AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

Taeniasis and cysticercosis remain a global public health problem in both the developing and developed countries. Infection is becoming increasingly common in the latter because of the increasing immigration and more frequent travel to regions of endemic disease. These parasitic diseases are related to poverty and poor sanitary infrastructure. Therefore, cysticercosis has been designated as a biological marker of the social and economic development of a community.

Neurocysticercosis (NC) commonly is associated with clinical manifestations such as seizures, headache, and focal neurological deficits, and may lead to long-term neurological sequelae such as epilepsy, hydrocephalus, and dementia. The pleomorphism of NC makes its diagnosis impossible on clinical grounds alone. An accurate diagnosis is possible only after suspicion on epidemiologic grounds, proper interpretation of clinical data, and synthesis of findings on neuroimaging studies specific immunologic tests on the cerebrospinal fluid (CSF).

Biology

Humans are the only known host to harbor the adult cestode parasite, Taenia solium, in the intestine. Infection is acquired by ingesting undercooked pork infected with Taenia larvae (ie, cysticerci). The cysticerci evaginate into the intestines where they mature into adult worms. The worms consist of a scolex, which attaches itself to the intestinal wall, and numerous proglottids (ie, segments). Proglottids and eggs are shed intermittently into the stool.

The intermediate host, typically the pig, is infected by ingesting parasite eggs or proglottids containing eggs (ie, porcine cysticercosis). The oncospheres escape from the eggs, penetrate the intestinal mucosa, migrate through the bloodstream, and lodge in the tissues. Over weeks to months, they evolve into larvae that enlarge and mature into cysticerci. The life cycle is completed when humans ingest pork contaminated with the cysts.

Human cysticercosis is acquired after eating food contaminated with fertilized eggs excreted in the feces of Taenia carriers. In humans, the most common routes of infection are ingestion of T solium eggs from contaminated food and rarely from fecal-oral autoinfestation from patients harboring the adult parasite in their intestines. While the cysts can develop in any human tissue, they have a predilection for the central nervous system (CNS), skeletal muscle, subcutaneous tissue, and eyes.

Immune response

In humans and pigs, the cysticerci may live within the host tissue without causing inflammation or disease. The immune response is unpredictable and may vary from a complete tolerance to an intense immune response. A single patient may show an intense inflammation around a cyst at any stage of the degeneration process, together with viable cysts with lack of inflammation and several calcifications scattered in the brain. Autopsies of victims of warfare and road/traffic accidents have revealed that a large proportion of NC infection is asymptomatic and discovered incidentally at necropsy. Individuals who undergo computed tomography (CT) of the head for unrelated reasons (eg, head injury) may demonstrate multiple parenchymal calcifications.

Several studies have analyzed the mechanisms of the immune response elicited against T solium cysticercus, such as the heterogeneity of the humoral immune response, the existence of immune evasive mechanisms, and the fact that the immune response can both protect and harm the host.

The humoral immune response to antigens of T solium cysticerci is evident from the number of immunodiagnostic assays that have been developed using different types of antigens. Several immunoglobulin (Ig) classes are produced as specific antibodies against the parasite. The most frequent is immunoglobulin G (IgG), which can be detected in serum, CSF, and saliva and suggests that infection is of long duration. The immune response against T solium cysticerci appears to have components of both T helper type 1 cells (Th1) and T helper type 2 cells (Th2), although the underlying mechanisms are yet to be clarified. The parasite is probably killed by eosinophils, which are attracted to the site by lymphoid cells. It is assumed that this specific response is mediated by Th2 cytokines.

Pathophysiology

The natural history of cysticerci in the CNS is not entirely understood. CT scan and magnetic resonance imaging (MRI) have been useful in the study of the evolution of the cysticercus within the brain parenchyma. MRI is more useful than CT scan in detecting intraventricular and subarachnoidal cysts, as well as the accompanying signs of cyst degeneration and pericystic inflammatory reaction. However, CT scan is preferred for detection of parenchymal calcifications.

Once the oncosphere has passed into the parenchyma, it grows and evolves through vesicular, colloidal, nodular-granular, and calcified phases. In the vesicular phase, the host tends to show immune tolerance, and, in most cases, no surrounding parenchymal reaction occurs. The larva lives inside a translucent liquid-filled cystic structure surrounded by a thin membrane, where it can remain viable from a few months to several years. When the larva is viable, the CT scan depicts circumscribed, rounded, hypodense areas, varying in size and number, without enhancement by contrast medium (Images 1-2). The average size of the cysts is 10 mm in diameter, but they range from 4-20 mm.

On MRI, the vesicular larva appears as CSF-like intensity signal on all sequences (Image 1), with no surrounding high signal on T2-weighted images. Both MRI and CT scan may show a high intensity, 2-4 mm mural nodule, depicting the scolex in the interior of some parenchymal vesicular cysts (Image 1). This picture could be considered pathognomonic of cysticercosis, and it corresponds to the active parenchymal form of NC. Two phases of pathologic changes take place when the host-immune system reacts to the parasite.

