A 3-year-old male came to the emergency room by ambulance after a non-provoked generalized seizure. The patient was in his normal state of health when his parents heard unusual sounds from his bedroom. They found him on the floor unresponsive and moving all extremities. This occurred until about the time the ambulance came which was estimated at more than 10 minutes. He had no fever or illnesses before. The past medical history was non-contributory. The family history was negative for any neurological or genetic conditions. The social history revealed that he had moved to the United States from Mexico 8 months earlier. In Mexico he had received routine care and his immunizations were current. The review of systems was negative.
The pertinent physical exam showed a groggy male who would awaken to his parents, and would appropriately cry with medical procedures and personnel. He had normal vital signs including being afebrile. His weight was estimated to be 50%. His examination was normal. Hs neurological examination showed normal cranial nerves, tone and strength. Deep tendon reflexes were 2+. Gait and balance could not be tested.
The work-up included a normal complete blood count except for some mild eosinophilia, C-reactive protein, complete metabolic panel, urinalysis. Cultures were pending. The radiologic evaluation of magnetic resonance imaging of his head showed a solitary ring-enhancing cystic parenchymal mass that was ~1.5 centimeters in size. The radiologist felt this could be consistent with neurocysticercosis. The diagnosis of a solitary mass was made as the probable seizure cause.
The patient’s clinical course included being admitted to the hospital, where he was placed on precautionary antibiotics after a lumbar puncture which showed white blood cells of 20 that were mononuclear, protein of 65 mg/100 ml, and glucose of 45 mg/100ml. The infectious disease specialist was also consulted who also felt this was consistent with neurocysticercosis. Additional testing including serology was positive for cysticercosis. He was started on a 30 day course of albendazole. Neurology consultation also agreed with beginning antiepileptic medication especially after he had another 30 second seizure witnessed in the hospital. At followup 2 weeks later, he was doing well. He had been quite tired for about 5 days after admission but his energy was almost back to normal as was his sleep. He had had one other 30 second seizure the day after leaving the hospital. He was tolerating his medications without problems.
Figure 131. Axial T2 (above left), FLAIR (above right), T1 without contrast (below left) and T1 MRI with contrast (below right) of the brain show a small round cystic lesion in the left frontoparietal region at the grey matter-white matter junction with a large amount of surrounding edema that enhances peripherally.
Neurocysticercosis (NCC) is the most common parasitic CNS infection world-wide. It is caused by the larval stage of the pork tapeworm Taenia solium. It is endemic in Southeast Asia including the Indian Subcontinent, sub-Saharan Africa and Latin America. It is becoming more common in other areas of the world because of immigration and the overall ease of travel.
The basic Taenia lifecycle is that humans eat un- or undercooked pork (pigs are the intermediate host) that is invested with the larvae called cysterici. The adult tapeworm forms in the human gastrointestinal tract and eggs are produced. Humans are the definitive host. The eggs are shed in the stool and pigs ingest the eggs, and the eggs infect the pig and form the larvae again. Eggs in the human gastrointestinal tract (from the adult tapeworm or by fecal-oral ingestion) form embryos which cross into the bloodstream and then can lodge in any human tissue in the larval form. Therefore there are two different types of human infections: the adult tapeworm called taeniasis and the larval form called cysticercosis.
Seizures are a common presenting symptom, so the differential diagnosis associated with first time seizures need to be considered such as febrile seizures, meningitis/encephalitis, masses, and electrolyte abnormalities. Also with NCC, other infections such as brain abscesses, brain granulomas (especially tuberculosis), fungal lesions and other types of brain cysts.
The diagnosis can be challenging. NCC criteria includes histological demonstration of the organism, characteristic neuroimaging features and laboratory evidence and exposure/history. Computed tomography or magnetic resonance imaging may show characteristic features such as a solitary cystic lesion with enhancement occurring at the grey-white matter junction, but often show other characteristics. If the organism’s scolex is seen this is considered diagnostic for NCC. Serological testing can be very helpful. Blood serology is very specific, and can be very sensitive depending on the patient’s clinical status. Positive testing is indicative of disease, but negative testing cannot exclude NCC as a possibility. Not surprisingly patients may have a peripheral blood eosinophilia. Cerebrospinal fluid examination may show moderate pleocytosis, increased protein levels and low glucose. Low glucose is associated with a poorer prognosis.
Treatment begins with controlling symptoms especially seizures and increased intracranial pressure with antiepileptic therapy and/or corticosteroids. Cysticidal therapy has been shown to hasten cyst resolution, but potentially could worsen the patients’ symptoms and so in some cases it is not used. Albendazole is preferred to praziquantel because of lower side effects and cost. Repeated imaging is performed about 3-6 months after treatment to monitor cyst resolution. Patients without resolution or continued symptoms are often treated again with another course of cysticidal therapy. Patients with single lesions have good prognosis with most having lesion resolution and seizures well-controlled by 6 months. More extensive initial disease and difficult to control symptoms have poorer outcomes.
Although cysticerosis can affect any human tissue, major problems occur when they affect the central nervous system and occular structures. NCC has 4 stages that the cyst undergoes from encystment to degeneration and calcification and has a long incubation period.
- Parenchymal NCC is the most common especially in children. The cysticeri usually lodge at the grey-white matter junction of the brain parenchyma where they can lie quiessent for many years until the immune system detects the cyst and local inflammation occurs.
As the body tries to kill off the invader, it can affect the brain mainly presenting as seizures but also mass effects, altered mental status, focal neurological effects and headaches.
- Intraventricular NCC can have cysts attached to the wall or potentially free floating. They can cause increased intracranial pressure through CSF obstruction and hydrocephalus.
- Subarachnoid NCC can also occur but is very rare and is often seen with intraventricular NCC. Patients usually present with increased intracranial pressure and/or meningitis or encephalitis.
- Spinal NCC can cause compression including mimicing transverse myelitis, radicular pain or cauda equina syndrome.
- Ocular cysticercosis usually is caused by cysts in the subretina. It can cause any type of visual abnormalities including ptosis, eye pain and can cause blindness.
Questions for Further Discussion
1. What are the classifications of seizures? A review can be found here
2. What other movement problems can be confused with seizures? A review can be found here
3. List some common pediatric parasitic diseases and how they are managed?
- Disease: Cysticercosis | Parasitic Diseases | Seizures | Epilepsy
- Symptom/Presentation: Seizures
- Specialty: Emergency Medicine | Infectious Diseases | Neurology / Neurosurgery
- Age: Preschooler
To Learn More
To view pediatric review articles on this topic from the past year check PubMed.
Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.
Information prescriptions for patients can be found at MedlinePlus for these topics: Parasitic Diseases and Seizures.
To view current news articles on this topic check Google News.
To view images related to this topic check Google Images.
To view videos related to this topic check YouTube Videos.
Singhi P, Suthar R. Neurocysticercosis. Indian J Pediatr. 2015;82(2):166-171. doi:10.1007/s12098-014-1576-3
de Oliveira RS, Viana DC, Colli BO, Rajshekhar V, Salomao JFM. Pediatric neurocysticercosis. Childs Nerv Syst. 2018;34(10):1957-1965. doi:10.1007/s00381-018-3889-4
Veeravigrom M, Thampratankul L. Neurocysticercosis in Children. Pediatr Clin North Am. 2022;69(1):115-127. doi:10.1016/j.pcl.2021.09.005
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa