Neurocysticercosis: The duration of its preclinical phase relies on the parasite location.

OBJECTIVES: Neurocysticercosis (NC) is a heterogeneous disease particularly in terms of response to treatment and prognosis. Parasite localization is one of the main factors involved in this heterogeneity. In this study we aim to determine whether differences in the duration of the preclinical phase associated with parasite location, could contribute to said heterogeneity. METHODS: Ninety-nine patients were included, 24 with parasites in the parenchyma (PAR), 56 in the subarachnoid (SA) space and 19 in the ventricular system (IV). A questionnaire designed to assess exposure to classic NC risk factors 5, 10, 15, 20 and more than 20 years prior to diagnosis was applied. The results were compared between the three groups. Also, asymptomatic relatives of patients who had shared their living conditions in childhood or more recently were included and underwent brain scan and blood testing for specific antibodies. RESULTS: Over the course of their lives, exposure to risk factors decreased significantly for all patients, although the decrease was more evident in patients with parasites in the SA space (p < 0.001) compared to patients with PAR (p = 0.011) or IV cysts (p = 0.020). Five years prior to diagnosis, exposure to risk factors was significantly higher in patients with PAR or IV NC than in patients with SA NC (p = 0.04). Furthermore, individuals in close contact with PAR or IV patients in the years preceding diagnosis were more likely to have asymptomatic NC, specific antibodies in sera, particularly IgM, compared to individuals in close contact with SA patients during the same period. CONCLUSIONS: All these findings are highly suggestive of the possibility of a more recent infection of patients affected by parenchymal and ventricular NC than of patients with subarachnoid NC. Consequently, subarachnoid disease could be considered a chronic disease, which, probably contributes to the severity of the disease as well as the minimal response to medical treatment.

Natural history of extraparenchymal neurocysticercosis.

BACKGROUND: In patients affected by neurocysticercosis (NCC), the extraparenchymal location of the parasites generates the most severe form of the disease. Due to the difficulty in its diagnosis and management, there are still many questions; in particular, the natural history of parasites at this location is not well known. METHODS: We included 21 patients with vesicular extraparenchymal NCC who had not received treatment for at least 18 months. We collected their demographic and clinical data, compared their imaging studies at the beginning and the end of the period without treatment and classified the patients, taking into account the evolution of their parasitic burden. RESULTS: A total of 10 men and 11 women were included. Patients had undergone a period of 63±48 months without treatment. During this period, 8 patients (38.1%) showed an increase, 7 (33.3%) a decrease and 6 (28.6%) showed no change in parasite burden. CONCLUSION: The natural history of extraparenchymal cysticerci is heterogeneous. The results show the ability of parasites to survive for a long time in the extraparenchymal location and explain the chronicity of the disease in some patients. The links between these findings and the difficulties in the therapeutic management of extraparenchymal NCC patients should be studied.