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Observational series assesses the localizing value of CDG in epilepsy, indicating its broader implications.
Background: The chapeau de gendarme (CDG) sign is classically linked to frontal lobe epilepsy, but its reliability as a localizing marker remains unclear. Objective: To evaluate the electroclinical and imaging correlates of CDG and assess its localizing value. Methods: We conducted a retrospective observational study (2014–2026) at a tertiary center, Mumbai, Maharashtra, India. Patients undergoing video-electroencephalography (EEG) monitoring with documented CDG were included. Clinical semiology, magnetic resonance imaging (MRI), positron emission tomography (PET), ictal single-photon emission computed tomography (SPECT), and electrophysiology (including magnetoencephalography when available) were analyzed for concordance and network localization. Results: Eleven patients were identified (10 focal, 1 multifocal epilepsy) to have CDG. CDG occurred early (≤ 5 seconds from onset). Frontal-type semiology was seen in 9/11 patients, temporal in 1, and parietal in 1. Ictal EEG showed diffuse attenuation followed by right or left frontal patterns in 10/11, suggesting deep-seated onset with rapid frontal network recruitment. MRI lesions were present in 4/11 (2 focal cortical dysplasia [FCD], 1 gliosis, 1 multifocal scars). Among MRI-negative cases, PET showed focal hypometabolism in 5/7 (frontal 3, parietal 1, temporal 1). Ictal SPECT ( n = 4) demonstrated frontal uptake in 2 and multifocal uptake in 2. Thus, the multimodal noninvasive evaluation identified frontal epileptic networks in 9/11patient. Extrafrontal networks were identified in 2 cases (posterior temporal and inferior parietal; the latter confirmed on stereoelectroencephalography). Both FCD patients underwent surgery with Engel class I outcomes at 7 years. Conclusion: CDG is predominantly associated with frontal network involvement but may arise from extrafrontal regions. It likely reflects rapid engagement of frontal networks rather than a strictly localizing sign. Publication History Article published online: 15 July 2026 © 2026. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/) Thieme Medical and Scientific Publishers Private Limited A-13A, Graphix Tower 1, 6th floor, Sector 62, Noida 201309, Uttar Pradesh, India
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Patel et al. (2026) studied this question.
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