Cysticercosis

Background

• Parasitic infection caused by larval stage of Taenia solium (pork tapeworm)
• Occurs when humans (definitive host) ingest poorly cooked pig (intermediate host) that is infected with larvae (cysticerci)
• Estimated 50-100 million people infected worldwide
  • 1,000 new cases in US per year, mostly in immigrants from Latin America but also seen in those from Asia or Africa
• More than 80% of those affected are asymptomatic
• Cysts can reside anywhere in body

Clinical Features

Divided into extraneural cysticercosis (outside CNS) and neurocysticercosis (which can be parenchymal, extraparenchymal or both)

• Extraneural cysticercosis
  • Subcutaneous tissue: nodules that are not cosmetically pleasing, but usually asymptomatic
  • Muscle: asymptomatic or sometimes painful due to surrounding inflammation
  • Cardiac cysts are rare: arrhythmias/conduction abnormalities
• Neurocysticercosis (NCC)
  • Parenchymal NCC
    • Most common presentation of NCC
    • Most cases are asymptomatic and discovered incidentally after resolution of infection (see image below)
    • Those with symptoms usually present with seizures (focal or generalized)
    • Focal neurologic deficit
  • Extraparenchymal NCC: more often present with headaches, vomiting, hydrocephalus
    • Intraventricular cysts: can get lodged in ventricular outflow tracts and cause obstructive hydrocephalus and increased ICP causing nausea, vomiting, AMS, papilledema
    • Subarachnoid cysts: can cause inflammatory response leading to arachnoiditis which may result in hydrocephalus, meningitis, stroke, and vasculitis
    • Ocular (1-3% of cases): diplopia if EOM involvement, vision loss or pain if intra-ocular
    • Spinal (1% of cases): radicular pain, paresthesias, cauda equina symptoms

Differential Diagnosis

• Brain abscess
• Vasculitis
• Tuberculomas or Mycotic granulomas
• Primary brain tumors or metastases

Workup

• Imaging is usually best
  • CT head (calcifications/edema); MRI (cysts +/- scolex, edema)
  • X-rays or CT for extraneural cysticercosis
• EITB assay for anticysticercal antibody
  • Serum (more sensitive) or CSF studies (less common)
• Labs
  • Usually not helpful
  • Eosinophilia not seen unless cyst is leaking/ruptured
• Depending on presentation, involvement of the following services may be needed:
  • Neurology: for seizures refractory to meds
  • Neurosurgery: hydrocephalus, mass effect, herniation
  • Infectious disease: if starting antiparasitic therapy
  • Ophthalmology: if suspect ocular involvement or if starting antibiotics and need to confirm no ocular involvement

Management

• Asymptomatic: observation
• Subcutaneous or intramuscular: typically observation
  • If just one lesion or cosmetic issue, surgical excision
  • Otherwise: NSAIDs
• Symptomatic NCC
  • Anticonvulsants (keppra, dilantin, newer agents)
  • Antihelminthic therapy and steroids
    • Treat if edema, mass effect, or vasculitis
    • Don’t treat if old calcifications on CT without edema
    • Before starting these meds, need to check for:
      • positive PPD
      • co-infection w/ Strongyloides (steroids can cause to disseminate)
      • ocular involvement (inflammation associated with dying organisms can result in vision loss by causing chorioretinitis, retinal detachment, or vasculitis)
    • Pts started on therapy get admitted to watch for any adverse events initially
    • First line: Albendazole 15mg/kg/day divided in 2 doses
    • Second line: Praziquantel: 50-100mg/kg/day divided in 3 doses
    • Steroids: Prednisone 1mg/kg/day or Dexamethasone 0.1mg/kg/day
  • If hydrocephalus present, CSF diversion with ventriculostomy or VP shunt by Neurosurgery and/or surgical resection of cysts.
• Ocular
  • Intra-ocular: surgery
  • Extra-ocular muscle involvement: albendazole and steroids
• Spinal intramedullary: possibly surgery

Disposition

• Home if asymptomatic or no complications w/ good pain control
• Admit if starting antihelminthic therapy for further testing as listed above and to monitor initial side effects of drug therapy
• ICU for uncontrolled seizures, AMS, increased ICP

Sources

• Mansur MM and Cunha BA. “Cysticercosis.” www.emedicine.medscape.com. Oct 2012.
• Khosla, A and Smirniotopoulos. “CNS Imaging in Cysticercosis.” www.emedicine.medscape.com. Oct 2012.
• White AC, Weller PF and Baron EL. “Treatment of cysticercosis.” www.uptodate.com. Jul 2014.
• White AC, Weller PF and Baron EL. “Clinical manifestations and diagnosis of cysticercosis.” www.uptodate.com. Jul 2014.
• Rosen’s Emergency Medicine