An epidemiological study of epilepsy and epileptic seizures in two rural Guatemalan communities.

A cross-sectional epidemiological study of two communities in Guatemala, El Jocote and Quesada, was conducted to determine the prevalence of epilepsy and epileptic seizures. An initial screening questionnaire was applied to detect individuals who had possibly suffered seizures in the past. These individuals were then examined more thoroughly by a neurologist, to confirm or reject them as cases of epilepsy. The crude prevalences of epilepsy so revealed were 28 cases/1000 in El Jocote and 29 cases/1000 in Quesada. The prevalence of active epilepsy in each community was approximately 18 cases/thousand. The most common type of seizure suffered was of the generalised tonic--clonic type. Seventy-six of the individuals who had a history of epileptic seizures and 51 individuals from the same communities with no such history were then given brain scans, using computerized axial tomography. These neuro-imaging studies revealed some form of abnormal image in 33% (17) of the subjects with no history of seizures and 70% (53) of those with a history of seizures (chi(2) = 12.2; P < 0.00006). The frequency of detected brain abnormalities in the individuals who had suffered a single episode of seizures was similar to that in those who were classified as epileptic. The most commonly observed type of abnormality was punctate calcification, followed by cerebral oedema and hypodensities. The reasons for the high prevalences of epilepsy, epileptic seizures and abnormal neuro-images observed in the present study merit further investigation. Although neurocysticercosis caused by Taenia solium was thought to be a significant cause of the epilepsy occurring in the study communities, many apparently non-epileptic individuals have brain lesions indicative of this disease.

Complex segregation analysis of non-myoclonic idiopathic generalized epilepsy in families ascertained from probands affected with idiopathic epilepsy with tonic-clonic seizures in Antioquia, Colombia.

In an attempt to identify the possible role of major genes, multifactorial inheritance, and cohort effects in the susceptibility to idiopathic epilepsy with generalized tonic-clonic seizures of the awakening type (GTCS), complex segregation analysis was performed in 196 nuclear families ascertained through affected probands with idiopathic epilepsy with GTCS belonging to the Paisa community of Antioquia (Colombia). Models postulating no transmission, single major locus (dominant and recessive) only, and multifactorial component only, were rejected. Since the codominant single major locus model could not be rejected and models that assign no major locus to transmission, no polygenic component to transmission, and no transmission of the major effect were rejected, complex segregation analysis suggested that a major autosomal codominant allele together with a multifactorial component (mixed model) best explained clustering of idiopathic epilepsy with GTCS in families of the Paisa community. The deficit of transmission of heterozygotes (0.17) is compatible with the existence of epistasis acting on a major gene whose frequency was estimated to be 0.0211. Its transmission variance accounts for 81% of the susceptibility to idiopathic epilepsy with GTCS. The complementary variance (19%) is due to the polygenic component.