Neurocysticercosis

Infectious Myelopathies

OBJECTIVE

Infectious myelopathy of any stage and etiology carries the potential for significant morbidity and mortality. This article details the clinical presentation, risk factors, and key diagnostic components of infectious myelopathies with the goal of improving the recognition of these disorders and guiding subsequent management.

LATEST DEVELOPMENTS

Despite our era of advanced multimodal imaging and laboratory diagnostic technology, a causative organism often remains unidentified in suspected infectious and parainfectious myelopathy cases. To improve diagnostic capability, newer technologies such as metagenomics are being harnessed to develop diagnostic assays with a greater breadth of data from each specimen and improvements in infection identification. Conventional assays have been optimized for improved sensitivity and specificity.

ESSENTIAL POINTS

Prompt recognition and treatment of infectious myelopathy decreases morbidity and mortality. The key diagnostic tools include serologies, CSF analysis, and imaging; however clinical presentation, epidemiologic risk factors, and history of recent illness are all vital to making the proper diagnosis because current laboratory and imaging modalities are often inconclusive. The cornerstone of recommended treatment is targeted antimicrobials with appropriate immune modulation, surgical intervention, supportive care, and interdisciplinary involvement, all of which further improve outcomes for patients with infectious myelopathy.

Cerebral Taenia crassiceps larvae infection in a 71-year-old immunocompetent male

We report a rare case of a cerebral infection with Taenia crassiceps tapeworm larvae in an immunocompetent 71-year-old German male. Initially, an intracerebral malignoma was suspected after the patient experienced stroke-like symptoms. After surgery, helminth larvae, later identified as T. crassiceps, were detected. Identification on the species level was possible by specific PCR and sequencing. After complete surgical removal, the patient was treated with albendazole and dexamethasone for two weeks. No residual symptoms were reported up to date.

Endoscopic endonasal surgery for massive subarachnoid neurocysticercosis: illustrative case

BACKGROUND

Subarachnoid neurocysticercosis (NCC) is associated with high morbidity and mortality rates. Conventional transcranial approaches and transventricular endoscopy have been previously reported for extraparenchymal NCC and ventricular NCC, respectively. By October 2019, endonasal endoscopic approaches had not been used for the treatment of NCC.

OBSERVATIONS

A 54-year-old-woman with NCC was admitted with acute neurological deterioration due to severe intracranial hypertension caused by massive subarachnoid NCC cysts, as evidenced on magnetic resonance imaging (MRI) with great brainstem compression. The case was discussed, and an endoscopic endonasal resection of the NCC cysts was scheduled. The diagnosis was confirmed by pathological anatomy. There were no complications in the surgery, with marked neurological improvement. Control MRIs demonstrated a significant reduction of NCC cysts.

LESSONS

Minimally invasive approaches are an excellent alternative for skull-base tumoral and infectious pathology. Prior knowledge of the pathophysiology and the authors’ experience in the management of patients with NCC allowed them to propose this approach, with optimal results.

Taenia solium proteins: a beautiful kaleidoscope of pro and anti-inflammatory antigens

Background: Neurocysticercosis (NCC) is an acquired infection of central nervous system associated with epileptic seizures. The parasite 'Taenia solium' causes this disease and has a complex life cycle and molts into various stages that influence the host-parasite interaction. The disease has a long asymptomatic phase with viable cyst and degeneration of cyst and leaking cyst fluid has been associated with symptomatic phase. The parasite proteome holds the answers and clues to this complex clinical presentation and hence unraveling of proteome of parasite antigens is needed for better understanding of host-parasite interactions. Objective: To understand the proteome make-up of T. solium cyst vesicular fluid (VF) and excretory secretory proteins (ESPs). Methodology: The VF and ESPs for the study were prepared from cyst harvested from naturally infected swine. The samples were prepared for nano LC-MS by in-tube digestion of proteins. The spectra obtained were annotated and enrichment analysis was performed and in silico analysis was done. Results: T. solium VF and ESPs have 206 and 247 proteins of varied make-up including pro-inflammatory and anti-inflammatory nature. Conclusions: Due to varied make-up of VF and ESPs it can generate complex humoral and cellular immune response.

