Personalised music as a treatment for epilepsy.

In this paper we look at non-pharmaceutical treatments for intractable epilepsy based on neurophysiological methods especially with EEG analysis. In summary, there are a number of limbic and thalamo-cortical related structures involved in the processing of musical emotion (exposure), including the amygdala (arousal, expression of mood, fear), hippocampus (memory, regulation of HPA axis, stress), parahippocampal gyrus (recognition, memory retrieval), insula (valence), temporal poles (connectivity), ventral striatum (expectation and experience of reward), orbitofrontal cortex (valence) and cingulate cortex (autonomic regulation). One method is to audify (a form of sonification) EEG activity to find music by feedback to entrain abnormal EEG activity. We discuss various methods and our use of X-System (https://www.x-system.co.uk/) which is a computational model of the musical brain capable of predicting the neurophysiological effects of music. It models structures and pathways related to responses to music, including the cochlea, brain stem, auditory and motor cortex, as well as basal ganglia, cerebellum and limbic structures. It can predict autonomic and endocrine activity as well as the substrates of electrical activity to select music which can regularise EEG abnormalities to decrease epileptic activity and seizures, especially in those unresponsive to antiepileptic medication or invasive treatments.

A spatial and temporal analysis of paediatric central nervous system infections from 2005 to 2015 in Ho Chi Minh City, Vietnam.

Central nervous system infections (CNSI) are a leading cause of death and long-term disability in children. Using ICD-10 data from 2005 to 2015 from three central hospitals in Ho Chi Minh City (HCMC), Vietnam, we exploited generalized additive mixed models (GAMM) to examine the spatial-temporal distribution and spatial and climatic risk factors of paediatric CNSI, excluding tuberculous meningitis, in this setting. From 2005 to 2015, there were 9469 cases of paediatric CNSI; 33% were ⩽1 year old at admission and were mainly diagnosed with presumed bacterial CNSI (BI) (79%), the remainder were >1 year old and mainly diagnosed with presumed non-bacterial CNSI (non-BI) (59%). The urban districts of HCMC in proximity to the hospitals as well as some outer districts had the highest incidences of BI and non-BI; BI incidence was higher in the dry season. Monthly BI incidence exhibited a significant decreasing trend over the study. Both BI and non-BI were significantly associated with lags in monthly average temperature, rainfall, and river water level. Our findings add new insights into this important group of infections in Vietnam, and highlight where resources for the prevention and control of paediatric CNSI should be allocated.

Quantitative Evaluation of Medial Temporal Lobe Morphology in Children with Febrile Status Epilepticus: Results of the FEBSTAT Study.

BACKGROUND AND PURPOSE: The pathogenesis of febrile status epilepticus is poorly understood, but prior studies have suggested an association with temporal lobe abnormalities, including hippocampal malrotation. We used a quantitative morphometric method to assess the association between temporal lobe morphology and febrile status epilepticus. MATERIALS AND METHODS: Brain MR imaging was performed in children presenting with febrile status epilepticus and control subjects as part of the Consequences of Prolonged Febrile Seizures in Childhood study. Medial temporal lobe morphologic parameters were measured manually, including the distance of the hippocampus from the midline, hippocampal height:width ratio, hippocampal angle, collateral sulcus angle, and width of the temporal horn. RESULTS: Temporal lobe morphologic parameters were correlated with the presence of visual hippocampal malrotation; the strongest association was with left temporal horn width (P < .001; adjusted OR, 10.59). Multiple morphologic parameters correlated with febrile status epilepticus, encompassing both the right and left sides. This association was statistically strongest in the right temporal lobe, whereas hippocampal malrotation was almost exclusively left-sided in this cohort. The association between temporal lobe measurements and febrile status epilepticus persisted when the analysis was restricted to cases with visually normal imaging findings without hippocampal malrotation or other visually apparent abnormalities. CONCLUSIONS: Several component morphologic features of hippocampal malrotation are independently associated with febrile status epilepticus, even when complete hippocampal malrotation is absent. Unexpectedly, this association predominantly involves the right temporal lobe. These findings suggest that a spectrum of bilateral temporal lobe anomalies are associated with febrile status epilepticus in children. Hippocampal malrotation may represent a visually apparent subset of this spectrum.

Estimating risk for developing epilepsy: a population-based study in Rochester, Minnesota.

