José F. Téllez-Zenteno

Psychiatric Comorbidity in Epilepsy: A Population-Based Analysis

Purpose: The estimated prevalence of mental health disorders in those with epilepsy in the general population varies owing to differences in study methods and heterogeneity of epilepsy syndromes. We assessed the population‐based prevalence of various psychiatric conditions associated with epilepsy using a large Canadian national population health survey.

Surgical outcomes in lesional and non-lesional epilepsy: A systematic review and meta-analysis

PURPOSES To provide evidence-based quantitative summary estimates of seizure outcomes in patients with non-lesional and lesional epilepsy treated with surgery, and to assess the consistency of results among published studies. METHODS An exhaustive literature search identified articles published since 1995, describing outcomes according to lesional status in patients of any age who underwent resective epilepsy surgery. Two reviewers independently assessed study eligibility and extracted the data. Disagreements were resolved through discussion. Random effects meta-analyses were used after assessing the dataset for heterogeneity. RESULTS Forty articles fulfilled eligibility criteria and described outcomes in 697 patients with non-lesional epilepsy and 2860 patients with lesional epilepsy. Overall, the odds of being seizure-free after surgery were 2.5 times higher in patients with lesions on MRI or histopathology (OR 2.5, 95%CI 2.1, 3.0, p<0.001). In patients with temporal lobe epilepsy surgery the odds were 2.7 times higher in those with lesions (OR 2.7, 95%CI 2.1, 3.5, p<0.001). In patients with extratemporal epilepsy surgery the odds were 2.9 higher in those with lesions (OR 2.9, 95%CI 1.6, 5.1, p<0.001). Outcomes were similar in children, adults, and studies that used MRI or histopathology to identify lesions. DISCUSSION Overall, the odds of seizure freedom after surgery are two to three times higher in the presence of a lesion on histopathology or MRI. The results are clinically and statistically significant, consistent across various subgroups, and quite homogeneous across studies.

Hippocampal electrical stimulation in mesial temporal lobe epilepsy

Background: Adjustable, reversible therapies are needed for patients with pharmacoresistant epilepsy. Electrical stimulation of the hippocampus has been proposed as a possible treatment for mesial temporal lobe epilepsy (MTLE). Methods: Four patients with refractory MTLE whose risk to memory contraindicated temporal lobe resection underwent implantation of a chronic stimulating depth electrode along the axis of the left hippocampus. The authors used continuous, subthreshold electrical stimulation (90 μsec, 190 Hz) and a double blind, multiple cross-over, randomized controlled design, consisting of three treatment pairs, each containing two 1-month treatment periods. During each treatment pair the stimulator was randomly turned ON 1 month and OFF 1 month. Outcomes were assessed at monthly intervals in a double blind manner, using standardized instruments and accounting for a washout period. The authors compared outcomes between ON, OFF, and baseline periods. Results: Hippocampal stimulation produced a median reduction in seizures of 15%. All but one patient’s seizures improved; however, the results did not reach significance. Effects seemed to carry over into the OFF period, and an implantation effect cannot be ruled out. The authors found no significant differences in other outcomes. There were no adverse effects. One patient has been treated for 4 years and continues to experience substantial long-term seizure improvement. Conclusion: The authors demonstrate important beneficial trends, some long-term benefits, and absence of adverse effects of hippocampal electrical stimulation in mesial temporal lobe epilepsy. However, the effect sizes observed were smaller than those reported in non-randomized, unblinded studies.

Neuropsychological outcomes after epilepsy surgery: systematic review and pooled estimates

Purpose:  Epilepsy surgery is a safe surgical procedure, but it may be associated with cognitive changes. Estimates of the risk of decline in specific neuropsychological domains after epilepsy surgery would assist surgical decision making in clinical practice. The goal of this study was to conduct a systematic review to derive pooled estimates of the rate of losses and gains in neuropsychological functions after epilepsy surgery, using empirically based methods for quantifying cognitive change.

Somatic Comorbidity of Epilepsy in the General Population in Canada

Summary:  Purpose: There is a notion that people with epilepsy have substantial and often unrecognized comorbidity of chronic conditions. However, most studies focus on selected patient groups; population‐based studies are scarce. We compared the prevalence of chronic somatic conditions in people with epilepsy with that in the general population using Canadian, nationwide, population‐based health data.

Sudden unexpected death in epilepsy: Evidence-based analysis of incidence and risk factors

PURPOSE To provide an evidence-based analysis of the risk factors and incidence of SUDEP, and to assess methodological aspects and sources of variation in studies dealing with SUDEP. METHODS An expert in library resources and electronic databases comprehensively searched Medline, Index Medicus, and the Cochrane library. We included case-control or cohort studies focusing on SUDEP in children or adults, published in the English language. Two reviewers independently applied study eligibility criteria and extracted data, resolving disagreements through discussion. RESULTS Of 404 citations identified, 83 potentially eligible articles were reviewed in full text and 36 studies fulfilled eligibility criteria (29 cohort and 8 case-control studies). In studies using non-SUDEP deaths as controls the most consistent risk factors were a seizure preceding death, and subtherapeutic antiepileptic drug levels. In studies that used persons living with epilepsy as controls the main risk factors for SUDEP were youth, high seizure frequency, high number of antiepileptic drugs and long duration of epilepsy. The annual incidence of SUDEP ranged from 0 to 10:1000. It was highest in studies of candidates for epilepsy surgery and epilepsy referral centers (2.2:1000-10:1000), intermediate in studies including patients with mental retardation (3.4:1000-3.6:1000), and lowest in children (0-0.2:1000). The incidence was similar in autopsy series (0.35:1000-2.5:1000) and in studies of epilepsy patients in the general population (0-1.35:1000). The median proportion of SUDEP in relation to overall mortality in epilepsy was 40 and 4% in high- and low-risk groups, respectively. CONCLUSIONS Although studies on SUDEP are heterogeneous in methodology, consistent patterns in incidence and risk factors emerge. Low- and high-risk patient groups are identified, which determine the relative contribution of SUDEP to overall mortality in epilepsy. In addition to patient population, risk factors for SUDEP depend on the type of controls used for comparison (dead versus live patients with epilepsy). Risk factors found in different studies are not necessarily contradictory, but are often complementary.

