Seasonal Variation in Neurologic Hospitalizations in the United States

Circadian attributes of neurological and psychiatric disorders as basis for their medication chronotherapy

This review focuses on (i) 24 h patterns in the symptom intensity of common neurologic and psychiatric disorders and (ii) medications prescribed for their management that have a recommended administration time or schedule, presumably to potentiate desired and minimize undesired effects and by definition qualify them as chronotherapies. Predictable-in-time patterning of symptoms is exhibited by many neurologic -- headaches, multiple sclerosis, neurogenic orthostatic hypotension, neuropathic pain, Parkinson's disease, epileptic seizure, attention deficit hyperactivity, Alzheimer's disease - and psychiatric - eating, depressive, obsessive-compulsive, post-traumatic stress, anxiety, and panic - disorders, due either to circadian rhythms of disease pathophysiology or inadequacies of medication-delivery systems. Circadian disruption and circadian misalignment of the sleep-wake and other 24 h rhythms plus late chronotype are characteristic of many of these disorders, suggesting involvement in the mechanisms or consequence of their pathology or as an adverse effect of therapy, especially when administered at an inappropriate biological time. The Prescribers' Digital Reference, a compendium of all prescription medications approved for marketing in the US, reveals 65 of them are utilized to manage neurologic and psychiatric disorders by a specified time-of-day or an asymmetrical interval or strength of dose schedule, presumably to optimize beneficial and minimize adverse effects, thereby qualifying them as chronotherapies. Overall, the contents of this review are intended to inform the development of future chronotherapies that incorporate state-of-the-art drug-delivery systems to improve management of neurologic and psychiatric disorders and associated circadian malalignment and disruption.

Seasonal and monthly variation in benign paroxysmal positional vertigo: a systematic review and meta‑analysis

PURPOSE

The relationship between seasonal variations and the incidence of benign paroxysmal positional vertigo (BPPV) has been widely studied, but the findings remain inconsistent. This systematic review and meta-analysis aimed to evaluate whether BPPV demonstrates seasonal variation.

METHODS

A comprehensive search was conducted across PubMed, Embase, Cochrane Library, Web of Science, and CNKI databases for studies on the monthly or seasonal incidence of BPPV from their inception up to August 2024. Pooled monthly or seasonal incidence rates, risk ratios (RRs) for one season versus another and 95% confidence intervals (CIs) were combined using the random-effects model. This meta-analysis has been registered at International Prospective Register of Systematic Reviews (PROSPERO) (NO. CRD42024583513).

RESULTS

Ten eligible studies were included, comprising 5,063 subjects. Pooled BPPV incidence was highest in winter (28%) and lowest in summer (21%). Additionally, the pooled monthly incidence was highest in December (12.6%) and lowest in July (7.4%). The overall RRs and 95% CIs are as follows: winter versus summer (1.30 [1.07,1.59]); winter versus spring (1.01 [0.88,1.17]); winter versus autumn (1.11[0.95,1.30]); spring versus autumn (1.09 [0.91,1.31]); spring versus summer (1.29 [1.00,1.66]); autumn versus summer (1.17 [0.97,1.42]).

CONCLUSION

Our meta-analysis suggests that there may be seasonal variation in the incidence of BPPV. The finding of seasonal patterns provides a new perspective to our understanding of BPPV, suggesting environmental factors may play a potential role in its pathophysiology. However, larger cohort studies and multicenter datasets are warranted to validate these findings in future research.

Correlation Analysis Between Physical-Chemical and Biological Conditions in the River and the Incidence of Diseases in the City of Piracicaba, Brazil

The Piracicaba River basin, in the State of São Paulo, Brazil, covers approximately 12,400 km2 and plays a crucial economic role in São Paulo's agribusiness corridor. However, it faces recurrent episodes of pollution, impacting water quality and public health, especially in urban areas exposed to contamination. Despite this, few studies have investigated the ecological and epidemiological consequences of this environmental degradation. Therefore, this study analyzed the correlation between physicochemical and biological variables of the Piracicaba River and the incidence of diseases in the city of Piracicaba between January 2019 and September 2024. Data on hospital admissions for respiratory, neurological, and liver symptoms were used, as well as environmental and water quality information, such as dissolved oxygen, turbidity, conductivity, and the presence of cyanobacteria, obtained from public databases. The results showed seasonal patterns and long-term trends, highlighting the health risks associated with the river's pollution. Parameters such as phosphorus, pH, cyanobacteria concentration and climatic factors (temperature and humidity) showed an influence on the occurrence of respiratory, digestive, and neurological diseases. The study reinforces the need for continuous monitoring of water quality and public policies to mitigate impacts on the population's health.

