Abstract Details

Title The iNPH Radscale May Better Predict Whether Ventriculoperitonal Shunting was Offered, Compared to Drain Trial Gait Variables

Topic Movement Disorders

Presentation(s) P1 - Poster Session 1 (11:45 AM-12:45 PM)

Poster/Presentation
Number 5-022

Objective Idiopathic normal pressure hydrocephalus (iNPH), can be treated surgically with ventriculoperitoneal shunting (VPS); however, there is no standardized way to evaluate VPS candidacy. Though physicians may consider the iNPH Radscale when screening patients for drain trials, the decision to offer a VPS is based on physician judgement of gait improvement in pre/post drain trial gait tests. For this study, we determined which Radscale and gait variables best predicted whether patients were offered VPS.

Background NA

Design/Methods iNPH Radscale scores from preoperative MRI/CT, and gait variables (walk speed and steps to complete standardized distance) from standard-of-care gait assessments pre and post drain trial, were collected from 221 patients who underwent iNPH workup (167 offered VPS and 54 not offered). From the imaging and gait variables, we used the Harrel step-down procedure to select a model predict to if VPS was offered. This procedure prioritizes the concordance (c) statistic for discriminatory ability and removes predictor variables sequentially in the order of their influence, from least to most important.

Results The final, best-fitting model contained the following predictors: 1) Radscale full score; Radscale subscores for 2) Narrow Sulci, 3) Sylvian Fissures, 4) Temporal Horns, and 5) Periventricular Hypodensities. This model correctly classified shunt status 92.5% of the time (C statistic). The gait variables were not part of this model, and were removed by the Harrel step-down procedure.

Conclusions Despite patients being offered VPS primarily based on gait improvements pre vs post drain trial, gait variables were not included in the best-fitting, most parsimonious model for prediction of whether VPS was offered. In other words, gait variables did not significantly improve the model’s C statistic of 0.925. This surprising finding needs confirmation with larger samples, and, should be extended to determine if iNPH Radscale predicts sustained VPS response, which is the most important clinical question.

Authors/Disclosures
Xavier Soehnlen PRESENTER	Mr. Soehnlen has nothing to disclose.
Claire Sonneborn	Claire Sonneborn has received personal compensation in the range of $0-$499 for serving as a Consultant with The Sumaira Foundation.
Stephen Jones, MD, PhD	Dr. Jones has nothing to disclose.
Sean Nagel, MD	Dr. Nagel has nothing to disclose.
Richard Rammo, MD	Dr. Rammo has nothing to disclose.
James Liao, MD	The institution of Dr. Liao has received research support from American Parkinson Disease Association. The institution of Dr. Liao has received research support from a Cleveland Clinic - IBM Research Collaboration, in the form of in-kind support. Dr. Liao has received intellectual property interests from a discovery or technology relating to health care. Dr. Liao has a non-compensated relationship as a Investigator with Adult Hydrocephalus Research Network that is relevant to AAN interests or activities.

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