Cysticercosis

Question 1

What the condition of cysticercosis caused by?

Answer 1

Cysticercosis is caused by the larval stage of the tapeworm Taenia solium.

Question 2

What is the estimated global burden of disease of cysticercosis?

Answer 2

Approximately 50 million people worldwide are estimated to have cysticercosis infection, although estimates are probably low since many infections are subclinical and there are relatively few population-based data on prevalence.

Question 3

In which regions is cysticercosis endemic?

Answer 3

Cysticercosis is endemic in many regions of Central and South America, sub-Saharan Africa, India, and Asia.

Question 4

Within its geographic distribution, in which kinds of areas does cysticercosis infection predominate?

Answer 4

The prevalence of cysticercosis varies within these countries and is often higher in rural or periurban areas where pigs are raised and sanitary conditions are suboptimal.

Question 5

How is cysticercosis transmitted?

Answer 5

Cysticercosis is transmitted by ingestion of T. solium eggs shed in the stool of a human tapeworm carrier.

Question 6

What happens once a person ingests T. solium eggs?

Answer 6

Following ingestion, embryos (oncospheres) hatch in the small intestine, invade the bowel wall, and disseminate hematogenously to brain, striated muscles, liver, and/or other tissues. Over a period of three to eight weeks, tissue cysticerci develop; these consist of membranous walls filled with fluid and an invaginated scolex. Cysts located in the brain result in neurocysticercosis; humans with cysticercosis are incidental dead end hosts.

Question 7

How do human beings become T. solium carriers?

Answer 7

Humans become T. solium tapeworm carriers by ingesting undercooked pork containing cysticerci in muscle tissue. Once ingested, the scolex evaginates and attaches to the human small intestine by its suckers and hooks. Proglottids (segments) arise from the base of the scolex, gradually enlarge and are displaced from the neck by new proglottids. Each proglottid segment contains 50,000 to 100,000 eggs.

Question 8

What is the difference between taeniasis and cysticercosis?

Answer 8

A common misconception is that cysticercosis is acquired by eating pork. However, as the life cycle illustrates, ingestion of infected pork only causes adult tapeworm infestation (taeniasis) because infected pork contains the larval cysts that develop into adult worms in human intestine but does not contain the eggs that cause cysticercosis.

Question 9

In terms of prevention, what are the three stages at which infection/transmission can be dealt with?

Answer 9

Taeniasis in humans, cysticercosis in pigs and transmission from humans to humans.

Question 10

How can one prevent taeniasis in humans?

Answer 10

Preventing human tapeworm infection is important for reducing the reservoir of egg carriers and can be done by eliminating human consumption of pork contaminated with viable cysticerci. Methods include:
●Inspection of pork for cysticerci, which are visible in raw meat (“measly meat”).
●Freezing or adequately cooking meat to destroy cysticerci; pickling and salting are not adequate techniques.

Question 11

How can one prevent cysticercosis in pigs?

Answer 11

Preventing the transmission of cysticercal infections to pigs can be accomplished by eliminating access of pigs to human fecal material.

Question 12

How can one interrupt the transmission of eggs between humans?

Answer 12

Reducing transmission — Mechanisms for interrupting the transmission of eggs between humans include:
●Community education regarding routes of transmission
●Good personal hygiene and hand washing prior to food preparation
●Targeted treatment for human tapeworm carriers (perhaps identified by history of proglottid passage)
●Mass community anthelminthic programs to treat tapeworm carriers.

Question 13

What vaccinations are available for T. solium infection?

Answer 13

There is no vaccine for human protection against T. solium.

Question 14

What clinical syndromes are related to cysticercosis?

Answer 14

Clinical syndromes related to this parasite are divided into neurocysticercosis (NCC) and extraneural cysticercosis. Neurocysticercosis, in turn, is divided into parenchymal and extraparenchymal forms. Extraparenchymal forms include intraventricular, subarachnoid, intraocular, and spinal disease.

Question 15

What do the clinical manifestations depend upon and what are the general trends in the clinical manifestations of cysticercosis? What are some less common features?

Answer 15

The clinical manifestations depend upon whether the cysts are localized to the brain parenchyma, the extraparenchymal tissues, or both. In general, parenchymal cysts are associated with seizures and headache, while extraparenchymal cysts are associated with symptoms of elevated intracranial pressure (eg, headache, nausea, and vomiting) and may be accompanied by altered mental status. Other less common manifestations include mass effect, altered vision, focal neurologic signs, altered mental status, and meningitis. Fever is not typically present. Neurologic examination usually does not demonstrate focal signs in the absence of mass effect or stroke.