Understanding the burden of epilepsy in Latin America: A systematic review of its prevalence and incidence

RATIONALE Epilepsy is the most common serious neurological condition in the world, and an important cause of mortality and disability in developing countries. Because epidemiological and clinical characteristics of epilepsy vary by region, it is important to know the peculiarities of epilepsy in this area of the American continent. METHODS We searched MEDLINE, IMBIOMED, and LILACS (The Latin-American and Caribbean biomedical database) to identify community-based studies reporting on the prevalence and incidence of epilepsy in Latin America. Studies were included if a definition of epilepsy was given, if data were obtained through standardized questionnaires and if raw population numbers were available for data confirmation. RESULTS Thirty-three studies fulfilled eligibility criteria, 32 reported on prevalence and three on incidence of epilepsy. The median lifetime prevalence in all countries was 17.8 (range 6-43.2) per 1000 people, and the range for incidence was 77.7-190 per 100,000 people per year. There were no differences between rural and urban areas, by gender, age-group (children, adult, all ages), ascertainment method, or year of study. CONCLUSIONS Measuring the global burden of disease in Latin America requires adequate epidemiological information. This systematic review of epidemiological studies identifies higher prevalence and incidence rates of epilepsy in the general population of Latin America than in northern hemisphere countries. The remarkable heterogeneity found between and even within countries, could be explained by several factors, importantly, socioeconomic and methodological aspects.

A Review of the Epidemiology of Temporal Lobe Epilepsy

Partial-onset epilepsies account for about 60% of all adult epilepsy cases, and temporal lobe epilepsy (TLE) is the most common type of partial epilepsy referred for epilepsy surgery and often refractory to antiepileptic drugs (AEDs). Little is known about the epidemiology of TLE, because it requires advanced neuroimaging, positive EEG, and appropriate clinical semiology to confirm the diagnosis. Moreover, recently recognized incidentally detected mesial temporal sclerosis in otherwise healthy individuals and benign temporal epilepsy indicate that the true epidemiology of TLE is underestimated. Our current knowledge on the epidemiology of TLE derives from data published from tertiary referral centers and/or inferred from population-based studies dealing with epilepsy. This article reviews the following aspects of the epidemiology of TLE: definitions, studies describing epidemiological rates, methodological observations, the interpretation of available studies, and recommendations for future studies.

National and Regional Prevalence of Self-reported Epilepsy in Canada

Summary:  Purpose: To assess the point prevalence of self‐described epilepsy in the general population nationally, provincially, and in different groups of interest.

Risk Factors Associated with Depression in Patients with Type 2 Diabetes Mellitus

BACKGROUND This study was undertaken in order to identify the prevalence and factors associated with depression in a group of patients with type 2 diabetes mellitus. METHODS Our design consisted of a cross-sectional study at the Department of Neurology and Psychiatry of the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán in Mexico City. Study units included 189 patients with type 2 diabetes mellitus (DM). Beck Depression Inventory scale was used to measure the presence of depression, while the independent variables evaluated to explain depression were sociodemographic (gender, marital status, religion, education, occupation, socioeconomic status) and characteristics of the disease were disease duration, comorbidity, compliance, and glycemic control. RESULTS Prevalence of depression was 39% (74 patients). The following risk factors were identified by univariate analysis: being widowed (OR 3.54, confidence interval [CI] 1.56-8.11, p = 0.0007); female (OR 2.95, CI 1.50-5.82, p = 0.006); housewife (OR 2.08, CI 1.10-3.94, p = 0.01); poor compliance (OR 2.14, CI 1.12-4.10, p = 0.01), and presence of comorbidity (OR 5.60, CI 1.51-24.5, p = 0.002). On the other hand, the most constant associations were presence of blood glucose at the last appointment >or=200 (OR 3.23, CI 1.59-6.60, p = 0.0003) and >or=250 (OR 2.15, CI 0.93-5.03, p = 0.05), as the average of the last five blood glucoses >or=200 (OR 3.67, CI 1.76-7.73, p = 0.0001), >or=250 (OR 4.07, CI 1.61-10.49, p = 0.0007) and >or=300 (OR 2.12, CI 1.48-3.02, p = 0.003). Discriminant function analysis of the variables, previously studied in univariate analysis, was carried out for the presence of depression. A stepwise model included the following variables: average of the last five blood glucoses; 2) widowed or divorced, and 3) female. CONCLUSIONS Frequency of depression in patients with type 2 DM was high (39%). High level of blood glucose stands out as a variable associated with presence of depression. Other associations were presence of comorbidity, being a female, and being widowed or divorced.