Infantile spasms: seasonal onset differences and zeitgebers

A vitamin D enriched diet attenuates sex-specific behavioral deficits, increases the lifespan, but does not rescue bone abnormalities in a mouse model of cortical dysplasia

Individuals who experience recurrent spontaneous seizures often show behavioral and physiological comorbidities. Those with epilepsy are at a high risk of bone fractures (independent of seizure-related falls) and show a higher rate of a diagnosis of Autism Spectrum Disorder. The neural subset-specific (NS) Pten knockout (KO) mouse has an epilepsy phenotype, has been characterized to show autistic-like deficits, and has an osteoporosis phenotype. The current study examined the effect of a vitamin D enriched diet (20,000 IU VD) in the NS-Pten KO and wildtype mice. Mice were placed onto a vitamin D enriched diet at 4 weeks of age and maintained on that diet throughout testing. Behavioral testing began at 6 weeks of age and included tests for general activity, anxiety, repetitive behaviors, social behaviors, and memory. Results indicated that a vitamin D diet attenuated hypoactivity levels in male KO mice (p < 0.05). In a social partition task, vitamin D increased sociability in male wildtype mice, (p < 0.05). Most significantly, vitamin D fortified diet increased percent survival in KO animals and decreased the level of microglia marker IBA-1 and mTOR (mammalian target of rapamycin) downstream targets pS6 and pAKT. A high vitamin D diet did not reverse bone deficits in male or female KO mice. Overall, these findings suggest that a vitamin D enriched diet had a significant impact on the behavioral phenotype of NS-Pten KO mice, suggesting that dietary manipulations could be a potential therapeutic option for autistic-like behavior.

Low ambient temperature as the only meteorological risk factor of seizure occurrence: A multivariate study

BACKGROUND

The onset of epileptic seizures is influenced by weather, which is multifactorial. It is unknown which specific weather factors affect the occurrence of seizures.

OBJECTIVES

We studied the correlation between the onset of epileptic seizures and multiple weather parameters based on a population-based registry profile.

METHODS

We determined the number of patients who visited emergency services in Taiwan diagnosed as having epilepsy. Then we used a linear regression model to analyze the monthly average number of patients who received emergency treatment for epilepsy in relation to temperature, barometric pressure, accumulated precipitation, relative humidity, and hours of sunshine. The Poisson regression model was used to analyze multiple meteorological factors in relation to the number of daily emergency visits because of epilepsy. A receiver operating characteristic curve was used to determine the cutoff temperature for the occurrence of seizures.

RESULTS

Temperature appeared to be the robust factor for the onset of epilepsy. For every 1 °C decrease in temperature, there was a relative risk increase of 1.016 in the number of emergency visits as a result of epilepsy. Temperature lower than 18 °C had the best predictive value for seizure. Barometric pressure, accumulated precipitation, relative humidity, and the number of hours of sunshine were not related to the occurrence of seizures.

SIGNIFICANCE

Our results suggest that temperature is the only influential meteorological factor that affects seizure occurrence.

Latitudinal differences on the global epidemiology of infantile spasms: systematic review and meta-analysis

BACKGROUND

Infantile spasms represent the catastrophic, age-specific seizure type associated with acute and long-term neurological morbidity. However, due to rarity and heterogenous determination, there is persistent uncertainty of its pathophysiological and epidemiological characteristics. The purpose of the current study was to address a historically suspected latitudinal basis of infantile spasms incidence, and to interrogate a geographical basis of epidemiology, including the roles of latitude and other environmental factors, using meta-analytic and -regression methods.

METHODS

A systematic search was performed in Ovid MEDLINE and Embase for primary reports on infantile spasms incidence and prevalence epidemiology.

RESULTS

One thousand fifteen studies were screened to yield 54 eligible publications, from which 39 incidence figures and 18 prevalence figures were extracted. The pooled incidence was 0.249 cases/1000 live births. The pooled prevalence was 0.015 cases/1000 population. Univariate meta-regression determined a continental effect, with Europe demonstrating the highest onset compared from Asia (OR = 0.51, p = 0.004) and from North America (OR = 0.50, p = 0.004). Latitude was also positively correlated with incidence globally (OR = 1.02, p < 0.001). Sub-analyses determined a particularly elevated Scandinavian incidence compared to the rest of world (OR = 1.88, p < 0.001), and lack of latitudinal effect with Scandinavian exclusion (p = 0.10). Metrics of healthcare quality did not predict incidence. Multiple meta-regression determined that latitude was the key predictor of incidence (OR = 1.02, p = 0.001).

CONCLUSIONS

This is the first systematic epidemiological study of infantile spasms. Limitations included lack of Southern hemispheric representation, insufficient study selection and size to support some sub-continental analyses, and lack of accessible ethnic and healthcare quality data. Meta-analyses determined a novel, true geographical difference in incidence which is consistent with a latitudinal and/or ethnic contribution to epileptogenesis. These findings justify the establishment of a global registry of infantile spasms epidemiology to promote future systematic studies, clarify risk factors, and expand understanding of the pathophysiology.