Question 16

What is the most common form of cysticercosis and how does it manifest?

Answer 16

Parenchymal cystic or enhancing lesions are the most common form of neurocysticercosis (NCC) in hospital-based series and is present in >60 percent of these patients.

Evaluation of imaging studies in endemic areas has suggested that most parenchymal neurocysticercal infections never cause symptoms. However, some small nodular calcifications (usually 1 to 10 mm in diameter) not previously thought to be associated with clinical manifestations may be an important cause of epilepsy.

Question 17

Comment on the clinical manifestations of cysticercal encephalitis.

Answer 17

In the setting of massive numbers of cysts in the brain parenchyma, an intense immune response with diffuse brain edema can cause a clinical picture resembling encephalitis. This syndrome can present with seizures, headache, nausea and vomiting, impaired consciousness, reduced visual acuity, and occasionally fever. It can occur spontaneously or can be provoked by therapy that causes a large number of cysts to degenerate simultaneously. This manifestation is most common in children and young women.

Question 18

Write brief notes on the clinical manifestations of intraventricular NCC.

Answer 18

Cysticerci develop in the ventricular system (as free floating cysts in the ventricular cavity or attached to the choroid plexus) in 10 to 20 percent of patients presenting for clinical attention. Symptoms typically develop when cysticerci become lodged in the ventricular outflow tracks, with consequent obstructive hydrocephalus and increased intracranial pressure of gradual or acute onset. Associated symptoms include headaches, nausea and vomiting, altered mental status, and decreased visual acuity associated with papilledema. Less frequent symptoms include seizures and focal neurologic signs. Mobile cysts in the third or fourth ventricle can occasionally cause intermittent obstruction, leading to episodes of sudden loss of consciousness related to head movements (Bruns’ syndrome).

Question 19

Write short notes on the clinical manifestations of subarachnoid NCC.

Answer 19

Cysticerci that lodge in the subarachnoid space of the fissures or basilar cisterns can generate an inflammatory response leading to chronic arachnoiditis, which may be accompanied by hydrocephalus, meningitis, stroke, and vasculitis.

Secondary occlusion of the foramina of Luschka or Magendie can lead to obstructive hydrocephalus. In addition, meningeal inflammation and leptomeningeal thickening at the base of the brain can lead to visual field defects and cranial nerve palsies due to entrapment of the cranial nerves arising from the brainstem. Vascular involvement can lead to proliferative angiitis and vascular obstruction with secondary cerebral infarcts. Focal neurologic motor signs, ataxia, and sensory dysfunction can ensue; this presentation tends to be associated with a relatively poor prognosis.

Cysticerci in the subarachnoid space may grow to 10 cm or larger. This is particularly common with cysticerci in the Sylvian fissure, since they are not limited by pressure from the brain parenchyma. These cysticerci, termed “giant cysticerci,” and accompanying inflammation can cause mass effect and focal neurologic defects.

Question 20

Write short notes on the clinical manifestations of spinal NCC.

Answer 20

Spinal cord involvement occurs in approximately 1 percent of cases. In addition, many cases with intracranial subarachnoid cysticercosis also have spinal lesions. Spinal cysticerci are usually located in the subarachnoid space where they can cause inflammatory and demyelinating changes in the peripheral nerve roots. Patients typically present with radicular pain, paresthesias and/or sphincter disturbances.

Less commonly, intramedullary cysticercosis can occur and may be associated with transverse myelitis.

Question 21

Write short notes on the clinical manifestations of ocular NCC.

Answer 21

Ocular cysticercosis occurs in approximately 1 to 3 percent of cases. Symptoms may include impaired vision, recurrent eye pain, and diplopia.

Ocular cysticercosis should be excluded by an ophthalmologic examination in all patients with NCC prior to initiating therapy.

Question 22

Which tissues may be involved with extraneural cysticercosis? Which are the two most common tissues affected?

Answer 22

Extraneural cysticercosis may involve a wide range of tissues but is typically diagnosed in the setting of muscle or subcutaneous tissue involvement.

Question 23

Write short notes on s/c/IM cystcercosis.