Seasonal variation in myasthenia gravis incidence

INTRODUCTION

Environmental factors may contribute to myasthenia gravis (MG) development, sometimes with seasonal patterns of exposure. However, whether seasonality has an impact on MG incidence remains unclear. We aimed to investigate the association between seasonality and MG onset.

METHODS

We reviewed data of MG patients with acetylcholine receptor (AChR)-IgG and disease onset between January 2010-December 2019, from two Italian cohorts: 1) an hospital-based cohort and 2) a population-based cohort. MG cases were assigned to four season-trimesters based on month of onset to determine seasonal association with MG incidence.

RESULTS

We enrolled 316 patients:214 in the hospital-based and 102 in the population-based cohort. Median age at onset was 66 years (range, 8-92); Female accounted for 41.1 %. The median number of new MG cases per season-trimester was significantly higher in summer than other trimesters (p = 0.009), and associated with higher environmental temperatures.

DISCUSSION

Our findings suggest that MG onset may be more common in summer and at higher environmental temperatures. Identifying the determinants of this association may improve our understanding of disease pathophysiology.

Relating Photoperiod and Outdoor Temperature With Sleep Architecture in Patients With Neuropsychiatric Sleep Disorders

While artificial light in urban environments was previously thought to override seasonality in humans, recent studies have challenged this assumption. We aimed to explore the relationship between seasonally varying environmental factors and changes in sleep architecture in patients with neuropsychiatric sleep disorders by comparing two consecutive years. In 770 patients, three-night polysomnography was performed at the Clinic for Sleep & Chronomedicine (St. Hedwig Hospital, Berlin, Germany) in 2018/2019. Sleep times were adjusted to patients' preferred schedules, patients slept in, and were unaware of day-night indicators. Digital devices and clocks were not allowed. Days were spent outside the lab with work or naps not allowed. After exclusions (mostly due to psychotropic medication), analysis was conducted on the second PSG-night in 377 patients (49.1 ± 16.8 year; 54% female). Sleep parameters were plotted as 90-day moving-averages (MvA) across date-of-record. Periodicity and seasonal windows in the MvA were identified by utilizing autocorrelations. Linear mixed-effect models were applied to seasonal windows. Sleep parameters were correlated with same-day photoperiod, temperature, and sunshine duration. The MvA of total sleep time (TST) and REM sleep began a 5-month-long decline shortly after the last occurrence of freezing 24-h mean temperatures (correlation of TST between 2018 and 2019 at 2-month lag: rs361 = 0.87, p < 0.001; maximum peak-to-nadir amplitude: ΔTST ~ 62 min, ΔREM ~ 24 min). The MvA nadirs of slow wave sleep (SWS) occurred approximately at the autumnal equinox (correlation between 2018 and 2019: rs361 = 0.83, p < 0.001). Post hoc testing following significant linear mixed-effect model indicate that TST and REM sleep were longer around November till February than May till August (ΔTST = 36 min; ΔREM = 14 min), while SWS was 23 min longer around February till May than August till November. Proportional seasonal variation of SWS and of REM sleep as percentages of TST differed profoundly (SWS = 31.6%; REM = 8.4%). In patients with neuropsychiatric sleep disorders living in an urban environment, data collected in 2018 show similar patterns and magnitudes in seasonal variation of sleep architecture as the 2019 data. Interestingly, whereas SWS patterns were consistent between years with possible links to photoperiod, annual variations of TST and REM sleep seem to be related to times of outside freezing temperature. For generalization, the data need to be confirmed in a healthy population. No clinical trial was registered.