Colloidal phase

In this phase, the parasite begins to show degenerative changes, the vesicular fluid takes on a gelatinous colloidal aspect, and the wall thickens. The contrast-enhanced CT scan shows an annular enhancement surrounded by irregular perilesional edema. On MRI, the capsule shows higher signal than the adjacent brain with thick-ring enhancement on T1-weighted images, while on T2-weighted images a low-ring signal surrounded by high signal lesion is seen (Images 1-2).

Nodular-granular phase

In this phase, the vesicle tends to shrink, and its contents become semisolid, being progressively replaced by granulomatous tissue. These findings could correspond to a diffuse hypodense area with irregular borders on noncontrast CT scan. Following administration of contrast medium, a small, hyperdense, rounded, nodular image surrounded by edema is observed (Images 2-3). In this stage, T2-weighted images depict the most striking picture of these lesions, as they show a change in the signal from the cyst fluid.

These 2 consecutive phases correspond to an intermediate stage named transitional form, inasmuch as the cysticercus has entered into a degenerative process. Although these pathologic changes generally are associated with symptoms (eg, seizures, headaches), some patients with these changes remain asymptomatic. The cysts in the transitional phase may be single or multiple. If multiple, and coexisting with other cysts in the vesicular phase and disseminated calcified nodules in the cerebral parenchyma, the most likely diagnosis is NC (Image 1). However, when only one cyst is seen in the transitional phase, it corresponds to the so-called "single enhancing lesion on CT" (SECTL) (Images 2-3), signifying a special syndrome.

When the parasite dies, a mineralization and resorption process occurs that ends in a calcified nodule that lodges permanently in the CNS. Noncontrast CT scan shows a rounded, homogeneous hyperdense area showing no enhancement with contrast medium (Images 1-2). This phase corresponds to the inactive parenchymal form of NC.

The parasite in the active stage may remain viable from a few months to several years. The transitional stage may last about 3-12 months or longer, usually 4-6 months. Finally, the dead parasite is reabsorbed, or it calcifies and lodges permanently in the CNS.

A NC form with different clinical and radiologic characteristics from those already described is termed "cysticercotic encephalitis." It occurs primarily in children and young women. The noncontrast CT image shows diffuse and intense cerebral edema and small or collapsed ventricles. Contrast-enhanced images show multiple, small, hyperdense, nodular or annular images disseminated throughout the whole cerebral parenchyma (Image 4).

When the parasites are located in the subarachnoidal space or inside the ventricular system, the clinical course also varies from the typical presentation. Being immersed in a CSF-rich environment, the cysticerci evolve into the racemose form of NC.

Racemose form

The racemose form constitutes a hydropic change that leads to large or even giant vesicles usually devoid of a scolex. These racemose cysts show a rapid process of hyalinization of the cyst wall. They are located most frequently either in the basal cisterns or inside the sylvian valley, and they can be as large as 100 mm in diameter. Noncontrast CT scans depict hypodense images in the subarachnoid or ventricular space. The cysts deform the surrounding structures, and a noncommunicating hydrocephalus occurs.

MRI shows the cyst more precisely as a hypointense CSF-like image in all the phases (proton or T2 weighted). It permits direct visualization of the intraventricular cysticerci by identifying the cyst wall, scolex, or both. The ventricular ependymal lining reacts to the cysts and an inflammatory reaction or ependymitis occurs, which can be visualized on CT scan or MRI as a high-intensity signal in the ependymal layer. When the parasite is located in the subarachnoid space, it can cause a meningeal inflammatory process, with pleocytosis and increased protein in the CSF. The parasite degenerates to a hyaline mass and remains trapped inside the gummatous thickening of the leptomeninges. As a sequel to the chronic intense inflammatory process, fibrosis and thickening of the leptomeninges also may lead to chronic hydrocephalus. Vasculitis with secondary ischemic lesions may be noted.

Classification of NC

Carpio proposed an improved and widely accepted classification system based on the viability and location of the parasite in the host CNS.

• Active, when the parasite is alive
• Transitional, if it is in the degenerative phase
• Inactive, if evidence of its death is apparent

Each viability category is subdivided into parenchymal and extraparenchymal forms. On the basis of this classification, relating clinical manifestations to each category of the proposed classification is possible. No definitive data exist regarding the duration of individual stages. Anecdotal evidence indicates that, once the parasite lodges in the brain, it may remain viable from months to years. The transitional phase lasts 4-6 months. Finally, the dead parasite is resorbed or it calcifies and lodges permanently in the CNS.

