Thresholds of resistance to CSF outflow in predicting shunt responsiveness

Abstract

Objectives:

Disturbances in cerebrospinal fluid (CSF) absorption capacity represent one of the primary causes of normal pressure hydrocephalus (NPH). The resistance to CSF outflow (R_out) may reflect the severity of this disturbance and has been used as a supplementary parameter to predict shunt responsiveness. However, there is no widely accepted threshold of R_out in this scenario. This study aimed to determine the most appropriate threshold through meta-analyses.

Methods:

A total of four previously reported cutoff values of R_out (10, 12, 15, and 18 mmHg/ml/minutes) were selected as potential thresholds. A systematic review of existing studies involving NPH, shunt surgeries, and R_out was conducted. The pooled results from retrieved articles were subjected to statistical analyses.

Results:

A total of nine studies were included in the meta-analyses based on the available preoperative R_out and postoperative improvement of subjects. The odds ratios of the four thresholds were 2·82, 3·58, 2·72, and 2·38 for 10, 12, 15, and 18 mmHg/ml/minutes of R_out, respectively. The R_out of 12 mmHg/ml/minutes yielded high accuracy (72·95%), high sensitivity (80·26%), and moderate specificity (46·79%).

Discussion:

The presented study conducted meta-analyses and revealed that a R_out of 12 mmHg/ml/minutes is the most suitable threshold for predicting shunt responsiveness in NPH patients.

Keywords:

• Resistance to CSF outflow
• Shunt responsiveness
• Meta-analysis
• Normal pressure hydrocephalus
• Infusion study