When an otherwise healthy 38-year-old man suddenly started having unexplained seizures, his illness was a mystery—until a CT scan of his head uncovered a strange anomaly not commonly found in the United States, according to a new case study published in the New England Journal of Medicine, Timothy Bella writes for the Washington Post.

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An unwelcome guest

After a 38-year-old man's wife found him shaking and "speaking gibberish" during a violent seizure, they rushed to the ED at Massachusetts General Hospital. Upon arrival, the man suffered another seizure—even though he had been in good health and had no history of related symptoms.

Initially, his doctors were puzzled by the man's condition, but a CT scan of his head revealed the cause: an unwelcome visitor. Specifically, the images showed three brain lesions that had been caused by larval cysts from a tapeworm that had been embedded into parts of the patient's brain for the past 20 years. As a result, he was diagnosed with neurocysticercosis.

Following clues to find 'the most likely diagnosis'

According to the study, the man emigrated to the United States from rural Guatemala—a region in which parasite-related illnesses are endemic.

"On the basis of the features of the patient's presentation, the fact that he had been healthy the day before the seizure, and his history of living in a rural area of Guatemala, neurocysticercosis [was] the most likely diagnosis in this case," wrote Andrew Cole, lead author of the study.

According to Bella, two of the most common ways to get a tapeworm generally are eating undercooked pork and being in unsanitary conditions. But neurocysticercosis specifically is commonly transmitted when a person has swallowed "microscopic eggs passed in the feces of a person who has an intestinal pork tapeworm," according to CDC. One example of how this can happen—and what the authors  believed to have happened in this patient's case—is when an individual ingests tapeworm eggs passed via a meal prepared by someone with a tapeworm.

"Once inside the body, the eggs hatch and become larvae that find their way to the brain," CDC said.

'A little atypical, but not amazingly rare'

While it is not common to see parasitic infections in the brain in the United States, some recent medical mysteries have ended with discoveries of tapeworms in the cerebrum, Bella writes.

According to Edward Ryan, director of global infectious diseases at Massachusetts General Hospital and a co-author of the study, the man's case was particularly interesting because the tapeworm caused seizures even though it had been dead for quite some time.

"This gentleman was a little atypical, but not amazingly rare, in that his parasites were dead and calcified and there was no living parasite in his brain for one or two decades," Ryan said. "The infection was long gone, but part of his brain was scarred — and that scarred area was leading to the seizures."

"He's not the only person this has happened to, but he's in the minority of individuals we see," Ryan added.

'Seizure-free'

After his doctors stabilized him with anti-seizure drugs, the patient was treated with two antiparasitic drugs and an anti-inflammatory drug, according to the study. The researchers reported that the man was released from the hospital five days later and has not had any additional symptoms or seizures in the three years since. Moreover, since his original diagnosis, the swelling around the patient's largest brain lesion has decreased.

"He seems to be doing fine," Ryan said. "The good news is he continues to do well and be seizure-free." (Bella, Washington Post, 11/16)