Epidemiology of status epilepticus in a rural area of northern Italy: a 2-year population-based study

The epidemiology of convulsive and nonconvulsive status epilepticus

Epidemiologic studies of status epilepticus (SE) depend on clear definitions of terms. Such a definition is available for convulsive generalized SE, but clear definitions of nonconvulsive SE (NCSE) are lacking. This as well as clinical difficulties to diagnose NCSE are one source of underascertainment. The minimal incidence of SE in the Caucasian population of industrialized countries is about 20/100,000/year. It depends on age, ethnic background and possibly gender. Case fatality rates lie between 1.9 and 40% depending on age, etiology and duration of the SE. Effective treatment can improve and focal SE itself may impair case fatality. Clearly increased rates of long term case fatality in patients with symptomatic SE suggest that these patients should be considered a population at high risk.

Incidence of status epilepticus in southern Europe: a population study in the health district of Ferrara, Italy

BACKGROUND

The epidemiologic features of status epilepticus (SE) are still in the course of definition.

METHODS

We carried out an intensive survey of multiple sources of case material in the resident population of the health district of Ferrara, Italy, in 2003. Information was collected on age, gender, duration, seizure type and etiology of SE.

RESULTS

The age- adjusted annual incidence rate of SE was 27.2/100,000 (95% CI = 19.4-36.9) and it was higher in men (41.7/100,000, 95% CI = 26.9-61.7) than in women (12.3/100,000, 95% CI = 6.9-20.4). The incidence was higher in the elderly (older than 60 years, 39.2/100,000) than in younger adults in the age group 20-59 years (14.7/100,000). The age-specific incidence showed a bimodal distribution peaking in the youngest (0-4 years) and in the oldest age group (75+ years). Cerebrovascular disease was the most frequent etiologic factor (45%). Epilepsy had previously been diagnosed in 40% of the patients. The case fatality was 5%.

CONCLUSIONS

The study found a higher incidence of SE than that expected on the basis of the previous European studies suggesting that the risk of SE in southern Europe is higher and more similar to that estimated in population studies in the United States. The case fatality was lower than that reported in previous South-European population studies despite the similar clinical features of the patients. Indirect evidence suggests that several factors related to the SE management could have positively influenced the outcome.

Who is at risk for prolonged seizures?

This article reviews how long seizures last and how frequently seizures are prolonged, risk factors for prolonged seizures, and a conceptual framework that links them. These data are derived from studies of patients with a first unprovoked seizure, studies of children with febrile seizures, studies of population-based and community-based cohorts with newly diagnosed epilepsy and patients with refractory epilepsy, and treatment trials. Prolonged seizures that exceed 5 to 10 minutes are relatively common, and the key factor in the identification of those at risk is a history of a prior prolonged seizure. A subgroup of patients with seizures is predisposed to prolonged although not necessarily frequent seizures, which are associated with increased morbidity, increased emergency department visits, and a decreased quality of life. This article also addresses criteria used to justify treatment of a seizure once it has continued longer than 5 minutes and the rationale for such treatment.

Treatment of convulsive status epilepticus

Status epilepticus (SE) is a medical and neurological emergency requiring prompt and aggressive treatment, particularly for elderly individuals in whom comorbid conditions may increase the severity of consequences in SE. Generalized convulsive status epilepticus (GCSE) is the most common and life-threatening type of SE. It may be overt or subtle in its presentation. Most cases are overt, but as the duration of GCSE increases, its presentation may become more subtle. Progressive electroencephalographic changes also occur during GCSE. A predictable sequence of five electroencephalographic patterns has been identified: (1) discrete seizures with interictal slowing, (2) merging seizures with waxing and waning ictal discharges, (3) continuous ictal sharp or spike-wave discharges, (4) continuous ictal discharges with episodes of generalized flattening, and (5) periodic epileptiform discharges superimposed on a relatively flat background. Several factors affect the prognosis of GCSE, including etiology, age, seizure type, gender, and duration. GCSE may lead to systemic complications and neuronal damage and is often fatal if untreated or inadequately treated. Treatment of GCSE should begin with basic life support measures and monitoring. Ideally, pharmacological treatment should be easy to administer and fast acting. Analysis of data on elderly patients with overt GCSE from a Veterans Affairs cooperative study revealed that success rates of first-line treatment were 71.4% for phenobarbital, 63.0% for lorazepam, 53.3% for diazepam followed by phenytoin, and 41.5% for phenytoin alone. In elderly patients with subtle GCSE, success rates for first-line treatment were 30.8% for phenobarbital, 14.3% for lorazepam, 11.8% for phenytoin, and 5.6% for diazepam followed by phenytoin. Because each drug has advantages and disadvantages, the choice of which agent to use as first-line treatment depends on individual patient characteristics.

[Refractory status epilepticus: diagnosis, therapy, course, and prognosis]

Status epilepticus (SE) is a frequent neurological emergency with an annual incidence of 10-20/100,000 individuals. The overall mortality is about 10-20%. Patients present with long-lasting fits or series of epileptic seizures or extended stupor and coma. Furthermore, patients with SE can suffer from a number of systemic complications possibly also due to side effects of the medical treatment. In the beginning, standardized treatment algorithms can successfully stop most SE. A minority of SE cases prove however to be refractory against the initial treatment and require intensified pharmacologic intervention with nonsedating anticonvulsive drugs or anesthetics. In some partial SE, nonpharmacological approaches (e.g., epilepsy surgery) have been used successfully. This paper reviews scientific evidence of the diagnostic approach, therapeutic options, and course of refractory SE, including nonpharmacological treatment.