained stable throughout all states of vigilance, while the dominant frequencies of synchronized phases changed markedly. Mean synchronization had high frontal and occipital levels and low central and midtemporal levels. Thus, a fundamental coupling pattern with recurrent increases of synchronization in the EEG ("RISE") seems to exist during the brain's resting state. The generators of RISE could be coupled corticocortical neuronal assemblies which might be modulated by subcortical structures. RISE designates the recurrence of transiently synchronized cortical microstates that are independent of specific EEG waves, the spectral content of the EEG, and especially the current state of vigilance. Therefore, it might be suited for EEG analysis in clinical situations without stable vigilance.

Pointwise transinformation distinguishes a recurrent increase of synchronization in the rapid eye movement sleep electroencephalogram.

The analysis of electroencephalogram (EEG) coupling patterns is essential for understanding how interrelations between cortical sites change with the wake-sleep cycle. Waking and sleep EEGs of 12 normal sleepers were analyzed by pointwise transinformation (PTI). Stage-dependent differences of PTI were assessed, and a spectral analysis of synchronized events was performed. A pattern of recurrent EEG synchronization was distinguished in all rapid eye movement (REM) sleep phases. The mean coupling of EEG leads differed regionally, with high coupling levels of frontal and occipital derivations and lower midtemporal and central coupling levels. Mean coupling levels were comparable in stages R, W, and N1 but were lower than in N2 and N3. An REM-specific pattern of low EEG synchronization was identified for F7-F8 and T3-T4, with lowest coupling levels during tonic REM sleep. Also, maximal intervals of uncoupled EEG were longer during tonic REM sleep. Because of these results, a new descriptive entity is proposed: the recurrent increase of synchronization in the EEG (RISE). This seems to reflect the dynamic aspects of spatiotemporal EEG synchronization on small time scales. A possibly specific low coupling pattern of the temporal leads may distinguish REM sleep from other states with a "desynchronized" EEG and, to some extent, tonic from phasic REM sleep.