Hypsarrhythmia in epileptic spasms: Synchrony in chaos

PURPOSE

Hypsarrhythmia is an electroencephalographic pattern associated with epileptic spasms and West syndrome. West syndrome is a devastating epileptic encephalopathy, originating in infancy. Hypsarrhythmia has been deemed to be the interictal brain activity, while the electrodecremental event associated with the spasms is denoted as the ictal event. Though characterized as chaotic, asynchronous and disorganized based on visual inspection of the EEG, little is known of the dynamics of hypsarrhythmia and how it impacts the developmental arrest of these infants.

METHODS

As an exploratory and feasibility study, we explored the dynamics of both hypsarrhythmia and electrodecremental events with EEG phase synchronization methods, and in a convenience sample of three outpatients with epileptic spasms. As ictal events are associated with prolonged phase synchronization, we hypothesized that if hypsarrhythmia was indeed the interictal brain activity that it would have lower phase synchronization than the electrodecremental event (ictal phase).

RESULTS

We calculated both the phase synchronization index and the temporal variability of the index in three patients with infantile spasms. Two patients had hypsarrhythmia and electrodecremental events and one had hemi-hypsarrhythmia. We found that the hypsarrhythmia pattern was a more synchronized state than the electrodecremental event.

CONCLUSIONS

We have observed that the hypsarrhythmia pattern may represent a more synchronized state than the electrodecremental event in infants with epileptic spasms. However, larger studies are needed to replicate and validate these findings. Additionally, further inquiry is required to determine the impact that increased synchronization may have on developmental outcomes in infants with epileptic spasms.

Epilepsy and vitamin D: a comprehensive review of current knowledge

Vitamin D has been considered as neurosteroid, and its pivotal role in neuroprotection, brain development, and immunomodulation has been noticed in studies; however, our knowledge regarding its role in neurological disorders is still developing. The potential role of vitamin D in the pathophysiology and treatment of epilepsy, as one the most prevalent neurological disorders, has received less attention in recent years. In this article, we review the possible relationship between vitamin D and epilepsy from different aspects, including the action mechanism of vitamin D in the central nervous system and ecological and epidemiological findings. We also present the outcome of studies that evaluated the level of vitamin D and the impact of administrating vitamin D in epileptic patients or animal subjects. We also review the current evidence on interactions between vitamin D and antiepileptic drugs.

Are Humans Seasonally Photoperiodic?

Humans exhibit seasonal variation in a wide variety of behavioral and physiological processes, and numerous investigators have suggested that this might be because we are sensitive to seasonal variation in day length. The evidence supporting this hypothesis is inconsistent. A new hypothesis is offered here—namely, that some humans indeed are seasonally photoresponsive, but others are not, and that individual variation may be the cause of the inconsistencies that have plagued the study of responsiveness to photoperiod in the past. This hypothesis is examined in relation to seasonal changes in the reproductive activity of humans, and it is developed by reviewing and combining five bodies of knowledge: correlations of human birthrates with photoperiod; seasonal changes in the activity of the neuroendocrine pathway that could link photoperiod to gonadal steroid secretion in humans; what is known about photoperiod, latitude, and reproduction of nonhuman primates; documentation of individual variation in photoresponsiveness in rodents and humans; and what is known about the evolutionary ecology of humans.

Epilepsy and vitamin D

Several disorders, both systemic and those of the nervous system, have been linked with vitamin D deficiency. Neurological disorders with a vitamin D link include but are not limited to multiple sclerosis, Alzheimer and Parkinson disease, as well as cerebrovascular disorders. Epilepsy which is the second leading neurological disorder received much less attention. We review evidence supporting a link between vitamin D and epilepsy including those coming from ecological as well as interventional and animal studies. We also assess the literature on the interaction between antiepileptic drugs and vitamin D. Converging evidence indicates a role for vitamin D deficiency in the pathophysiology of epilepsy.

Chronopharmacology of anti-convulsive therapy

Approximately one-third of patients with epilepsy continue to have seizures despite antiepileptic therapy. Many seizures occur in diurnal, sleep/wake, circadian, or even monthly patterns. The relationship between biomarkers and state changes is still being investigated, but early results suggest that some of these patterns may be related to endogenous circadian patterns whereas others may be related to wakefulness and sleep or both. Chronotherapy, the application of treatment at times of greatest seizure susceptibility, is a technique that may optimize seizure control in selected patients. It may be used in the form of differential dosing, as preparations designed to deliver sustained or pulsatile drug delivery or in the form of 'zeitgebers' that shift endogenous rhythms. Early trials in epilepsy suggest that chronopharmacology may provide improved seizure control compared with conventional treatment in some patients. The present article reviews chronopharmacology in the treatment of epilepsy as well as future treatment avenues.

