Demonstration of scolex within calcified cysticercus cyst: its possible role in the pathogenesis of perilesional edema

Serological and molecular detection of neurocysticercosis among epileptic patients in Nagpur, Maharashtra state (India)

Neurocysticercosis (NCC), one of the most important neuroparasitic diseases in humans, is caused by Cysticercus cellulosae, the metacestode stage of digenetic zoonotic cestode Taenia solium. The present study aims at the detection of anti-cysticercus antibodies in the sera of epileptic patients (n=26) visiting a tertiary care hospital in Nagpur, Maharashtra state, India, by an in-house developed indirect IgG-ELISA and enzyme-linked immunoelectro transfer blot (EITB) assay using different antigens (namely, Whole Cyst Antigen (WCA), Cystic Fluid Antigen (CFA), Scolex Antigen (SA), Excretory-Secretory Antigen (ESA) and Membrane-Body Antigen (MBA)) prepared from T. solium metacestodes to find out the status of NCC. An attempt has also been made for molecular detection of NCC from blood samples of those patients by Polymerase Chain Reaction (PCR) assay targeted at large subunit rRNA gene of T. solium. The IgG ELISA level of anti-cysticercus antibodies against WCA, CFA, SA, ESA and MBA antigens were as follows: 19.23 %, 23.07 %, 38.46 %, 30.76 % and 15.38 %. The seroreactivity to CFA, SA and ESA was found in equal proportions in patients with ring-enhancing lesions. In the EITB assay, the lower and medium molecular weight protein bands of SA and ESA were immunodominant compared to the higher WCA and CFA peptides. PCR positivity could be observed in 34.6 % (9/26) of the patients under study. It is the first report of detecting NCC among epileptic patients of the Nagpur region of Maharashtra state in India using serological and molecular tools.

Epilepsy Due to Solitary Calcified Cysticercus Granuloma

The calcified stage of the neurocysticercosis (NCC) is the common cause of acquired epilepsy in low and middle income countries in people aged > 20 years. Approximately 30% of adult onset seizures and epilepsy are attributable to NCC. In India and some of the Latin American countries, epilepsy due to solitary calcified NCC is the common adult onset epilepsy. The current evidence suggests that the calcified cysticercus granuloma is probably the epileptogenic focus. The mechanisms involved in the epileptogenic process are not well understood; Focal-onset seizures with or without impaired awareness are the common seizure type. Focal-onset seizure can evolve to bilateral tonic-clonic seizure. Seizure outcome with anti-seizure medication, most often with monotherapy, is very good. The seizure disorders associated with various stages of NCC can be preventable.

Neurocysticercosis-related Seizures: Imaging Biomarkers

Neurocysticercosis (NCC)-a parasitic CNS infection endemic to developing nations-has been called the leading global cause of acquired epilepsy yet remains understudied. It is currently unknown why a large proportion of patients develop recurrent seizures, often following the presentation of acute seizures. Furthermore, the presentation of NCC is heterogenous and the features that predispose to the development of an epileptogenic state remain uncertain. Perilesional factors (such as oedema and gliosis) have been implicated in NCC-related ictogenesis, but the effects of cystic factors, including lesion load and location, seem not to play a role in the development of habitual epilepsy. In addition, the cytotoxic consequences of the cyst's degenerative stages are varied and the majority of research, relying on retrospective data, lacks the necessary specificity to distinguish between acute symptomatic and unprovoked seizures. Previous research has established that epileptogenesis can be the consequence of abnormal network connectivity, and some imaging studies have suggested that a causative link may exist between NCC and aberrant network organisation. In wider epilepsy research, network approaches have been widely adopted; studies benefiting predominantly from the rich, multimodal data provided by advanced MRI methods are at the forefront of the field. Quantitative MRI approaches have the potential to elucidate the lesser-understood epileptogenic mechanisms of NCC. This review will summarise the current understanding of the relationship between NCC and epilepsy, with a focus on MRI methodologies. In addition, network neuroscience approaches with putative value will be highlighted, drawing from current imaging trends in epilepsy research.

Complex neurocysticercosis lesions on imaging: Explained through correlative histomorphology

OBJECTIVES

Neurocysticercosis, the commonest neuro-parasite, sometimes presents as complex ring enhancing lesion causing diagnostic dilemma. We aim to establish radio-histo-morphological equivalents of early events in degeneration of the parasite to explain such imaging phenotypes.

METHODS

We compared patterns of degeneration in 23 randomly selected complex NCC on MRI with histo-morphology in 30 cysts obtained from an unrelated post mortem brain.