Answer 23

Muscle or subcutaneous cysticercosis is more common in patients from Asia and Africa than from Latin America. Patients may notice subcutaneous nodules 0.5 to 2.0 cm in diameter; cysticerci at these sites are usually asymptomatic but may cause discomfort when inflamed. Intramuscular cysts often undergo calcification and may be detected incidentally as “cigar-shaped calcifications” when radiographs are performed for unrelated reasons. In the setting of extensive muscle involvement, acute myopathy can develop.

Question 24

Can cysticercosis affect the heart? If yes, what does it cause?

Answer 24

Cardiac cysts have also been described. Depending on their location, these may be asymptomatic or may result in arrhythmias and/or conduction abnormalities.

Question 25

What do routine lab investigations (blood and stool) usually show in cysticercosis?

Answer 25

Most patients with cysticercosis have no specific diagnostic finding on routine blood counts and liver function tests. Peripheral eosinophilia is usually absent. Stool examination is insensitive since most individuals with cysticercosis do not have a viable intestinal tapeworm at the time of diagnosis.

Question 26

How does one make a diagnosis of cysticercosis?

Answer 26

The diagnosis of neurocysticercosis (NCC) is largely based on clinical presentation and radiographic imaging. Serologic tests can be helpful but are not always necessary; invasive procedures such as brain biopsy are rarely required.

Question 27

What determines the extent of the diagnostic work-up in cysticercosis?

Answer 27

The extent of diagnostic evaluation needed depends upon the clinical presentation. For example, in a patient from an endemic area presenting with seizures (in the absence of focal neurologic findings, fever, sweats, or evidence of other diseases) together with a typical single enhancing lesion (without midline shift) on brain imaging, the likelihood of the diagnosis of neurocysticercosis is very high. Further diagnostic procedures may not be necessary. However, for circumstances in which the diagnosis is less certain, additional diagnostic evaluation may be warranted, including serologic testing.

Question 28

Outline a clinical approach to the diagnosis of cysticercosis.

Answer 28

A reasonable clinical approach to diagnosis of cysticercosis is to begin with computed tomography (CT) imaging of the brain and serology with enzyme-linked immunoelectrotransfer blot assay (EITB). Magnetic resonance imaging (MRI) is appropriate for evaluation of small lesions, subarachnoid or intraventricular lesions, and scolex visualization. If the appearance on radiographic imaging is nonspecific and serologic tests are negative, it may not be possible to differentiate NCC from other brain lesions such as abscess or malignancy.

Ocular cysticercosis should be excluded by an ophthalmologic examination in all patients with NCC prior to initiating therapy.

Question 29

What radiographic findings are pathognomonic for NCC? Which are highly suggestive?

Answer 29

Identification of a scolex in a cystic lesion is the only pathognomonic radiographic finding.

Other radiographic findings highly suggestive of neurocysticercosis include cystic lesions, enhancing lesions, and parenchymal brain calcifications. Radiographic findings compatible with neurocysticercosis include hydrocephalus, leptomeningeal enhancement, and myelograms with contrast filling defects.

Question 30

If basal subarachnoid NCC is found on neuroimaging, what further investigation is required?

Answer 30

Patients with basal subarachnoid NCC should also undergo spine imaging (MRI > CT myelography).

Question 31

Under what conditions is plain radiography useful in the diagnosis of cysticercosis?

Answer 31

Plain radiography can be useful for evaluation of extraneural cysticercosis such as calcified lesions (“cigar-shaped calcifications”) in muscle or subcutaneous tissue, although CT is more sensitive for these findings.

Question 32

Give a general outline for the use of serology in the diagnosis of cysticercosis.

Answer 32

Serologic testing is an important adjunct in cases of suspected cysticercosis when neuroimaging studies are not diagnostic. However, negative serology does not exclude the diagnosis in patients with a compatible clinical presentation and radiographic findings. In addition, for individuals from highly endemic areas with positive serologic results, it is also important to consider the possibility of previous infection and/or extraneural cysticercosis.

Question 33

In general, what kinds of assays are preferable for T. solium: antigen or antibody? Why?

Answer 33

In general, assays for detection of antibody to specific T. solium antigens are preferable to assays employing unfractionated antigens, which have poor specificity and sensitivity.

Question 34

Write short notes on the serological test of choice for T. solium infection.

Answer 34

The test of choice for antibody detection is the EITB.

The EITB assay can be performed on serum or CSF, but sensitivity is usually higher with serum.