Circadian profiles of focal epileptic seizures: a need for reappraisal

Circadian rhythm of seizure is underestimated in the study of focal epilepsies. A review of the current literature revealed a clear correlation between cortical epileptogenic focus and the circadian phase of seizure peak occurrence in adult patients. A single diurnal peak at 19:00 was found in seizures originating from the occipital lobe, between 5:00 and 7:00 in frontal lobe seizures, and between 16:00 and 17:00 h in temporal lobe seizures. Two diurnal peaks, between 5:00 and 7:00, and at 23:00 are reported in seizures from the parietal lobe, and between 7:00 to 8:00 and 16:00 to 17:00 in mesial temporal onset seizures. This circadian character of seizure occurrence in focal epilepsies may not be unique to partial seizures since recent clinical and experimental data indicate that generalized seizures also demonstrate circadian effects. The clinical evidence on generalized seizures and epilepsies is not recent, but a formal integration of circadian rhythmicity in our understanding and clinical management of epilepsies may be warranted.

Infantile spasms: does season influence onset and long-term outcome?

To study whether onset of infantile spasms manifests seasonal variation, as previously reported, and whether any such seasonality is associated with treatment response and long-term outcome, data for 57 patients were retrospectively reviewed. The data were collected from hospital files and through a mail survey of children with infantile spasms born from 1980 to 2002 and monitored at the University Children's Hospital of Berne, Switzerland. The mean age at time of onset of infantile spasms was 7 months (range, 0.75-40), at diagnosis 8 months (range, 1-42) and at follow-up 11.3 years (range, 1-23 years). In 77% of participants, the etiology of infantile spasms was known (symptomatic); in the remaining 23% it was not known (nonsymptomatic). In contrast to previous findings, onset of infantile spasms was not associated with calendar month, photoperiod, or global solar radiation. Long-term prognosis was poor: 4 of the 57 (7%) children died; 49 (86%) had cognitive impairment and 40 (70%) had physical impairment; 31 (54%) had cerebral palsy, 37 had (65%) persistent seizures, and 9 (16%) had Lennox-Gastaut syndrome. Symptomatic infantile spasms were associated with worse cognitive outcome (P < 0.001), but treatment modality and overall duration of infantile spasms were not. There was no association of calendar month or photoperiod at onset with cognitive outcome or treatment response.

Daily rhythms of seizure activity and behavior in a model of atypical absence epilepsy

We studied daily rhythms of chronic seizure activity and behavior in adult rats and mice treated with the cholesterol biosynthesis inhibitor AY-9944 (AY) during early postnatal development. Chronic atypical absence seizures were verified in the AY-treated animals by the presence of spontaneous 5- to 6-Hz slow spike-wave discharges (SSWDs) in the neocortex. General behavioral activity, as measured by total movements (TM), movement time (MT), ambulatory movement time (AMT), time spent in center of arena (CT), jumps (JFP), and rotational behavior (TURNS), were continuously recorded under a 12-hour light:12-hour dark photocycle. The average SSWD duration in AY-treated rats varied daily, with two peaks occurring at approximately dark phase and light phase onset. Mice treated with AY exhibited significant increases in all behavioral measures during the light and dark phases, with the exception of light-phase CT, which did not differ from that of controls. Consequently, the daily rhythm of total behavioral activity (TM) exhibited a significantly higher mean oscillation (mesor) and amplitude without evidence of phase shift compared with the TM rhythm of controls. The occurrence of SSWD activity in the AY model appears to be subject to regulation by biological timing mechanisms and, furthermore, associated with motor hyperactivity that does not alter the timing of behavioral rhythmicity.

The epidemiology of infantile spasms

OBJECTIVE

The aim of this study was to estimate population based incidence rates for infantile spasms (IS) and to study our clinical impression that the incidence of IS has recently decreased in the Canadian Provinces of Nova Scotia and Prince Edward Island.

METHODS

Birth cohorts from 1978 to 1998, identified through the hospital health records, EEG records and physician computerized databases, were followed for two years for the development of IS. Disease incidence rates were calculated using denominators derived from Statistics Canada's reported annual live birth rates.

RESULTS

The inclusion criteria for IS were fulfilled by 75 patients. The overall incidence of IS was 30.7/100,000 live births (95% Cl 24.3, 38.8). Etiologic classification was symptomatic for 51 cases (68%), cryptogenic for 18 (24%), and idiopathic in six children (8%). Although there were more males (N=44) than females (N=31), the incidence rates were similar. There was a marked variability in annual and five-year incidence rates.

CONCLUSIONS

Although the clinical characteristics of our patients were similar to other reported IS populations, the instability in IS incidence rates indicates a need for caution in interpreting smaller IS epidemiologic studies.