OBJECTIVES: Previous studies that have assessed the risk of developing epilepsy have failed to account for the competing risk of death, significant in the elderly where epilepsy incidence is highest. We report the lifetime risk for epilepsy, accounting for the competing risk of mortality. METHODS: Lifetime risk and cumulative incidence of epilepsy were examined among Rochester, MN, residents between 1960 and 1979. Age-, gender-, and calendar year-specific deaths were obtained for Rochester, MN. Lifetime risk was calculated as the conditional probability of developing epilepsy by a specific age for a person reaching that age who had not yet developed epilepsy. Lifetime risk and cumulative incidence were compared for age and time period. RESULTS: We identified 412 individuals with incident epilepsy diagnosed between January 1, 1960, and December 31, 1979. Lifetime risk was 1.6% to age 50 and 3.0% to age 80; cumulative incidence was 1.7% to age 50 and 3.4% to age 80. Similar differences were seen across epilepsy etiologies. Lifetime risk through 87 years of age increased over time from 3.5% in 1960-1969 to 4.2% in 1970-1979. CONCLUSIONS: One in 26 people will develop epilepsy during their lifetime. Lifetime risk provides an estimate of an individual's risk for epilepsy over his or her remaining lifetime, translates into the number of people who are expected to develop epilepsy, and assists health care planners as they estimate service needs for epilepsy.

Adverse antiepileptic drug effects in new-onset seizures: a case-control study.

OBJECTIVE: Adverse effects (AEs) are a major concern when starting antiepileptic drug (AED) treatment. This study quantified the extent to which AE reporting in people with new-onset seizures started on AEDs is attributable to the medication per se, and investigated variables contributing to AE reporting. METHODS: We pooled data from 2 large prospective studies, the Multicenter Study of Early Epilepsy and Single Seizures and the Northern Manhattan Study of incident unprovoked seizures, and compared adverse event profile (AEP) total and factor scores between adult cases prescribed AEDs for new-onset seizures and untreated controls, adjusting for several demographic and clinical variables. Differences in AEP scores were also tested across different AED monotherapies and controls, and between cases and controls grouped by number of seizures. RESULTS: A total of 212 cases and 206 controls were identified. Most cases (94.2%) were taking low AED doses. AEP scores did not differ significantly between the 2 groups. Depression, female gender, symptomatic etiology, younger seizure onset age, ≥2 seizures, and history of febrile seizures were associated with higher AEP scores. There were no significant differences in AEP scores across different monotherapies and controls. AEP scores increased in both cases and controls with increasing number of seizures, the increment being more pronounced in cases. CONCLUSIONS: When AED treatment is started at low doses following new-onset seizures, AE reporting does not differ from untreated individuals. Targeting specific factors affecting AE reporting could lead to improved tolerability of epilepsy treatment.

Phenomenology of prolonged febrile seizures: results of the FEBSTAT study.

BACKGROUND: Febrile status epilepticus (FSE) has been associated with hippocampal injury and subsequent mesial temporal sclerosis and temporal lobe epilepsy. However, little is known about the semiology of FSE. METHODS: A prospective, multicenter study of the consequences of FSE included children, aged 1 month through 5 years, presenting with a febrile seizure lasting 30 minutes or more. Procedures included neurologic history and examination and an MRI and EEG within 72 hours. All information related to seizure semiology was reviewed by three epileptologists blinded to MRI and EEG results and to subsequent outcome. Inter-rater reliability was assessed by the kappa statistic. RESULTS: Among 119 children, the median age was 1.3 years, the mean peak temperature was 103.2 degrees F, and seizures lasted a median of 68.0 minutes. Seizure duration followed a Weibull distribution with a shape parameter of 1.68. Seizures were continuous in 52% and behaviorally intermittent (without recovery in between) in 48%; most were partial (67%) and almost all (99%) were convulsive. In one third of cases, FSE was unrecognized in the emergency department. Of the 119 children, 86% had normal development, 24% had prior febrile seizures, and family history of febrile seizures in a first-degree relative was present in 25%. CONCLUSIONS: Febrile status epilepticus is usually focal and often not well recognized. It occurs in very young children and is usually the first febrile seizure. Seizures are typically very prolonged and the distribution of seizure durations suggests that the longer a seizure continues, the less likely it is to spontaneously stop.

