Prognostic Utility of Disproportionately Enlarged Subarachnoid Space Hydrocephalus in Idiopathic Normal Pressure Hydrocephalus Treated with Ventriculoperitoneal Shunt Surgery: A Systematic Review and Meta-analysis

Abstract

Background: Disproportionately enlarged subarachnoid space hydrocephalus is a specific radiologic marker for idiopathic normal pressure hydrocephalus. However, controversy exists regarding the prognostic utility of disproportionately enlarged subarachnoid space hydrocephalus.

Purpose: Our aim was to evaluate the prevalence of disproportionately enlarged subarachnoid space hydrocephalus in idiopathic normal pressure hydrocephalus and its predictive utility regarding prognosis in patients treated with ventriculoperitoneal shunt surgery.

Data sources: We used MEDLINE and EMBASE databases.

Study selection: We searched for studies that reported the prevalence or the diagnostic performance of disproportionately enlarged subarachnoid space hydrocephalus in predicting treatment response.

Data analysis: The pooled prevalence of disproportionately enlarged subarachnoid space hydrocephalus was obtained. Pooled sensitivity, specificity, and area under the curve of disproportionately enlarged subarachnoid space hydrocephalus to predict treatment response were obtained. Subgroup and sensitivity analyses were performed to explain heterogeneity among the studies.

Data synthesis: Ten articles with 812 patients were included. The pooled prevalence of disproportionately enlarged subarachnoid space hydrocephalus in idiopathic normal pressure hydrocephalus was 44% (95% CI, 34%-54%). The pooled prevalence of disproportionately enlarged subarachnoid space hydrocephalus was higher in the studies using the second edition of the Japanese Guidelines for Management of Idiopathic Normal Pressure Hydrocephalus compared with the studies using the international guidelines without statistical significance (52% versus 43%, P = .38). The pooled sensitivity and specificity of disproportionately enlarged subarachnoid space hydrocephalus for prediction of treatment response were 59% (95% CI, 38%-77%) and 66% (95% CI, 57%-74%), respectively, with an area under the curve of 0.67 (95% CI, 0.63-0.71).

Limitations: The lack of an established method for assessing disproportionately enlarged subarachnoid space hydrocephalus using brain MR imaging served as an important cause of the heterogeneity.

Conclusions: Our meta-analysis demonstrated a relatively low prevalence of disproportionately enlarged subarachnoid space hydrocephalus in idiopathic normal pressure hydrocephalus and a poor diagnostic performance for treatment response.

FIG 1.

Typical imaging features of DESH in a 77-year-old patient who presented with gait disturbance, urinary symptoms, and cognitive impairment. A coronal 3D T1-weighted image shows a dilated Sylvian fissure (arrows), tightened subarachnoid space near the vertex (square), and ventriculomegaly (asterisks).

FIG 2.

Flow diagram of the study-selection process.

FIG 3.

Forest plots of the pooled prevalence of DESH in iNPH. Numbers are pooled estimates with 95% CIs in parentheses. Horizontal lines indicate 95% CIs.

FIG 4.

Coupled forest plots showing the pooled sensitivity and specificity for the diagnostic performance of DESH in the prediction of treatment response. Numbers are pooled estimates with 95% CIs in parentheses. Horizontal lines indicate 95% CIs.

FIG 5.

HSROC curve of the diagnostic performance of DESH in the prediction of treatment response. A notable difference was observed between the 95% confidence region and the 95% prediction region in HSROC, indicating considerable heterogeneity.