Involvement of the posterior cingulate gyrus in temporal lobe epilepsy: A study using stereo-EEG.

OBJECTIVE: To analyze the involvement of the posterior cingulate gyrus (PCG) during mesial temporal lobe seizures (MTLS). METHODS: We retrospectively reviewed the stereo-EEG (SEEG) recordings of patients with MTLS performed in our institution from February 2013 to December 2020. Only patients who had electrode implantation in the PCG were included. Patients with lesions that could potentially alter the seizure spread pathways were excluded. We assessed the propagation patterns of MTLS with respect to the different structures sampled. RESULTS: Nine of 97 patients who had at least one seizure originating in the mesial temporal region met the inclusion criteria. A total of 174 seizures were analyzed. The PCG was the first site of propagation in most of the cases (8/9 patients and 77.5% of seizures, and 7/8 patients and 65.6% of seizures after excluding an outlier patient). The fastest propagation times were towards the contralateral mesial temporal region and ipsilateral PCG. Seven patients underwent standard anterior temporal lobectomy and, of these, all but one were Engel 1 at last follow up. CONCLUSION: We found the PCG to be the first propagation site of MTLS in this group of patients. These results outline the relevance of the PCG in SEEG planning strategies. Further investigations are needed to corroborate whether fast propagation to the PCG predicts a good surgical outcome.

EEG and MRI Abnormalities in Patients With Psychogenic Nonepileptic Seizures.

OBJECTIVE: To compare the rate of EEG and MRI abnormalities in psychogenic nonepileptic seizures (PNES) patients with and without suspected epilepsy. Patients were also compared in terms of their demographic and clinical profiles. METHODS: A retrospective analysis of 271 newly diagnosed PNES patients admitted to the epilepsy monitoring unit between May 2000 and April 2008, with follow-up clinical data collected until September 2015. RESULTS: One hundred ninety-four patients were determined to have PNES alone, 16 PNES plus possible epilepsy, 14 PNES plus probable epilepsy, and 47 PNES plus confirmed epilepsy. Fifty-seven of the 77 patients (74.0%) with possible, probable, or definite epilepsy exhibited epileptiform activity on EEG, versus only 16 of the 194 patients (8.2%) in whom epilepsy was excluded. Twenty-four of these 194 patients (12.4%) had MRI abnormalities. Three of 38 patients (7.9%) with both EEG and MRI abnormalities were confirmed not to have epilepsy. In PNES patients with EEG or MRI abnormalities compared with those without, patients with abnormalities were more likely to have epilepsy risk factors, such as central nervous system structural abnormalities, and less likely to report minor head trauma. The presence of EEG abnormalities in PNES-only patients did not influence antiseizure medication reduction, whereas those with MRI abnormalities were less likely to have their antiseizure medications reduced. CONCLUSIONS: Psychogenic nonepileptic seizure patients without MRI or EEG abnormalities are less likely to have associated epilepsy, risk factors for epilepsy, and had different demographic profiles. There is a higher-than-expected level of EEG and MRI abnormalities in PNES patients without epilepsy.

Epilepsy surgery in stroke-related epilepsy.

PURPOSE: To provide a descriptive analysis on the presurgical evaluation and surgical management of a cohort of patients with stroke related epilepsy (SRE). METHODS: We retrospectively examined the clinical characteristics, results of non-invasive and invasive presurgical evaluation, surgical management and outcome of consecutive patients with drug-resistant SRE in our institution from January 1, 2013 to January 1, 2020. RESULTS: Twenty-one of 420 patients (5%) who underwent intracranial EEG (iEEG), resective epilepsy surgery and/or vagus nerve stimulation (VNS) placement, had SRE. Of 13 patients who had iEEG, the ictal onset (IO) was exclusively within the stroke lesion in only one patient. In five patients the IO was extra-lesional and in the remaining seven patients it included the stroke lesion as well as extra-lesional structures. The IO included the mesial temporal region in 11 of the 13 patients (85%). The posterior margin of the stroke lesion was always involved. Five patients underwent surgery without iEEG. In total, 10 patients underwent resective surgery, four VNS placement and two had both corpus callosotomy and VNS placement. Of the patients who had resective surgery, nine were Engel I or II at last follow up. CONCLUSION: We found that seizures in patients with drug resistant SRE were more frequently originated in the mesial temporal region than in the stroke lesion itself. Despite the complex epileptic network underlying drug-resistant SRE, a thorough presurgical assessment and adequate use of surgical options can lead to excellent surgical outcomes.