Diffuse Parenchymal Neurocysticercosis: A Case Report and Review of Literature

Neurocysticercosis is the commonest parasitic disease of the central nervous system and the leading cause of seizure in the developing world. Human cysticercosis is caused by the dissemination of the embryo of Taenia solium in the intestine via the hepatoportal system to the tissues and organs of the body. The organs most commonly affected are the subcutaneous tissues, skeletal muscles, lung, brain, eye, liver, and occasionally the heart, thyroid, and pancreas. Widespread dissemination of the cysticerci can result in the involvement of almost any organ in the body. We report a case of 60 years old male presented with head injury due to fall, which was diagnosed as diffuse parenchymal neurocysticercosis on computed tomography scan of brain. We discuss the radiological feature, diagnostic criteria, management plan, and literature review of such reported cases.

Understanding the association of neurocysticercosis and mesial temporal lobe epilepsy and its impact on the surgical treatment of patients with drug-resistant epilepsy

Mesial temporal lobe epilepsy associated with hippocampal sclerosis (MTLE-HS) is one of the most common types of focal epilepsies. This is an epileptic syndrome commonly associated with treatment-resistant seizures, being also the most prevalent form of drug-resistant epilepsy which is treated surgically in most epilepsy surgery centers. Neurocysticercosis (NCC) is one of the most common parasitic infections of the central nervous system, and one of the most common etiological agents of focal epilepsy, affecting millions of patients worldwide. Recently, researchers reported a curious association between MTLE-HS with NCC, but this association remains poorly understood. Some argue that calcified NCC lesions in MTLE-HS patients is only a coincidental finding, since both disorders are prevalent worldwide. However, others suppose there might exist a pathogenic relationship between both disorders and some even suspect that NCC, by acting as an initial precipitating injury (IPI), might cause hippocampal damage and, eventually, MTLE-HS. In this review, we discuss the various reports that examine this association, and suggest possible explanations for why calcified NCC lesions are also observed in patients with MTLE-HS. We also propose mechanisms by which NCC could lead to MTLE-HS. Finally, we discuss the implications of NCC for the treatment of pharmacologically-resistant focal epilepsies in patients with calcified NCC or in patients with MTLE-HS and calcified NCC lesions. We believe that investigations in the relationship between NCC and MTLE-HS might offer further insights into how NCC may trigger epilepsy, and into how MTLE-HS originates. Moreover, observations in patients with drug-resistant epilepsy with both NCC and hippocampal sclerosis may not only aid in the understanding and treatment of patients with MTLE-HS, but also of patients with other forms of dual pathologies aside from NCC. This article is part of a Special Issue titled Neurocysticercosis and Epilepsy.

Neurocysticercosis in a rural population with extensive pig production in Angónia district, Tete Province, Mozambique

Neurocysticercosis (NCC) is an important neurological disease in countries with high prevalence of Taenia solium infection and is emerging as a serious public health and economic problem. The aim of this study was to estimate the prevalence of NCC in Angónia district, Tete province, Mozambique based on: prevalence of human T. solium cysticercosis assessed by antigen Enzyme-linked Immunosorbent Assay (Ag-ELISA) seropositivity, history of epilepsy, and brain computed tomography (CT) scan results. A cross sectional study was conducted between September and November 2007 in Angónia district. Questionnaires and blood samples were collected from 1,723 study subjects. Brain CT-scans were carried out on 151 study subjects with confirmed history of epilepsy. A total of 77 (51.0% (95% CI, 42.7–59.2)) and 38 (25.2% (95% CI, 18.5–32.9)) subjects met the criteria for definitive and probable diagnosis of NCC, respectively. T. solium Ag-ELISA seropositivity was found in 15.5% (95% CI, 12.8–16.2) of the study subjects. The estimated life time prevalence of epilepsy was 8.8% (95% CI, 7.5–10.2). Highly suggestive lesions of NCC were found on CT-scanning in 77 (71.9%, (95% CI, 62.4–80.2)) of the seropositive and 8 (18.1%, (95% CI, 8.2–32.7)) of the seronegative study subjects, respectively. The present findings revealed a high prevalence of NCC among people with epilepsy in Angónia district. Determination of effective strategies for prevention and control of T. solium cysticercosis are necessary to reduce the burden of NCC among the affected populations.

