Exploring the complex associations over time among albendazole treatment, cyst evolution, and seizure outcomes in neurocysticercosis

The prevalence of and contributors to neurocysticercosis in endemic regions

BACKGROUND

Neurocysticercosis is one of the most common causes of acquired epilepsy worldwide. Caused by Taenia solium, the infection uses pigs as an intermediate host and thus is often associated with proximity to and consumption of pigs.

OBJECTIVE

This review explores the epidemiology of neurocysticercosis in endemic regions across Africa, Asia, and Latin America and examines common risk factors in these areas.

METHODS

A literature review was conducted using pubmed to search for articles with key words including neurocysticercosis, Taenia, solium, epidemiology, and the names of countries and continents in the regions of interest.

FINDINGS

Multiple risk factors for neurocysticercosis were identified, including inadequate regulation of pig farms and food safety, poor sanitation, and water contamination. In addition, additional barriers to appropriate diagnosis and management were found, including resource limitations and poor health literacy.

CONCLUSION

Despite its global prevalence, effective limitation of neurocysticercosis is still achievable through projects which address common risk factors.

Neurocysticercosis: an update on diagnosis, treatment, and prevention

Neurocysticercosis (NCC) is an important cause of neurological disease worldwide, including imported cases in nonendemic countries.

PURPOSE OF REVIEW

The purpose of this review is to update information on diagnosis, management, and prevention of neurocysticercosis.

RECENT FINDINGS

WHO and Infectious Diseases Society of America/American Society of Tropical Medicine and Hygiene guidelines emphasize the importance of corticosteroids and antiparasitic drugs for viable parenchymal disease and single enhancing lesions. Subarachnoid NCC is associated with a high fatality rate unless optimally treated. Advances in subarachnoid NCC include use of prolonged antiparasitic and anti-inflammatory courses and the increasing use of antigen-detection and quantitative PCR assays in diagnosis and follow-up. Emerging data support the safety and efficacy of minimally invasive surgery in ventricular cases. Calcified neurocysticercosis continues to be associated with a high burden of disease. Field studies are demonstrating the feasibility of eradication using a combination of mass chemotherapy for human tapeworms and vaccination/treatment of porcine cysticercosis.

SUMMARY

NCC remains an important and challenging cause of neurological disease with significant morbidity despite advances in treatment and prevention.

Efficacy of Combination Therapy of Albendazole and Praziquantel vs Albendazole Monotherapy in Children With Persistent Neurocysticercosis: A Randomized Controlled Trial

AIM

To compare the efficacy of combined albendazole and praziquantel therapy vs albendazole monotherapy in a placebo-controlled, double-blinded, randomized trial in children with persisting neurocysticercosis.

METHODS

Children with persistent neurocysticercosis were randomized into 3 groups-albendazole (n = 19), albendazole and praziquantel (n = 21), and placebo (n = 20)-for 30 days and followed up at 3 and 6 months for resolution and recurrence of seizures.

RESULTS

Mean age of children was 9.3 ± 2.9 years (range 3-14). At baseline, the majority of lesions were ring-enhancing (70%), colloidal (97%), with scolex (68%) and perilesional-edema (45%), and located in the parietal (58%) lobe. One case each in albendazole and placebo groups had a recurrence of seizure in the first month of treatment. The majority (62%) of children in the combination therapy group showed complete resolution of the persisting lesion at the end of 6 months compared to the albendazole alone group (26.3%, P = .02). Percentage reduction in the lesion's mean area at 6 months was highest in the combination group compared with other groups (P = .006). Rate of calcification was identical in all 3 groups (10%). None of the patients required interruption of therapy.

CONCLUSION

Our study demonstrates the safety and efficacy of albendazole and praziquantel in combination for complete radiologic resolution in children with persistent neurocysticercosis when compared with albendazole monotherapy or placebo. The combination therapy did not result in increased seizure recurrence or adverse drug reaction compared with albendazole monotherapy.

Anthelmintics for people with neurocysticercosis

BACKGROUND

Neurocysticercosis is a parasitic infection of the central nervous system by the larval stage of the pork tapeworm and is a common cause of seizures and epilepsy in endemic areas. Anthelmintics (albendazole or praziquantel) may be given alongside supportive treatment (antiepileptics/analgesia) with the aim of killing these larvae (cysticerci), with or without corticosteroid treatment. However, there are potential adverse effects of these drugs, and the cysticerci may eventually die without directed anthelminthic treatment.

OBJECTIVES

To assess the effects of anthelmintics on people with neurocysticercosis.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, LILACS, the WHO ICTRP, and ClinicalTrials.gov, up to 21 October 2020.

SELECTION CRITERIA

Randomized controlled trials comparing anthelmintics and supportive treatment (+/- corticosteroids) with supportive treatment alone (+/- corticosteroids) for people with neurocysticercosis.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the title and abstract of all articles identified by the search. We obtained full-text articles to confirm the eligibility of all studies that passed screening. One review author extracted data, which a second review author checked. Two review authors assessed the risk of bias of each trial and performed GRADE assessments. In cases of disagreement at consensus discussion stage between review authors, we consulted a third review author. We calculated risk ratios (RR) for dichotomous variables, with 95% confidence intervals (CIs) for pooled data from studies with similar interventions and outcomes.