RESULTS

The anatomy of the parasite and the degenerative patterns of the scolex (hydropic changes, calcification, evagination, and fragmentation) and the cyst wall (undulation, accessory loculi, and frank disruption) were well demonstrated on both. The intact scolex remarkably resembled head of intestinal Taenia. The complex lesions were conglomeration of multiple communicating cysts with a single parent cyst and multiple daughter cysts. The parent cysts contained a solitary variably degenerated scolex, had thicker walls and associated chronic inflammation. The remaining cysts of the lesion complex contained no scolex, had poorly organized walls, turbid contents, and florid perilesional enhancement with leakage of contrast. Three lesions assumed a multi-cystic pseudo-tumorous pattern, of which two resolved into solitary calcific remnants on follow up.

CONCLUSION

Complex lesion in NCC result from degeneration of solitary parasite with perilesional gliosis, surrounded by multiple non-larval daughter cysts inciting acute intra and perilesional inflammation due to enhanced antigenic challenge. Possibly, attempted abortive asexual reproduction by the cellulose cyst as a preterminal event results in a "limited Racemose like transition." Correct interpretation has diagnostic and therapeutic implications as active lesions and their fibrocalcific residue may have greater epileptogenic potential.

Predictors of Seizure Recurrence in Solitary Calcified Neurocysticercosis in Relation to Computed Tomography Scan: Prospective Observational Study

Background and Purpose

Solitary calcified neurocysticercosis (NCC) on the computed tomography (CT) scan of brain in patients of epilepsy is common finding in endemic regions. Factors causing seizures in such cases are debatable. Immature calcification may be the causative factor for seizure recurrence. Thus, we aimed to study predictors of seizure recurrence specific to morphological characteristics on CT scan.

Methods

Patients with solitary calcified NCC on CT scan brain and active seizures were prospectively included. The protocol included clinical evaluation, contrast-enhanced CT scan of the brain, and electroencephalogram (EEG) at baseline and 9th month of 1-year follow-up in all patients. Seizure recurrence after 1 week of enrolment was recorded.

Results

One hundred twenty patients with a mean age of 23.33±12.81 years were included with a final follow-up of 109 patients and 35 patients had seizure recurrence. On univariate analysis, seizure frequency of more than 1 episode/month (45.7% vs. 25.7%, p=0.037; odds ratio [OR], 2.06; 95% confidence interval [CI], 1.05–5.68), perilesional edema on CT head (45% vs. 10.8%, p<0.001; OR, 6.95; 95% CI, 2.58–18.7), lower density (HU) of lesion on CT head (139.85±76.54 vs. 204.67±135.9 HU p=0.009) and abnormal EEG at presentation (p<0.001; OR, 18.25; 95% CI, 2.15–155.13) were significantly associated with seizure recurrence. On multivariate analysis, presence of perilesional edema on CT head (p=0.001; OR, 6.854; 95% CI, 2.26–20.77), density of lesion on CT (HU) (p=0.036; OR, 0.995; 95% CI, 0.99–1) and abnormal EEG (p=0.029; OR, 12.125; 95% CI, 1.29–113.74) were independently associated with seizure recurrence.

Conclusions

The presence of perilesional edema, HU of calcification on CT brain, and abnormal EEG suggest an increased risk of seizure recurrence in patients of epilepsy with solitary calcified NCC.

Frequency and Determinant Factors for Calcification in Neurocysticercosis

BACKGROUND

Neurocysticercosis is a major cause of acquired epilepsy. Larval cysts in the human brain eventually resolve and either disappear or leave a calcification that is associated with seizures. In this study, we assessed the proportion of calcification in parenchymal neurocysticercosis and risk factors associated with calcification.

METHODS

Data for 220 patients with parenchymal NCC from 3 trials of antiparasitic treatment were assessed to determine what proportion of the cysts that resolved 6 months after treatment ended up in a residual calcification at 1 year. Also, we evaluated the risk factors associated with calcification.

RESULTS

The overall proportion of calcification was 38% (188/497 cysts, from 147 patients). Predictors for calcification at the cyst level were cysts larger than 14 mm (risk ratio [RR], 1.34; 95% confidence interval [CI], 1.02-1.75) and cysts with edema at baseline (RR, 1.39; 95% CI, 1.05-1.85). At the patient level, having had more than 24 months with seizures (RR, 1.25; 95% CI, 1.08-1.46), mild antibody response (RR, 1.14; 95% CI, 1.002-1.27), increased dose albendazole regime (RR, 1.26; 95% CI, 1.14-1.39), lower doses of dexamethasone (RR, 1.36; 95% CI, 1.02-1.81), not receiving early antiparasitic retreatment (RR, 1.45; 95% CI, 1.08-1.93), or complete cure (RR, 1.48; 95% CI, 1.29-1.71) were associated with a increased risk of calcification.

