January 2003

A 10-year-old girl presented for evaluation of recent migraine headaches. During her evaluation by her primary physician, she was found to have mild mental status changes consisting of some memory loss and disorientation. There had also been an episode of emesis. Her medical history denoted she was born in Mexico, where she lived for her first three years. She has lived in central Texas since leaving Mexico with her family. She has never been back to Mexico, but relatives from Mexico have visited her family on numerous occasions. Her family is healthy with no history of headaches. There has been neither insect nor animal exposure. There are no unusual dietary habits, and they drink city water. Her immunizations are up to date, and she does well in school.

Her examination revealed normal vital signs and normal examination at the time of the consult. Her mental status had returned to normal. Her primary physician had performed a PPD (purified protein derivative for screening of TB) and chest radiograph, which were normal. She came with the MRI shown in figures 1 and 2.

What’s your diagnosis?

1. Brain abscess
2. Tuberculoma
3. Neurocysticercosis
4. Toxoplasmosis

Answer

The answer is C, neurocysticercosis, which reveals the characteristic ring-enhancing lesion with surrounding edema shown on the MRI. This condition is the consequence of ingesting the eggs of the pork tapeworm, Taenia solium (figures 3, egg; and 4, adult worms), and tends to occur where sanitation is poor. It is usually imported, but can be locally acquired. It is most common from Mexico, South & Central America, Africa, Asia, Spain and Portugal. Ingestion of the egg is usually via the fecal-oral route from humans carrying adult tapeworms in their gut. This is probably what happened in the case presented when the patient’s relatives from Mexico visited and helped prepare food. The ingested egg hatches in the stomach, and the larva penetrates the gut wall and enters the circulation. It may then travel anywhere in the body, lodge and become encysted, making the human an intermediate host. The subcutaneous tissues, muscle and brain are common sites. Neurocysticercosis is the most significant result of this disease. There is a wide degree of variation in the neuropsychiatric manifestations from no symptoms to intractable seizures or psychosis. Patients often complain of headache as their initial manifestation, but a seizure is what usually leads the patient to be evaluated with imaging and diagnosed. As with the patient being presented, imaging will reveal characteristic ring-enhancing lesions with surrounding edema. Neuroradiologists consider this appearance to be virtually diagnostic of neurocysticercosis. Either recovery of a lesion for examination or positive serologic testing by Western blot can confirm the diagnosis. The serologic test however is often negative with solitary lesions.

Once the diagnosis is made, the decision to treat may depend on several factors, such as the number of lesions, whether they are old (calcified) or active, their location(s) and the clinical severity. Also, part of the evaluation should include an eye exam by an ophthalmologist to rule out ophthalmic cysticercosis before initiating therapy as surgery may be the best treatment there. Drug treatment is controversial, but most experts recommend either albendazole (Albenza, GlaxoSmithKline) or praziquantel (Biltricide, Bayer) after several days of steroid therapy to help control the inflammatory response. Of course, anticonvulsants are usually required initially to manage the possibility of more seizures if that is how the patient presented. It is advisable to consult a pediatric neurologist and an infectious disease specialist to help guide therapy. The patient presented was treated with albendazole for one month, and a follow-up scan was performed six weeks later (figures 5-6), showing some improvement in the edema and size of the lesion.

A brain abscess may have a similar appearance on imaging (figure 7) but not quite the same. Also the patient would likely have fever and probably a history of injury or other factors that lead to an abscess.

Tuberculoma, rare in the United States, is an intracranial mass of M. tuberculosis organisms and is a complication of TB meningitis. They usually present as space-occupying lesions, most times near the base of the brain. They should not be confused on scanning with neurocysticercosis.

Toxoplasmosis may result in brain lesions that are calcified. They also would not be ring-enhancing and not likely have the edema seen with neurocysticercosis.

This case illustrates the increasing occurrence of neurocysticercosis outside the usual environment due to increased travel. The same is true of other previously uncommon diseases, as movement, both nationally and internationally occurs with greater frequency. This was the case when, 20-years-ago in Hawaii as a fellow, I saw a case of Rocky Mountain Spotted Fever (RMSF), which is not endemic there. The child had just moved with his military family from North Carolina, where a tick had bitten him approximately a week earlier. Military families tend to move in the summer months, so of course they may be coming from foreign countries, or parts of the U.S., incubating a disease spread by mosquitoes or ticks upon arrival to their new home. This puts more responsibility on primary care providers to be familiar with diseases that are not normally seen in their geographic area. I have found that the CDC travel site or www.mdtravelhealth.com can be good resources for seeing what’s common in various parts of the world. These web-sites can help, but you still need to have an elevated index of suspicion and include a travel history in the H&P (history and physical) to get to the answer. The travel history should also include visitors to the family from outside the area.

Acknowledgement: Figures 3 and 4 were previously obtained from the late Jim Bass.

Addendum to the November issue: I would like to make some additional comments about the column on omphalitis. My friend, Itzhak Brook, MD, reminded me of the role anaerobes play in omphalitis, which I left out of my discussion. Dr. Brook pointed out a study he published in the Journal of Infection (a British publication) in 1982 where he reported recovering anaerobes from 87% on neonates with omphalitis, and emphasized the likelihood of this being a polymicrobial infection. He also reminds us that we should be performing more anaerobic cultures on these cases (only if you really want to know what’s causing the problem). The data from that study as well as others can be found, neatly summarized in chapter 11 of his textbook, Pediatric Anaerobic Infections, Diagnosis and Management. This is the third edition, published by Marcel Dekker, 2002. I have referred to Dr. Brook’s book before, but I stupidly forgot to on this case. It is a very reader-friendly text that I recommend for anyone who sees children with infections (isn’t that just about all of us?).

I truly hope your year ended well and that the New Year finds you safe and healthy. Asking for financial prosperity on top of that may be pushing our luck.

For Your Information:

• James H. Brien, DO, Pediatric Infectious Disease, Scott and White's Children's Health Center and Texas A&M University, College of Medicine, Temple, Texas. E-mail: jhbriend@aol.com