Neurocysticercosis is a parasitic infection resulting from ingesting eggs from the adult tapeworm, Taenia solium. This central nervous system manifestation of cysticercosis is the most common parasitic brain infection and a leading cause of epilepsy in the developing world.

• In recent years, neurocysticercosis has become a significant cause of seizures, accounting for up to 10% of emergency room visits for seizures.

Natural History

• Acquired through consuming contaminated food with the feces of a T. solium tapeworm carrier (fecal-oral contact).
• Tapeworm eggs, shed in stool, contaminate food through poor hygiene.
• Ingested eggs transform into larval cysts (oncospheres) in the human stomach.
• Oncospheres migrate to the brain, muscles, eyes, and other structures via the vascular system.
• Larval cysts may remain viable in the brain for years.

Epidemiology

• Endemic in Central and South America, Asia, and Africa.
• Linked to poor sanitation and hygiene.
• No gender or race predilection; affects symptomatic patients aged 15-40 years.

Clinical Presentation

• Seizures: Most common symptom, a leading cause of seizures in young adults in endemic areas.
• Headaches
• Hydrocephalus
• Altered mental status
• Neurological deficits

Stages of Neurocysticercosis

1. Vesicular: Viable parasite with intact membrane; no host reaction.
2. Colloidal Vesicular: Parasite dies within 4-5 years, cyst fluid becomes turbid; most symptomatic stage.
3. Granular Nodular: Edema decreases, cyst retracts, enhancing persists.
4. Nodular Calcified: End-stage quiescent calcified cyst remnant; no edema.

Location

• Cysts can occur intraaxially or extraaxially in the neuraxis.
• Parenchyma: Most common, usually involving the grey-white matter junction.
• Subarachnoid space over the cerebral hemispheres: Can be very large.
• Ventricles
• Spinal forms: Usually associated with concomitant intracranial involvement.

Imaging Features by Stage

1. Vesicular Stage
   • Cyst with dot sign.
   • CSF density/intensity.
   • Eccentric hyperintense scolex on T1.
   • No enhancement; no surrounding vasogenic edema.
2. Colloidal Vesicular Stage
   • Turbid cyst fluid.
   • CT: Hyperattenuating to CSF.
   • MRI T1: Hyperintense to CSF.
   • Surrounding edema; thickened, brightly enhancing cyst wall.
3. Granular Nodular Stage
   • Edema decreases.
   • Cyst retracts, becoming a small enhancing nodule.
   • Less marked enhancement persists.
4. Nodular Calcified Stage
   • Quiescent calcified nodule.
   • No edema.
   • No enhancement on CT.
   • Signal drop-out on T2 and T2* sequences.
   • Long-term enhancement may predict ongoing seizures.

Case Report

• Patient:
  • Age: 34-year-old male.
  • Clinical Presentation: Headache & Seizure.
• NCCT Brain Findings:
  • Multiple calcified 3-7 mm nodules scattered throughout the bilateral cerebral hemispheres.
  • Some nodules causing minimal surrounding edema, particularly in the left frontal lobe.
  • Indicative of varying stages of healed neurocysticercosis.