Recurrence of afebrile status epilepticus in a population-based study in Rochester, Minnesota.

OBJECTIVE: To determine the risk of recurrence of status epilepticus (SE) in a population-based sample and to identify risk factors for recurrence. METHODS: We ascertained all first episodes of afebrile SE in residents of Rochester, MN, through the Rochester Epidemiology Project's records-linkage system between January 1, 1965, and December 31, 1984. Information was collected on age, gender, duration, seizure type, etiology, therapeutic response to initial antiepileptic drug medication, and subsequent episodes of SE. RESULTS: Among the 183 episodes of first afebrile SE, the risk of recurrent SE was 31.7% over a 10-year follow-up period. The risk of recurrence was about 25% for those with acute symptomatic SE, remote symptomatic SE, and idiopathic cryptogenic SE. Recurrence was 100% for those with progressive symptomatic SE. Female gender (rate ratio [RR] = 2.3, 95% CI = 1.1 to 5.0) and progressive symptomatic etiology (RR = 2.4, 95% CI = 0.6 to 8.9) increased the risk for recurrent SE. Both partial SE (RR = 0.5, 95% CI = 0.2 to 1.1) and good therapeutic response to the initial antiepileptic drug therapy (RR = 0.3, 95% CI = 0.1 to 0.7) were associated with a decreased risk of recurrent SE. CONCLUSIONS: Status epilepticus (SE) recurs in about one-third of individuals with a first episode of SE. Except for SE occurring in the setting a progressive brain disorder, the risk of recurrence is about 25%, regardless of the underlying etiology. Female gender and lack of response to the first antiepileptic drug medication after the initial episode of SE identify those individuals at greatest risk for recurrence.

Epilepsy and mortality in Africa: a review of the literature.

PROBLEM: The prevalence of epilepsy is high in many areas of Africa. This condition is stigmatized, and there are limited health personnel and facilities for diagnosis and treatment. A huge treatment gap is suspected for epilepsy, and data suggest that nearly 80-85% of people with epilepsy have never been diagnosed or treated. It is reported worldwide that the mortality among people with epilepsy is two- to threefold higher than in general population. An increase of at least this magnitude is suspected in Africa, but there are very few data. Verbal autopsy studies may be one way of carrying out studies of mortality for epilepsy in Africa because these methods do not rely on autopsies, which are rare, or upon death certificates, which are a poor source of information on death in Africa. METHODS: This paper presents the literature on mortality after seizures in Africa, although there are few studies of mortality among people with epilepsy in Africa. RESULTS: The existing studies suggest an increased risk of dying and a greater proportion of deaths that are epilepsy-related. One study reports a sixfold increase in mortality in people with epilepsy. This is higher than the two- to threefold increase reported in developed countries. CONCLUSIONS: Considering the high prevalence of this condition, the public health impact of epilepsy mortality is likely to be enormous.

Long-term mortality after a first episode of status epilepticus.

OBJECTIVE: To evaluate long-term mortality among people with status epilepticus (SE). METHODS: The authors performed a population-based retrospective cohort study to determine long-term mortality after SE. Between January 1, 1965, and December 31, 1984, all first episodes of SE receiving medical attention were ascertained through the Rochester Epidemiology Project Records-Linkage System. Cases surviving the first 30 days (n = 145) were followed until death or study termination (February 1996). RESULTS: At 10 years, cumulative mortality among 30-day survivors was 43%. The standardized mortality ratio (SMR) at 10 years was 2.8 (95% CI, 2.1-3.5). The mortality rate of those with idiopathic/cryptogenic SE was not increased (SMR = 1.1; 95% CI, 0.5-2.3). The following characteristics of SE increased long-term risk for mortality: SE > or = 24 hours in duration vs. SE < 2 hours (relative risk [RR] = 2.3; 95% CI, 1.1-5.1); acute symptomatic etiology vs idiopathic/cryptogenic etiology (RR = 2.2; 95% CI, 1.0-5.1) SE; myoclonic SE vs generalized convulsive SE (RR = 4.0; 95% CI, 1.3-13). CONCLUSION: Forty percent of subjects who survived the first 30 days after an incident episode of SE die within the next 10 years. The long-term mortality rate was threefold that of the general population over the same time period. The long-term mortality rate at 10 years was worse for those with myoclonic SE, for those who presented with SE lasting more than 24 hours, and for those with acute symptomatic SE. The long-term mortality rate was not altered in those with idiopathic/cryptogenic SE. We conclude that SE alone does not modify long-term mortality.

