Intraventricular NCC

Meningeal cysticerci elicit an intense inflammatory response in the subarachnoid space, with development of a dense exudate composed of collagen fibers, lymphocytes, multinucleated giant cells, eosinophils and hyalinised parasitic membranes. This causes abnormal thickening of the leptomeninges at the base of the skull, from the optochiasmatic area (optochiasmatic arachnoditis) to the foramen magnum. The optic chiasm and cranial nerves ascending from the ventral aspect of the brainstem are usually entrapped in this dense exudate, leading to visual field defects and other cranial nerve dysfunction. Luschka’s and Magendie’s foramina may be obstructed by the stiffened leptomeninges, with the ensuing development of hydrocephalus. Blood vessels, mainly those arising from the circle of Willis, may also be exaggerated by this inflammatory reaction. The walls of small penetrating arteries are invaded by inflammatory cells, leading to a proliferative endarteritis with occlusion of the lumen (cysticercal vasculitis). In addition, large vessels may be occluded by atheroma-like deposits resultant from disruption of the endothelium; this vascular involvement may result in the development of a cerebral infarct

Causes of hydrocephalus

1. Direct obstruction by intraventricular cysts

2. Cysticercal meningitis

3. Ependymitis (obstructive by granular proliferations and communicative by reducing absorption)

Intraventricular and Subarachnoid: This form of NCC is seen in 15−54% of cases. The oncosphere reaches the ventricular cavity by way of the choroid plexus. It migrates through the ventricular system, occluding vital communication corridors causing acute episodes of ventriculomegaly with sudden death or mass effect with focal compression. Thirtyeight per cent of patients are present with rapid clinical deterioration. Larval death initiates ependymitis and occlusion of ventricular outlets producing hydrocephalus. The fourth ventricle is the commonest site (53%) followed by third ventricle (27%), lateral ventricle (11%) and the aqueduct (9%).

Diagnostic criteria for neurocysticercosis (NCC)

 Absolute criteria

• Histological demonstration of the parasite from biopsy of a brain or spinal cord lesion

• Evidence of cystic lesions showing the scolex on neuroimaging studies

• Direct visualization of subretinal parasites by fundoscopic examination

Major criteria

• Evidence of lesions highly suggestive of neurocysticercosis on neuroimaging studies

• Positive serum immunoblot for the detection of anticysticercal antibodies

• Resolution of intracranial cystic lesions after therapy with albendazole or praziquantel

• Spontaneous resolution of small single enhancing lesions

Minor criteria

• Evidence of lesions compatible with neurocysticercosis on neuroimaging studies

• Presence of clinical manifestations suggestive of neurocysticercosis

• Positive cerebrospinal fluid ELISA for detection of anticysticercal antibodies or cysticercal antigens

• Evidence of cysticercosis outside the central nervous system

Epidemiological criteria

• Individuals coming from or living in an area where cysticercosis is endemic

• History of travel to disease-endemic areas

• Evidence of a household contact with Taenia solium infection

 Degrees of diagnostic certainty

Definitive: Presence of one absolute criterion

Presence of two major plus one minor and one epidemiological criteria

Probable:  Presence of one major plus two minor criteria.

Presence of one major plus one minor and one epidemiological criteria .

Presence of three minor plus one epidemiological criteriaA number of patients with NCC present with increased intracranial pressure that may be associated with seizures, focal neurological signs or dementia. Hydrocephalus, related to cysticercotic arachnoiditis, granular ependymitis or ventricular cysts, is the most common cause of this syndrome.

In these cases, intracranial hypertension has a subacute onset and a slowly progressive course that may be punctuated by episodes of sudden loss of consciousness related to movements of the head (Bruns’ syndrome) when the cause of hydrocephalus is a fourth ventricle cyst.