NORSE seasonality may vary geographically in adults

The mechanisms causing new onset refractory status epilepticus (NORSE) are often unknown. Recently, a seasonal variation with NORSE peaking during the summer was described in a mixed cohort of adults and children why we here studied the seasonal variation in a Danish status epilepticus (SE) cohort. This retrospective cohort study comprised SE patients aged ≥18 diagnosed and treated 2008-2017 at the Odense University Hospital. Clinical characteristics and seasonality of patients fulfilling the diagnostic criteria for NORSE were compared with patients with refractory SE (RSE) due to other reasons and with the seasonal variation of autoantibodies associated with autoimmune encephalitis in the Danish autoimmune encephalitis register. In this cohort, 26 patients met NORSE criteria. As compared to RSE patients not fulfilling NORSE criteria (n = 152), NORSE patients were more likely to have symptoms of systemic inflammation (C-reactive protein concentrations ≥10 mg/L or fever ≥38°C) at admission; nine fulfilled the criteria for febrile infection related epilepsy syndrome (FIRES). In contrast to the even seasonal distribution of patients with RSE not fulfilling the NORSE criteria, admissions due to NORSE peaked during the winter (46.1%, p = 0.04 as compared to non-NORSE RSE); six out of nine FIRES episodes occurred in the winter season. The seasonal variation was not explained by a seasonal variation of the detection rates of autoantibodies associated with autoimmune encephalitis (incl. NMDAR, LGI1, CASPR2, GABAR, GFAP) in a Danish nationwide register (n = 259). In conclusion, we confirm the seasonality of NORSE in a Danish cohort, however, with a peak during winter suggesting a geographical variation not solely explained by autoimmune encephalitis associated with known autoantibodies. PLAIN LANGUAGE SUMMARY: The study investigated the seasonal patterns of new-onset refractory status epilepticus (NORSE), i.e. severe seizures that occur without an obvious cause and require very intensive treatment. In contrast to the previously observed peak frequency in summer, this Danish study found that NORSE cases peak in winter. Furthermore, the seasonal variation in NORSE cases was not found to be associated with autoimmune encephalitis caused by known autoantibodies. Together with the high rate of patients showing symptoms of systemic inflammation compared to other status epilepticus patients, the data suggest a link between misdirected immune system responses and NORSE. The study can therefore help in the further search for the currently unknown causes of NORSE.

Assessment of potential adverse events following the 2022-2023 seasonal influenza vaccines among U.S. adults aged 65 years and older

BACKGROUND

While safety of influenza vaccines is well-established, some studies have suggested potential associations between influenza vaccines and certain adverse events (AEs). This study examined the safety of the 2022-2023 influenza vaccines among U.S. adults ≥ 65 years.

METHODS

A self-controlled case series compared incidence rates of anaphylaxis, encephalitis/encephalomyelitis, Guillain-Barré Syndrome (GBS), and transverse myelitis following 2022-2023 seasonal influenza vaccinations (i.e., any, high-dose or adjuvanted) in risk and control intervals among Medicare beneficiaries ≥ 65 years. We used conditional Poisson regression to estimate incidence rate ratios (IRRs) and 95 % confidence intervals (CIs) adjusted for event-dependent observation time and seasonality. Analyses also accounted for uncertainty from outcome misclassification where feasible. For AEs with any statistically significant associations, we stratified results by concomitant vaccination status.

RESULTS

Among 12.7 million vaccine recipients, we observed 76 anaphylaxis, 276 encephalitis/encephalomyelitis, 134 GBS and 75 transverse myelitis cases. Only rates of anaphylaxis were elevated in risk compared to control intervals. With all adjustments, an elevated, but non-statistically significant, anaphylaxis rate was observed following any (IRR: 2.40, 95% CI: 0.96-6.03), high-dose (IRR: 2.31, 95% CI: 0.67-7.91), and adjuvanted (IRR: 3.28, 95% CI: 0.71-15.08) influenza vaccination; anaphylaxis IRRs were 2.54 (95% CI: 0.49-13.05) and 1.64 (95% CI: 0.38-7.05) for persons with and without concomitant vaccination, respectively.

CONCLUSIONS

Rates of encephalitis/encephalomyelitis, GBS, or transverse myelitis were not elevated following 2022-2023 seasonal influenza vaccinations among U.S. adults ≥ 65 years. There was an increased rate of anaphylaxis following influenza vaccination that may have been influenced by concomitant vaccination.

Occurrence and severity of myasthenic crisis in an unselected Turkish cohort of patients with myasthenia gravis

Myasthenia gravis (MG) is a disorder of the neuromuscular junction that can deteriorate into myasthenic crisis, involving weakness of bulbar and respiratory muscles. In this study, we describe the clinical manifestations of myasthenic crisis, identify risk factors, and examine treatments and outcomes. All 95 patients with generalized MG treated at our center during the last 10 years were included in this retrospective study. We collected data from the patients' records, including clinical follow-ups, muscle antibodies, thymic status, and treatments. The characteristics of patients who did and did not experience myasthenic crisis were compared. Features of all myasthenic crises were also assessed. Twelve patients (13%) developed myasthenic crisis during the observation period. Men were more often affected at older ages. Seven patients experienced multiple myasthenic crises. Thymoma increased the risk of a crisis, whereas thymic hyperplasia decreased the risk. Myasthenic crises were more common in the summer months. No patients died during a myasthenic crisis. Risk factors for myasthenic crisis were thymoma, older age, MuSK antibodies, and previous crises. Individualized and active immunosuppressive treatment and optimal intensive care during crises provide a good outcome for patients with generalized MG.