MAIN RESULTS

We included 16 studies in the review. Only two studies investigated praziquantel and did not report data in a format that could contribute to meta-analysis. Most results in this review are therefore applicable to albendazole versus placebo or no anthelmintic. The aggregate analysis across all participants with neurocysticercosis did not demonstrate a difference between groups in seizure recurrence, but heterogeneity was marked (RR 0.94, 95% CI 0.78 to 1.14; 10 trials, 1054 participants; I² = 67%; low-certainty evidence). When stratified by participants with a single cyst or multiple cysts, pooled analysis suggests that albendazole probably improves seizure recurrence for participants with a single cyst (RR 0.61, 95% CI 0.4 to 0.91; 5 trials, 396 participants; moderate-certainty evidence). All studies contributing to this analysis recruited participants with non-viable, intraparenchymal cysts only, and most participants were children. We are uncertain whether or not albendazole reduces seizure recurrence in participants with multiple cysts, as the certainty of the evidence is very low, although the direction of effect is towards albendazole causing harm (RR 2.05, 95% CI 1.28 to 3.31; 2 trials, 321 participants; very low-certainty evidence). This analysis included a large study containing a highly heterogeneous population that received an assessment of unclear risk for multiple 'Risk of bias' domains. Regarding radiological outcomes, albendazole probably slightly improves the complete radiological clearance of lesions (RR 1.22, 95% CI 1.07 to 1.39; 13 trials, 1324 participants; moderate-certainty evidence) and the evolution of cysts (RR 1.27, 95% CI 1.10 to 1.47; 6 trials, 434 participants; moderate-certainty evidence). More adverse events appeared to be observed in participants treated with either albendazole or praziquantel compared to those receiving placebo or no anthelmintic. The most commonly reported side effects were headache, abdominal pain, and nausea/vomiting.

AUTHORS' CONCLUSIONS

For participants with a single cyst, there was less seizure recurrence in the albendazole group compared to the placebo/no anthelmintic group. The studies contributing to this evidence only recruited participants with a non-viable intraparenchymal cyst. We are uncertain whether albendazole reduces seizure recurrence for participants with multiple cysts. We also found that albendazole probably increases radiological clearance and evolution of lesions. There were very few studies reporting praziquantel outcomes, and these findings apply to albendazole only.

A prospective cohort study to assess the frequency and risk factors for calcification in single lesion parenchymal neurocysticercosis

BACKGROUND

Calcified neurocysticercosis (NCC) predisposes patients to an enduring state of epilepsy. The predictors for calcification in parenchymal neurocysticercosis are not well defined.

METHOD

In this prospective cohort study, consecutive children with single-lesion parenchymal NCC were enrolled and followed up for one year. All patients were investigated with brain 3 T-MRI and electroimmunotransfer blot (EITB). Clinical follow-ups were performed every 3 months. Radiology was repeated at the 6-month and one-year follow-ups. The proportion of calcified lesions at one year and the predictors of calcification were studied.

RESULT

During the study period from June 2013 to December 2015, 93 children with single lesion parenchymal NCC were enrolled. At presentation, 90 % of the lesions were in the colloidal stage, and 71 % of the lesions had moderate to severe perilesional oedema. All children had 6 months of follow-up, and 86 (92.5 %) had one year of follow-up. Seizure recurrence was present in 13 (14 %) children. Follow-up radiology at one year showed lesion resolution in 51 (59 %) lesions and calcification in 28 (32.5 %) lesions. Children with calcified lesions during follow-up had a higher odds of seizure recurrences {OR, 95 % CI 3.6(2.3-5.6)}. The presence at baseline of diffusion restriction {OR, 95% CI 2.9 (1.01-8.8)}, scolex or wall calcification in the T2 Star weighted angiography MRI images {OR, 95% CI 3.7 (1.7-8.2)} and >10 mm size of the lesion {OR, 95 % CI 2.4 (1.2-5.01)} predicted lesion calcification.

CONCLUSION

Children with calcification of the parenchymal NCC lesions have a higher risk for seizure recurrence during follow-up. The presence of diffusion restriction, calcified nidus in the colloidal nodular stage, and >10 mm size of the lesion at baseline predicted calcification of the lesion during follow-up.

Neurocysticercosis-related seizures in the post-partum period: two cases and a review of the literature

Neurocysticercosis, the infection of the CNS with larval cysts of Taenia solium, is a leading cause of seizures in low-income countries. The clinical presentation of neurocysticercosis is variable and depends on the number, size, and location of cysticerci, and on the immune response of the host. In most patients, the affected site is the brain parenchyma, where cysts can precipitate seizures. Neurocysticercosis has seldom been described in pregnant women. In this Grand Round, we report two cases of pregnant women who immigrated to Italy from Bolivia and Ecuador, and who developed seizures in the early post-partum period, due to calcified parenchymal neurocysticercosis lesions. We discuss the complex interactions between neurocysticercosis and the immune system in pregnancy and the post-partum period. Building on this scenario, we propose practices for the management of neurocysticercosis in pregnancy and the post-partum period, highlighting important gaps in the literature that should be addressed.

Zoonotic and vector-borne parasites and epilepsy in low-income and middle-income countries

Zoonotic and vector-borne parasites are important preventable risk factors for epilepsy. Three parasitic infections - cerebral malaria, Taenia solium cysticercosis and onchocerciasis - have an established association with epilepsy. Parasitoses are widely prevalent in low-income and middle-income countries, which are home to 80% of the people with epilepsy in the world. Once a parasitic infection has taken hold in the brain, therapeutic measures do not seem to influence the development of epilepsy in the long term. Consequently, strategies to control, eliminate and eradicate parasites represent the most feasible way to reduce the epilepsy burden at present. The elucidation of immune mechanisms underpinning the parasitic infections, some of which are parasite-specific, opens up new therapeutic possibilities. In this Review, we explore the pathophysiological basis of the link between parasitic infections and epilepsy, and we consider preventive and therapeutic approaches to reduce the burden of epilepsy attributable to parasitic disorders. We conclude that a concerted approach involving medical, veterinary, parasitological and ecological experts, backed by robust political support and sustainable funding, is the key to reducing this burden.