Pediatric Neurocysticercosis Workup

Updated: Mar 03, 2015
  • Author: Vinod K Dhawan, MD, FACP, FRCPC, FIDSA; Chief Editor: Russell W Steele, MD  more...
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Workup

Laboratory Studies

Laboratory diagnosis of neurocysticercosis is facilitated by serological and imaging studies. [18, 19]

Enzyme-linked immunotransfer blot assay

If neurocysticercosis is suspected on the basis of clinical and radiographic evidence, an enzyme-linked immunotransfer blot (EITB) assay of a patient's serum may confirm the diagnosis.

Specificity is 100% and sensitivity is 90% for children with more than 2 lesions. Sensitivity is only 50-70% in children with just one lesion (the majority); therefore, the usefulness of this test may be limited.

EITB can be ordered by sending serum to the state public health department laboratory in the area or to the Centers for Disease Control and Prevention (CDC). One private laboratory in the United States (Specialty Laboratories; Los Angeles, California) also performs the test. The CDC Web site provides further information.

HP10 antigen testing

Detection of the metacestode HP10 antigen in serum is a useful tool for diagnosis and follow-up of patients with severe forms of neurocysticercosis treated with cysticidal drugs. [20]

Polymerase chain reaction

More recently, T solium DNA has been observed in the cerebrospinal fluid (CSF) of patients. The polymerase chain reaction amplification of the parasite DNA in the CSF enabled the investigators in correct identification of 29 cases (96.7%). [21]

Stool samples

Examine stools from patients and their contacts for ova and parasites. Obtain 3 consecutive daily stool specimens.

The presence of ova may be the sole diagnostic confirmation in some children, but more importantly, detecting ova in children with neurocysticercosis is worthwhile as a public health measure to prevent further exposure to the tapeworm ova.

Stool test for T solium ova is rarely positive.

Enzyme-linked immunosorbent assay

Enzyme-linked immunosorbent assay (ELISA) can be used on serum and CSF. Detection of antigen in the CSF using a monoclonal antibody-based ELISA has been shown to increase the diagnostic sensitivity. [22]

ELISA can aid in diagnosis in cases with few lesions and relatively mild disease.

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Imaging Studies

CT scanning

CT scanning shows the cyst and granuloma stages of neurocysticercosis. [23] These cysts can be solitary or multiple and are usually 5-20 mm in diameter.

Perform CT scanning on all children considered for the diagnosis. Most likely, CT scanning is performed upon presentation of a child with new-onset focal seizures. CT scanning can be performed without contrast.

Approximately 75% of children who are affected with neurocysticercosis have a solitary lesion. Lesions are located most often in the cortex or at the gray-white junction. Approximately one half of lesions have a punctate high density within the ring (scolex). Between 10-20% of children have no abnormality (also observed in MRI studies).

CT scanning is superior to MRI study in detecting calcification, which can be useful in differentiating the punctate cyst of neurocysticercosis in the granuloma wall from other causes of granulomas; however, calcification is observed less frequently in children than in adults. See the images below.

Case 2: MRI of a 40-year-old patient with a single Case 2: MRI of a 40-year-old patient with a single parietal calcified cyst.
Case 2: CT scan of a 40-year-old patient with a si Case 2: CT scan of a 40-year-old patient with a single parietal calcified cyst.

CT scanning can also detect edema around the cyst, which is associated with the death of the organism.

CT scanning can be performed quickly, which is important when caring for young children.

MRI

MRI is the best imaging test overall for the diagnosis. Perform MRI in all patients for whom the clinical history and CT scan findings suggest neurocysticercosis. Use gadolinium contrast.

MRI is useful for lesions of the spinal cord, posterior fossa, brainstem, subarachnoid, and ventricles.

Use of contrast also shows larval death, visible as enhancement of the cyst wall, which indicates that the cyst has changed into a granuloma. In addition, MRI (as well as CT scanning) shows any vasogenic edema around the cyst, indicative of the body's inflammatory response to organism death.

MRI can be used as follow-up imaging to document improvement based on both a decrease in the granuloma diameter and a resolution of vasogenic edema.

A 2000 study of 108 patients by Pradhan et al indicated the prognostic usefulness of gliosis as observed in a T1-weighted magnetization transfer spin-echo MRI. This gliosis was associated with seizure recurrence after at least 2 years of antiepileptic medications were tapered and then discontinued.

See the images below.

MRI of multiple cysts. Image courtesy of the Cente MRI of multiple cysts. Image courtesy of the Centers for Disease Control and Prevention.
Case 3: MRI of a 47-year-old man with 2 right pari Case 3: MRI of a 47-year-old man with 2 right parietal cysts, one with edema.
Case 3: MRI of a 47-year-old man with 2 right pari Case 3: MRI of a 47-year-old man with 2 right parietal cysts, one with edema, after the larger cyst had involuted.

Radiography

Soft tissue radiography can be performed to look for extraneural cysts. [24]

Radiography is rarely helpful. Perform radiography only when all other tests have failed to provide a diagnosis.

For unknown reasons, children in the United States with neurocysticercosis rarely have cysts in subcutaneous or intramuscular tissue.

Skull radiography can be performed, although they are rarely helpful with the advent of the MRI. Occasionally, separation of the cranial sutures can be observed, which indicates increased intracranial pressure.

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Other Tests

Electroencephalography

Perform electroencephalography (EEG) in children with recalcitrant seizures.

Occasionally, evidence of periodic lateralized epileptiform discharges (PLEDs) is present.

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Procedures

Lumbar puncture

In approximately 50% of cases, a lumbar puncture can reveal pleocytosis (often lymphocytic, but occasionally eosinophilic), decreased glucose, increased protein, and elevated opening pressure. A lumbar puncture can help exclude other infectious or malignant diagnoses.

Serum EITB is more sensitive than the CSF EITB assay, so CSF testing is not usually indicated.

Brain biopsy

Brain biopsy can be performed in cases where the diagnosis remains questionable and the lesion has not resolved. The procedure may be indicated in areas of low prevalence.

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