Are certain diuretics also anticonvulsants?

A history of diuretic use has been shown to be protective for first unprovoked seizure in adult patients. Recent animal studies suggest that certain diuretics have anticonvulsant activity. We evaluated the potential for the anticonvulsant activity of current diuretic use in a population-based, case-control study in older adults. We also tested chlorthiazide and furosemide for seizure protection in animal models of epilepsy. Concurrent medical prescription of any diuretic was protective for the development of epilepsy [odds ratio (OR) = 0.62, 95% confidence interval (CI) = 0.39-0.99]. A protective effect for current thiazide use was observed (OR = 0.53, CI = 0.31-0.90), and a protective effect for furosemide was suggested (OR = 0.44, CI = 0.1-1.9). In mice, both chlorthiazide and furosemide suppressed the occurrence of maximal electroshock-induced seizures in a dose-dependent manner. Chlorthiazide's toxic dose for 50% of animals tested (TD50) could not be achieved even with dosing as high as 1,500 mg/kg for furosemide; TD50 was 549 mg/kg. Results were similar in rats. Furosemide and chlorthiazide are protective for unprovoked seizures in an epidemiological study and in animal models. Given the potential therapeutic value for seizure control, low toxicity, and low cost, therapeutic efficacy should be explored in clinical studies.

Time trends in incidence, mortality, and case-fatality after first episode of status epilepticus.

PURPOSE: Status epilepticus (SE) is a medical emergency associated with a high mortality. Clinical series have suggested that mortality after SE has decreased. No studies have systematically examined trends in incidence, mortality, and case fatality after SE in a well-defined population. METHODS: All first episodes of SE receiving medical attention between January 1, 1935, and December 31, 1984, were ascertained through the Rochester Epidemiology Project Records-Linkage System and followed up until death or study termination (February 1, 1996). We calculated incidence rates in the 50-year period (1935-1984), while we considered mortality and case-fatality in the last 30-year period (1955-1984). RESULTS: Incidence of SE increased over time to 18.1/100,000 (1975 through 1984). The increase was related to an increased incidence in the elderly and to the advent of myoclonic SE after cardiac arrest, a condition not seen in the early decades. In the last decade, approximately 16% of the incidence was due to myoclonic SE. The mortality rates increased from 3.6 per year in the decade 1955-1965 to 4.0/100,000 per year between 1975 and 1984. The 30-day case-fatality (CF) was unchanged, although a trend toward improvement was shown after excluding myoclonic SE. CONCLUSIONS: Incidence and mortality rates of SE have increased in the last 30 years. Case fatality remained the same. The increased incidence and mortality are due to the occurrence in the last decade of myoclonic SE after cardiac arrest. The mortality in the elderly was twice that of the youngest age group, across all study periods. Changes in the age and cause distribution of SE over time are responsible for the stable survivorship. There is improvement in survivorship in the last decade when myoclonic SE is excluded.

Status epilepticus and tiagabine therapy: review of safety data and epidemiologic comparisons.

PURPOSE: To determine whether an increased risk of status epilepticus (SE) and complex partial status epilepticus (CPSE) is associated with tiagabine (TGB) therapy. METHODS: Thirteen cases in which an EEG, performed on patients with altered mental status taking TGB, was reported to demonstrate spike-and-wave discharges (SWDs) were reviewed by a panel of experts. In addition, all cases of suspected SE from TGB clinical trials were reviewed. The occurrence of SE in four epidemiologic cohorts from Rochester, Minnesota, Turku, Finland, Bronx, New York, and New Haven, Connecticut was analyzed as an external comparison. RESULTS: Review of the 13 cases with reported SWDs found that the majority had had prior EEGs with similar findings, and only three were thought to have electrographic evidence of SE. There was no difference in the frequency of SE or CPSE in the placebo-controlled clinical trials between the TGB-treated (1.0% SE, 0.8% CPSE) and placebo-treated (1.5% SE, 1.5% CPSE) groups. The 5% frequency of SE and 3% frequency of CPSE in the TGB-treated patients in the long-term safety studies, which included 2,248 patients, were very similar to the rates of occurrence of SE and CPSE in the four external cohorts. The major risk factor for the occurrence of SE and CPSE in all groups was a prior episode of SE (p < 0.0001). CONCLUSIONS: Over a 3-year period, SE will occur in 5-10% of patients with epilepsy not in remission. At highest risk are those who have had a prior episode of SE. Treatment with TGB in recommended doses does not increase the risk of SE in patients with partial seizures.

