Differential diagnosis between ventriculitis and fourth ventricle cyst in neurocysticercosis.

The fourth ventricle is frequently affected in patients with cysticercosis of the central nervous system, due either to a large cyst occluding the cavity or to granular ependymitis (ventriculitis) as a consequence of diffuse inflammation within the intraventricular and subarachnoid spaces. In some cases, the differential diagnosis between these two forms of neurocysticercosis is difficult to make, even after special radiological procedures. It is important to establish the correct diagnosis, since a surgical approach is beneficial only when the fourth ventricle is obstructed by a large cyst. In this paper, the clinical differences between fourth ventricle cysts and ventriculitis are presented in 16 patients with neurocysticercosis who were subjected to surgical exploration of the posterior fossa. Patients with a large cyst occluding the fourth ventricle had a short evolution of signs and symptoms, Bruns' syndrome, and discrete or no inflammatory reaction in the cerebrospinal fluid (CSF). Patients with ventriculitis generally had a longer duration of signs and symptoms, Parinaud's syndrome, a consistently positive complement fixation test to cysticerci, and more cells and proteins in the CSF. The clinical picture and ancillary studies can give the precise diagnosis in most patients before surgical exploration is performed.