Pathogenesis of Taenia solium taeniasis and cysticercosis

Taenia solium infections (taeniasis/cysticercosis) are a major scourge to most developing countries. Neurocysticercosis, the infection of the human nervous system by the cystic larvae of this parasite, has a protean array of clinical manifestations varying from entirely asymptomatic infections to aggressive, lethal courses. The diversity of clinical manifestations reflects a series of contributing factors which include the number, size and location of the invading parasites, and particularly the inflammatory response of the host. This manuscript reviews the different presentations of T. solium infections in the human host with a focus on the mechanisms or processes responsible for their clinical expression.

Longer epilepsy duration and multiple lobe involvement predict worse seizure outcomes for patients with refractory temporal lobe epilepsy associated with neurocysticercosis

OBJECTIVE

To investigate the surgical outcomes of temporal lobe epilepsy associated with hippocampal sclerosis (TLE-HS) and neurocysticercosis (NCC).

METHODS

A retrospective investigation of patients with TLE-HS was conducted in a tertiary center.

RESULTS

Seventy-nine (62.2%), 37 (29.1%), 6 (4.7%), and 5 (3.9%) patients were Engel class I, II, III, and IV, respectively. Fifty-two (71.2%) patients with epilepsy durations ≤ 10 years prior to surgery were seizure-free 1 year after the operation compared to 27 (50.0%) patients with epilepsy durations > 10 years (p = 0.0121). Forty-three (72.9%) patients with three or fewer lobes affected by NCC were seizure-free one year after the operation, and 36 (52.9%) patients with more than three involved lobes were seizure-free after surgery (p = 0.0163).

CONCLUSIONS

Longer epilepsy durations and multiple lobe involvement predicted worse seizure outcomes in TLE-HS plus NCC patients.

Anti-Taenia solium monoclonal antibodies for the detection of parasite antigens in body fluids from patients with neurocysticercosis

Neurocysticercosis (NCC), an infection of the brain by Taenia solium (Ts) cysts, is the most common cause of adult-onset epilepsy in developing countries. Serological testing consists primarily of varying methods to detect antibodies in body fluids and more recently antigen (Ag) detection assays to identify individuals or animals with viable parasites. Antigen assays currently in use employ monoclonal antibodies (mAbs) raised against T. saginata, which have known cross reactivity to animal cestodes but are highly specific in human samples. We produced, characterized and tested 21 mAbs raised against T. solium whole cyst antigens, vesicular fluid or excretory secretory products. Reactivity of the TsmAbs against specific cyst structures was determined using immunofluorescence and immunohistochemistry on histological sections of Ts muscle cysts. Four TsmAbs reacted to vesicular space alone, 9 to the neck and cyst wall, one to the neck and vesicular space and 7 to the neck, cyst wall and vesicular space. An in-house ELISA assay to detect circulating Ts antigen, using the TsmAbs as capture antibodies and a rabbit polyclonal anti-Ts whole cyst antibody as a detector antibody demonstrated that eight of the 21 TsmAbs detected antigens in known NCC-positive human sera and three of these also in urine samples. Reactivity was expressed as normalized ratios of optical densities (OD positive control/OD negative control). Three TsmAbs had ratios >10 and five between 2 and 10. The TsmAbs have potential utility for the diagnosis and post-treatment monitoring of patients with viable NCC infections.

Evaluation of activity of triclabendazole against Taenia solium metacestode in naturally infected pigs

OBJECTIVE

To assess the efficacy of triclabendazole (TCBZ) in porcine cysticercosis.