Frequency

United States

Traditionally NC has been considered an exotic disease in the United States. This infection now accounts for as many as 2% of neurologic and neurosurgical admissions in southern California. More than 1000 cases are reported per year in the United States. Persons who have never left the United States are at risk as well as visitors to disease-endemic regions. An outbreak of cysticercosis among orthodox Jews living in New York City was reported after food was contaminated with T solium eggs by immigrant cooks infected with the pork tapeworm. The Centers for Disease Control and Prevention (CDC) considers NC an emerging infection, and they are developing programs to track and hopefully eradicate the condition.

International

NC is the most common neurological infection in the world. NC is endemic in much of the developing world. Most publications on the frequency of NC are based either on autopsy or biopsy materials or on data culled from neurologic settings and general hospitals. These data are hardly representative of the general population.

T solium is endemic in Latin America, India, and China, and it also may be endemic in sub-Saharan Africa. In countries where the disease is endemic, NC is also widely prevalent in the urban middle class areas.

Epidemiological surveys for human cysticercosis, using immunoserologic assays, such as the enzyme-linked immunoelectrotransfer blot assay (EITB) or the enzyme-linked immunosorbent assay (ELISA) have been explored. These assays are useful for identification of individuals who have had systemic contact with the parasite at some time. However, seropositivity does not necessarily mean an active systemic infection or CNS involvement at any time.

EITB assays report a seroprevalence from 8-12% in some regions of Latin America. Most seropositive individuals in these populations are asymptomatic. No prospective studies provide information on the proportion of seropositive individuals that will develop seizures or other neurological symptoms. Some studies, but not all, have reported an association between seizures and seropositivity. Although a higher proportion of patients with epilepsy have been shown to be EITB positive when compared to those without epilepsy, the proportion of seropositivity in epileptic patients is similar to that reported in the general population in these same areas.

Recent epidemiological studies have shown that persons engaged in household contacts with patients with NC had a risk of positive serology for cysticercosis that was 3 times higher than the general population. While these findings are still consistent with a common environmental source of infection with T solium eggs, they also suggest a potential for direct human-to-human contamination.

Mortality/Morbidity

No reliable information is available regarding mortality rates. This is probably because a large percentage of patients (perhaps as many as 50%) with NC are asymptomatic. Most patients with parenchymal NC have a benign clinical cause. However, patients with subarachnoidal cysticercosis (approximately 10-15%, including intraventricular cysts) may develop complications such as vasculitis and hydrocephalus.

• Permanent neurological deficits may result secondary to infarction in the case of vasculitis, and high mortality rates or severe clinical morbidity such as dementia may result from hydrocephalus.
• Hydrocephalus has been reported as a complication (8%) of treatment of NC with albendazole or praziquantel.
• Anecdotal reports have circulated concerning patients with intraventricular cysts who experienced sudden death due to acute obstruction of the intraventricular system, particularly the aqueduct of Sylvius.

Race

No racial risks or protection are known in cestode infestation.

Sex

Men and women are affected similarly. However, cysticercotic encephalitis, one of the most severe forms of NC, is seen more frequently in young women than in men.

Age

• NC has been reported in all age groups. The most frequent presentation occurs in the third and fourth decades of life.
• Reports of cysticercosis are very unlikely in children younger than 2 years of age because of the prolonged incubation period of T solium. Most often, the disease is recognized in children older than 7, due to this incubation period.
• The clinical course of NC in children is usually benign and self-limited and the prognosis good.

CLINICAL

Section 3 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

History

• NC is frequently asymptomatic. Cysticercosis of other tissues is almost always asymptomatic.
• Clinical manifestations of NC are variable and dependent on the number and location of cysts as well as the host-immune response to the parasite.
• The most frequent clinical manifestations are the following:
• • Seizures
  • Intracranial hypertension
  • Focal neurological deficits
  • Mental changes
• A myriad of syndromes have been described, including brainstem dysfunction, cerebellar ataxia, sensory deficits, involuntary movements, stroke, dementia, and hydrocephalus.
• Ten percent of patients present with ventricular cysts, with seizures, or with meningeal inflammation.
• Symptoms include nausea, vomiting, headache, ataxia, and confusion.
• Most of these clinical manifestations develop over a period of a few days, weeks, or months, with periods of remission and relapse, probably due to different evolutionary stages of the parasite.

Physical

• No pathognomonic physical findings unmistakably identify a patient with NC. Virtually any neurological sign or symptom can occur, depending on the CNS location of the parasite.
• Patients with cysts in the basal cisterns can present with meningeal signs, hydrocephalus, vasculitis, and stroke.
• Cysticercal encephalitis with multiple parenchymal cysts (ie, associated inflammatory response, diffuse cerebral edema) is a rare presentation often seen in young girls. These patients are at a risk of developing severe neurological sequelae.
• In patients with seizures, SECTL or hyperintense lesions on MRI are a common finding. The lesion is usually small, about 5-10 mm, well defined, annular or nodular, contrast enhancing, cortical or subcortical, and generally associated with perilesional edema and minimal mass effect, but without midline shift (Image 3). These patients, mainly children and young adults, have some benign and transitory clinical manifestations, predominantly partial or partial secondary generalized seizures, and occasionally Todd paresis or focal neurological deficits.

Causes

• Risk factors associated with the disease include the following:
• • Immigration from areas of endemic disease
  • Family history of parasitic infestation
  • Household visitors from an endemic area
  • History of travel to an endemic area
• Other diagnostic considerations
• • Focal signs may occur abruptly in patients who develop a cerebral infarction as a complication of subarachnoid NC.
  • Some manifestations of spinal NC are nonspecific, and the differential diagnosis with other diseases of the spinal cord is difficult on clinical grounds.
  • Arachnoiditis is characterized by root pain and weakness of subacute onset. Cysts in the spinal cord parenchyma usually occur with motor and sensory deficits that vary according to the level of the lesion.
  • Diffuse muscle involvement may result in a pseudohypertrophic myopathy. Patients have diffuse swelling of the muscles mimicking hypertrophy, myalgia, and muscle weakness.

DIFFERENTIALS

Section 4 of 11  

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• Clinical
• Differentials
• Workup
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• Follow-up
• Miscellaneous
• Multimedia
• References

Other Problems to be Considered

Blastomycosis
Chronic meningitis
Histoplasmosis
Postinfectious vasculitis
Spinal cysts

WORKUP

Section 5 of 11  

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• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• Laboratory studies are inferior to imaging in the diagnosis of cysticercosis but may play an adjunctive role.
• On complete blood count (CBC), peripheral eosinophilia is usually not present, but eosinophils may comprise 10-15% of white blood cells (WBCs).
• Immunoserologic assays may be useful.
• • Immunoserologic assays, such as EITB or enzyme-linked immunosorbent assay (ELISA) can detect antibodies against T solium or cysticercus and are useful in identifying the population at risk of contact with the parasite.
  • These assays demonstrate a potential impact of cysticercosis on public health, but clinicians should be aware that the presence of antibodies in the host against both T solium and/or cysticercus does not necessarily indicate that an individual has active neurocysticercosis.
  • In ELISA, cross-reactions with other helminthic infections may occur.
  • An EITB using specific glycoprotein antigens was developed for the immunodiagnosis of human cysticercosis, the sensitivity and specificity of which are reported to be high (98% and 100%, respectively). Another study confirmed these results in patients with 2 or more cysts shown by CT scan or MRI (94% sensitivity), but sensitivity was markedly low in patients with single enhancing cysts and calcifications (28%).
  • ELISA and EITB are performed in many (but certainly not all) laboratories in the United States.
• Immunologic techniques for the detection of anticysticercal antibodies in the CSF are more reliable than those performed in serum.
• • However, the accuracy depends on the viability of cysticerci and their location within the CNS.
  • EITB are used mainly in serum samples. The complement fixation test and the ELISA in the CSF are highly sensitive and specific in cases of subarachnoidal NC.
  • Sensitivity decreases considerably when the lesions are calcified or when viable parenchymal cysts are not in contact with the subarachnoid space.

Imaging Studies

• The only truly reliable standard for diagnosing NC is pathologic confirmation through biopsy or autopsy. Nevertheless, even without definitive scientific data, CT scan and MRI are considered the main tools for the diagnosis of NC.
• Multiple calcifications disseminated in the parenchyma simultaneously with viable cysts and transitional stage lesions are a typical finding on imaging studies in NC.
• The relationship between imaging studies and the anatomopathologic changes has been well described. It can be summarized with the following recommendations:
• • Brain CT scan should be obtained as a first imaging study. CT is more widely available, less expensive, and has a faster imaging time than MRI. Contrast and noncontrast studies should be obtained.
  • Noncontrast studies will show calcification of inactive cysts, which is the most common disease form at presentation.
  • Contrast studies will show ring enhancement, signifying edema surrounding the involuting live cysticercus.
• MRI is recommended as an adjunctive diagnostic tool.
• • Demonstration of viable cystic lesions with a mural nodule (ie, the invaginated scolex) associated with transitional or degenerative cysts and calcifications corresponds to a typical image of cysticercosis (see Image 1). However, this typical imaging is not necessarily the most frequent one. Conversely, single enhancing lesions are probably more common, especially in children
  • MRI is a superior imaging study for intraventricular or subarachnoid cysts, while CT is better for calcification of inactive lesions.
• Lesions at different stages are not uncommon. Multiple calcifications disseminated in the parenchyma with viable cysts and transitional stage lesions are actually the rule as opposed to the exception in NC.
• Soft tissue x-ray: Plain films may show calcification of inactive cysts.

Other Tests

• Electroencephalography: EEG may be normal or may show focal or generalized abnormalities.
• Stool for ova and parasites: Many patients will have simultaneous intestinal tapeworm infestation. The test is nonspecific for T solium species.
• • Serologic-based assay: An immunoblot assay, EITB-T, has been developed for detection of human taeniasis carriers. It uses coproantigens of adult T solium tapeworms. The results from studies that use coproantigen detection have indicated that these assays are considerably more sensitive than microscopy.

Procedures

• Biopsy of a subcutaneous nodule or muscle lesion: Demonstration of the organism is diagnostic of cysticercosis.
• Brain biopsy: Brain biopsy is not justified in a suspected NC lesion. In addition to the obvious morbidity (and possibly mortality) associated with this procedure, the cysts can reduce spontaneously. Moreover, cysts can resolve in response to anticysticercal therapy. Finally, waiting 1-2 months and repeating the CT scan or MRI can clarify the diagnosis.
• Lumbar puncture
• • Lumbar puncture should be performed when arachnoiditis is suspected (ie, headache, cranial nerve palsies, cognitive changes).
  • Inflammatory changes in the CSF are largely related to the extraparenchymal location, especially with arachnoiditis. The most consistent finding is moderate mononuclear pleocytosis, usually not exceeding 200-300 cells/mm³. Protein levels are also raised to within the range of 50-200 mg/dL. CSF glucose levels are normal or moderately low. These CSF abnormalities may be difficult to distinguish from those of granulomatous infections such as tuberculosis meningitis.
  • This test is insensitive and nonspecific in the diagnosis of cysticercosis.
• An imaging study should be done prior to lumbar puncture to exclude an intracranial mass lesion.

Histologic Findings

• Macroscopic and microscopic pathology
  • Cysticercus cellulosae presents a characteristic rounded and ovoid form of about 4-20 mm in length (Image 5) covered by a thin membrane surrounding hyaline liquid. It invaginates in some sites of the membrane, giving origin to the scolex (Image 6), which is constituted by a neck, 4 suckers, and a double crown of hooks.
  • The cysts usually are located in the gray matter due to the richer vascularization of this tissue, and in the subcortical white matter (Image 7). In severe cases of parenchymal cysticercosis, the number of parasites may reach several hundreds, but commonly only a scattered few are seen. Cysts also may be found in the subarachnoidal location, and less frequently inside the ventricles and in the spinal cord.
  • The parasite produces an inflammatory reaction composed of a conglomerate of round mononuclear lymphocytic and plasma cells. Some of the inflammatory cells are found around the perivascular spaces in the adjacent nervous tissue. A variable number of eosinophils are also present; this eosinophilic reaction is highly variable and occurs in almost every patient (Image 8).

TREATMENT

Section 6 of 11  

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• Follow-up
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Medical Care

• Because of the variable clinical course of the disease, treatment must be individualized for each patient.
• Symptomatic treatment (Image 9) includes corticosteroids for intracranial edema and inflammation, antiepileptic drugs for secondary acquired epilepsy, analgesic medication for headache, and osmotic agents such as mannitol or glycerol for intracranial hypertension.
• Antiepileptic treatment
• • First seizures due to inflamed cysticercal lesions should be considered acute symptomatic seizures. Therefore, they should be treated only for the duration of the acute condition. However, treatment may be continued during the period when the inflammatory response is active, which might last several months.
  • No guidelines exist for the time for which antiepileptic drugs (AED) should be continued following an acute neurocysticercosis episode. The risk of seizures is substantial as long as an active ongoing process, as characterized by persistence of edema around the degenerating lesion, is present. Because of this risk, CT scans are useful for treatment decisions.
  • Seizures in the context of edema and a degenerative lesion should be considered acute symptomatic seizures, even if they occur many months after presentation. After resolution of the acute lesion, AED administration may be discontinued.
  • Seizures occurring after resolution of edema or calcification of the degenerating cyst should be considered unprovoked, and, in this situation, long-term AED administration is warranted (see Image 10). Other authors also suggest that AED administration can be safely withdrawn once the follow-up CT scan shows resolution of the lesion.
• Anthelmintic treatment
• • Clinical controversy has centered on the role of cysticidal agents for the treatment of symptomatic NC. Cysticidal agents in current use for NC include praziquantel and albendazole. However, no evidence exists to indicate that cysticidal treatment does more good than harm. Cysticidal therapy may hasten radiologic resolution of cysts but can be associated with exacerbation of neurological symptoms; the possibility exists of massive cerebral edema and death in some individuals who have multiple cysts.
  • Some authors have advocated simultaneous administration of steroids to reduce the inflammatory response and exacerbation of symptoms, but the safety of this treatment has not been evaluated fully. In developing countries, most neurologists administer the steroids and anthelmintic drugs at the same time. Some have claimed that more patients remain seizure free after cysticidal treatment. Randomized clinical trials of cysticidal therapy versus placebo for NC have not shown any clinical benefit of cysticidal therapy.
  • A systematic review (Cochrane Collaboration) has been performed using the tools of evidence-based medicine. The objective was to assess the effect of drug treatment in human NC in relation to survival, cyst resolution on imaging studies, subsequent seizures, and hydrocephalus.
  • • The review included randomized or quasirandomized trials comparing an antihelminthic drug (albendazole) with a placebo or a control group receiving symptomatic therapy in patients with NC. Only four studies involving 305 people met the inclusion criteria.
    • A difference just approaching significance was detected between antihelminthic drug and placebo in relation to cyst persistence up to 6 months (relative risk: 0.83; 95% CI: 0.70-0.99).
    • Two trials reported on seizures at 1-2 years follow-up time and found no difference (relative risk: 0.95; 95%CI: 0.59-1.51).
    • In the study by Carpio, no difference was detected for hydrocephalus (relative risk: 2.19; 95%CI: 0.29-16.55).
    • The authors concluded that insufficient evidence was available to assess whether antihelminthic drug is associated with beneficial results in NC.
• No definitive data exist pertaining to combination antihelminthic therapy or whether the use of steroids increases or decreases antihelminthic dosage requirements.

Surgical Care

• Surgical treatment should be restricted to removal of the parasite located in the subarachnoid (racemose form) or ventricular area, and to ventriculoperitoneal shunting for the treatment of decompensated hydrocephalus (Image 9).
• Surgery should not be considered for parenchymal cysts without regard to location, size, or stage of evolution, because this form of NC can be controlled only by symptomatic treatment (or presumably by etiologic treatment). In addition, surgical sequelae could result in more brain damage than the parasite itself.
• Transitional or degenerative cysts, regardless of their size or location (see Image 1 and Image 3), should not be biopsied or removed since the parasite is dead and will disappear or be calcified spontaneously.

MEDICATION

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The goals of pharmacotherapy are to reduce morbidity and prevent complications.

Drug Category: Anthelmintics

Parasite biochemical pathways are sufficiently different from the human host to allow selective interference by chemotherapeutic agents in relatively small doses.

FOLLOW-UP

Section 8 of 11  

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• Follow-up
• Miscellaneous
• Multimedia
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Further Inpatient Care

• Neurosurgical intervention is required only in cases of obstructive hydrocephalus or ventricular or subarachnoid cysticerci.
• Ophthalmic surgery is recommended in all cases of ocular cysticercosis, because the inflammatory reaction to medical therapy may threaten vision.
• Isolation is not required for hospitalized patients.

Further Outpatient Care

• Follow-up CT scan is needed to assess response to medical and surgical treatment.
• Long-term anticonvulsant therapy is usually not necessary.

Deterrence/Prevention

• Family members should be screened for parasitic disease. Attention should be given to personal hygiene.

Complications

• Intracranial herniation
• Stroke
• Status epilepticus
• Hydrocephalus

Prognosis

• Prognosis is excellent in almost all cases. Many investigators affirm that most patients with NC with seizures or epilepsy have a good prognosis. Conversely, in patients with extraparenchymal forms the prognosis is unfavorable, especially those patients with hydrocephalus due to arachnoiditis.
• Recent prospective cohort studies determined the risk of seizure recurrence after a first seizure due to NC and evaluated risk factors for seizure recurrence, including the influence of antihelminthic treatment.
• • Seventy-seven patients were prospectively followed for over 7 years. Thirty-one patients (40.3%) experienced seizure recurrence.
  • Kaplan-Meier estimated recurrence to be 22% at 6 months, 32% at 12 months, 39% at 24 months, and 49% at 48 and 84 months. Treatment with albendazole did not influence recurrence. No significant differences in the Kaplan-Meier curves of recurrence were present when treatment groups were compared (see Image 11).
  • The authors concluded that seizure recurrence is high following a first acute symptomatic seizure due to NC, but this risk seems related to persistence of active brain lesions. Recurrence risk is low and in keeping with seizure risk following other brain insults leading to a static encephalopathy in those in whom the neurocysticercosis lesion clears.

Patient Education

• Education, especially in developing countries, should include the following:
• • Teaching self-diagnosis of taeniasis/cysticercosis; promotion of preventive measures through proper feeding habits
  • Encouragement of general hygiene education
  • Disclosure of relevant information to schools and universities
  • Use of mass media in education
• Veterinary educational activities should include the following:
• • Advise on farm hygiene and on the importance of meat inspection
  • Development of special educational programs for farmers and workers in the meat industry
• Ecological and environmental measures include the following:
• • Improvement of sanitation throughout the country, particularly elimination of open-air defecation by farm workers and peasants
  • Improvement of sewage systems
  • Improvement of methods of animal husbandry

MISCELLANEOUS

Section 9 of 11  

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Special Concerns

• Cysticercosis is a disease of poverty and social underdevelopment.
• Human cysticercosis can be prevented by providing proper sanitary facilities and improving health care and socioeconomic status of the people in developing countries.

