A 27-year-old man is brought to the hospital after having a generalized tonic-clonic seizure an hour ago. The patient has no chronic medical conditions and takes no medication. He emigrated from Nicaragua to the United States 5 years ago. Vital signs are within normal limits. Complete neurologic examination reveals no abnormalities. A CT scan of the head is shown in the image below. Complete blood count and cerebrospinal fluid evaluation are within normal limits. Which of the following is the most likely diagnosis?

Question

A 27-year-old man is brought to the hospital after having a generalized tonic-clonic seizure an hour ago.  The patient has no chronic medical conditions and takes no medication.  He emigrated from Nicaragua to the United States 5 years ago.  Vital signs are within normal limits.  Complete neurologic examination reveals no abnormalities.  A CT scan of the head is shown in the image below.  Complete blood count and cerebrospinal fluid evaluation are within normal limits.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec160b_384c_52cd_9249_bd9d79f7589b_MD0001_00 This patient's immigration history, new seizure, and brain calcifications indicate neurocysticercosis, an infection caused by Taenia solium (pork tapeworm) eggs. Although rare in the United States, cases are common in rural regions of the developing world (eg, South and Central America, sub-Saharan Africa, Asia) where pigs roam freely in human waste. Humans develop T solium tapeworm infection following ingestion of larvae in undercooked pork. The larvae mature into adult worms in the gastrointestinal tract and shed thousands of eggs in the stool. Cysticercosis occurs when humans ingest T solium eggs in contaminated food or water. The eggs hatch in the small intestine, invade the bowel wall, and lodge in tissue (eg, muscle, brain, eyes). Symptoms are rare initially but may develop months or years later when the cysts degrade. Most cases present with adult-onset seizure due to an intraparenchymal cyst in the brain. Examination, laboratory evaluation, and cerebrospinal fluid (CSF) analysis tend to be normal. However, imaging usually reveals ≥1 cysts in various stages of viability, as follows: A scolex, the anterior portion of the worm with suckers and hooks, is sometimes visible and is pathognomonic for the condition. (Choice A) Cryptococcal meningitis, a yeast infection common in patients with AIDS, usually presents with subacute fever, malaise, and headache. CSF evaluation usually shows increased pressure, mildly elevated leukocyte count, and low glucose level. Imaging may reveal hydrocephalus, but focal lesions (eg, calcifications) indicate an alternate diagnosis. (Choice B) Tuberculosis can spread to the CNS and form a tuberculoma. Although patients may develop seizure, CSF usually shows lymphocyte-predominant pleocytosis and elevated protein. In addition, neuroimaging will show ring-enhancing lesions. (Choice D) Neurosyphilis can cause meningovascular disease early after infection and tabes dorsalis or general paresis years later. However, seizures are fairly uncommon, and CSF evaluation typically shows lymphocyte-predominant pleocytosis and elevated protein. (Choice E) Toxoplasmosis is most common in patients with AIDS. Although seizure may occur, neuroimaging usually reveals ring-enhancing lesions, not calcifications. Patients also typically have fever. Educational objective: Neurocysticercosis is common in developing regions and usually presents years after infection with new-onset seizure. Physical examination, laboratory evaluation, and cerebrospinal fluid analysis are generally normal. However, brain imaging typically shows ≥1 cysts in various stages of viability.

A 27-Year-Old Man Is Brought to the Hospital After Having