Open-aqueduct LOVA, LIAS, iNPH: a comparative clinical-radiological study exploring the "grey zone" between different forms of chronic adulthood hydrocephalus

Abstract

Purpose: The definition of chronic adult hydrocephalus encompasses different pathological entities with overlapping characteristics, including long-standing overt ventriculomegaly in adults (LOVA), late-onset idiopathic aqueductal stenosis (LIAS) and idiopathic normal pressure hydrocephalus (iNPH). The aim of our study was to identify preoperative clinical and radiological features peculiar of these diseases providing some pathophysiology inferences on these forms of hydrocephalus.

Methods: Clinical and radiological preoperative records, type of surgical treatment and clinical outcome of patients with chronic adult hydrocephalus who were surgically treated between 2013 and 2019 were retrospectively reviewed. Univariate and multivariate analyses were performed to evaluate the contribution of each variable to the differential diagnosis.

Results: In total, 105 patients were included: 18 with LOVA, 23 with LIAS and 64 with iNPH. On multivariate analysis, an enlarged cisterna magna and a more severe ventriculomegaly were associated with the diagnosis of LOVA, while an older age and DESH with iNPH. LIAS patients tend to have an higher prevalence of raised ICP symptoms. Based on that, a clinical and radiological scoring system was developed to distinguish between iNPH and no iNPH cases. A precise cut-off value with a sensitivity of 95.1% and a specificity of 90.6% was identified.

Conclusions: LOVA, LIAS and iNPH are different forms of chronic adulthood hydrocephalus and present different and peculiar clinical and radiological features, with an impact on the treatment and outcome prediction. The implementation of a clinical-radiological score for differential diagnosis may help the differentiation. Further studies are warranted.

Keywords: Differential diagnosis; Idiopathic normal pressure hydrocephalus (iNPH); Late-onset idiopathic aqueductal stenosis (LIAS); Longstanding overt ventriculomegaly in adults (LOVA); Score.

Fig. 1

Incidences of categorical neuroradiological and clinical features in the three cohorts are reported. Significant differences according to univariate analysis are also underlined. *LOVA vs. LIAS. °LOVA vs iNPH. #LIAS vs iNPH

Fig. 2

ROC curve describing diagnostic accuracy of the proposed score to differentiate between iNPH and no iNPH patients, AUC = 0.97, standard error = 0.017. Accuracy 94%. Best cutoff value: 3.5, J = 0.857, OR 188.5, 95% CI 36.166–982.469. Sensitivity: 95.1%. Specificity: 90.6%

Fig. 3

T2-weighted MRI showing landmark features of LOVA in midsagittal (A), axial (B) and coronal (C) view. A Empty sella, patent aqueduct with turbulent flow and an enlarged cisterna magna are reported. B, C Concomitant severe supratentorial ventriculomegaly is observed. Evans Index: 0.47. Third ventricle width: 26 mm

Fig. 4

T2-weighted MRI in midsagittal view of the three different types of adult hydrocephalus analysed in our study is compared. A LOVA, distorted and empty sella, bulging of third ventricle floor, turbulent flow through the aqueduct and an enlarged cisterna magna with upwards shifted cerebellar vermis are showed. B LIAS, CSF flow throughout the aqueduct, which is totally obstructed by a thin septum, is absent. C iNPH, with a patent aqueduct, and no abnormalities in the anatomy of sella turcica, third ventricle floor and cisterna magna