Laboratory Studies
The enzyme immunotransfer blot assay for the detection of serum and cerebrospinal fluid (CSF) antibodies to T solium is the antibody test of choice for cysticercosis. It is available through the Centers for Disease Control and Prevention. The test is more sensitive with serum than with CSF specimens. Serum antibody testing has a sensitivity and specificity of more than 90%. The serum antibody assay results are often negative in children with solitary parenchymal lesions or old calcified disease, and results are usually positive in patients with multiple inflamed lesions.
The complement fixation (CF) test for the detection of anticysticercus antibodies in CSF is highly specific and sensitive. The CF test results are negative in the absence of active forms of the parasite. Results may remain positive for several months following successful treatment. Antibody may be demonstrated in the CSF but not in the serum of patients with parenchymal or ventricular neurocysticercosis.
The use of both the enzyme immunotransfer blot assay and the CF test increases the probability of antibody detection.
Cysticercosis may result in CSF eosinophilia.
Imaging Studies
The diagnosis of neurocysticercosis is primarily based on CT scanning or MRI results. [9] See the images below.
MRI of 6-year-old boy from Peru with single right frontal cyst (coronal image). Image courtesy of Eric H. Kossoff, MD.
Axial image MRI of same patient as in Media file 2. Image courtesy of Eric H. Kossoff, MD.
CT scan of intraparenchymal cysticercosis with lesions in different stages. Lesions that are breaking down demonstrate peripheral enhancement after intravenous contrast injection, whereas lesions without peripheral enhancement are intact. Typical residual calcification from an old focus of infection is observed in the left occipital lobe. Image courtesy of Fred Greensite, MD.
Racemose (extraparenchymal) cysticercosis (T1-weighted MRI). Note the cyst in the fourth ventricle, causing obstructive hydrocephalus. Image courtesy of Fred Greensite, MD.
Racemose cysticercosis (T1-weighted MRI). Note cluster of cysts anterior to the pons and inferior to the hypothalamus in a different patient. Image courtesy of Fred Greensite, MD.
Racemose cysticercosis (same patient as in Media file 6). Note the enhancing margin of the cysts in the suprasellar cistern and in the left sylvian fissure after gadolinium injection (T1-weighted MRI). Image courtesy of Fred Greensite, MD.
Racemose cysticercosis (same patient as in Media files 6-7). Coronal image (postgadolinium T1-weighted MRI) posterior to the slice in Media file 7. Cysts in this slice (below the hypothalamus) do not have enhancing margins. Also, unlike intraparenchymal lesions, scolexes are typically not identified in the cysts of racemose cysticercosis. Image courtesy of Fred Greensite, MD.
CT scanning is more readily available and less expensive but is less sensitive than MRI in the depiction of inflammation around a cyst.
MRI better depicts cysts in the ventricles and spinal cord because it delineates the membranes of the parasite and the differences in the signal intensities of the fluids and tissues of the cysticercus. The protoscolex may even be visible within the cyst on MRI; it is a pathognomonic sign of cysticercosis.
Regardless of the neuroimaging modality, granulomas are the most common finding in patients with neurocysticercosis.
Parenchymal cysts with inflammation appear as ring enhancement on neuroimages.
The presence of hydrocephalus on a CT scan finding may suggest intraventricular cysts, which are otherwise difficult to detect because the cyst fluid often has the same density as that of CSF.
The most common findings in children are a solitary parenchymal cyst with or without contrast enhancement and numerous calcifications.
Plain radiography may reveal calcifications in muscle or brain that are consistent with cysticercosis, but these are more often nondiagnostic in children than in adults. On images, cysticerci can be mistaken for calcified tuberculomas, toxoplasmosis, or CNS tumors.
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Cysticercosis life cycle. Image courtesy of the Centers for Disease Control and Prevention.
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MRI of 6-year-old boy from Peru with single right frontal cyst (coronal image). Image courtesy of Eric H. Kossoff, MD.
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Axial image MRI of same patient as in Media file 2. Image courtesy of Eric H. Kossoff, MD.
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CT scan of intraparenchymal cysticercosis with lesions in different stages. Lesions that are breaking down demonstrate peripheral enhancement after intravenous contrast injection, whereas lesions without peripheral enhancement are intact. Typical residual calcification from an old focus of infection is observed in the left occipital lobe. Image courtesy of Fred Greensite, MD.
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Racemose (extraparenchymal) cysticercosis (T1-weighted MRI). Note the cyst in the fourth ventricle, causing obstructive hydrocephalus. Image courtesy of Fred Greensite, MD.
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Racemose cysticercosis (T1-weighted MRI). Note cluster of cysts anterior to the pons and inferior to the hypothalamus in a different patient. Image courtesy of Fred Greensite, MD.
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Racemose cysticercosis (same patient as in Media file 6). Note the enhancing margin of the cysts in the suprasellar cistern and in the left sylvian fissure after gadolinium injection (T1-weighted MRI). Image courtesy of Fred Greensite, MD.
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Racemose cysticercosis (same patient as in Media files 6-7). Coronal image (postgadolinium T1-weighted MRI) posterior to the slice in Media file 7. Cysts in this slice (below the hypothalamus) do not have enhancing margins. Also, unlike intraparenchymal lesions, scolexes are typically not identified in the cysts of racemose cysticercosis. Image courtesy of Fred Greensite, MD.