The diagnostic performance of the EITB can vary in different patient populations depending on the activity of the cyst and number of lesions. In a study of 50 patients with pathologically confirmed neurocysticercosis, for example, detectable antibodies were more readily observed in patients with two or more lesions than patients with a single lesion (94 versus 28 percent, respectively). Patients with only calcified cysts (single or multiple) were also less likely to have positive EITB results than those with noncalcified, enhancing lesions. In addition, antibodies can persist for years following death of the parasites, so a positive antibody test does not necessarily indicate the presence of live parasites or active disease.

Question 35

What fundoscopic finding is pathognomonic for cysticercosis?

Answer 35

Direct visualization of the parasite by funduscopic examination is pathognomonic for diagnosis of cysticercosis.

Question 36

Comment on the use of LP as a diagnostic test in NCC and outline typical findings.

Answer 36

A lumbar puncture for CSF examination is usually not necessary for the diagnosis of NCC but can be helpful for excluding other diagnoses.

If a lumbar puncture is performed in the setting of parenchymal lesions, examination of the CSF typically demonstrates mildly elevated white cell counts with normal concentrations of glucose and protein. In the setting of active arachnoiditis or ventriculitis, however, pleocytosis with markedly elevated protein concentrations and decreased glucose concentrations may be observed. Cell counts may demonstrate a predominance of mononuclear cells, neutrophils, or eosinophils.

The EITB assay can be performed on serum or CSF, but sensitivity is usually higher with serum. Antigen detection assays are more sensitive with CSF.

Question 37

When is a biopsy warranted for diagnosis of cysticercosis? What is the pathognomonic finding?

Answer 37

Brain biopsy is warranted only in rare cases for which noninvasive testing is insufficient to establish the diagnosis of cysticercosis. However, excisional biopsy of a skin or muscle lesion can be useful for diagnosis of extraneural cysticercosis.

Histopathology typically demonstrates membranous walls filled with fluid. Less often, scolices (composed of rudimentary bodies and heads with suckers and hooks) may also be visualized; this finding is pathognomonic for the diagnosis of cysticercosis.

Question 38

Mention differentials for the following clinical manifestations of cysticercosis:

• Single/Multiple RELs
• Cystic lesions in the brain
• Parenchymal brain calcifications
• Arachnoiditis with ventricular enlargement
• Other

Answer 38

Other conditions that can mimic single or multiple ring or nodular enhancing lesions include tuberculoma, pyogenic brain abscess, mycotic granuloma, and primary or metastatic brain tumor.

Cystic lesions of the brain include cystic echinococcosis, coenurosis, cystic glioma, and glioblastoma.

Parenchymal brain calcifications may be observed in the setting of metabolic disorders, vascular malformation, intracranial neoplasm, and congenital anomalies.

Arachnoiditis with ventricular enlargement may be seen in the setting of tuberculous and fungal meningitis and meningeal carcinomatosis.

Other conditions include toxoplasmosis, nocardiosis, and septic emboli. Noninfectious conditions include epilepsy, stroke, and hematoma.

Question 39

Cysticercosis infection can be divided into an asymptomatic, a symptomatic and resolution/calcification phase, pathophysiologically speaking. What happens during the asymptomatic phase and why is this phase ‘asymptomatic’?

Answer 39

Tissue cysticerci develop over a period of three to eight weeks following ingestion of T. solium eggs shed in the stool of a human tapeworm carrier. Cysticerci can develop at one or multiple sites; during the initial viable phase, cysticerci do not cause much inflammation in surrounding tissues. This phase of infection is usually asymptomatic, and cysticerci typically remain in this stage for many years.

Taenia parasites have sophisticated means of evading destruction, and a number of mechanisms for host immune tolerance have been postulated. Metacestodes elaborate a variety of substances that inhibit or divert host inflammatory responses. Parasite molecules may interfere with lymphocyte proliferation and macrophage function, thereby inhibiting normal cellular immune defenses. Secreted proteases degrade host molecules including cytokines. In addition, humoral antibodies do not kill the mature metacestode.

Question 40

Cysticercosis infection can be divided into an asymptomatic, a symptomatic and resolution/calcification phase, pathophysiologically speaking. What happens during the symptomatic phase? Comment on both parenchymal and extraparenchymal disease.

