DIAGNOSIS

Diagnosis of neurocysticercosis stems from suspicions that arises from the clinical manifestations of the disease

Most useful diagnostic test and the primary diagnostic criteria is neuroimaging 1. Contrast CT 2. MRI Useful in the evolution of cysticercus in th eparenchyma of brain.

4 Phases 1.Vesicular 2.Colloidal 3.Nodular-granular 4.Calcified phase

VesicularColloidalNodular-granularCalcified CT circumscribed, rounded, hypodense areas, ave. size 10 mm, range 4-20 mm, no enhancement annular enhancement surrounded by irregular perilesional edema diffuse hypodense area with irregular borders (non-contrast) a small, hyperdense, rounded, nodular image surrounded by edema (ff contrast) rounded, homogeneous hyperdense area showing no enhancement with contrast medium MRI CSF-like intensity signal on all sequences, with no surrounding high signal on T2-weighted images. higher signal than the adjacent brain with thick-ring enhancement (T1) a low-ring signal surrounded by high signal lesion (T2) change in the signal from the cyst fluid (T2) Both high intensity, 2-4 mm mural nodule, depicting the scolex in the interior of some parenchymal vesicular cysts.

Vesicular Phase No surrounding parenchymal reaction. 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. CT scan depicts circumscribed, rounded, hypodense areas, varying in size and number, without enhancement by contrast medium. 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, 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. This picture could be considered pathognomonic of cysticercosis, and it corresponds to the active parenchymal form of NC.

Colloidal 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.

Nodular-Granular The vesicle tends to shrink, and 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. T2-weighted images depict the most striking picture of these lesions, as they show a change in the signal from the cyst fluid.

Calcified Mineralization and resorption process occurs that lodges permanently in the CNS. Noncontrast CT scan shows a rounded, homogeneous hyperdense area showing no enhancement with contrast medium.

When only one cyst is seen in the transitional phase, it corresponds to the so-called "single enhancing lesion on CT" (SECTL), signifying a special syndrome.

Immunologic Assay Enzyme ImmunoBlot – The current serological assay of choice for the diagnosis of neurocysticercosis – CDC's immunoblot is based on detection of antibody to one or more of 7 lentil-lectin purified structural glycoprotein antigens from the larval cysts of T. solium in an immunoblot format. – It is 100% specific. – No serum samples from patients with other microbial infections react with any of the T. solium-specific antigens. – Cumulative clinical experience has confirmed that in patients with multiple (more than two) lesions, the test has more than 95% sensitivity.

ELISA - Lack of specificity has been a major problem because of cross-reacting components in crude antigens derived from cysticerci - these components react with antibodies specific for other helminthic infections, especially echinococcosis and filariasis. - lower sensitivity than crude antigens and do not necessarily achieve higher specificity Assays employing crude antigens for the detection of antibody are not reliable for the identification of this disease

Diagnostic Criteria Absolute criteria Histologic demonstration of parasite Direct visualization of parasite by fundoscopic examination. Evidence of cystic lesions showing scolex on CT/MRI. Major Criteria Lesions suggestive of neurocysticercosis on neuroimaging studies Positive immunological tests Plain X-ray films showing calcifications in thigh and calf muscles Minor criteria Subcutaneous nodules Soft tissue or intracranial calcification on plain x-ray Clinical manifestations suggestive of neurocysticercosis Disappearance of intracranial lesions after a trial with anticysticercal drug

Epidemiologic Living or coming from endemic area Frequent travel to endemic areas Household contact with Taenia solium infection Definitive: 1 absolute 2 major 1 major + 2 minor + 1 epidemiologic Probable: 1 major + 2 minor 1 major + 1 minor + 1 epidemiologic 3 minor + 1 epidemiologic Possible: 1 major 2 minor 1 minor + 1 epidemiologic

Revised Absolute criteria Histologic demonstration of parasite Direct visualization of parasite by fundoscopic examination Evidence of cystic lesions showing scolex on CT/MRI. Major Criteria Lesions suggestive of neurocysticercosis on CT or MRI Positive serum EITB (Enzyme Immunoblot Assay) Resolution of cyst after therapy. Spontaneous resolution of single enhancing lesions. Minor Criteria Lesions compatible with neurocysticercosis on CT/MRI Suggestive clinical features Positive CSF ELISA Cysticercosis outside CNS

Definitive diagnosis of extra-neural cysticercosis will require one of the following: a) histopathological demonstration of parasite from excisional biopsy of a subcutaneous nodule. Demonstration of larval parts (hooks, suckers etc.) by fine needle aspiration cytology may provide a satisfactory alternative to open biopsy b) plain X-ray films showing multiple "cigar-shaped calcifications in the arm, thigh and calf muscles c) direct visualization of a cysticercosis larva in the anterior chamber of the eye with ultrasonography.

Epidemiologic Living or coming from endemic area Frequent travel to endemic areas Household contact with Taenia solium infection Definitive: 1 absolute 2 major + 1 minor + 1 epidemiologic Probable: 1 major + 2 minor 1 major + 1 minor + 1 epidemiologic 3 minor + 1 epidemiologic