Case Presentation: A 32-year-old male Mexican immigrant with no past medical history presented to the emergency department with sudden onset altered mentation. Four days prior to presentation, he had developed a headache, which had developed into confusion. On the morning of presentation, he became non-verbal and unresponsive, and his wife drove him to the emergency department. An MRI initially revealed hydrocephalus with enlargement of all portions of the lateral and third ventricle. He was intubated for airway protection and started on vancomycin, ceftriaxone, and acyclovir for presumed meningitis. An external ventricular drain was placed, and he was transferred to our hospital.
Within 24 hours, his mental status rapidly improved, and he was extubated. Physical exam was remarkable for bradycardia (heart rate 57) and a right frontal external ventricular drain. He was alert and oriented to person, place, time, and situation. His labs revealed transaminitis (AST 84, ALT 189), and cerebrospinal fluid analysis revealed 23 white blood cells per milliliter (86% lymphocytes) with normal glucose and protein. A repeat MRI of his brain revealed a large cystic structure in the posterior left ventricle concerning for a cysticercus. Anti-infectives were stopped, and neurosurgery was consulted for minimally invasive neuroendoscopic extraction.

Discussion: Neurocysticercosis (NCC) is caused by consuming Taenia solium eggs from the stool of a human tapeworm carrier. Most cases are from Central and South America, sub-Saharan Africa, and parts of Asia. After ingestion, the embryos hatch in the small intestine and disseminate to the brain, muscle, or liver. Within 3-8 weeks, cysticerci develop walls with an invaginated scolex. The median time from exposure to the first signs and symptoms of neurocysticercosis is 3.5 years. While the viable phase is the longest, symptoms typically occur during the degenerating or non-viable phase when there is an inflammatory response leading to cyst calcification. Cysticerci that reside in the brain parenchyma can cause seizures or encephalitis-like symptoms. Cysticerci in extraparenchymal regions, such as the ventricles or subarachnoid areas, may present with headaches, nausea, and vomiting from increased intracranial pressure (ICP).

Treatment includes managing elevated ICP with corticosteroids or a ventricular shunt. Surgical removal of the cysticercus is advised for intraventricular cysts causing obstruction. Antiparasitic therapy is warranted only if there is no evidence of hydrocephalus, a high cyst burden, or calcified lesions.

Conclusions: Intraventricular (extraparenchymal) NCC is a parasitic disease that can present with altered mental status due to elevated ICP in patients from an endemic area. The recommended management of an intraventricular cyst is neuroendoscopical extraction and fenestration of the anterior wall of the third ventricle during the same procedure to avoid the need for a shunt.

IMAGE 1: Sagittal view revealing scolex and cyst wall

IMAGE 2: Transverse view revealing cyst wall