CONCLUSIONS

Approximately 38% of parenchymal cysts calcify after antiparasitic treatment. Some factors associated with calcification are modifiable and may be considered to decrease or avoid calcification, potentially decreasing the risk for seizure relapses.

Imaging correlates of serum enzyme-linked immunoelectrotransfer blot (EITB) positivity in patients with parenchymal neurocysticercosis: results from 521 patients

BACKGROUND

The presence of perilesional edema among patients with parenchymal neurocysticercosis (pNCC) of various lesion subtypes has not been correlated with results of serum enzyme-linked immunotransfer blot (EITB) for cysticercal antibodies.

METHODS

In total, 521 patients with pNCC were classified into solitary cysticercus granuloma (SCG), multiple lesions, at least one of which was an enhancing granuloma (GMNCC), solitary calcified cysticercal lesion (SCC) and multiple calcified cysticercal lesions (CMNCC). The proportion of EITB positivity among each lesion subtype and its association with perilesional edema were determined.

RESULTS

There were significantly higher positive EITB results in patients with GMNCC (90/111, 81.1%) compared with other lesion types. Perilesional edema was associated with positive EITB in patients with CMNCC. On univariate analysis, perilesional edema and GMNCC were associated with EITB positivity. On multivariate analysis, only GMNCC (OR 7.5; 95% CI 3.5 to 16.2) was significantly associated with EITB positivity.

CONCLUSIONS

In patients with pNCC, the presence of perilesional edema is associated with a higher probability of a positive EITB result in patients with CMNCC, suggesting a synchronicity in the mechanisms associated with formation of perilesional edema and the antibody response in this subtype. In patients with enhancing granulomas, edema is not an independent predictor of a positive EITB, suggesting that the enhancement itself is associated with a strong antibody response.

Brain calcification because of neurocysticercosis: a vast field to be explored

PURPOSE OF REVIEW

Neurocysticercosis is the most common helminthic infection of the central nervous system caused by the larval stage of the pork tapeworm, Taenia solium. Endemic regions include Latin American countries, sub-Saharan Africa, and large regions of Asia, including the Indian subcontinent and is a global health problem. Seizures are the most common manifestation and approximately 30% of adult-onset seizures in endemic regions are attributable to NCC. Calcifications because of neurocysticercosis is the most common finding on imaging in endemic regions and are important seizure foci contributing to the burden of epilepsy.

RECENT FINDINGS

After treatment with antiparasitics for multiple viable parenchymal disease, approximately 38% of cysts that resolved after 6 months of therapy will result in residual calcifications, which represents a significant burden of residual disease. Calcified disease has been referred to as 'inactive disease', but there is accumulating evidence to suggest that calcified granulomas are actually dynamic and substantially contribute to the development and maintenance of seizures.

SUMMARY

Calcified parenchymal neurocysticercosis contributes significantly to the development and maintenance of seizures in endemic regions. Understanding the pathogenesis of the role of calcified NCC in seizure development and risk factors for development of calcifications after treatment is critical to decreasing the burden of symptomatic disease in endemic regions.

Inflammation in neurocysticercosis: clinical relevance and impact on treatment decisions

INTRODUCTION

Neurocysticercosis is caused by the localization of Taenia solium larvae in the central nervous system. The disease remains endemic in most countries of Latin America, Asia and Africa. While major improvements have been made in its diagnosis and treatment, uncertainties persist regarding the clinical implications and treatment of the inflammatory reaction associated with the disease.

AREAS COVERED

In this review, based on PubMed searches, the authors describe the characteristics of the immune-inflammatory response in patients with neurocysticercosis, its clinical implications and the treatment currently administered. The dual role of inflammation (participating in both, the death of the parasite, and the precipitation of serious complications) is discussed. New therapeutic strategies of potential interest are presented.

EXPERT OPINION

Inflammatory reaction is the main pathogenic mechanism associated to neurocysticercosis. Its management is mainly based on corticosteroids administration. This strategy had improved prognostic of patients as it allows for the control of most of the inflammatory complications. On the other side, it might be involved in the persistence of parasites in some patients, despite cysticidal treatment, due to its immunosuppressive properties. New strategies are needed to improve therapeutical management, particularly in the severest presentations.

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.

Clinical characteristics of migraine in patients with calcified neurocysticercosis

BACKGROUND

Patients with neurocysticercosis (NCC) may have an increased frequency of migraine. We studied the characteristics of migraine attacks in patients with calcified NCC on brain imaging.

