A large-scale clinico-epidemiological study of epileptic seizures has been carried out in a highland area in northern Ecuador, South America. This paper describes the design and the two-staged validation procedures undertaken to authenticate the screening questionnaire, which was used to detect epileptic seizures in the community during this project. An initial questionnaire consisting of 20 questions was devised and then validated in a group of healthy subjects and a group of patients with known epileptic seizures. This questionnaire was found to have a sensitivity of 100% and a specificity of 50.8%. A cluster analysis of the responses rates was undertaken and a set of nine questions which presented a specificity of 92% and sensitivity of 98% were chosen to be used during the survey. The validation of this nine-question instrument was then undertaken by direct application to a general population of 72,121 persons. Positive, negative, false positive and false negative rates were derived. The screening instrument was found to have a sensitivity of 79.3%, a specificity of 92.9%, a positive predictive value of 18.3%, a negative predictive value of 99.6% and a Youden's index of 0.79. The methodology of the study and the instruments developed are recommended for future neuro-epidemiological work in epilepsy. The problems of validation are discussed, and previous epidemiological studies of epilepsy reviewed with special emphasis on the handling of questions of validation.

A large-scale neuro-epidemiological study was carried out in a population of 72,121 inhabitants of a region of Northern Ecuadorian Andean Sierra, to identify prevalence and incidence rates of epileptic seizures and to identify demographic and geographic variations in these rates. Calculations were made using three datasets. First, rates were calculated from all cases identified in the field (raw dataset); secondly, lower rates were calculated based on a further diagnostic and reclassification procedure (minimum estimated dataset); thirdly, higher rates were derived by calculating false negative rates from the screening procedures, and adding these to the cases actually identified (maximum estimated dataset). Lifetime point-prevalence rates between 12.2/1000 and 19.5/1000 were recorded (minimum and maximum estimated rates), and the prevalence of active epileptic seizures was between 6.7/1000 and 8.0/1000 (minimum estimated and raw datasets). Incidence rate ranging between 122/100,000/year and 190/100,000/year were found (minimum, estimated and raw datasets). A marked difference in prevalence rates was found in two subregions of the survey area, and also in urban and rural areas. The reasons for these differences were not identified.

The complicated pathophysiological and immunological changes in the central nervous system of patients with neurocysticercosis produce a variety of signs and symptoms, which complicate the clinical and surgical management of this disease. A complete and objective classification is needed, to improve the medical approach as a whole. We studied 336 patients, in whom we classified neurocysticerosis according to criteria of viability and location of the parasite in the CNS: active form (37.2%) when the cysticercus is alive, transitional form (32.8%) when it is in the degenerative phase, and inactive form (30%) when the parasite is dead. This classification establishes the correlation between the different forms of neurocysticerosis and its clinical manifestations, and can be used for planning therapeutic strategies.Resume: La neurocysticerose : ebauche de classification. Les changements physiopathologiques et immunologiques complexes du systeme nerveux central chez les patients atteints de neurocysticercose donnent lieu a des signes et a des symptomes varies qui compliquent le traitement clinique et chirurgical de cette maladie. Nous avons besoin d'une classification complete et objective de la neurocysticercose afin d'ameliorer l'approche medicale globale. Nous avons etudie 336 patients atteints de neurocysticercose, dont nous avons classifie la maladie selon des criteres de viabilite et de localisation du parasite dans le systeme nerveux central : la forme active (37.2%) quand le cysticerque est vivant, la forme transitionnelle (32.8%) quand le parasite est en phase degenerative et la forme inactive (30%) quand le parasite est mort. Cette classification etablit la correlation entre les differentes formes de neurocysticercose et leurs manifestations cliniques et peut etre utilisee pour planifier des strategies therapeutiques.Can. J. Neurol. Sci. 1994; 21: 43-47 Human cysticercosis, or larval stage of the Taenia solium, is the most common parasitic illness that affects the central nervous system (CNS), especially in countries where the sanitary infrastructure is deficient. In Latin American countries, the frequency of neurocysticercosis (NC) is very high, reaching 3.6% in some regions, 1 and it is becoming increasingly common in developed countries, because of immigration from endemic regions. 2 We find it even in communities which do not eat pork and whose residents have not traveled to a country where T. solium infection is endemic.3 Since NC is a great public health problem, it is important to have a clear understanding of this disease in order to implement the necessary preventive measures.The natural history of the cysticercus in the CNS is, to date, not completely known; however, the CT scan in the last decade, and now the MRI, 4 have been very useful in the study of the biologic evolution of the cysticercosis in the CNS, especially in the brain parenchyma. Many authors have described the CT appearance of parenchymal lesions of NC related to the stage of the larva.5-9 When the larva is alive, the ...

A house-

The methodology is presented of a large-scale study of epilepsy carried out in a highland area in northern Ecuador, South America, covering a population of 72,121 people; The study was carried out in two phases, the first, a cross-sectional phase, consisted of a house-to-house survey of all persons in this population, screening for epileptic seizures using a specially designed questionnaire. Possible cases identified in screening were assessed in a cascade diagnostic procedure applied by general doctors and neurologists. Its objectives were: to establish a comprehensive epidemiological profile of epileptic seizures; to describe the clinical phenomenology of this condition in the community; to validate methods for diagnosis and classification of epileptic seizures by a non-specialised team; and to ascertain the community''s knowledge, .attitudes and practices regarding epilepsy. A sample was selected in this phase in order to study the social aspects of epilepsy in this community. The second phase, which was longitudinal, assessed the ability of non-specialist care in the treatment of epilepsy. It consisted of a prospective clinical trial of antiepileptic therapy in untreated patients using two standard anti-epileptic drugs. Patients were followed for 12 months by a multidisciplinary team consisting of a primary health worker, rural doctor, neurologist, anthropologist, and psychologist. Standardised, reproducible instruments and methods were used. This study was carried out through co-operation between the medical profession, political agencies and the pharmaceutical industry, at an international level. We consider this a model for further large-scale studies of this type.