Case Study Answers
1. What differential diagnoses are you considering for this child?
Differential diagnoses for this patient includes autism with new onset of epilepsy, parasitic or infectious etiology, or a possible cerebrovascular event because of the focal neurologic signs reported by the mother. Other possible causes include tuberous sclerosis, a brain abscess or neoplasm, tuberculosis, cytomegalovirus infection, mycosis, arteriovenous malformation, or even toxoplasmosis. Laboratory and radiologic findings are key to the diagnosis.
Autistic patients often have a dual diagnosis of epilepsy (Canitano, 2006). A recent study showed that one of three patients with autism also had some form of epilepsy and that autism is significantly associated with seizure activity (Danielsson, Gillberg, Billstedt, Gillberg, & Olsson, 2005). An MRI or computed tomography (CT) scan is frequently ordered with new-onset seizures. In this case an MRI scan revealed small hyperdense areas consistent with the scolex of a tapeworm, or Taenia solium (pig tapeworm) infestation. An MRI scan is more accurate than a CT scan in detecting the scolex, which can be used to confidently diagnosis neurocysticercosis (Khosla, 2008). An MRI scan can detect other tapeworms such as the beef tapeworm, Taneia saginate, which is often found in North America, and the fish tapeworm, Diphyllobothrium latum, which is common in Asia. The pork tapeworm, T. solium, is most commonly found in Latin America.
The recent visit to Mexico and the patient's diet of pork and beef products supports the suspicion of a parasitic infection such as Taenia saginata, as well as Diphyllobothrium latum. Stool testing was negative for parasites and is not diagnostic for neurocysticercosis (Del Brutto et al., 2001). Demonstrating T. solium eggs in the stool only allows diagnosis of taeniasis and not active cysticerci in the brain (John & Petri, 2006). Enzyme-linked immunoblot assay (ELISA) of the serum was positive for T. solium, demonstrating detection of anti-cysticercal antibodies. ELISA has the greatest sensitivity and specificity for diagnosing neurocysticercosis (Kraft, 2007).
2. How is Taenia solium diagnosed?
MRI visualization of the scolex, or sucking parts of the larva, is diagnostic for neurocysticercosis (Kraft, 2007). CT or MRI neuroimaging are the most useful methods for diagnosing neurocysticercosis (Del Brutto et al., 2001). CT scans show calcified and uncalcified cysts. Unlike CT scans, MRI scans can detect intraventricular cysts. This child's MRI scan demonstrated intraventricular multiple calcified cystic lesions. Single non-enhancing cystic lesions occur with hydatid disease, arachnoid cysts, cystic astrocytoma, and colloid cysts. Multiple non-enhancing cystic lesions occur with multiple metastasis, hydatid disease, tuberculosis, mycosis, toxoplasmosis, early gliomas, and arteriovenous malformations. Calcifications of these lesions may occur with tuberous sclerosis, tuberculosis, cytomegalovirus infection, and toxoplasmosis (Kraft, 2007).
A brain lesion biopsy of T. solium as well as a direct visualization of sub-retinal parasites by funduscopic examination also may be used to diagnose neurocysticercosis. Absolute criteria for diagnosis involves a brain or spinal cord biopsy of the lesion, but other clinical and laboratory data should be used first to avoid invasive diagnostic tests (Burneo et al., 2009, Del Brutto et al., 2001, Kraft,). With patients who are severely developmentally delayed or have cognitive deficits, such as autistic patients, eye examinations and radiologic imaging often must be done under sedation.
The ELISA has been reported to have 98% sensitivity and 100% specificity. The serologic diagnosis of T. solium may be done with the enzyme-linked immune-transfer blot for detection of any circulating antibodies. A negative serologic result, however, does not exclude cysticercosis (Khosla, 2008). The sensitivity of serologic testing is decreased in patients with calcified lesions (Khosla, 2008).
3. What key historical finding leads you to consider neurocysticercosis?
Contact with T. solium must occur for infection. Travel to an endemic area or any endemic exposure to a person from or living in an area with cysticercosis raises suspicion for this diagnosis. T. solium is transmitted mainly in areas where pigs have access to untreated human sewage or feces (Kraft, 2007). The parasite has been eradicated in the more developed countries with improved sanitation and control of domestic pig farming. T. solium is endemic in China, Southeast Asia, India, sub-Sahara Africa, and Latin America (Kraft, 2007). In Mexico alone, 3.1% to 3.9% of people carry the parasite (World Health Organization [WHO], 2009). In the United States, the disease is usually found in immigrants from Mexico and Central and South America (WHO, 2009). Furthermore, the presence of multifocal calcifications on an MRI scan is highly suggestive of cysticercosis, especially in patients from endemic areas (Khosla, 2008).
Neurocysticercosis is a parasitic infection caused by the pork tapeworm T. solium. Infection occurs in humans when ingesting eggs or larvae from undercooked pork containing the larvae or from food or water contaminated with fecal matter (John & Petri, 2006). After ingestion, the ova release oncospheres that eventually reach the bloodstream and are able to develop into cysticerci in any organ but are most common in the brain and eyes (John & Petri, 2006). Clinical symptomatology depends on the number and location of the cysts and the immune system's response to the parasite. Most patients present with clinical signs and symptoms, such as seizures or other neurologic signs such as headaches and increased intracranial pressure (Khosla, 2008). Patients will present any time from 2 to 10 years from when cysts become mature (Davis, 2005). Because of the long incubation period, children do not account for a large percentage of clinical presentations of neurocysticercosis, and seropositive results tend to increase with age (Khosla, 2008).