Answer 40

Eventually (after a variable number of years) the cysts degenerate and lose their ability to modulate the host immune response. Host immune and inflammatory cells attack the cysticercus, which leads to the appearance of edema and/or contrast enhancement on imaging studies. This inflammatory response is associated with onset of seizures.

In contrast with parenchymal disease, which is associated with seizures, extraparenchymal disease is associated with symptoms of hydrocephalus. Cysticerci in the ventricles frequently become trapped in the foramena or aqueduct, causing obstructive hydrocephalus. When cysticerci develop in the subarachnoid space, they may enlarge to cause mass effect (especially when found in the Sylvian Fissure) or an inflammatory response may lead to chronic arachnoiditis. Arachnoiditis may be accompanied by communicating hydrocephalus, vasculitis, meningitis, and strokes. Patients with multiple cysts frequently have cysts in more than one location, and it is not uncommon to have viable, inflamed, and calcified lesions present in the same patient.

Question 41

Cysticercosis infection can be divided into an asymptomatic, a symptomatic and resolution/calcification phase, pathophysiologically speaking. What happens during the calcification/resolution phase? How can this phase be associated with seizures?

Answer 41

Ultimately, the cystic lesions either resolve or form a calcified granuloma. When present, the calcifications are associated with recurrent seizures, although the mechanism of seizures associated with calcified lesions is not completely clear. Seizures may result from inflammation, perhaps from intermittent antigen release. Alternatively, changes in brain plasticity and scarring (eg, hippocampal sclerosis) may result in epileptogenic foci.

Question 42

What do the terms ‘active’ and ‘inactive’ cysts refer to? Is this nomenclature helpful? Why?

Answer 42

Some experts have termed cysticerci as “active” if they are viable or in the process of degenerating. If calcified granulomas are visualized radiographically in the absence of cysticerci, the lesions are considered “inactive.” Active and inactive cysts may be present in the same patient simultaneously. However, these terms do not correlate with symptoms or the host inflammatory response and probably should be abandoned.

Question 43

Outline the principles of therapy for cysticercosis.

Answer 43

The initial approach to patients with clinical manifestations of neurocysticercosis (NCC) should focus on management of symptoms such as seizure control with antiepileptics and treatment of increased intracranial pressure, if present. Subsequently, a determination should be made regarding the role of antiparasitic and antiinflammatory therapy.

Question 44

Discuss anti-epileptic use in NCC. Comment on:

• Indications
• Suggested AEDs
• Seizure risk
• Treatment duration

Answer 44

Antiepileptics should be administered to patients with NCC who present with seizures. Most reports in the literature on management of seizure due to NCC describe use of phenytoin or carbamazepine. Newer therapies (eg, levetiracetam or topiramate) are likely to be at least as effective, perhaps better tolerated, although more costly.

Antiepileptic therapy may also be appropriate for patients who do not present with seizures but who are at high risk for seizures. The risk of seizures appears to be highest in the setting of multiple lesions, particularly when the lesions are degenerating and are surrounded by inflammation. Calcified lesions can also serve as foci for seizures but, in an otherwise asymptomatic patient, are not generally considered an indication for prophylactic antiepileptic drug therapy.

The optimal duration of antiepileptic therapy is uncertain. In general, indefinite therapy may be appropriate in the setting of calcified lesions, especially in those with recurrent seizures. In some cases, these patients may taper therapy successfully. Although it is uncertain whether the radiographic resolution of cysts results in seizure remission, most experts favor administering antiepileptic therapy for 6 to 12 months after radiographic resolution of active parasitic infection. If the patient has recurrence of seizures during a trial off of antiepileptic therapy, long-term treatment should be reinstituted.

Question 45

Discuss anti-parasitic therapy in NCC. Comment on:

• Benefits
• Risks
• Suggested drugs

Answer 45

The potential benefit of antiparasitic therapy for treatment of neurocysticercosis is hastened resolution of active cysts, decreased risk for seizures, and decreased recurrence of hydrocephalus.

The potential risk of treatment with antiparasitic therapy is exacerbation of neurologic symptoms due to increased inflammation around the degenerating cyst, particularly in patients with a large number of lesions. The inflammation can be so severe that it can lead to disability or death. For this reason, corticosteroids should be routinely administered together with antiparasitic therapy.

If a determination has been made that antiparasitic therapy is indicated, albendazole is preferred over praziquantel given its favorable pharmacokinetic profile although information is emerging on the use of combinations of albendazole and praziquantel dosed together. The combination is generally safe and may be more effective than albendazole alone. Combination therapy has been associated with improved radiographic resolution among patients with more than two cystic lesions.