Long-term fracture risk among infertile women: a population-based cohort study.

Nulliparity has been linked to bone loss and fractures, but the contribution of infertility is unclear. The purpose of this study was to assess the long-term risk of fractures among infertile women. In a population-based retrospective cohort study, all 658 Olmsted County, Minnesota, women with infertility (failure to conceive after 1 year despite intercourse without contraception) first diagnosed at Mayo Clinic in 1935-1964 were followed for fractures. Risk was assessed by comparing new fractures of each type to the number expected from sex-specific and age-specific fracture rates in the general population (standardized incidence ratios [SIR]). During 18,130 person-years of follow-up, 184 women experienced at least one fracture when 291 would have been expected on the basis of fracture incidence rates in the general population (SIR 0.6, 95% CI 0.5-0.7). There was no increase in proximal femur fractures (SIR 1.0, 95% CI 0.6-1.6) and a statistically significant decrease in the risk of distal forearm fractures (SIR 0.7, 95% CI 0.5-0.97), two of the three sites traditionally associated with osteoporosis. By contrast, there was a significant increase in subsequent vertebral fractures (SIR 1.9, 95% CI 1.4-2.4) that was consistent across divergent causes of infertility and reported menstrual patterns. Although an apparent increase in the risk of vertebral fractures requires further investigation, we saw no indication of an increase in limb fractures, suggesting that infertility does not have long-term adverse skeletal effects like those reported for athletes and dieters with irregular menses.

Treatment of nonfebrile status epilepticus in Rochester, Minn, from 1965 through 1984.

OBJECTIVE: To investigate the adequacy and efficacy of antiepileptic drug (AED) treatment of nonfebrile status epilepticus (SE). PATIENTS AND METHODS: We performed a population-based retrospective cohort study to evaluate the medical management of SE. Participants included 184 residents of Rochester, Minn, who experienced a first episode of nonfebrile SE between 1965 and 1984. RESULTS: Of the 184 patients, 133 (72.2%) received appropriate, prompt medical treatment for SE, i.e., intravenous diazepam, phenytoin, or phenobarbital. In 100 patients (75.8%), the dose of the first AED administered was less than that currently recommended. The first treatment was effective in terminating SE in 41 (31.1%) of 132 patients. The adequacy of treatment was highly predictive of drug efficacy (P = .002). The dose of the second AED treatment was inadequate in 52 (80%) of 65 patients treated. CONCLUSION: Based on this retrospective study, the treatment of SE is remarkable for both inadequacy and ineffectiveness. The inappropriate use of therapeutic regimens in the management of SE may be an important cause of ineffective medical treatment.

Major depression is a risk factor for seizures in older adults.

We tested the hypothesis that major depression meeting DSM-III-R criteria or medical therapies for depression increase the risk for unprovoked seizures. Major depression was associated with a sixfold increased risk for unprovoked seizures (95% CI, 1.56-22). The risk remained increased even when controlling for age, sex, length of medical follow-up, and medical therapies for depression. In the absence of known prior neurological insult, major depression is associated with an increased risk for unprovoked seizures.

Hip fractures among infertile women.

A retrospective cohort study was conducted in a population-based inception cohort of 1,157 Olmsted County, Minnesota, women with infertility (failure to conceive after 1 year despite intercourse without contraception) that was first diagnosed at the Mayo Clinic (Rochester, Minnesota) between 1935 and 1964. In this relatively young cohort, 31 hip fractures were observed during 35,849 person-years of follow-up; 36.5 had been expected (standardized incidence ratio = 0.85, 95% confidence interval 0.58-1.20). Standardized incidence ratios did not differ by type or cause of infertility. The data suggested that women with consistently irregular menses may have a greater risk of hip fracture. This finding should be confirmed by additional studies with longer follow-up periods and with assessment of other fracture outcomes.

Risk of unprovoked seizure after acute symptomatic seizure: effect of status epilepticus.