METHODS

Of 350 migraine patients who visited our outpatient department from January 2016 through June 2018, 166 had undergone brain imaging. Seventy-two patients with migraines had calcified NCC. The migraine attacks of the patients with calcification (MiC) were compared with those of 94 patients without calcification (MiNC).

RESULTS

Side-locked headaches were seen in 48.6% of the MiC patients. Aura preceding the migraine attack was more common in the MiC group than in the MiNC group (22.22% vs 7.4%; p=0.001). The MiC group had fewer headache episodes per month (5 vs 6; p<0.0001) with fewer common associated features (62.5% vs 84.1%; p=0.006). They also required fewer drugs for secondary prophylaxis (2 vs 3; p=0.002).

CONCLUSIONS

Some of the clinical characteristics of migraine attacks are sufficiently different in patients with and without NCC. This may suggest some influence of NCC in the pathophysiology of migraine to account for alterations in the clinical manifestations of the disease. Whether this difference could be inferred as NCC having a causative role in migraine needs further research.

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.

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

OBJECTIVE

To develop a causal model for the occurrence of neurocysticercosis (NC)-related seizures and test hypotheses generated from the model.

METHODS

We used data from a randomized controlled trial comparing albendazole with placebo among patients newly diagnosed with NC. Based on our causal model, we explored the associations among albendazole treatment, NC cyst evolution, and seizure outcomes over 24 months of follow-up using generalized linear mixed effect models.

RESULTS

We included 153 participants, of whom 51% received albendazole. The association between seizure outcomes and treatment over time demonstrated lack of linearity and heterogeneity, requiring the inclusion of time-treatment interaction terms for valid modeling. Participants in the albendazole group had fewer seizures overall and of partial onset at all time points compared with the placebo group, but the difference increased over the first few months following treatment, then decreased over time. Generalized seizures exhibited a more complex association; those in the albendazole group had fewer seizures compared with those in the placebo group for the first few months after treatment, and then the association reversed and those in the placebo arm had fewer seizures. Adjusting for the number of NC cysts in each phase resulted in an attenuation of the strength of association between albendazole and seizure outcomes, consistent with mediation. Among participants in whom all cysts had disappeared (n = 21), none continued to have seizures.

SIGNIFICANCE

Albendazole treatment is associated with a possible reduction in focal seizures in the short term (3-6 months), perhaps by hastening the resolution of the cysts. However, the effect is not discernible over the long term, because most cysts either calcify or resolve completely, regardless of whether treated with albendazole. The stage of evolution of the cysticercus is an important consideration in the evaluation of albendazole effect on seizure outcome.

Dynamic contrast-enhanced (DCE) MRI derived kinetic perfusion indices may help predicting seizure control in single calcified neurocysticercosis

BACKGROUND

The factors responsible for seizure recurrence in patients with Solitary calcified neurocysticercosis (NCC) are not well understood. Blood brain barrier (BBB) breach may be associated with seizure recurrence. Dynamic contrast enhanced (DCE) MRI derived indices k_ep, k^trans and v_e are useful in quantifying BBB permeability. In this study, we assessed the possible role of DCE-MRI and matrix metalloproteinases (MMP)-9 levels in predicting seizure recurrence.

METHODS

In this prospective-observational study, patients with new-onset seizures and a solitary calcified NCC were included. DCE-MRI was done to quantify BBB integrity. DCE-MRI parameters were measured as k_ep, k^trans and v_e. MMP-9 levels were estimated. Patients were followed for 1 year, when DCE-MRI and MMP-9 levels were repeated. Patients were classified into two groups on the basis of seizure recurrence, which was defined as the recurrence of an episode of seizure at least 1 week after the initiation of the anti-epileptic drugs. Logistic regression analysis was done.

RESULTS

At 1-year of follow up, 8 out of 32 patients had seizure recurrence. Baseline DCE-MRI derived k_ep (p = 0.015) and MMP-9 levels (p = 0.019) were significantly higher in the seizure "recurrence" group compared with the "no recurrence" group. On within-group analysis, a significant increase in k_ep (p = 0.012), v_e (p = 0.012), and MMP-9 levels (p = 0.017) was observed in the seizure "recurrence" group while a decrease was seen in v_e and MMP-9 levels in the "no recurrence" group.

CONCLUSION

Higher values of DCE-MRI indices and MMP-9 levels, with a corresponding trend in the follow-up, can be useful in predicting lesions with a higher propensity for seizure recurrence.

