Neurocysticercosis in Children

While the current COVID-19 pandemic has significantly reduced travel (especially for those of us in the USA… hmmm… who would have thought a US passport would be of such little value?) we are all acutely aware of the potential benefits and hazards that travel offers. Sure, it is lovely to fly around the world, but sometimes critters like to fly home with us. Global infectious diseases have gained a lot of notoriety this year (well, at least a specific one) and hopefully remind us that we are merely a short trip away from an endemic area. Malaria and Dengue may not be common in your area, but they may still present to your Emergency Department. Let’s take a minute to consider another important global infection that may not be common in your backyard, but may still be affecting your patients – Neurocysticercosis in Children:

Neurocysticercosis: Basics

  • Neurocysticercosis is an acquired infection: [Singhi, 2019; de Oliveira, 2018; Singhi, 2016]
    • Caused by Encysted Larvae of Taenia solium
    • Taenia solium is the most common helminth infection of the nervous system in humans.
  • Travel involving endemic areas has lead to increased incidence in USA, UK, and Australia. [de Oliveira, 2018; Singhi, 2016]
  • Is endemic to: [Singhi, 2019; de Oliveira, 2018; Singhi, 2016]
    • Southeast Asia
    • Sub-Saharan Africa
    • Mexico and Latin America
    • Other developing countries
  • Neurocysticercosis “life cycle”: [Singhi, 2019; de Oliveira, 2018; Singhi, 2016]
    • Taenia solium infects two common hosts: Pigs (and dogs) and Humans.
    • Transmission occurs via fecal-oral route (the grossest of routes)
      • Adult worms release eggs while lodged in human intestines.
      • Pigs / dogs become infected from contact with contaminated soil.
      • Cysticerci develop in muscles of pigs/dogs.
    • Humans become infected by:
      • Ingestion of undercooked pork that is infected with live encysted larvae
      • Ingestion of contaminated foods
        • ex, vegetables grown in contaminated soil, water contaminated by runoff, food contaminated by infected food handlers
        • so, being vegetarian is not wholly protective.
      • Autoinfection (also gross)

Neurocysticercosis: Presentation

  • Neurocysticercosis causes significant morbidity in endemic areas: [de Oliveira, 2018; Singhi, 2016]
    • Major cause of Seizure Disorders/ Epilepsy in the Tropic regions.
    • Most common cause of focal seizures in North Indian children.
    • While it can be asymptomatic, it can also lead to death.
  • Symptoms are dependent upon: [Singhi, 2019; Singhi, 2016]
    • Location of cysts
      • Typically are intraparenchymal
      • Can be extraparenchymal
        • Ventricles, Subarachnoid space, Cisterns
        • Can grow irregularly and large (given large potential space).
        • Can elicit strong inflammatory responses.
    • Number of cysts
      • More cysts = worse symptoms
      • Less cysts = better prognosis
    • Size of cysts
    • Host response to cysts and therapy
  • Neurocysticercosis presentations based on location: [Singhi, 2019; Singhi, 2016]
    • Parenchymal:
      • Seizures (70 – 90% of symptomatic cases will develop seizures)
      • Focal motor deficits and focal seizures
      • Signs of hydrocephalus (ex, papilledema, headache and vomiting)
      • Encephalitis (Cysticercal encephalitis) – rare, due to massive cyst burden
    • Extra-Parenchymal:
      • Obstructive hydrocephalus
      • Communicating hydrocephalus
      • Chronic Meningitis
      • Stroke
      • Spinal cysticercosis – radicular pain, cord compression
      • Vasculitis
      • Ptosis
      • Amaurosis fugax or Unilateral blindness
      • Dystonia
      • Neurocognitive deficits

Neurocysticercosis: Management

  • Making the diagnosis of Neurocysticercosis is difficult: [Singhi, 2016]
    • There is no gold standard test (or test strategy) for it.
    • Many infected individuals are asymptomatic.
    • Detection of eggs in stool is difficult:
      • Eggs are only shed once or twice a day.
      • Eggs look similar to other less concerning tapeworm eggs.
    • Testing and imaging is expensive and imprecise.
  • Imaging: [Singhi, 2019; Singhi, 2016]
    • CT imaging is commonly obtained.
      • Cysts appearance changes based on stage.
      • Cysts exist in 4 stages: [Singhi, 2016]
        • Vesicular – small, thin walled, no edema
        • Colloidal – thick walled, ring-like enhancement
        • Granular Nodular – enhancing cyst, mild edema
        • Nodular Calcified – small calcified nodule, no edema
    • MRI may be required:
      • To image posterior fossa and extra-parenchymal involvement
      • To detect the scolex (the creepy heads of the worms)
  • Other testing: [Singhi, 2019; Singhi, 2016]
    • Serology, Antigen testing, and Antibody testing all play a role, but no single test is the gold standard.
    • Most are helpful when positive, but negative tests do not rule-out the condition.
  • Treatment: [Singhi, 2019; Singhi, 2016]
    • Albendazole – 15mg/kg/Day for ~4 weeks
      • Evidence that it may decrease number of lesions and improve seizure control.
      • Use should be DELAYED in setting of markedly elevated intracranial pressure or ophthalmic involvement (concern for worsening inflammatory response).
      • Praziquantel may be added if no improvement after initial therapies.
    • Corticosteroids
      • Oral prednisolone 2 mg/kg/Day (~2 days before albendazole and for total of 5-6 days)
      • Dexamethasone 0.1 mg/kg/Day IV has been used for cases of increased intracranial pressure or extensive cerebral edema.
    • Antiepileptic Therapy
      • Carbamazepine and phenytoin are most commonly selected as 1st line therapy.
      • Often continued until seizure-free for 1 year.
    • Surgical procedures
      • Not typically used to treat the infection or cysts themselves (unless significant mass), but…
      • May be needed to treat hydrocephalus or in cases where medical therapy has failed.

Moral of the Morsel

  • Travel history is important! We must all think outside of the confines of our own little worlds.
  • New onset seizures in patient with potential exposure… maybe don’t forgo the Head CT.
  • Don’t eat undercooked pork (or dog) and wash your hands. Hmm… again… simple strategies to reduce disease burden… where have I heard that before?

References

Sean M. Fox

I enjoy taking care of patients and I finding it endlessly rewarding to help train others to do the same. I trained at the Combined Emergency Medicine and Pediatrics residency program at University of Maryland, where I had the tremendous fortune of learning from world renowned educators and clinicians. Now I have the unbelievable honor of working with an unbelievably gifted group of practitioners at Carolinas Medical Center. I strive every day to inspire my residents as much as they inspire me.

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