MULTIMEDIA

Section 10 of 11  

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• Multimedia
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Media file 1:  Neuroimaging in neurocysticercosis. CT scans showing different phases of neurocysticercosis.Top left: CT scan showing many calcifications and active cysts with scolices in both hemispheres. Top right: T1-weighted MRI showing 2 active cysts with the scolex in their interior (vesicular phase).Bottom left: Postcontrast CT scan showing a ring-enhancing cyst (colloidal phase) on left. Bottom right: Proton density-weighted MRI showing a thick capsule with adjacent scolex and perilesional edema (colloidal phase).
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Media type:  CT

Media file 2:  Neuroimaging in neurocysticercosis. Natural history of neurocysticercosis. Top left: This CT scan shows a large occipital active cyst (vesicle phase), many calcifications, and small cortical cysts. Top right: After 18 months, the occipital cyst has been replaced by a calcification and the remaining cysts have disappeared.Bottom left: A single parietal nodular-enhancing lesion (transitional, nodular-granular phase) is shown.Bottom right: Six months later, the lesion has disappeared.
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Media type:  CT

Media file 3:  Neuroimaging in neurocysticercosis. Noncontrast and contrast-enhanced CT scan of neurocysticercosisLeft: Normal noncontrast CT scanRight: After administration of the contrast medium, the CT scan of the same patient shows a single parietal nodular-enhancing lesion (transitional, nodular phase).
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Media type:  CT

Media file 4:  Neuroimaging in neurocysticercosis. Cysticercotic encephalitis. Left: Contrast-enhanced CT scan showing multiple, small, nodular, and annular areas of abnormal enhancement in brain parenchyma. Right: Gadolinium-enhanced T1-weighted MRI showing hyperintense lesions.
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Media type:  MRI

Media file 5:  Neuroimaging in neurocysticercosis. Cysticercus cellulosae in neurocysticercosis.
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Media type:  Photo

Media file 6:  Neuroimaging in neurocysticercosis. Cysticercus cellulosae showing the invaginated scolex in neurocysticercosis.
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Media file 7:  Neuroimaging in neurocysticercosis. Subcortical parenchymatous cysticercosis
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Media file 8:  Neuroimaging in neurocysticercosis. Inflammatory reaction in parenchymatous cysticercosis.
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Media file 9:  Neuroimaging in neurocysticercosis. Treatment of neurocysticercosis.
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Media file 10:  Neuroimaging in neurocysticercosis. Antiepileptic treatment for patients with first seizure due to neurocysticercosis.
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Media file 11:  Neuroimaging in neurocysticercosis. Probability of seizure recurrence (Kaplan-Meier curve) after a first seizure in patients with NC as function of cysticidal treatment.
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Media type:  Graph