We asked whether acute symptomatic status epilepticus (SE) increases the risk for subsequent unprovoked seizure compared with less prolonged acute symptomatic seizure. We also explored whether the risk of unprovoked seizure differs by cause. We ascertained all first episodes of acute symptomatic seizure among residents of Rochester, Minnesota, through the Rochester Project's records-linkage system. Information was collected on seizure duration, age, sex, cause, and subsequent unprovoked seizure. At 10 years of follow-up, the risk of unprovoked seizure was 41% for those with acute symptomatic seizure with SE and 13% for those without SE. Controlling for age, sex, and cause, SE increased the risk for subsequent unprovoked seizure 3.3-fold (95% confidence interval, 1.8-6.1) compared with brief acute symptomatic seizures. Among patients with SE, the risk of unprovoked seizure was increased 18.8-fold for patients with anoxic encephalopathy, 7.1-fold for patients with a structural cause, 3.6-fold for patients with a metabolic cause. The increased risk for unprovoked seizure after SE compared with shorter seizures may be due to SE being a marker for severity of injury, damage caused by SE, or a biological substrate associated with the tendency to experience SE.

Morbidity of nonfebrile status epilepticus in Rochester, Minnesota, 1965-1984.

PURPOSE: To analyze the nonfatal adverse events (AE) associated with a first episode of status epilepticus (SE). METHODS: We performed a population-based retrospective cohort study to determine the morbidity of SE. Participants included 184 residents of Rochester, Minnesota who experienced nonfebrile SE between 1965 and 1984. RESULTS: The etiology of SE was acute symptomatic in 100 patients and unprovoked in 84 patients. The most common seizure-types were continuous partial (n=56, 30%), generalized convulsive (n=52, 28%), and generalized with focal features (n=32, 17%). Morbidity related to SE was noted in 5 of the 146 patients (3.4%) surviving 30 days. The AE included hemiparesis (n=3), encephalopathy (n=2), mental retardation (n=1), and aphasia (n=1). All patients with morbidity had an acute symptomatic (n=4) or remote symptomatic (n=1) etiology. Thirty-four patients (18.5%) had a second episode of SE. CONCLUSIONS: Based on this retrospective study, significant morbidity related to SE is uncommon and is associated with the underlying etiology.

Incidence of status epilepticus in Rochester, Minnesota, 1965-1984.

We determined the incidence of status epilepticus (SE) by ascertaining all first episodes of SE in Rochester, Minnesota through the Rochester Epidemiology Project's records-linkage system between January 1, 1965 and December 31, 1984. Information was collected on age, gender, duration, seizure type, and etiology. The age-adjusted incidence of SE was 18.3 per 100,000 population. SE incidence was U-shaped, peaking under 1 year and over 60 years of age. The incidence of SE was greater for males than for females, for acute symptomatic etiology than any other etiology, and for partial SE that did not generalize than any other seizure type. Status of long duration (at least 2 hours) occurred more frequently among infants and the elderly than among persons aged 1 to 65 years. Cumulative incidence was 4 per 1,000 to age 75 and showed the greatest increase after age 60. Given the aging of the population, SE will become an increasingly important public health problem.

Short-term mortality after a first episode of status epilepticus.

PURPOSE: Studies evaluating short-term mortality among people who experience status epilepticus (SE) have produced conflicting results. Most studies are derived from clinical series with results affected by unspecified follow-up period and select referral of cases. This study was planned to evaluate short-term mortality after a first episode of SE. METHODS: We performed a population-based retrospective cohort study to determine the short-term mortality following a first episode of SE. Between January 1, 1965 and December 31, 1984, we studied all first episodes of afebrile SE who received medical attention in Rochester, Minnesota. Cases were followed until death or end of the study (February 1996). RESULTS: Mortality within the first 30 days was 19% (38 deaths out of 201 incident SE). Thirty-four deaths (89%) occurred among those with nonfebrile acute symptomatic SE, while 4 deaths (11%) occurred among those with unprovoked SE. Within the acute symptomatic group, after adjusting for age, there was a decreased risk of death in women (RR = 0.4; 95% CI: 0.2-0.9). No effect of duration or seizure type was shown after adjusting for other risk factors. CONCLUSIONS: One out of 5 subjects with SE died within the first 30 days. Short-term mortality is associated with the presence of an underlying acute etiology. Among acute symptomatic cases, women had a decreased risk of dying.