Clinical presentation of neurocysticercosis-related epilepsy

Neurocysticercosis (NCC) is the most common parasitic infection of the central nervous system and a major risk factor for seizures and epilepsy. Seizure types in NCC vary largely across studies and seizure semiology is poorly understood. We discuss here the studies regarding seizure types and seizure semiology in NCC, and examine the clinical presentation in patients with NCC and drug-resistant epilepsy. We also provide evidence of the role of MRI and EEG in the diagnosis of NCC-related epilepsy. Focal seizures are reported in 60-90% of patients with NCC-related epilepsy, and around 90% of all seizures registered prospectively are focal not evolving to bilateral tonic-clonic seizures. A great number of cases suggest that seizure semiology is topographically related to NCC lesions. Patients with hippocampal sclerosis and NCC have different clinical and neurophysiological characteristics than those with hippocampal sclerosis alone. Different MRI protocols have allowed to better differentiate NCC from other etiologies. Lesions' stages might account on the chances of finding an interictal epileptiform discharge. Studies pursuing the seizure onset in patients with NCC are lacking and they are specially needed to determine both whether the reported events of individual cases are seizures, and whether they are related to the NCC lesion or lesions. This article is part of a Special Issue entitled "Neurocysticercosis and Epilepsy".

Natural History of Patients With Perilesional Edema Around Taenia solium Calcified Granulomas

Background

The transient development of perilesional edema (PE) around ≥1 calcification (defined as 1 episode) occurs in about 50% of the patients with recurrent seizures in calcified neurocysticercosis (NCC). We determined the long-term clinical and radiological course of persons undergoing PE episodes.

Methods

Twenty-one persons with NCC who experienced ≥1 PE episode were followed for a median of 10.6 years (range, 0.4-29.2 years). Clinical evaluations and magnetic resonance imaging (MRI) were performed at the time of suggestive symptoms and during routine follow-up.

Results

PE episodes were documented 78 times, involving 50 of 729 calcifications. Episodes reoccurred in all but 3 persons. The pattern, rate, and number of episodes were variable, commonly chronic, and not significantly associated with time from treatment, number of calcifications, or sex. Seizure was the most common symptom, but almost 30% of episodes were asymptomatic and detected by MRI during routine follow-up. Persons with delayed recurrent episodes were significantly older (age, 42.3 vs 28.8 years; P = .045). Seizures continued to occur in 37.5%, and 2 persons had a severe disabling clinical course.

Conclusions

The number and timing of PE episodes in individuals with calcified NCC are variable and commonly chronic, sometimes recurring over decades. A minority of patients developed significant disability.

Disease Centered Around Calcified Taenia solium Granuloma

Taenia solium (the pork tapeworm) is present in most developing countries, where it is a frequent cause of seizures and other neurological disease. Parasitic larvae invade the human brain, establish, and eventually resolve, leaving a calcified scar. While these lesions are common in endemic regions, and most of these are clinically silent, a proportion of individuals with calcified cysticerci develop seizures from these lesions, and 30-65% of these cases are associated with perilesional edema (PE), likely due to host inflammation. This manuscript summarizes the importance, characteristics, natural history, and potential prevention and treatments of symptomatic calcified neurocysticercosis (NCC).

Intermittent enhancement in chronic nodular calcified neurocysticercosis

Neurocysticercosis (NCC) is the most common cause of new onset seizures and epilepsy in the developing and tropical world. There has been a marked increase in domestic cases of diseases traditionally associated with developing countries, and now NCC should be high on a radiologist's differential diagnosis list for a patient with seizures. Radiologic findings of NCC correlate with the parasite's life cycle within the host. The calcified granulomas signify the final stage (nodular calcified) as nonenhancing punctate calcifications on imaging and are traditionally known to remain without enhancement. Here we describe a unique case of intermittent enhancement of a cortical calcified nodule secondary to NCC that was followed for over 10 years. Radiologists must challenge the traditionally accepted progression of imaging findings and accept that calcified nodules of chronic NCC may intermittently enhance.

Calcified neurocysticercus, perilesional edema, and histologic inflammation

Abstract. Here, we present the second report of the histopathology of a Taenia solium calcification giving rise to perilesional edema. This has important implications, because if perilesional edema lesions are inflammatory in character, immunosuppressive or anti-inflammatory medications, not just antiepileptic drugs alone, may be useful to prevent or treat recurring episodes in such patients.

