Standardization of tomographic indexes of the fourth ventricle and its characteristics in patients with neurocysticercosis

Abstract

Cysticercosis of the fourth ventricle is characterized by manifestations of a posterior fossa hypertension. Its isolated enlargement constitutes a clinical-pathological entity denominated isolated fourth ventricle which pathophysiology remains controversial. There are few reports on the methodology for the diagnosis of an isolated dilation of the fourth ventricle. The objectives of the present study were to propose a pattern of normality of representative indexes of the fourth ventricle dimensions in patients with normal computerized tomography (CT) of the skull and to study characteristics of these indexes in patients with neurocysticercosis (NCC).In normal CT scans of 114 patients (control group, CG) and in CT scans of 80 patients with diagnosis of NCC (NCC group, NG) the following measures were performed: distance between frontal horns (FH) of lateral ventricles, inner cranial diameter (IC), anteroposterior (AP) and laterolateral (LL) diameters of the fourth ventricle. Six indexes were established: FH/IC, AP/IC, LL/IC, AP/FH, LL/FH and AP/LL. After statistical analysis, the most representative parameters of fourth ventricle dimensions were the indexes AP/IC and AP/FH and AP/LL. Based on these three indexes 51 patients with NCC (NG-IV th ) who presented at least one of these indexes with value above two standard deviations of the statistical average obtained in the CG were selected. This group of patients was analysed in more detail.In The study of NG-IV th showed that epilepsy prevailed (55.9%) among patients with good evolution (GEv), and intracranial hypertension (75%) in those with sequels (SEv) and in all of those who died (DEv). In most (82.5%) of the patients with GEv the indexes were within normal values in at least one of the evolution CT scans. The association between FH/IC with one or more of the three representative indexes was higher (77.8%) in patients with DEv -essentially to AP/LL. When presence of ventriculoperitoneal shunt (VPS) in patients with DEv was considered, there was a preponderance (66.7%) of these three indexes, even before shunt procedure.AP/LL index > 1 was found in: 95.2% of patients with VPS; 87.7% of those with depression; 81.6% of patients who had two or more clinical manifestations; and 78.6% of patients who presented Parinaud syndrome. This AP/LL index characteristics was also detected in: 73.5% of patients who had GEv; 87.5% of those with SEv; and all patients who died.Depressive manifestations were seen in 38.2% of patients with GEv and in all of those with SEv and DEv; men were more frequently (56.7%) affected and the onset of these manifestations were more common (88.9%) after VPS also in patients with DEv. The classic syndrome of cerebrospinal fluid (CSF) in NCC occurred in 66.7% of patients with DEv; normal CSF was more frequent (29.4%) in those with GEv.Possible implications of AP/IC, AP/FH and AP/LL indexes for the diagnosis of fourth ventricle enlargement -either isolated or not -in NCC are discussed.It is concluded that: AP/LL index may be considered as the fourth ...