Perinatal Factors and Seizure Disorders: An Epidemiologic Review

Abstract

In this review, we assess the following six aspects of the epidemiological literature addressing the association between perinatal factors and seizure disorders (mainly of the grand mal type): (1) study design; (2) selection of cases; (3) selection of controls; (4) definition and ascertainment method of seizures; (5) definition and ascertainment method of perinatal factors; (6) sample size and power. Needed are studies of perinatal factors in a homogeneous group of seizure patients, such as those with grand mal seizures. Because of the rarity of the seizure disorder, most follow-up studies of this subject suffer from inadequate sample size. Improvements are suggested for case-control studies, which appear, by necessity, to be the more appropriate design.

Risk factors for a first epileptic seizure after stroke: A case control study

“…The lack of correlation between hypertension and seizures when cases and controls are matched for age, gender, and stroke as in our study, lend us to suggest that hypertension is a confounder. Many other risk factors for a first seizure have been suggested [5,9,10,11]; in an attempt to evaluate their effect also in presence of a powerful seizure etiology such as stroke, we ascertained these risk factors in our patients. This was made possible by our case-control approach, whereas it is probably unfeasible with a cohort design.…”

“…All risk factors were defined, where possible, in accordance with previous reports, to ensure uniform interpretation of the events to be measured: family history of seizures: first-degree relative, first-degree cousin, uncle/aunt, or grandparent affected by at least one afebrile seizure of any type; complications of pregnancy [9]: any complication (toxemia, hemorrhage, nausea) requiring hospitalization longer than two days; low gestational age: birth before the beginning of the 38th week of gestation; low birth weight: weight ≤2500 g; complications of delivery [9]: any of the followings: mechanical complications, abnormal fetal position, coiling of cord, or prolonged delivery; psychomotor retardation: any problem during the first five years of life causing a delay in achieving the milestones of normal development; febrile seizures [10]: seizures occurring between the age of 30 days and 5 years, with no previous afebrile seizure (except neonatal), and associated with fever but with no evidence of intracranial infection or other recognized acute neurological illness; average daily intake of absolute alcohol (ADAA): this was calculated with reference to the six months before inclusion in the study, asking about different beverages separately to obtain a total intake in grams per day [11]; history of cerebral palsy [10]: disorder of movement and posture diagnosed before age 16 years, not attributable to a progressive brain lesion or postneonatal brain injury; epileptogenic drugs: these included iv. penicillin, or aminophylline, antiarrhythmic, antitubercular, tricyclic antidepressants, neuroleptic drugs in the seven days before the seizure or the interview; metabolic alterations at admission: history of diabetes, therapy with insulin or oral hypoglycemic drugs, or hypoglycemia or electrolyte alterations at admission.…”

The epidemiology of the epilepsies in children

“…Most studies that have examined various perinatal factors, especially those related to "birth asphyxia," have failed to find any significant associations with risk of epilepsy [Degen, 1978;Ellenberg and Nelson, 1979;Nelson and Ellenberg, 1984;Deymeer and Leviton, 1985;Rocca et al, 1987a;b;. The factors that have been consistently associated with an increased risk of epilepsy in children include: congenital malformations and metabolic disorders, febrile seizures, seizures within the first 28 days of life (neonatal seizures), moderate to severe head trauma, CNS infections, and family history of afebrile or febrile seizures.…”

Predisposing and Causative Factors in Childhood Epilepsy

“…Papers by co-workers (Leviton andCowan, 1981~7, 1982;Deymeer and Leviton, 1985) discuss some of the major methodologic issues and testify to the limitations of current knowledge.…”