Neurocysticercosis is a leading cause of seizures and epilepsy in developing countries (DeGiorgio, Medina, Reynalds, & Pietsch-Escueta, 2004). Chief symptoms are often seizures (70% to 90%) and headaches, but patients also may present with nausea, vomiting, behavioral disturbances, or memory impairment (DeGiorgio et al., 2004). Cysts and disease in the brain develop in almost 60% of patients with cysticerci (John & Petri, 2006).
4. What is the appropriate treatment for neurocysticercosis?
Antihelmintic drugs should be considered only after a thorough ophthalmic examination to rule out any intraocular cysts before treatment with a cysticercoidal drug. Cysticidal drugs cause cyst degeneration and can result in visual impairment if cysts are present in the eye (Garcia et al., 2002). This patient did not have any ocular involvement as evidenced by an ophthalmologic examination under sedation, so cysticidal medication was indicated. Surgery is indicated for ophthalmic cysticercosis, and antihelminth drugs should be avoided until ocular lesions are removed (Garcia et al., 2002).
Albendazole and praziquantel are the principal cysticidal drugs (DeGiorgio et al.,, Sotelo and Brutto, 2002). Albendazole is preferred over praziquantel because it is less costly and has a better clinical response for seizure control in persons with neurocysticercosis (Burneo et al., 2009; Matthaiou et al., 2008). Albendazole should be given at 15 mg/kg/day (up to 400 mg twice daily) for 4 weeks to reduce seizure recurrence and existing lesions (Bureno, 2009; Matthaiou, Panos, Adamidi, & Falagas, 2008). Adverse effects include nausea, headache, cerebral edema, gastrointestinal upset, seizures, and increased intracranial pressure (Carpio, 2002). Steroids commonly are used with cysticercosis in the brain because cysticidal drugs damage the parasite and release antigens that often trigger inflammatory response (Burneo et al., 2009). Corticosteroids may decrease the seizure frequency (Yancey, Diaz-Marchan, & White, 2005). An open-label randomized trial found a reduced seizure rate when prednisone therapy, 1 mg/kg/day for 10 days, was followed by a 4-day tapering of the drug (Mall, Agarwall, Garg, Kar, & Shukla, 2003).
5. What is the recommended follow-up for neurocysticercosis?
Neuroimaging should be repeated in 3 months, after completion of therapy with albendazole. If there is only a partial resolution of the cystic lesion, a repeat MRI scan of the head should be repeated in 3 months (Garcia et al., 2002). A second course of albendazole may be needed if the lesions are persistent after 6 months (Garcia et al., 2002). Some patients will require long-term antiepileptic medications such as phenytoin (Dilantin) and carbamazepine (Tegretol) for seizure control (Kraft, 2007). Referral to a pediatric neurologist or epilepsy clinic is indicated. Seizure recurrence depends on the number of cyst calcifications on an MRI scan and the cyst burden of the brain. Prognosis varies from patient to patient and the specific clinical findings in each case. The patient should follow up with a neurologist for this condition every 6 months, and the patient's clinical course and outcome should be communicated to the patient's primary care provider.
6. What patient education would you provide for the family?
Emphasizing the importance of cooking pork thoroughly or keeping unused portions frozen along with close inspection of the meat should be taught to people who frequently travel or live in endemic areas. Consumption of raw or undercooked meat should be avoided. The WHO stresses the importance of treating or vaccinating pigs against cysticercosis (WHO, 2007). Cysticercosis can be prevented by routine inspection of meat and destruction of infected meat by the local government. However, in areas where food is scarce, cyst-infected meat is still eaten, which is one of the reasons cysticercosis has not been eliminated in endemic area (WHO, 2007).
Family care and support is important for patients with neurocysticercosis infection. Case management may be necessary to coordinate infectious disease follow-up, neurology visits, or possible referral to an epileptologist. The patient's medication regimen and rationale should be reviewed with the parents, and the importance of compliance with follow-up diagnostic imaging and the health care provider must be emphasized. The family also can be given useful references to explore, such as the Neurocysticercosis and Epilepsy Research Network and the Centers for Disease Control Working Group on Parasitic Diseases at https://whqlibdoc.who.int/hq/2007/WHO_CDS_NTD_2007.3_eng.pdf
Neurocysticercosis can present in many forms depending on cyst location and disease progression. It should be high on the list of differential diagnoses in children presenting with new-onset seizures who have traveled to endemic areas. Neurocysticercosis is a leading cause of epilepsy in the developing world (DeGiorgio et al., 2004). Treatment with albendazole improves the prognosis for recurrent tonic-clonic seizures in highly selected patients. The WHO is developing and enforcing global strategies for control (DeGiorgio, 2004).
J Pediatr Health Care. 2010;24(4):270-274. © 2010 Mosby, Inc.
Cite this: Seizures in a Non-communicative Child - Medscape - Jul 01, 2010.