The Relationship Between Epilepsy and Neurocysticercosis: Evidence and Myths.

Background Neurocysticercosis (NCC) remains a neglected cause of neurological disease in endemic regions of low- and middle-income countries in Latin America, Asia, and Africa, contributing substantially to morbidity and mortality. Although epileptic seizures are the most common clinical manifestation of NCC, the mechanisms underlying NCC-related epilepsy remain poorly understood, and its role as a direct cause of epilepsy remains controversial. Summary For decades, the high prevalence of epilepsy in some endemic regions has been attributed to parasitic infections, particularly Neurocysticercosis (NCC). However, estimates of NCC frequency among people with epilepsy vary widely because of inappropriate generalization of findings from hyperendemic areas, temporal changes in NCC prevalence, and methodological limitations. Many studies have failed to distinguish epilepsy from epileptic seizures and acute symptomatic seizures, and most evidence has been derived from descriptive case series, case-control, or cross-sectional studies of prevalent cases. In some studies, NCC diagnosis relied solely on serology, which may indicate only prior exposure, or on CT identification of calcified lesions, which poorly detect active or degenerating cysts associated with acute symptomatic seizures. Indeed, the presence of active or degenerating cysts in some cohorts suggests that participants may have experienced acute symptomatic seizures rather than epilepsy. Furthermore, intracranial calcifications from other causes are frequently assumed to represent NCC. More recent studies support an association between NCC and mesial temporal lobe epilepsy with hippocampal sclerosis, suggesting possible mechanisms linking NCC-related hippocampal injury to epileptogenesis. Nevertheless, this mechanism alone cannot explain the large proportion of epilepsy cases attributed to NCC in the literature, and limitations related to timing, sampling, and methodology make these estimates questionable. Key Messages Well designed prospective epidemiological studies of NCC remain scarce, particularly in low- and middle-income countries. Further research is needed to improve diagnostic accuracy and epidemiological surveillance and to provide stronger evidence regarding the relationship between NCC and epilepsy. Future studies should clearly distinguish epileptic seizures from epilepsy and avoid equating association with causation.