TMS-evoked potentials: Neurophysiological biomarkers for diagnosis and prediction of response to ventriculoperitoneal shunt in normal pressure hydrocephalus

Davidy T, Anis S, Suminski A, Zauberman Y, Fay-Karmon T, Saar A, Zifman N, Fogel H, Abulher E, Lesman-Segev O, Hassin-Baer S

Key finding

In this initial cohort, a TEP-based Delphi-NPH index separated shunt responders from non-responders with an ROC-AUC of 0.91, higher than the imaging, gait and tap-test measures studied.

Study design

Clinical study, TMS-EEG with automated TEP analysis (Delphi)

Participants

37 patients with possible iNPH and 16 healthy controls

Summary

Selecting patients with normal pressure hydrocephalus (NPH) for a ventriculoperitoneal shunt (VPS) currently relies on clinical presentation, imaging and invasive procedures such as the cerebrospinal fluid tap test. This study assessed whether an evaluation based on TMS-evoked potentials (TEPs) could predict which patients respond to the shunt.

Study design

Participants: 37 patients with possible idiopathic NPH (iNPH) and 16 age-matched healthy controls.
All participants underwent Delphi (TMS-EEG with automated TEP analysis) with stimulation of the primary motor cortex (M1) and dorsolateral prefrontal cortex (DLPFC).
16 patients underwent VPS. Response after 3 months was assessed with the modified Rankin Scale, the clinical global impression of change (CGIC) for gait, and a repeated 3-meter timed up and go (TUG) test.

Key findings

The TEP Delphi-NPH index discriminated VPS responders with an ROC-AUC of 0.91 (p = 0.006).
For comparison, imaging measures reached AUCs of 0.58 to 0.83, the TUG test 0.63 and the tap test 0.65.
M1 P60 and P180 latencies were earlier in responders than in controls (p = 0.016 and p = 0.009).
TEP measures correlated with the CGIC rank and with the change in TUG times.

Authors' conclusions

The authors describe these as initial results suggesting that TEPs may be an alternative to the tap test for predicting response to VPS in suspected iNPH, with less discomfort and risk for patients, pending replication in a larger sample with longer follow-up.

Read the full article

Davidy T, Anis S, Suminski A, Zauberman Y, Fay-Karmon T, Saar A, Zifman N, Fogel H, Abulher E, Lesman-Segev O, Hassin-Baer S. TMS-evoked potentials: Neurophysiological biomarkers for diagnosis and prediction of response to ventriculoperitoneal shunt in normal pressure hydrocephalus. Journal of Clinical Neuroscience. 2025;136:111234. doi:10.1016/j.jocn.2025.111234

Summary prepared by QuantalX from the published abstract. All results are as reported by the authors. The full text is available from the publisher.

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