METHODS: A literature review was conducted for systematic reviews, meta-analyses, and scoping reviews published between January 1, 2020 and January 1, 2023. Literature assessing individuals with pre-existing neurological diseases and COVID-19 infection was included. Information regarding infection severity was extracted, and potential limitations were identified.

RESULTS: Thirty-nine articles met inclusion criteria, with data assessing >3 million patients from 51 countries. 26/51 (50.9%) of countries analyzed were classified as high income, while the remaining represented middle-low income countries (25/51; 49.0%). A majority of evidence focused on the impact of cerebrovascular disease (17/39; 43.5%) and dementia (5/39; 12.8%) on COVID-19 severity and mortality. 92.3% of the articles (36/39) suggested a significant association between neurological conditions and increased risk of severe COVID-19 and mortality. Cerebrovascular disease, dementia, Parkinson's disease, and epilepsy were associated with increased COVID severity and mortality.

METHODS: We used publicly available data from the U.S. Vaccine Adverse Event Reporting System (VAERS) collected between January 1, 2021 and June 14, 2021. All free text symptoms that were reported within 42 days of vaccine administration were manually reviewed and grouped into 36 individual neurological diagnostic categories. Post-vaccination neurological event rates were compared between vaccine types and to age-matched baseline incidence rates in the U.S. and rates of neurological events following COVID.

METHODS: We searched PubMed, Medline, Cochrane library, ClinicalTrials.gov, and EMBASE for studies from December 31, 2019, to December 15, 2020, enrolling consecutive patients with COVID-19 presenting with neurologic manifestations. Risk of bias was examined with the Joanna Briggs Institute scale. A random-effects meta-analysis was performed, and pooled prevalence and 95% confidence intervals (CIs) were calculated for neurologic manifestations. Odds ratio (ORs) and 95% CIs were calculated to determine the association of neurologic manifestations with disease severity and mortality. Presence of heterogeneity was assessed with I 2, meta-regression, and subgroup analyses. Statistical analyses were conducted in R version 3.6.2.

RESULTS: Of 2,455 citations, 350 studies were included in this review, providing data on 145,721 patients with COVID-19, 89% of whom were hospitalized. Forty-one neurologic manifestations (24 symptoms and 17 diagnoses) were identified. Pooled prevalence of the most common neurologic symptoms included fatigue (32%), myalgia (20%), taste impairment (21%), smell impairment (19%), and headache (13%). A low risk of bias was observed in 85% of studies; studies with higher risk of bias yielded higher prevalence estimates. Stroke was the most common neurologic diagnosis (pooled prevalence 2%). In patients with COVID-19 ≥60 years of age, the pooled prevalence of acute confusion/delirium was 34%, and the presence of any neurologic manifestations in this age group was associated with mortality (OR 1.80, 95% CI 1.11-2.91).

DISCUSSION: Up to one-third of patients with COVID-19 analyzed in this review experienced at least 1 neurologic manifestation. One in 50 patients experienced stroke. In those >60 years of age, more than one-third had acute confusion/delirium; the presence of neurologic manifestations in this group was associated with nearly a doubling of mortality. Results must be interpreted with the limitations of observational studies and associated bias in mind.

METHODS: The study protocol was registered with PROSPERO (CRD42022325505). MEDLINE (PubMed), Embase, and the Cochrane Library were used as information sources. Eligible studies included original articles of cohort studies, case-control studies, cross-sectional studies, and case series with ≥5 subjects that reported the prevalence and type of neurological manifestations, with a minimum follow-up of 3 months after the acute phase of COVID-19 disease. Two independent reviewers screened studies from January 1, 2020, to June 16, 2022. The following manifestations were assessed: neuromuscular disorders, encephalopathy/altered mental status/delirium, movement disorders, dysautonomia, cerebrovascular disorders, cognitive impairment/dementia, sleep disorders, seizures, syncope/transient loss of consciousness, fatigue, gait disturbances, anosmia/hyposmia, and headache. The pooled prevalence and their 95% confidence intervals were calculated at the six pre-specified times.

RESULTS: 126 of 6,565 screened studies fulfilled the eligibility criteria, accounting for 1,542,300 subjects with COVID-19 disease. Of these, four studies only reported data on neurological conditions other than the 13 selected. The neurological disorders with the highest pooled prevalence estimates (per 100 subjects) during the acute phase of COVID-19 were anosmia/hyposmia, fatigue, headache, encephalopathy, cognitive impairment, and cerebrovascular disease. At 3-month follow-up, the pooled prevalence of fatigue, cognitive impairment, and sleep disorders was still 20% and higher. At six- and 9-month follow-up, there was a tendency for fatigue, cognitive impairment, sleep disorders, anosmia/hyposmia, and headache to further increase in prevalence. At 12-month follow-up, prevalence estimates decreased but remained high for some disorders, such as fatigue and anosmia/hyposmia. Other neurological disorders had a more fluctuating occurrence.

OBJECTIVES: To estimate the global incidence and prevalence of neonatal and infantile-onset epilepsies and epilepsy syndromes and to characterize their associated etiological profiles.

DATA SOURCES: PubMed, Embase, Web of Science, and Scopus were searched from inception through December 18, 2025.

STUDY SELECTION: Population-based observational studies reporting the incidence or prevalence of neonatal and infantile-onset epilepsies or epilepsy syndromes were eligible for inclusion.

DATA EXTRACTION AND SYNTHESIS: Two authors independently and in duplicate performed study selection, data extraction, and quality assessment of included studies using the Joanna Briggs Institute Critical Appraisal checklist for prevalence studies. Generalized linear mixed-model random-effects meta-analysis was used to pool the estimates of incidence, prevalence, and etiology. Subgroup meta-analyses were conducted by country, World Health Organization (WHO) region, World Bank income, and diagnostic criteria. Metaregression was used to investigate the association between study-level covariates and pooled incidence estimates of infantile-onset epilepsy syndromes.

MAIN OUTCOMES AND MEASURES: Cumulative incidence and prevalence of neonatal and infantile-onset epilepsies and epilepsy syndromes.

RESULTS: A total of 86 population-based studies from 30 countries across 4 WHO regions were included. The pooled cumulative incidence of infantile-onset epilepsies within the first 2 years of life was 236.0 cases (95% CI, 164.7-338.2; 95% prediction interval [PI], 53.0-1044.3) per 100 000 live births. Among epilepsy syndrome subgroups, developmental and epileptic encephalopathies (DEEs) had the highest incidence at 67.7 cases (95% CI, 42.1-108.9; 95% PI, 7.1-636.1) per 100 000 live births. Infantile epileptic spasms syndrome (IESS) was the most incident DEE, with 31.6 cases (95% CI, 27.5-36.2; 95% PI, 13.7-72.6) per 100 000 live births. Among self-limited epilepsies, self-limited infantile epilepsy had the highest incidence at 13.0 cases (95% CI, 9.2-18.2; 95% PI, 6.4-26.4) per 100 000 live births. Subgroup analyses revealed limited geographical representativeness, with the majority of studies from high-income countries in the European Region.