Question 46

Give a brief overview of the use of albendazole in the management of NCC.

Answer 46

Albendazole (15 mg/kg per day [usually 800 mg/day in two divided doses; taken with food to increase bioavailability]) facilitates the destruction of parenchymal cysticerci.

Coadministration of corticosteroids has no adverse effect on albendazole levels and may even raise serum drug concentrations.

In general, patients with parenchymal lesions appear to benefit from albendazole therapy.

The optimal duration of therapy depends on the form of disease. Patients with a single enhancing lesion appear to benefit from a short course of therapy (three to seven days). Patients with multiple viable parenchymal lesions should receive a longer course of treatment (10 to 14 days); this approach is largely based on expert opinion with limited data. Patients with subarachnoid disease may benefit from prolonged therapy guided by the response on imaging studies (≥28 days).

Question 47

Give a brief overview of the use of praziquantel in the management of NCC.

Answer 47

Praziquantel (50 to 100 mg/kg per day in three divided doses) is an alternative to albendazole. However, the efficacy of praziquantel may be reduced by induction of cytochrome P-450 hepatic metabolism by coadministered drugs such as corticosteroids, phenytoin, carbamazepine, and phenobarbital.

Question 48

Discuss anti-inflammatory therapy in NCC.

Answer 48

Corticosteroids should be administered to patients with parenchymal neurocysticercosis receiving treatment with antiparasitic therapy to reduce inflammation associated with the dying organisms.

Corticosteroids appear to play a useful role in the following circumstances:
●Steroids are the mainstay of therapy in patients with cysticercal encephalitis (diffuse cerebral edema due to numerous inflamed cysticerci) given their capacity to reduce cerebral edema.
●Steroids have been used to reduce symptoms in subarachnoid cysticercosis; prolonged tapers have been used in the setting of recurrent symptoms. In cases requiring extended courses of steroids, methotrexate may be a useful steroid-sparing agent.

Doses used are typically 1 mg/kg/day of prednisone or prednisolone or 0.1 mg/kg/day of dexamethasone for 5 to 10 days followed by a rapid taper. Higher doses (eg, 8 mg per day of dexamethasone for 28 days followed by a taper) may be more effective. Methotrexate can be used as a steroid-sparing regimen in those with more prolonged disease.

Question 49

What precautions must be taken prior to initiating anti-parasitic and anti-inflammatory therapy in patients with NCC?

Answer 49

The following considerations should be made prior to the initiation of therapy with antiparasitic medications and corticosteroids:
●Most regions and groups at risk for neurocysticercosis are also at risk for tuberculosis. Thus, they should be screened for latent tuberculosis prior to initiation of corticosteroids. This can be accomplished using a tuberculin skin test or interferon-gamma release assay. If either test is positive, individuals receiving steroids for longer than a few weeks should receive treatment for latent tuberculosis.
●Since many patients with cysticercosis also have risk factors for strongyloidiasis, which can disseminate during treatment with corticosteroids, it may be wise to screen for strongyloidiasis prior to embarking on steroid therapy.
●An ophthalmologic examination should be performed to rule out ocular cysticercosis. A direct fundoscopic examination is usually adequate for visualization of cysticerci.

Question 50

Give an overview of the role of surgery in the management of NCC.

Answer 50

Surgical intervention is generally required in the setting of symptomatic hydrocephalus due to NCC.

Patients with altered mental status or impending herniation generally require emergent cerebrospinal fluid (CSF) diversion via either a ventriculostomy or placement of a ventriculo-peritoneal shunt. Shunt failure is common, and placement should be accompanied by antiparasitic therapy and corticosteroids (although it is unproven whether these decrease the risk of shunt blockage and malfunction).

Patients with subarachnoid cysticercosis and arachnoiditis frequently develop communicating hydrocephalus; in such cases, management requires placement of a ventriculoperitoneal shunt together with medical therapy.

Open resection is rarely required in NCC but may be warranted in certain circumstances such as giant cysticerci with life-threatening mass effect, cysticerci adjacent to vascular structures, and cysticerci at sites inaccessible by flexible endoscopy (such as ocular or spinal NCC).

Question 51

What are the four therapeutic subtypes of parenchymal NCC?

