Criteria

Revised diagnostic criteria for neurocysticercosis[51]

Absolute criteria:

  • Histological demonstration of the parasite from biopsy of a brain or spinal cord lesion

  • Visualisation of sub-retinal cysticercus

  • Conclusive demonstration of a scolex within a cystic lesion on neuroimaging studies.

Neuroimaging criteria:

  • Major neuroimaging criteria:

    • Cystic lesions without a discernible scolex

    • Enhancing lesions

    • Multilobulated cystic lesions in the subarachnoid space

    • Typical parenchymal brain calcifications

  • Confirmative neuroimaging criteria:

    • Resolution of cystic lesions after cysticidal drug therapy

    • Spontaneous resolution of single small enhancing lesions (use of corticosteroids makes this criterion invalid)

    • Migration of ventricular cysts documented on sequential neuroimaging studies

  • Minor neuroimaging criteria:

    • Obstructive hydrocephalus (symmetrical or asymmetrical) or abnormal enhancement of basal leptomeninges.

Clinical/exposure criteria:

  • Major clinical/exposure:

    • Detection of specific anticysticercal antibodies or cysticercal antigens by well-standardised immunodiagnostic tests

    • Cysticercosis outside the central nervous system

    • Evidence of a household contact with Taenia solium infection

  • Minor clinical/exposure:

    • Clinical manifestations suggestive of neurocysticercosis

    • Individuals coming from or living in an area where cysticercosis is endemic.

Definitive diagnosis:

  • One absolute criterion

  • Two major neuroimaging criteria plus any clinical/exposure criteria

  • One major and one confirmative neuroimaging criterion plus any clinical/exposure criteria

  • One major neuroimaging criterion plus two clinical/exposure criteria (including at least one major clinical/exposure criterion), together with the exclusion of other pathologies producing similar neuroimaging findings.

Probable diagnosis:

  • One major neuroimaging criterion plus any two clinical/exposure criteria

  • One minor neuroimaging criterion plus at least one major clinical/exposure criterion.

Separate diagnostic criteria for parenchymal and extraparenchymal neurocysticercosis have been suggested.[52]

World Health Organization (WHO): staging of cystic echinococcosis cysts[20][53]​​

Treatment options for cystic echinococcosis depend on the stage of development of the parasitic cyst based on ultrasound imaging. The classification applies to any cyst, except for osseous cysts, because it describes morphology.

Active cysts likely to contain viable protoscoleces

  • CE1

    • Active

    • Unilocular

    • Liquid content

    • Viable

    • Visible pathognomonic double wall sign

  • CE2

    • Active

    • Multivesicular

    • Liquid content

    • Viable

    • Visible pathognomonic honeycomb appearance (mother cyst filled with daughter cysts)

  • CE3a

    • Transitional unilocular

    • Liquid content with detached parasitic layers

    • Viable or non-viable

    • Visible pathognomonic water lily sign

  • CE3b

    • Active multivesicular

    • Partially solid content with daughter cysts

    • Viable

    • Visible pathognomonic Swiss cheese appearance

Inactive stages

  • CE4

    • Solid content

    • Unlikely to contain viable protoscoleces

    • Visible pathognomonic ball of wool or canalicular or cerebroid appearance

  • CE5

    • Solid content with eggshell calcified wall

    • Non-viable

    • Visible pathognomonic ball of wool or canalicular appearance

Cystic lesions

  • Not a cystic echinococcosis stage; indicates a cyst that could be a suspected young echinococcal cyst.

  • Unilocular with anechoic content without double wall sign or evident signs of non-parasitic aetiology.

Complicated cysts

  • A cyst with complications which might include rupture (outside, or internally in structures of the infected organ); cysts causing clinically significant compression of internal structures of the infected organ or of neighbouring organs, superinfection of the cyst with bacteria or fungi; and anaphylactic reactions to echinococcal antigens due to loss of integrity of the cyst wall.

Uncomplicated cysts

  • Cysts without complications.

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