Neurocystercicosis

Case contributed by Dr Rajalakshmi Ramesh

Presentation

A 21-year-old male, recently migrated from Thailand, presenting to the emergency department with generalised tonic-clonic seizure on a background of an unknown duration of headaches, increasing confusion and lethargy. Unremarkable neurological examination.

Patient Data

Age: 21-year-old
Gender: Male

CT Brain

Modality: CT

Small rounded hyperdensities measuring 2-3mm diameter throughout the brain parenchyma consistent with calcified neuro cystercicosis. No significant mass effect from any of the lesions. A few lesions have a subtle hypodense rim consistent with a small amount of surrounding oedema. No other significant abnormality is seen. An MRI may be of value to differentiate any active neurocystercicosis.

MRI Brain

Modality: MRI

Comparison has been made to the previously obtained CT scan. Scattered throughout all parts of the brain are innumerable small rounded predominantly cystic lesions that measure approximately 5 mm in diameter, and contain eccentric nodule. They demonstrate widespread faint peripheral enhancement as well as some intrinsic high T1 signal of the central nodule, in keeping with the calcification seen on CT. There is essentially no oedema surrounding any of these lesions, and no convincing evidence of intraventricular or subarachnoid disease. The remainder of the brain is unremarkable.

Conclusion: Features are consistent with neurocysticercosis, with lesions being in the granular nodular stage, with some already at the calcified nodular stage. The number of lesions present in this patient is consistent with its origin from a region where silicosis is endemic.

CYSTICERCOSIS SEROLOGY:

Cysticercosis IgG Antibody by EIA: POSITIVE

COMMENT: Serological evidence of infection with Taenia solium cysticerci at an unknown time. This specimen was sent to the CDC for confirmation by immunoblot

CYSTERICERCOSIS SEROLOGY CONFIRMATORY ASSAY REPORT

Immunoblot Assay: POSITIVE

Case Discussion

This case illustrates the image findings of a patient with neurocysticercosis.

Neurocysticercosis is caused by the infection of the central nervous system (CNS) with encysted larvae of Taenia solium 1. The lifecycle of Taenia solium 1,2  comprises of human ingestion of swine meat infected with lava (cysticercus/ cysticerci). Within the human host, the cysticerci attach to the intestinal wall, where they gradually mature into tapeworm. The female tapeworm releases fertile eggs, containing infective embryos, some of which are released from the egg within the intestines, actively cross the intestinal mucosa into the bloodstream, thereby traveling to peripheral tissues including the central nervous system 3.

The remaining embryos are passed into the environment through human feces where a combination of poor sanitation and open defecation leads to soil contamination with these fertile eggs. Pigs after that can ingest the infective eggs in human stools whilst grazing on the contaminated soil. The eggs hatch into larvae in the pig’s intestine that pass through the mucosa and reach various tissues, where they mature into cysticerci. The life cycle is once again thereby propagated upon human consumption of this swine meat.

Taenia solium is endemic in most developing countries, particularly Latin America, Southeast Asia, and wide parts of sub-Saharan Africa 1. The clinical manifestations of neurocysticercosis include seizures, headache, cognitive decline, intracranial hypertension and focal neurological deficits; although no pathognomic clinical picture exists 4. Taken together with the clinical picture, diagnosis is based on neuroimaging and confirmed by serology.

Cysticerci in the CNS may be located in the brain parenchyma, subarachnoid space, ventricles, or spinal cord 4.

Parenchymal neurocysticercosis can be classified into four discrete disease stages: vesicular, colloidal vesicular, granular nodular and nodular calcified 2. Imaging findings in each stage reflect underlying changes in the disease process 4-6:

  1. In the vesicular stage, the cystericus contain clear fluid. These are readily discernible on CT and MRI, measuring at 5-20mm. CT demonstrates non-enhancing cyst wall contained a scolex with CSF density cystic fluid. T1-weighted MR imaging demonstrates a low-signal-intensity cystic cavity containing a nodule that is isointense/hyperintense about white matter.  On T2-weighted images, the scolex is also isointense/hyperintense and can be obscured by high-signal intensity cystic fluid. Cysts commonly occur at the gray-white matter junction, basal ganglia, cerebellum, and brainstem.
  2. The colloid vesicular stage is characterized by hyaline degeneration of the cysticercus. Fluid within the cyst becomes proteinaceous, opaque and gelatinous, eliciting a strong immune response as it leaking into surrounding tissue. CT demonstrates ring-enhancing cystic lesions containing hyperdense fluid, and surrounding vasogenic edema. On MRI, T1-weighted images show a cystic cavity hyperintense to CSF, and on T2, hyperintense cyst surrounded by hyperintense parenchymal edema.
  3. In the granular nodular stage, the cyst retracts and forms a granulomatous nodule. CT demonstrates an enhancing nodule with surrounding vasogenic edema. MR shows enhancing ring or nodule with or without surrounding edema.
  4. The nodular calcified stage is characterized calcification of the granulomatous nodule. CT demonstrates calcified lesions within the brain parenchyma, which appear isointense on all MR imaging sequences.

Cisternal cysticercosis is characterized by disease involvement of the subarachnoid spaces and adjacent meninges 4 and may manifest as obstructive hydrocephalus on CT and MRI 5. The latter is also true of intraventricular cysticercosis. Spinal cysticercosis is uncommon, and if present, can appear as a ring-enhancing lesion expanding the spinal cord on MRI 4.

Treatment of neurocysticercosis involves 4-6:

-          control of seizures: antiepileptic treatment

-          anti-parasitic medication (cysticidal therapy)

Case courtesy of Associate Professor Pramit Phal

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Case Information

rID: 41047
Case created: 13th Nov 2015
Last edited: 22nd Mar 2016
Inclusion in quiz mode: Included

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