{"doi":"10.1002/epd2.70062","title":"Hidden inside the sulci: Utility of voxel‐based morphometric analysis program in localizing precuneus epilepsy","abstract":"Precuneus epilepsy is rare and complex and arises from the precuneus, a highly connected structure located in the mesial superior parietal lobe.1 Due to its rarity, it remains poorly understood.2 Precuneus has widespread functional connectivity to other lobes,3 which leads to a myriad of semiologic features, making localization difficult.4 This may lead to a prolonged diagnostic odyssey before an accurate localization is reached, especially when neuroimaging is unyielding.5 Voxel-based morphometry is an emerging post-processing tool that may identify cortical abnormalities on non-lesional MRIs.6 In here, we present a case demonstrating the crucial role of a unique voxel-based morphometric analysis program (VB-MAP) in localizing a challenging MRI-negative precuneus epilepsy. A 31-year-old left-handed-male was evaluated for drug-resistant epilepsy (DRE). Video-EEG recorded right posterior temporal interictal discharges (Figure 1A) and stereotyped seizures with the following semiology: An altered perception of motion (described as “dizziness,” “roller coaster inside the head” → impaired responsiveness with orofacial automatisms). Ictal EEG demonstrated a poorly localized electrographic onset (Figure 1B). MRI was negative (Figure 2A). FDG PET showed asymmetric right > left bitemporal and right superior parietal lobule hypometabolism. Stereotactic EEG (sEEG) targeting bifrontotemporal and right parietal regions recorded nine habitual seizures with an illusory motion, nonversive right head turn, right eye blinking, and unresponsiveness. Broad ictal onset on SEEG suggested that the epileptogenic zone (EZ) was not covered. VB-MAP analysis of two prior MRIs showed a right precuneus lesion (Figure 2B), with increased cortical thickness and gray-white blurring, suggestive of a subtle polymicrogyria. VB-MAP pipeline, as described by the Cleveland Clinic, was implemented for our patient.7 During the same SEEG, additional electrodes were placed in the VB-MAP-identified lesion, and a typical seizure was recorded arising from the VB-MAP lesion, with later spread to the superior temporal sulcus, angular gyrus, and parietal operculum (Figure 1C). Interictally, independent spike populations were present in the precuneus lesion, the right lateral temporal neocortex/parietal operculum, the right hippocampus, and rarely the left hippocampus. Therefore, our SEEG confirmed that the VB-MAP lesion was concordant with the seizure-onset zone. Cortical stimulation of VB-MAP lesion replicated his habitual aura and seizures (parameters: 50 Hz frequency, 6 mA current, 4 s train duration). He underwent laser ablation of the VB-MAP-identified precuneus lesion (Figure 2) and remains seizure-free after 1.5 years. Our case demonstrates VB-MAP as a critical tool in aiding the identification of structural abnormalities in MRI-negative epilepsies. For extratemporal MRI-negative DREs, seizure freedom is seen in ~42%, highlighting the potential value of VB-MAP in improving surgical outcomes.8 In precuneus epilepsy, the rapid ictal propagation can lead to a semiology that appears as frontal, mesial temporal, or occipital, which can lead to incorrect localization.1 Ictal and interictal EEG is commonly non-localizing and non-lateralizing in precuneus DRE because of its mesial location.4, 9-11 In parietal lobe epilepsies (PLE), only 20% have parietal spikes and ~25% have parietal ictal onset.12 MRI is helpful if a lesion is identified. However, subtle dysplasias may be difficult to detect13 PET's sensitivity for extratemporal epilepsy is low at 50%.14 In PLE, even ictal SPECT may be non-localizing or falsely localizing in >50% of cases.15 Our case also adds to the scarce literature on precuneal epilepsy semiology.1, 2, 4 Our patient's initial symptom was a sensation of “dizziness” or “shaking inside the head” but shared a common feature of an illusory motion. The literature on the semiology of precuneal seizures describes an array of motor and non-motor phenomena.4 Stimul","journal":"Epileptic Disorders","year":2025,"id":570387,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9628,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1368463,"name":"Rithvik Gundlapalli","orcid":null,"position":1,"is_corresponding":false},{"id":1084440,"name":"Shayan Moosa","orcid":null,"position":2,"is_corresponding":false},{"id":1031933,"name":"Ifrah Zawar","orcid":"0000-0002-6103-4250","position":3,"is_corresponding":false},{"id":1475683,"name":"Patrick E. Hartnett","orcid":"0009-0005-2466-1916","position":0,"is_corresponding":true}],"reference_count":17,"raw_metadata":null,"created_at":"2026-07-19T02:57:07.857542Z","pmid":"40662624","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}