METHODS

Eighteen naturally infected cysticercosis pigs were divided into 3 groups of 6 individuals each. The first group was treated orally with TCBZ at a single dose of 30 mg/kg of body weight, the second group was treated orally with oxfendazole at a single dose of 30 mg/kg of body weight and the third group received a placebo (control group). All animals were kept under the same management conditions. The pigs were euthanized 17 wk post-treatment and the number of surviving cysts in muscles was assessed and compared between groups.

RESULTS

All pigs treated with oxfendazole had only degenerated cysts in their carcasses. In contrast, TCBZ had very little effect against the parasitic cysts. Cysts from pigs in the TCBZ group looked apparently normal after treatment. However, histological evaluation showed a mild to moderate degree of inflammation.

CONCLUSIONS

TCBZ is not an efficacious drug against Taenia solium cysticercosis in swine using a single dose.

Spinal Taenia solium cysticercosis in Mexican and Indian patients: a comparison of 30-year experience in two neurological referral centers and review of literature

OBJECTIVE

To present a retrospective study from patients with spinal cysticercosis (SC), diagnosed within the last 30 years in Mexican and Indian neurological referral centers.

METHODS

This is a retrospective and comparative study of the clinical and radiological profile between Mexican and Indian patients with spinal neurocysticercosis during a 30-year period and a review of the literature during the same period.

RESULTS

Twenty-seven SC patients were included: 19 from Mexico and 8 from India. SC presented predominantly with motor symptoms (21/27 patients): paraparesis and paraplegia were the most common signs; one-third of patients presented sphincter dysfunction. Imaging studies showed that parasites in vesicular stage were more frequent in patients from Mexico, while degenerative stages predominated in India. Association of subarachnoid cysticerci and hydrocephalus was observed only in Mexican patients.

CONCLUSIONS

Despite the limitations of this study, the collected information supports the existence of differences in the clinical and radiological traits of SC patients between Asian and Latin-American hospitals. The possible biological factors that may underlie these differences are discussed.

Managing neurocysticercosis: challenges and solutions

Taenia solium neurocysticercosis (NCC) is a major cause of neurological morbidity in the world. Variability in the neuropathology and clinical presentation of NCC often make it difficult to diagnose and manage. Diagnosis of NCC can be challenging especially in endemic and resource-limited countries where laboratory and imaging techniques are often lacking. NCC management can also be challenging as current treatment options are limited and involve symptomatic agents, antiparasitic agents, or surgery. Although antiparasitic treatment probably reduces the number of active lesions and long-term seizure frequency, its efficacy is limited and strategies to improve treatment regimens are warranted. Treatment decisions should be individualized in relation to the type of NCC. Initial measures should focus on symptomatic management, with antiparasitic therapy only to be considered later on, when appropriate. Symptomatic treatment remains the cornerstone in NCC management which should not only focuses on epilepsy, but also on other manifestations that cause considerable burden (recurrent headaches, cognitive decline). Accurate patients’ categorization, better antiparasitic regimens, and definition of new clinical outcomes for trials on NCC could improve management quality and prognosis of NCC. Prevention strategies targeting tapeworm carriers and infected pigs are yielding good results in local models. If local elimination of transmission is confirmed and replicated, this will open the door to cysticercosis eradication efforts worldwide.

Recent advances and perspectives in molecular epidemiology of Taenia solium cysticercosis

Cysticercosis caused by accidental ingestion of eggs of Taenia solium is spreading all over the world through globalization and is one of the most neglected, neglected tropical diseases (NTDs) or neglected zoonotic diseases (NZDs). In the present study, the reason why T. solium cysticercosis has been neglected is discussed at first, and followed with an overview on the most recent advances and perspectives in molecular approaches for epidemiology of T. solium taeniasis/cysticercosis, since although taeniasis does not constitute recognized zoonoses, transmission and complete development are dependent on human definitive hosts. Main topics are discussions on (1) the two, Asian and Afro/American, genotypes of T. solium, (2) comparative analysis of mitochondrial (haploid) and nuclear (diploid) genes, and (3) the presence of hybrids of these two genotypes which indicates out-crossing of two genotypes in hermaphrodite tapeworms in Madagascar. Additional topics are on (4) the usefulness of phylogeographic analyses to discuss where the infection was acquired from, and (5) miscellaneous unsolved topics around these genetic diversity of T. solium.