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

• Caplan LR. How to manage patients with neurocysticercosis. Eur Neurol. 1997;37(2):124. [Medline].
• Carpio A, Escobar A, Hauser WA. Cysticercosis and epilepsy: a critical review. Epilepsia. Oct 1998;39(10):1025-40. [Medline].
• Carpio A, Placencia M, Santillan F. A proposal for classification of neurocysticercosis. Can J Neurol Sci. Feb 1994;21(1):43-7. [Medline].
• Carpio A, Santillan F, Leon P. Is the course of neurocysticercosis modified by treatment with antihelminthic agents?. Arch Intern Med. Oct 9 1995;155(18):1982-8. [Medline].
• Carpio A. Neurocysticercosis: an update. Lancet Infect Dis. Dec 2002;2(12):751-62. [Medline].
• Carpio A, Hauser WA. Neurocysticercosis and epilepsy. In, Singh G, Prabhakar S, eds. Taenia Solium Cysticercosis. Oxon, UK:CABI Publis. 2002;211-20.
• Carpio A. Neurophysiological aspects of Neurocysticercosis. In, Reisin R, Nuwer MR, Hallett M, Medina C. Advances in Clinical Neurophysiolog. 2002;490-96.
• Carpio A, Hauser WA. Prognosis for seizure recurrence in patients with newly diagnosed neurocysticercosis. Neurology. Dec 10 2002;59(11):1730-4. [Medline].
• Correa D, Medina-Escutia, E. Host-parasite immune relationship in Taenia solium taeniosis and cysticercosis. In Garcia HH, Martinez, SM eds. Taenia solium Taeniasis/Cysticercosis. 1999;15-24.
• Davis L. Neurocysticercosis and seizures: Avoiding the cost of antihelminthic treatment. Neurology. 2002;59:1669-71.
• Dixon HBF, Lipscomb FM. Cysticercosis: an analysis and follow up of 450 cases. Med Res Council Special Reports. 1961;299:1-58.
• Escobar A. The pathology of neurocysticercosis. Cysticercosis of Central Nervous System. 1983:27-54.
• Estanol B, Corona T, Abad P. A prognostic classification of cerebral cysticercosis: therapeutic implications. J Neurol Neurosurg Psychiatry. Oct 1986;49(10):1131-4. [Medline].
• Flisser A, Correa D, Evans CAW. Taenia solium cysticercosis: New revisited immunological aspects. In, Singh G, Prabhakar S, eds. Taenia Solium Cysticercosis Oxon, UK:CABI Publish. 2002;24-44.
• Garcia HH, Martinez M, Gilman R. Diagnosis of cysticercosis in endemic regions. The Cysticercosis Working Group in Peru. Lancet. Aug 31 1991;338(8766):549-51. [Medline].
• Garg K, Singh K, Misra S. Single-enhancing lesions in Indians patients with seizures: a review. Epilepsy Res. Epilepsy Res. 2002;59:1730-1734.
• Garg RK, Kar AM, Jain S. Failure of albendazole therapy in two common types of parenchymal neurocysticercosis. J Assoc Physicians India. Oct 1995;43(10):706-7. [Medline].
• Goodman KA, Ballagh SA, Carpio A. Case-control study of seropositivity for cysticercosis in Cuenca, Ecuador. Am J Trop Med Hyg. Jan 1999;60(1):70-4. [Medline].
• Kramer LD, Locke GE, Byrd SE. Cerebral cysticercosis: documentation of natural history with CT [published erratum appears in Radiology 1989 Oct;173(1):286]. Radiology. May 1989;171(2):459-62. [Medline].
• Kramer LD. Medical treatment of cysticercosis--ineffective. Arch Neurol. Jan 1995;52(1):101-2. [Medline].
• Manreza ML. Neurocysticercosis in children. Trends in Pediatric Neurology. 1993;295-8.
• Martinez HR, Rangel-Guerra R, Arredondo-Estrada JH. Medical and surgical treatment in neurocysticercosis a magnetic resonance study of 161 cases. J Neurol Sci. May 1995;130(1):25-34. [Medline].
• McCormick GF, Zee CS, Heiden J. Cysticercosis cerebri. Review of 127 cases. Arch Neurol. Sep 1982;39(9):534-9. [Medline].
• Mitchell WG, Crawford TO. Intraparenchymal cerebral cysticercosis in children: diagnosis and treatment. Pediatrics. Jul 1988;82(1):76-82. [Medline].
• Padma MV, Behari M, Misra NK. Albendazole in single CT ring lesions in epilepsy. Neurology. Jul 1994;44(7):1344-6. [Medline].
• Pal DK, Carpio A, Sander JW. Neurocysticercosis and epilepsy in developing countries. J Neurol Neurosurg Psychiatry. Feb 2000;68(2):137-43. [Medline].
• Ramos-Kuri M, Montoya RM, Padilla A. Immunodiagnosis of neurocysticercosis. Disappointing performance of serology (enzyme-linked immunosorbent assay) in an unbiased sample of neurological patients. Arch Neurol. Jun 1992;49(6):633-6. [Medline].
• Salinas R, Prasad K. Drugs for treating neurocysticercosis (Cochrane Review). The Cochrane Database Syst Rev. 2000;(2):CD000215. 2000.
• Schantz PM. Cysticercosis in non-endemic countries: the example of United States. Teniasis/Cysticercosis por T. solium. 1996;277-86.
• Singhal BS, Salinas RA. Controversies in the Drug Treatment of Neurocysticercosis. In, Singh G, Prabhakar S, eds. Taenia Solium Cysticercosis. Oxon, UK:CABI Publis. 2002;713-43.
• Suss RA, Maravilla KR, Thompson J. MR imaging of intracranial cysticercosis: comparison with CT and anatomopathologic features. AJNR Am J Neuroradiol. Mar-Apr 1986;7(2):235-42. [Medline].
• Teitelbaum GP, Otto RJ, Watanabe AT. MR imaging of neurocysticercosis. AJNR. 1989;10:709-18.
• Tsang VC, Brand JA, Boyer AE. An enzyme-linked immunoelectrotransfer blot assay and glycoprotein antigens for diagnosing human cysticercosis (Taenia solium). J Infect Dis. Jan 1989;159(1):100-2. [Medline].
• White AC, Garcia HH. Recent Developments in the Epidemiology, Diagnosis, Treatment, and Prevention of Neurocysticercosis. Curr Infect Dis Rep. Dec 1999;1(5):434-440. [Medline].
• Xiao ZX, Zhao CY, Liu YP. [Albendazole treatment in cerebral cysticercosis]. Chung Hua Nei Ko Tsa Chih. Feb 1986;25(2):100-2, 127. [Medline].
• Zee CS, Segall HD, Destian S. MRI of intraventricular cysticercosis: surgical implications. J Comput Assist Tomogr. Nov-Dec 1993;17(6):932-9. [Medline].

Article Last Updated: Apr 17, 2006