From seizures to epilepsy and its substrates: neurocysticercosis

Neurocysticercosis (NCC) is the main risk factor for late-onset seizures in many Taenia solium endemic countries and is also increasingly recognized in high income countries, where it was once thought to have been eliminated. The course and outcome of NCC-associated seizures and epilepsy are poorly understood. Substrates underlying NCC-associated seizures and epilepsy are unknown. Another unknown is if there is an association between NCC and hippocampal sclerosis (HS) and if it leads to intractable epilepsy. We review evidence regarding the structural basis of seizures and epilepsy in NCC and its association with HS. There are only a limited number of prospective studies of NCC-associated seizures and epilepsy. From these, it can be inferred that the risk of seizure recurrence is high following a first seizure, even though seizures are well-controlled with antiepileptic drugs. The single most important risk factor for ongoing or recurrent seizures is the persistence of either degenerating or residual calcified cysticercus cysts in the brain parenchyma on follow-up imaging studies. Medically intractable epilepsy requiring surgical treatment appears to be rare in people with NCC. In few cases that have been operated, gliosis around the cysticerci is the principal pathologic finding. Reports of the association between NCC and HS might be categorized into those in which the calcified cysticercus is located within the hippocampus and those in which the calcified cysticercus is located remote from the hippocampus. The former are convincing cases of medically intractable epilepsy with good seizure control following hippocampal resection. In the remaining, it is unclear whether a dual pathology relationship exists between HS and the calcified cysticercus. Carefully planned, follow-up studies incorporating high-resolution and quantitative imaging are desirable in order to clarify the outcome, the structural basis of NCC-associated epilepsy, and also its association with HS.

Edema surrounding calcified intracranial cysticerci: clinical manifestations, natural history, and treatment

Calcified granulomas are the most common radiological finding in neurocysticercosis (10-20% of endemic populations). A small proportion serves as foci of seizure activity, which results in large numbers of persons with epilepsy. Calcified granulomas are not all the same. Some demonstrate blood-brain barrier dysfunction (magnetic resonance imaging enhancement) most likely due to the presence of inflammation, visualizable scolices, and/or gliosis. About half the patients with a recent history of seizures, positive serology, and only calcified lesions develop perilesional edema at the time of a seizure recurrence. The natural history, treatment, and pathophysiology of this phenomenon are not well studied. Episodes are usually associated with seizures or other neurological manifestations, resolve by 4-6 weeks, sometimes occur repeatedly, and usually involve a subset of the same calcifications. Treatment is supportive. Histopathological examination of one calcification associated with multiple perilesional edema episodes revealed significant inflammation and supports the concept that perilesional edema is inflammatory in nature. This most likely is due to host responses to released or newly recognized parasite antigen and/or upregulation of the host immune response. Immunosuppressive and anti-inflammatory agents may be useful in prevention and/or treatment of this phenomenon.

T1-weighted dynamic contrast-enhanced MR evaluation of different stages of neurocysticercosis and its relationship with serum MMP-9 expression

BACKGROUND AND PURPOSE

Epileptogenesis in NCC is associated with perilesional inflammation and disruption in BBB. We quantified BBB in different stages of NCC by using DCE-MR imaging to look for the differences in perfusion indices and to correlate these indices with serum MMP-9 expression.

MATERIALS AND METHODS

DCE-MR imaging along with conventional MR imaging was performed in 57 single cysticercous brain lesions to quantify the kep, K(trans), and ve around the lesions, which were in different stages of evolution. There were 6 lesions in the vesicular stage and 17 lesions each in the colloidal, granular-nodular, and calcified stages. Serum MMP-9 was quantified from all patients, whereas perfusion indices were quantified from all stages except for the vesicular stage.

RESULTS

We observed significant differences among the 3 stages of NCC in serum MMP-9 expression as well as DCE-derived kep values. In addition, kep showed a strongly significant positive correlation with MMP-9 expression when modeled with the individual stage of the disease as well as with all stages when pooled together. Other DCE-derived hemodynamic and pharmacokinetic parameters showed inconsistent differences with each stage of the disease. The correlation of DCE-derived parameters with serum MMP-9 expression and edema volume also showed inconsistency with the stage of the disease.

CONCLUSIONS

We conclude that kep correlates best with serum MMP-9 expression among the pharmacokinetic indices and most closely represents the degree of BBB breakdown, which is highest in the colloidal stage and lowest in the calcified stage. kep may be used as a noninvasive image biomarker of BBB breakdown in different stages of NCC.

Improved detection of parenchymal cysticercal lesions in neurocysticercosis with T2*-weighted angiography magnetic resonance imaging

RATIONALE AND OBJECTIVES

Magnetic resonance imaging (MRI) is an important tool for the diagnosis and management of various central nervous system infections. In the present study, we investigated the role of T2*-weighted angiography (SWAN) imaging in the diagnosis of neurocysticercosis (NCC) viz-a-viz conventional MRI.

METHODS

Symptomatic (n = 46) and asymptomatic (n = 88) cases from a pig-farming community were imaged using both conventional and SWAN MRI between July 2009 and May 2011. Two experienced neuroradiologists independently reviewed all the images to characterize the lesions as well as detection of the scolex.