Neurocysticercosis

Neurocysticercosis is the commonest parasitic disease of the nervous system in humans, and constitutes a major public health problem for most of the developing world. The clinical manifestations of Neurocysticercosis (NCC) largely depend on number of lesions, site, and host immune response against the parasite. Diagnosis is mainly based upon neuro imaging studies and is supported by antibody/antigen detection in the serum and occasionally the cerebrospinal fluid. Randomized controlled trials evaluating the clinical benefit of treatment with cysticidal agents have shown hastened resolution of lesions in most, and reduced seizure recurrence in some studies. Outcome is favourable in single lesion parenchymal NCC but is guarded in multiple lesion and extra parenchymal NCC.

Neurocysticercosis: A natural human model of epileptogenesis

OBJECTIVE

To develop a better understanding of mechanisms of seizures and long-term epileptogenesis using neurocysticercosis.

METHODS

A workshop was held bringing together experts in epilepsy and epileptogenesis and neurocysticercosis.

RESULTS

Human neurocysticercosis and parallel animal models offer a unique opportunity to understand basic mechanisms of seizures. Inflammatory responses to degenerating forms and later-stage calcified parasite granulomas are associated with seizures and epilepsy. Other mechanisms may also be involved in epileptogenesis.

SIGNIFICANCE

Naturally occurring brain infections with neurocysticercosis offer a unique opportunity to develop treatments for one of the world's most common causes of epilepsy and for the development of more general antiepileptogenic treatments. Key advantages stem from the time course in which an acute seizure heralds a start of the epileptogenic process, and radiographic changes of calcification and perilesional edema provide biomarkers of a chronic epileptic state.

Clinical symptoms, diagnosis, and treatment of neurocysticercosis

The infection of the nervous system by the cystic larvae of Taenia solium (neurocysticercosis) is a frequent cause of seizure disorders. Neurocysticercosis is endemic or presumed to be endemic in many low-income countries. The lifecycle of the worm and the clinical manifestations of neurocysticercosis are well established, and CT and MRI have substantially improved knowledge of the disease course. Improvements in immunodiagnosis have further advanced comprehension of the pathophysiology of this disease. This knowledge has led to individualised treatment approaches that account for the involvement of parenchymal or extraparenchymal spaces, the number and form of parasites, and the extent of degeneration and associated inflammation. Clinical investigations are focused on development of effective treatments and reduction of side-effects induced by treatment, such as seizures, hydrocephalus, infarcts, and neuroinjury.

Neurocysticercosis: an update

Neurocysticercosis (NCC) is the most common helminthic disease of the nervous system in humans and a major cause of acquired epilepsy worldwide. The presentation of the disease is dependent on both the immunological response of the host against the parasite as well as the location of the encysted organisms within the central nervous system (CNS). The principles of management utilized for intraparenchymal disease cannot be applied to extraparenchymal NCC. An advance in management of intraparenchymal NCC, the most common form encountered by physicians, is the use of both albendazole and praziquantel as a treatment strategy. Patients with subarachnoid NCC (SANCC) require months of treatment with both an antiparasitic agent and steroids to avoid complications such as hydrocephalus and vascular events during treatment. The determinants of successful treatment in SANCC have not been established, but response to therapy can be determined by evaluating several endpoints related to disease evolution including radiographic changes, serum antigen, and CSF antigen. Intraventricular NCC is primarily a surgical disease and data supports minimally invasive endoscopic removal of cysts in many of these patients. NCC is increasingly recognized in non-endemic countries due to increased immigration making it important for physicians to become familiar with the management of this disease.