Neurocysticercosis

General Considerations

• Most common parasitic infestation of central nervous system worldwide
• Caused by the pork tapeworm, Taenia solium
• Most important manifestation of disease is in central nervous system-neurocysticercosis (NCC)
• Endemic areas include Mexico and Latin America, sub-Saharan Africa, India and east Asia
• Incidence in USA is increasing from immigration and travel
• Life cycle
  • Humans are definitive host of intestinal tapeworm
• Pigs are intermediate host
• Human cysticercosis develops when eggs or larva are ingested through fecal-oral transmission from a tapeworm host or in undercooked pork
• Cysticerci (larval cysts) develop within organs
• Skin, skeletal muscle, CNS, heart, eye

Life Cycle of Taenia Solium (Pork Tapeworm) (From CDC)

Clinical Findings

• Dependent on pericystic inflammation
• If no inflammation, usually asymptomatic
• Seizures
• Chronic headache
• Nausea and vomiting
• Mental status change
• Vision changes

Imaging Findings

• Usually parenchymal in brain
  • May be ventricular or subarachnoid
• Involuted, degenerated cysts calcify and appear oblong or cigar-shaped
• CT is the imaging study of choice for NCC
  • Calcifications
• Calcified cysts are usually not associated with surrounding inflammation
• Non-enhancing cystic lesions with/without surrounding edema
• Mass effect
• Hydrocephalus
• MRI may demonstrate cysts with then ventricular system
• Lateral, 3^rd and 4^th ventricles

Differential Diagnosis

• Coccidiomycosis
• Toxoplasmosis
• Tumor
• Trichinosis
• TB

Treatment

• Anti-helminthic medications

Complications

• Encephalopathy
• Obstructive hydrocephalus
• Sequelae of treatment from steroids or anti-convulsants
• Calcified cysts may be epileptogenic

Prognosis

• Excellent in most cases 

Cysticercosis. White arrows point to calcified cysticerci scattered throughout the
brain parenchyma with no surrounding inflammation. The right shoulder demonstrates
multiple cigar-shaped, muscular calcifications, again representing cysticerci.
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Cysticercosis: Differential Diagnoses & Workup. eMedicine. Ryan Tenzer, R and Blumstein, H.