RESULTS

A total of 250 lesions were detected in 70 individuals. On conventional MRI, the lesion and scolex visibility was 82.4% (206/250) and 60% (150/250), respectively, which increased to 96.8% and 81%, respectively, using SWAN imaging. On combining SWAN with conventional MRI, the scolex visibility increased to 85% (213/250) of the total 250 lesions detected. Overall, adding SWAN to conventional MRI increased the lesion detection and scolex visibility up to 18% (206 vs. 250) and 30% (150 vs. 213), respectively.

CONCLUSION

SWAN imaging when added to the conventional MRI protocol for population screening for NCC in endemic regions improves both lesion detection and definitive diagnosis of neurocysticercosis.

Short report: A calcified Taenia solium granuloma associated with recurrent perilesional edema causing refractory seizures: histopathological features

We describe the first detailed histological description of an excised calcified Taenia solium granuloma from a patient who developed recurrent seizures associated with perilesional edema surrounding a calcified cysticercus (PEC). The capsule, around a degenerated cysticercus, contained marked mononuclear infiltrates that extended to adjacent brain, which showed marked astrocytosis, microgliosis, and inflammatory perivascular infiltrates. The presence of large numbers of mononuclear cells supports an inflammatory cause of PEC. Immunosuppression or anti-inflammatory measures may be able to treat and prevent PEC and recurrent seizures.

Perilesional brain oedema and seizure activity in patients with calcified neurocysticercosis: a prospective cohort and nested case-control study

BACKGROUND

Cysticercosis due to Taenia solium is a cause of adult-acquired seizures and epilepsy even in patients with only calcified larval cysts. Transient perilesional brain oedema is seen around the calcified foci but its importance, association with seizures, incidence, and pathophysiology are unknown.

METHODS

110 patients with only calcified lesions and a history of seizures or severe headaches were followed prospectively in a cohort design to assess the incidence of seizure relapse. In a nested case-control substudy, perilesional oedema was assessed by MRI at the time of seizure in symptomatic patients and in matched asymptomatic controls taken from the study population.

FINDINGS

Between November, 1999, and December, 2006, 29 patients had an incident seizure during a median follow up of 32.33 (SD 19.99) months, with an estimated 5-year seizure incidence of 36% (95% CI 25% to 49%). 24 of 29 (83%) patients with seizure relapse had an MRI evaluation within 5 days of the event; perilesional oedema was seen in 12 patients (50%) compared with two (9%) of 23 asymptomatic matched controls.

INTERPRETATION

Perilesional oedema is common and associated with episodic seizure activity in patients with calcified neurocysticercosis. Our findings are probably representative of symptomatic patients in regions where T solium neurocysticercosis is endemic and suggest a unique and possibly preventable cause of seizures in this population.

A study of neurocysticercosis in the foothills of the Himalayas

OBJECTIVES

The present study was planned and carried out with the aim of determining the incidence of neurocysticercosis (NCC) among patients with clinically manifested neurological disorders attending the Himalayan Institute of Medical Sciences (HIMS) hospital.

METHODS

Spanning a period of 18 months, serum samples of consecutively selected patients were screened by ELISA for the presence of anti-cysticercus antibodies after obtaining a detailed history. Physical examinations were performed along with routine hematological, stool and urine tests. All patients included in the study group were also subjected to radiological investigations such as CT scan/MRI/X-ray and/or ultrasonography.

RESULTS

One hundred and three new patients were selected for the study group, with a male:female ratio of 2:1. Of these, 33 (32.0%) patients were positive for Taenia solium IgG antibodies in sera. Children in the 11-20 years age group were most affected (39.4%). Only 10 patients (30.3%) were found to be positive for ova in stool, which correlated well with the presence of multiple lesions in the central nervous system (p<0.01). Solitary lesions were more common (66.7%) than multiple lesions (33.3%) on radiological diagnosis by CT scan/MRI.

CONCLUSIONS

A high incidence of neurocysticercosis in the region reflects the endemic presence of T. solium and advocates the practice of better hygiene, cooking methods and water filtration procedures for the prevention of infection.

Neurocysticercosis: evaluation with advanced magnetic resonance techniques and atypical forms

Neurocysticercosis (NCC) is the most common helminthic infection of the central nervous system, but its diagnosis remains difficult. The purpose of this article is to perform a critical analysis of the literature and show our experience in the evaluation of NCC. We discuss the advanced MR technique applications such as diffusion and perfusion-weighted imaging, spectroscopy, cisternography with FLAIR, and supplemental O2 and 3D-CISS. The typical manifestations of NCC are described; emphasis is given to the unusual presentations. The atypical forms of neurocysticercosis were divided into: intraventricular, subarachnoid, spinal, orbital, and intraparenchymatous. Special attention was also given to reactivation of previously calcified lesions and neurocysticercosis associated with mesial temporal sclerosis.

