Neurocysticercosis: still some unanswered questions.

Correspondence: Luís dos Ramos Machado; Praça Amadeu Amaral, 47 / conj. 33; 01327-010 São Paulo SP; Brasil. E-mail: [email protected] Conflict of interest: There is no conflict of interest to declare. Received 04 April 2014 Accepted 11 April 2014 Neurocysticercosis (NC), the cerebral infection with Taenia solium, is an important public health problem worldwide. Nevertheless, many important questions regarding NC remain unanswered, not only in relation to its etiopathogenesis and diagnosis but also in relation to its treatment. In a magnificent text published in this issue of Arquivos de Neuro-Psiquiatria, Carpio, a world authority in studies on NC, in collaboration with Romo, masterfully bring their experience to bear on some important points that remain somewhat unclear in relation to this disease. The natural history of cysticerci in the central nervous system (CNS) is not entirely understood. Their history is described more through information from computed tomography (CT) and magnetic resonance imaging (MRI) than from classical clinical or experimental models. A morphological classification based on the viability and location of the parasite in the CNS has been proposed: active, when the parasite is alive; transitional or degenerative, if it is in the colloidal or granular-nodular phase; or inactive, if there is evidence of its death. Seizures are the main symptom in transitional parenchymal cysts. However, these images are not pathognomonic of NC: (1) a single enhanced lesion on CT or hyperintense lesion on MRI is a common finding in patients with newly identified seizures in endemic countries; these patients, who are mainly children and young adults, have some benign and transitory clinical manifestations, predominantly focal seizures or focal seizures with secondary generalization; occasionally, they have Todd’s paresis or focal neurological deficits; (2) these lesions may be seen in CNS tuberculosis and in other inflammatory pathological conditions. Seizures are the most common clinical manifestation of NC. Carpio and Romo emphasize that it is essential to distinguish between seizures and epilepsy in relation to neurocysticercosis. Acute symptomatic seizures may result from transitional or degenerating cysts, but are ultimately a consequence of the acute inflammatory response (seizures, not epilepsy). In contrast, a patient with seizures who has viable cysts and/or inactive, non-inflamed calcified cysts may be categorized as having unprovoked or remote seizures (epilepsy). This difference is often difficult to assess. Although NC is one of the most frequent antecedents in patients with epilepsy, it may not necessarily be the main cause of epilepsy. It has consistently been reported in the literature that seizures are the most common symptom of NC, occurring in 70% to 90% of symptomatic patients. However, in a study on patients with newly-diagnosed epilepsy, perinatal brain damage (9%), NC (8.3%), other CNS infections (4.2%), stroke (4.8%) and head trauma (4.2%) were the disorders most frequently reported as causes of epilepsy. The lack of validated diagnostic criteria for NC is another important problem. This makes it difficult to estimate the prevalence of symptomatic NC. Additionally, because NC can be completely asymptomatic, this makes it almost impossible to estimate what proportion of the population will actually have symptomatic disease. Seropositivity through the enzyme-linked immunoelectrotransfer blot assay (EITB) or through the enzyme-linked immunosorbent assay (ELISA), a diagnostic criterion that has classically been accepted, does not necessarily imply the presence of active systemic infection with T. solium, nor does it DOI: 10.1590/0004-282X20140074 EDITORIAL