Answer 51

Single cyst, multiple cyst, cysticercal encephalitis and calcified disease.

Question 52

How do you manage single cyst parenchymal NCC?

Answer 52

A single enhancing lesion accompanied by seizure is a common clinical presentation of neurocysticercosis (NCC). The seizures are controllable with antiepileptic medication alone, and the prognosis is favorable with symptomatic treatment alone.

Controlled trials have demonstrated that patients treated with antiparasitic drugs have slightly shorter duration of seizure risk and time to radiologic resolution. Thus, we favor management with antiparasitic therapy (eg, albendazole 15 mg/kg/day for 3 to 8 days) and a short course of corticosteroids (eg, prednisone 1 mg/kg/day for 8 to 10 days followed by a taper). Combination therapy using both albendazole and praziquantel had more potent antiparasitic activity in a single study.

Patients with a single enhancing lesion typically have resolution over the course of six months.

Question 53

How do you manage multiple cyst parenchymal NCC?

Answer 53

In the setting of multiple parenchymal cysts, active and inactive cysts may be present in the same patient simultaneously. Administration of antiparasitic therapy may hasten degeneration of viable cysts, thereby increasing inflammation at the site of these lesions and potentially increasing risk for seizure. Nonetheless, most favor treatment of multiple viable, parenchymal cysticerci with antiparasitic therapy (albendazole 15 mg/kg/day in two daily doses for 8 to 15 days) administered together with high-dose steroids.

The combination of praziquantel and albendazole has been associated with a higher rate of radiographic resolution than albendazole alone: praziquantel (50 mg/kg/day) and albendazole (15 mg/kg/day).

Antiparasitic medications are not helpful in the absence of viable parasites.

Question 54

How do you manage cysticercal encephalitis?

Answer 54

Cysticercal encephalitis (diffuse cerebral edema associated with multiple inflamed cysticerci) is a contraindication for antiparasitic therapy, since enhanced parasite killing can exacerbate host inflammatory response and lead to diffuse cerebral edema and potential transtentorial herniation. Most cases of cysticercal encephalitis improve with corticosteroid therapy. The duration of therapy should be individualized based on the clinical and radiologic resolution of edema. Determination of antiparasitic therapy should be made once cerebral edema has resolved.

Question 55

How do you manage calcified parenchymal cysts?

Answer 55

Radiographic evidence of parenchymal calcifications is a significant risk factor for recurrent seizure activity. Seizures in these patients should be treated with antiepileptic therapy. Patients with a single seizure and no recurrence can often be tapered off of the antiepileptic drugs.

Question 56

Which form of NCC is more serious: parenchymal or extra-parenchymal?

Answer 56

Extraparenchymal forms of neurocysticercosis (NCC) generally carry a higher risk for complication or death than parenchymal disease.

Question 57

How do you manage subarachnoid cysticercosis?

Answer 57

Subarachnoid cysticercosis (cysticercal involvement of the basilar cisterns) is the most severe form of neurocysticercosis and is frequently complicated by obstructive hydrocephalus, vasculitis, and stroke. There are few data on optimal management, although most agree that treatment should include antiparasitic therapy, corticosteroids, and, in most cases, cerebrospinal fluid (CSF) diversion.

Inflammation plays an important role in the pathogenesis of subarachnoid neurocysticercosis, and corticosteroids are often used in management, although there are no published controlled trials on dose or duration of therapy. A reasonable approach is to use prednisone (up to 60 mg per day) or dexamethasone (up to 24 mg per day) along with the antiparasitic therapy (albendazole + praziquantel). The dose can often be tapered after a few weeks. However, in cases for which more prolonged steroid therapy is required, methotrexate can be used as a steroid-sparing agent.

CSF diversion via ventriculostomy or placement of a ventriculo-peritoneal shunt is often warranted for management of subarachnoid NCC. There are anecdotal reports of clinical improvement with endoscopic cysticercal debulking.

Question 58

How do you manage giant cysts in subarachnoid NCC?

Answer 58

Subarachnoid cysticerci may enlarge to >5 cm in diameter, especially when located in the sylvian fissure or basilar cisterns. These giant cysticerci are usually accompanied by cerebral edema and mass effect, which should be managed with high-dose corticosteroids (with or without mannitol). Rarely, surgical decompression is required. When mass effect is controlled, giant cysticerci can be treated similarly to other forms of subarachnoid cysticerci.

