Objective: Assess the ability of Delphi-MD (TMS-evoked potential (TEP)-based test) to predict long-term (over one year) response to VPS as an ancillary tool to improve decision-making.

Background: Current approaches for normal pressure hydrocephalus (NPH) depend on clinical assessment, imaging, and procedures like CSF tap tests to guide ventriculoperitoneal shunt (VPS) decisions.

Method: Forty-one patients with possible iNPH underwent Delphi-MD evaluation of wave form adherence (WFA), a composite measure assessing how closely their TEPs resembled an ideal benchmark TEP. Eighteen patients received VPS based on multidisciplinary team decision. Response was assessed over >1 year using the clinical global impression of change (CGIC), along with the 10-meter timed up and go test and the modified Rankin scale.

Results: Responders showed higher baseline left primary motor cortex (M1L) WFA values than non-responders (median 0.51 [95% CI 0.36–0.76] vs. 0.14 [95% CI -0.02–0.38], p=0.012). Furthermore, M1L WFA effectively distinguished responders (11/18) from non-responders (7/18), with an ROC-AUC of 0.935 (bootstrap 95% CI 0.792–1.00, p<0.0001). The cutoff, validated via leave-one-out cross-validation, yielded 90.9% sensitivity, 85.7% specificity, and 88.9% accuracy. CSF tap tests, in contrast, did not predict responsiveness.

Conclusion: This study indicates that higher M1L WFA obtained through Delphi-MD, signifies better preservation and functional integrity of the motor network in patients with probable iNPH that had a sustained response to VPS than those that did not. Thus Delphi-MD shows promise as an objective, accurate, and accessible ancillary screening tool for iNPH candidates, prior to referral for VPS treatment.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/motor-network-neurophysiological-tms-eeg-markers-as-predictors-of-long-term-outcomes-following-ventriculoperitoneal-shunt-in-normal-pressure-hydrocephalus/