Electroclinical characteristics of seizures arising from the posterior cingulate cortex and surgical outcomes based on stereoelectroencephalography (SEEG)

Abstract Background Seizures arising from the posterior cingulate cortex are rare, and few studies have to characterized the clinical presentation of such seizures within the anatomic context of the limbic network. We aimed to characterize the electrophysiological properties and clinical features of seizures arising from the PCC and surgical outcomes based on data from stereoelectroencephalography (SEEG).Methods The present retrospective study included 12 patients with medically intractable epilepsy, all diagnosed with posterior cingulate epilepsy via stereoelectroencephalography (SEEG) at Sanbo Hospital between 2014 and 2018.This retrospective analysis included clinical semiology, scalp EEG/SEEG findings and surgical outcomes of twelve intractable PCE patients.Results Six of the twelve patients reported auras, including vestibular responses (3/6),blurred vision (2/6), and fear and déjà vu(1/6). Clinical semiology included dialeptic seizures(3/12),automotor seizures(4/12) and complex motor behaviours(5/12).The classifications of scalp EEG varied, including bilateral regional posterior temporal-occipital discharges in eight cases, regional anterior-middle temporal discharges in two cases, and no epileptic discharge in two cases.In five patients, ictal onset occurred mainly in the tempo–parietal–occipital area.In ten patients, the seizure onset zone by SEEG occurred in the posterior cingulate gyrus, which spread to the medial temporal, precuneus, inferior parietal lobe and long insular gyrus. However, for the two patients with posterior cingulate lesions, the seizure onset zone was the contralateral hippocampal head that spread to the posterior cingulate lesion. One patient was seizure free after posterior cingulate gyrus lesion resection, but another had 50% fewer seizures by using SEEG-guided radiofrequency thermocoagulation. Nine patients who underwent epilepsy surgery were seizure-free(Engel IA: 7/9;EngelIB: 2/9).One patient showed a 30% reduction in seizures by using SEEG-guided radiofrequency thermocoagulation but not surgical resection.Conclusions Our findings indicate that the clinical characteristics of posterior cingulate epilepsy vary among patients, and recognition of a posterior cingulate focus is challenging, especially with MRI-negative epilepsies.Scalp EEG is of little use when attempting to localize posterior cingulate seizures.For patients with pharmacoresistant posterior cingulateepilepsy, favourable outcomes (Engel class I) could be observed by using SEEG.The SEEG findingsin PCE showed that the seizure onset zone and epileptogenic zone were a set of interconnected regional systems.Clinical trial registration Restrospective case reports do NOT need registration of clinical trials.