Imaging of neurocysticercosis
Section snippets
Hosts
For Tenia Solium to become clinically manifested, two hosts are needed to complete its life cycle.1 The initial host is the pig. The larvae migrate preferentially toward muscle and are released into the human gastrointestinal tract when undercooked pork meat is consumed. This results in intestinal teniasis generally at the level of the small bowel. The larva remain attached by the scolex to the intestinal mucosa. As the larvae grow, body segments (proglottids) develop progressively from the
Epidemiology
Although cysticercosis occurs worldwide, it is endemic in Latin America, India, and China where 5 to 25% of the population will be seropositive (this is a gross underestimation because only about 50% of infected patients are seropositive).1, 2, 3 In Latin America, nearly 50% of adults with new onset of seizures will show cysticercal lesions on neuroimaging studies. In Africa, nearly 40% of the population in non-Muslim countries harbors the disease. In India, cysticercosis is the most important
Intraparenchymal cysticercosis
Cysticerci must live in the muscle of the pig for weeks to months to grow and mature.1, 2, 3 The scolex is usually attached to the wall of the cyst that is composed of an eosinophilic cuticular layer, a cellular layer with multiple nuclei, musculature, and a loose reticular layer (this is called the “vesicular” stage). These parasites have little neighboring inflammation consisting of lymphocytic and eosinophilic infiltrates. Cysticerci secrete substances that modulate, complement, and
Criteria for diagnosis and classification
Despite its high incidence, the diagnosis of CNS cysticercosis remains difficult. The clinical manifestations are generally nonspecific and the serologic tests have varying degrees of accuracy. The most widely used laboratory examination is an enzyme-linked immunoabsorbent assay (ELISA) that is based on the use of a crude parasite antigen (IgG).4 As stated before, the rate of false-negatives using this test may be as high as 40%.5 A different method uses a T. Solium specific glycoprotein-based
Inactive form (nodular stage)
In these patients, the parasites are no longer viable or degenerating. There is no active immune response from the host and neuroimaging studies show only the sequela of the disease. The most commonly encountered manifestation is that of multiple, small parenchymal calcifications on CT7 (Fig. 1). The calcifications generally measure between 2 and 10 mm. At this stage of the disease, CT is superior to MRI for visualization of the lesions. A recent report indicates that MRI may show persistent
Differential diagnosis of parenchymal cysticercosis
During the vesicular stage, the lesions may be difficult to distinguish (particularly if solitary) from echinococcus (usually a large solitary cyst in the region of the distribution of the middle cerebral artery), sparganosis (seen in patients from southeast Asia, multiple cystic lesions), coenurosis (a very rare disease caused by the cestode Multiceps multiceps), cystic metastases, and multiple abscesses.2, 1, 12, 13 During the colloidal and granular stages, both solitary and multiple cysts
Ventricles
Approximately 10 to 20% of patients with cysticercosis will be shown to have lesions in the ventricles.2, 17 Symptoms are generally the result of obstruction and hydrocephalus (which may be fatal). Viable lesions are cyst-like and may be difficult to identify on CT. For intraventricular cysticercosis, MR is the imaging method of choice. The cyst contents are generally isointense to CSF on T1- and T2-weighted and FLAIR images (Fig. 5A and B). Occasionally they are slightly brighter than CSF on
Spinal cord
There are two types of cysticercal spinal involvement. The most common involvement is when the parasites are located in the subarachnoid space and the least common involvement is when the cysts are inside of the spinal cord.20 Approximately 5% of patients with cisternal cysticercosis will have disease involving the spinal subarachnoid space. The appearance of the disease in the latter location is identical to that of cysticercosis involving other CSF-containing spaces. The cysts may “float” in
Antiparasitic drugs
Both praziquantel and albendazole have been extensively and effectively used to treat CNS cysticercosis.3 The courses of the treatments vary between one week to one month. Between 60 and 85% of parasites are killed after such courses (the success rate is higher with albendazole).3 Treatment with antiparasitic medications is considered somewhat controversial because with time all parasites die. In addition, the death of the parasites induced by the drugs results in an inflammatory reaction that
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Cited by (28)
Imaging of Neurocysticercosis
2012, Neuroimaging Clinics of North AmericaCitation Excerpt :CT and MR imaging demonstrate enhancement of the nodular lesion or a small ring-enhancing lesion at this stage. Mild associated edema may be identified in adjacent brain parenchyma (Fig. 5).5,9 The nodular calcified stage is the end stage of cysticercal degeneration, with transformation into a small calcified granulomatous lesion.
NEUROCYSTICERCOSIS in Pregnancy: Not Just Another Headache
2012, Nursing for Women's HealthOther Infections of the Brain
2012, Imaging of the BrainParasitic diseases of the central nervous system
2011, Neuroimaging Clinics of North AmericaCitation Excerpt :The main differential diagnosis includes glioma and echinococcus.20,21 Encephalitic cysticercosis occurs when multiple lesions are simultaneously in the granular stage and there is diffuse brain edema and overwhelming inflammation around the cyst.9 The disseminated miliary form represents a massive cysticercus infestation of the CNS and is characterized by multiple small cystic formations diffusely spread out in the brain parenchyma.8
Central nervous system infection
2010, Neuroimaging Clinics of North AmericaCitation Excerpt :The colloidal stage mimics other ring-enhancing lesions. In these cases, DWI may be helpful to differentiate a cysticercosis cyst from a pyogenic abscess because cysticercal cysts are dark.23 Also, ADC values are higher in neurocysticercosis than in TB granulomas.26