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A previously healthy 27-year-old woman presented to the emergency department with 2 weeks of headache, photophobia, vomiting, and confusion. She denied fevers or chills. She was born in Guatemala and had immigrated to the US approximately 1 year ago, without subsequent international travel. She took no medications. On examination, she was afebrile (36.8 °C) and hemodynamically stable, with heart rate 70/min and blood pressure 95/53 mm Hg. She was somnolent and confused without focal neurologic deficits. Serum white blood cell count was elevated to 14.9 ×109/L (86% segmented neutrophils, 9% lymphocytes, 5% monocytes, 0% basophils/eosinophils). A computed tomography scan of her brain was notable for diffuse ventriculomegaly and sulcal effacement consistent with hydrocephalus and cerebral edema. Given her diminished level of consciousness, a ventriculostomy was placed emergently. Laboratory analysis of cerebrospinal fluid (CSF) obtained from the ventriculostomy was notable for 40 red blood cells/mm3; 3 nucleated cells/mm3; protein level, 11 mg/dL; and glucose level, 73 mg/dL. Magnetic resonance imaging (MRI) of the brain with and without contrast demonstrated ventriculomegaly of the lateral and third ventricles, with a 0.4 × 0.4 × 0.6–cm nonenhancing lesion obstructing the aqueduct of Sylvius (Figure 1A). No abnormal meningeal enhancement or parenchymal lesion was identified. On hospital day 5, in the midst of an ongoing infectious diseases workup, the measured intracranial pressure and rate of CSF drainage from the ventriculostomy suddenly decreased. Repeat MRI demonstrated resolved hydrocephalus, a patent aqueduct of Sylvius, and the aforementioned nonenhancing lesion now located in the fourth ventricle (Figure 1B).
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Mobile isolated intraventricular neurocysticercosis
C. Extract the lesion surgically
The key to the correct diagnosis is the MRI finding of a mobile intraventricular mass that had provoked obstructive hydrocephalus. The abrupt paroxysmal onset of hydrocephalus as a result of transient ventricular obstruction by a mobile mass has a small differential diagnosis that is limited to intraventricular tumors and free-floating cystic lesions. A mobile intraventricular cyst is essentially pathognomonic for the diagnosis of neurocysticercosis.1
Neurocysticercosis is the most common helminthic infection of the central nervous system and remains a major cause of seizures and hydrocephalus, both in endemic areas and in the US.2,3 The infection is transmitted via ingestion of Taenia solium eggs and spreads to the central nervous system from the stomach by way of vascular and lymphatic channels. The robust immunologic response to the cyst, which has a terminal life span, results in cerebral edema and associated symptoms.2 Although any neurologic deficit is possible, focal seizures are the most common manifestation.
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Corresponding Author: Tianyi Niu, MD, Department of Neurosurgery, The Warren Alpert School of Medicine, Brown University, Rhode Island Hospital, 593 Eddy St, APC 6, Providence, RI 02903 (firstname.lastname@example.org).
Published Online: October 9, 2020. doi:10.1001/jama.2020.10167
Conflict of Interest Disclosures: None reported.
Additional Contributions: We thank the patient for providing permission to share her information.
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