Diagnostic criteria for neurocysticercosis, revisited

Abstract

Diagnosis of neurocysticercosis (NCC) can be a challenge. Clinical manifestations are non-specific, most neuroimaging findings are non-pathognomonic, and some serologic tests have low sensitivity or specificity. A set of diagnostic criteria was proposed in 2001 to avoid the over diagnosis of NCC that occurs in epidemiologic surveys, and to help clinicians evaluating patients with suspected NCC. The set included four stratified categories of criteria, including: (1) absolute: histological demonstration of cysticerci, cystic lesions showing the scolex on neuroimaging studies, and direct visualization of subretinal parasites by fundoscopic examination; (2) major: lesions highly suggestive of NCC on neuroimaging studies, positive serum enzyme-linked immunoelectrotransfer blot (EITB) for the detection of anticysticercal antibodies, resolution of intracranial cystic lesions after cysticidal drug therapy, and spontaneous resolution of single enhancing lesions; (3) minor: lesions compatible with NCC on neuroimaging studies, suggestive clinical manifestations, positive cerebrospinal fluid (CSF) ELISA for detection of anticysticercal antibodies or cysticercal antigens, and cysticercosis outside the nervous system; and (4) epidemiological: evidence of a household contact with Taenia solium infection, individuals coming from or living in cysticercosis endemic areas, and history of travel to disease-endemic areas. Interpretation of these criteria permits two degrees of diagnostic certainty: (1) definitive diagnosis, in patients who have one absolute criterion or in those who have two major plus one minor and one epidemiological criteria; and (2) probable diagnosis, in patients who have one major plus two minor criteria, in those who have one major plus one minor and one epidemiological criteria, and in those who have three minor plus one epidemiological criteria. After 10 years of usage, this set has been proved useful in both, field studies, and hospital settings. Recent advances in neuroimaging and immune diagnostic methods have enhanced its accuracy for the diagnosis of NCC.

Figure 1

Contrast-enhanced CT scan showing vesicular parenchymal brain cysticerci showing the pathognomonic ‘hole-with-dot’ imaging (arrow).

Figure 2

Left: T1-weighted MRI showing multiple parenchymal brain cysticerci in the acute encephalitic phase, appearing as small ring-enhancing lesions surrounded by edema; right: plain CT scan showing a small parenchymal brain calcification.

Figure 3

Contrast-enhanced CT scan showing obstructive hydrocephalus associated with mild abnormal enhancement of leptomeninges.