Pediatric epilepsy - an Indian perspective

Prevalence studies from India suggest that epilepsy prevalence is similar to developed nations. Neurocysticercosis (NCC) predominates as an etiology. A large treatment gap is still a public health problem. Benign epilepsies and West syndrome appear to be underrepresented in studies on classification of seizures/syndromes. Febrile seizures prevalence in India is similar to other countries and appear to be as benign. Risk factors of intractable epilepsy (IE) in Indian studies include early age of onset, neurodevelopmental abnormalities and certain seizure types. Perinatal injuries underlie many IE. Many IE are not truly intractable and respond to simple therapeutic measures. The ketogenic diet and surgery are other methods now being used in Indian centers. Neurocysticercosis and neonatal hypoglycemic brain injury, two widely prevalent etiologies are reviewed in detail.

Cysticercosis: Recent Advances in Diagnosis and Management of Neurocysticercosis

Neurocysticercosis, caused by infection with the pork tapeworm Taenia solium, is increasingly recognized as a cause of neurologic disease worldwide. Because the clinical presentation is nonspecific, diagnosis has been difficult. Advances in imaging studies and serodiagnostic techniques are facilitating the diagnosis of neurocysticercosis and tapeworm carriers. Neurocysticercosis represents a spectrum of disease. Seizures are the main clinical manifestation in parenchymal neurocysticercosis. Recent studies emphasize that such seizures are the result of the host inflammatory response, even in patients who only have calcifications with no viable cysticerci. Controlled clinical trials have demonstrated that antiparasitic drugs can decrease the number of generalized seizures, although the benefit is small and confined to a subgroup of patients. Corticosteroids can also decrease seizure frequency. Case studies have demonstrated that endoscopic surgery appears to be the optimal approach to ventricular cysts. Recombinant vaccines are being developed and may prove important in disease control.

Calcific neurocysticercosis and epileptogenesis

Neurocysticercosis is responsible for increased rates of seizures and epilepsy in endemic regions. The most common form of the disease, chronic calcific neurocysticercosis, is the end result of the host's inflammatory response to the larval cysticercus of Taenia solium. There is increasing evidence indicating that calcific cysticercosis is not clinically inactive but a cause of seizures or focal symptoms in this population. Perilesional edema is at times also present around implicated calcified foci. A better understanding of the natural history, frequency, epidemiology, and pathophysiology of calcific cysticercosis and associated disease manifestations is needed to define its importance, treatment, and prevention.

Epidemiology, clinical manifestations and diagnosis of zoonotic cestode infections: an update

This paper reviews the literature on zoonotic cestode infections with specific reference to the years 1999-2003. The sources and prevalence of various zoonotic tapeworm infections caused by adult and larval stages of the genera Taenia, Echinococcus, Diphyllobothrium, Hymenolepis and Dipylidium continue to be an important cause of morbidity and mortality, not only in most underdeveloped countries but also in industrialized countries, particularly in rural areas or among immigrant groups from endemic areas. The review gives a detailed report on recent molecular epidemiological studies on the taxonomy and phylogenetic variations in Echinococcus granulosus, immunological tests and imaging techniques used in epidemiological surveys and clinical investigations of important adult and larval tapeworm infections of animals and humans. Larval stages or metacestodes of Taenia solium, Echinococcus spp. and pseudophyllidean tapeworms (Spirometra syn. Diphyllobothrium spp.) may reside in various tissues of their intermediate hosts, including humans. In particular, Cysticercus cellulosae (T. solium) and the larvae of E. granulosus, and E. multilocularis, which are predominantly located in the liver, lungs and central nervous system forming various types of cysts, lead to a complex of systemic diseases such as cysticercosis, cystic echinococcosis and alveolar echinococcosis, respectively. Relatively rare clinical manifestations are seen in the muscles, subcutaneous tissue, spleen, kidneys, bones and body cavities.

Taenia solium cysticercosis

The larval stage of the pork tapeworm (Taenia solium) infects the human nervous system, causing neurocysticercosis. This disease is one of the main causes of epileptic seizures in many less developed countries and is also increasingly seen in more developed countries because of immigration from endemic areas. Little information is available on the natural evolution of taeniasis or cysticercosis. Available therapeutic measures include steroids, treatments for symptoms, surgery, and, more controversially, antiparasitic drugs to kill brain parasites. Efforts to control and eliminate this disease are underway through antiparasitic treatment of endemic populations, development of pig vaccines, and other measures.