Clinical Symptoms, Imaging Features and Cyst Distribution in the Cerebrospinal Fluid Compartments in Patients with Extraparenchymal Neurocysticercosis

Abstract

Extraparenchymal neurocysticercosis has an aggressive course because cysts in the cerebrospinal fluid compartments induce acute inflammatory reactions. The relationships between symptoms, imaging findings, lesion type and location remain poorly understood. In this retrospective clinical records-based study, we describe the clinical symptoms, magnetic resonance imaging features, and cyst distribution in the CSF compartments of 36 patients with extraparenchymal neurocysticercosis. Patients were recruited between 1995 and 2010 and median follow up was 38 months. During all the follow up time we found that 75% (27/36) of the patients had symptoms related to raised intracranial pressure sometime, 72.2% (26/36) cysticercotic meningitis, 61.1% (22/36) seizures, and 50.0% (18/36) headaches unrelated to intracranial pressure. Regarding lesion types, 77.8% (28/36) of patients presented with grape-like cysts, 22.2% (8/36) giant cysts, and 61.1% (22/36) contrast-enhancing lesions. Hydrocephalus occurred in 72.2% (26/36) of patients during the follow-up period. All patients had cysts in the subarachnoid space and 41.7% (15/36) had at least one cyst in some ventricle. Cysts were predominantly located in the posterior fossa (31 patients) and supratentorial basal cisterns (19 patients). The fourth ventricle was the main compromised ventricle (10 patients). Spinal cysts were more frequent than previously reported (11.1%, 4/36). Our findings are useful for both diagnosis and treatment selection in patients with neurocysticercosis.

Fig 1. Flowchart of participants recruitment.

There were included 36 patients. By the end of the follow up, eight patients had definitive diagnosis of neurocysticercosis by fulfilling the absolute criterion of histological demonstration of the parasite after surgical removal. Beside the evidence of lesion highly suggestive of neurocysticercosis on neuroimaging studies and clinical manifestations suggestive of neurocysticercosis, 21 patients had positive ELISA and 7 patients had an epidemiological criterion.

Fig 2. Different presentation patterns of extraparenchymal neurocysticercosis as revealed by brain MRI.

Grape-like lesions in the basal cisterns are evident on T2 axial (A) and sagittal (B) views of a patient’s brain. C, An axial fluid-attenuated inversion recovery (FLAIR) coronal view of the same patient showing lesions in the Sylvian and interhemispheric fissures as well as basal cisterns. D, A giant cyst (*) in the right Sylvian fissure and a parenchymal enhancing cyst (arrow). E, A T1 axial view showing contrast enhancing in the Sylvian fissures (arrow), mainly on the left, which is associated with intense inflammatory reactions due to degenerating cysts. F. Ventricle enlargement (*) in a patient with neurocysticercosis-associated hydrocephalus.

Fig 3. Spinal cysts.

A spinal cyst (arrows) at the cervical level in a patient with extraparenchymal neurocysticercosis (A, sagittal view; B, axial view).

Fig 4. Schematic representation of the distribution of cysts in the study cohort among the CSF compartments.

A, In the subarachnoid space, the posterior fossa cisterns were involved in 86.1% of patients, the supratentorial basal cisterns in 52.8%, the Sylvian fissures in 41.7%, and the interhemispheric fissure in 13.9% of patients. B, Among the patients with cysts in the ventricles, 66.7% had cysts in the fourth ventricle, 46.7% in the lateral ventricles, and 26.7% in the third ventricle. NB: percentages are higher than 100% because a single patient could have more than one compromised site.

Fig 5. MRI images of cysts inside brain ventricles.

The fourth ventricle is the most common site for ventricular neurocysticercosis. A large cyst (*) in the fourth ventricle (A) resulted in perilesional edema (arrows) in the patient’s posterior fossa (B). The lateral ventricles are also common sites of cyst location (C). Meningeal enhancement (arrowheads) is in a patient with a cyst (*) inside the left lateral ventricle. In some patients, multiple ventricles can be compromised. D, Cysts in the left lateral (arrow) and fourth (*) ventricles of a patient.