Provocative techniques for functional/dissociative seizure: the colored pad test - a safe and reliable procedure

Abstract

Introduction: Suggestive seizure induction during video-EEG is a widely used and valuable tool for diagnosing functional/dissociative seizures (FDS). However, there is currently no standardized protocol. In this study, we describe the technical procedure of the induction/suppression test using colored cotton pads applied to the patient's neck and report our experience with this method over an eight-year period in routine clinical practice.

Methods: We retrospectively reviewed the induction/suppression test performed using the cotton pads procedure in consecutive patients referred to our Epilepsy Centre with suspected FDS between February 2016 and July 2024. The technical details of the procedure are provided. We compared patients with a positive (T+) versus negative (T-) induction test and assessed the rate of patients responding to the suppression phase of the test.

Results: An FDS episode was recorded during the induction test in 82/130 (63.1 %) patients with suspected FDS. T+ patients did not differ from T- patients in terms of sex, concomitant epileptic seizures, history of psychiatric disorders, age at FDS onset, type of FDS, or neuropsychological evaluation results (all p > 0.05). However, T+ patients had a significantly lower level of schooling compared to T- patients (median: 8 vs. 13 years; p = 0.016). The suppression procedure effectively terminated induced FDS episodes in 79/82 (96.3 %) of T+ patients.

Conclusion: The induction/suppression test using colored cotton pads during video-EEG monitoring is a feasible, effective, safe and ethically sound method for achieving a diagnosis of documented FDS.

Keywords: Functional disorders; Induction test; Psychogenic functional seizures; Soaked pad; Suppression.