Question 59

How do you manage intraventricular NCC?

Answer 59

Patients with intraventricular cysts and hydrocephalus in the setting of altered mental status or impending herniation should undergo emergent management with CSF diversion via a ventriculostomy or placement of a ventriculo-peritoneal shunt.

For patients with mild or intermittent symptoms of hydrocephalus due to intraventricular cysts, the preferred treatment is elective endoscopic removal.

Antiparasitic drugs should not be administered prior to surgery since they can weaken the cyst membrane, causing friability and/or adherence to the ventricular wall. Antiparasitic medications and corticosteroids are not necessary in most cases after cyst removal unless the patients have coexisting parenchymal disease.

Question 60

How do you manage ocular cysticercosis?

Answer 60

Although many patients are asymptomatic, inflammation around degenerating cysticerci can threaten vision by causing chorioretinitis, retinal detachment, or vasculitis. For this reason, ocular cysticercosis should be excluded by an ophthalmologic examination in all patients with NCC prior to initiating therapy.

Surgical excision is warranted in the setting of intraocular cysts.

Cysticercal involvement of the extraocular muscles should be managed with albendazole and corticosteroids.

Question 61

How do you manage spinal NCC?

Answer 61

The traditional approach to management of spinal cysticercosis is surgical removal, although some cases may respond to medical therapy with corticosteroids and antiparasitic drugs.

Question 62

How do you manage s/c/IM cysticercosis?

Answer 62

Subcutaneous or intramuscular cysticerci causing symptoms due to inflammation can be excised or treated with nonsteroidal antiinflammatory medication. Excision is reasonable for symptomatic solitary lesions.
Asymptomatic patients with cysticerci in subcutaneous or intramuscular sites generally do not require specific therapy; excision of single lesions can be considered. Such patients should undergo radiographic imaging of the brain to evaluate for neurocysticercosis.

Question 63

How do you manage asymptomatic NCC?

Answer 63

Asymptomatic patients with an incidental radiographic finding of a nonviable cysticercus lesion in the brain do not appear to benefit from antiparasitic therapy. Patients with asymptomatic viable disease are extremely rare. There are no data to guide management for such cases.

Question 64

How should patients with NCC be monitored and followed up?

Answer 64

Patients with parenchymal or subarachnoid neurocysticercosis should undergo intermittent radiographic surveillance to evaluate for resolution of the cysticerci and development of calcifications. Imaging may be performed one to two months and six months following treatment. The frequency of subsequent imaging should be individualized; once lesions have resolved, follow-up imaging is less useful. Imaging should be repeated prior to discontinuing antiepileptic drugs. New, worsening, or persistent symptoms should prompt evaluation.

An alternative approach may include serial antigen-detection assays.

Question 65

How does one make a diagnosis of cysticercosis using the diagnostic criteria?

Answer 65

Definitive:

• Presence of one absolute criterion;
• Presence of two major plus one minor and one epidemiologic criterion.

Probable:

• Presence of one major plus two minor criteria;
• Presence of one major plus one minor and one epidemiologic criterion;
• Presence of three minor plus one epidemiologic criterion.

Question 66

What are the absolute criteria for the diagnosis of cysticercosis?

Answer 66

• Histologic demonstration of the parasite from biopsy of a brain or spinal cord lesion;
• Cystic lesions showing the scolex on CT or MRI;
• Direct visualization of subretinal parasites by funduscopic examination.

Question 67

What are the major criteria for the diagnosis of cysticercosis?

Answer 67

• Lesions highly suggestive of neurocysticercosis on neuroimaging studies;
• Positive serum EITB for the detection of anticysticercal antibodies;
• Resolution of intracranial cystic lesions after therapy with albendazole or praziquantel;
• Spontaneous resolution of small single enhancing lesions.

Question 68

What are the minor criteria for the diagnosis of cysticercosis?

Answer 68

• Lesions compatible with neurocysticercosis on neuroimaging studies;
• Clinical manifestations suggestive of neurocysticercosis;
• Positive CSF ELISA for detection of anticysticercal antibodies or cysticercal antigens;
• Cysticercosis outside the CNS.

Question 69

What are the epidemiological criteria for the diagnosis of cysticercosis?

Answer 69

• Evidence of a household contact with Taenia solium infection;
• Individuals coming from or living in an area where cysticercosis is endemic;
• History of frequent travel to disease-endemic areas.