The role of the amygdala in ictal central apnea: insights from brain MRI morphometry.

OBJECTIVE: Ictal central apnea (ICA) is a frequent correlate of focal seizures, particularly in temporal lobe epilepsy (TLE), and regarded as a potential electroclinical biomarker of sudden unexpected death in epilepsy (SUDEP). Aims of this study are to investigate morphometric changes of subcortical structures in ICA patients and to find neuroimaging biomarkers of ICA in patients with focal epilepsy. METHODS: We prospectively recruited focal epilepsy patients with recorded seizures during a video-EEG long-term monitoring with cardiorespiratory polygraphic recordings from April 2020 to September 2022. Participants were accordingly subdivided into two groups: patients with focal seizures with ICA (ICA) and without (noICA). A pool of 30 controls matched by age and sex was collected. All the participants underwent MRI scans with volumetric high-resolution T1-weighted images. Post-processing analyses included a whole-brain VBM analysis and segmentation algorithms performed with FreeSurfer. RESULTS: Forty-six patients were recruited (aged 15-60 years): 16 ICA and 30 noICA. The whole-brain VBM analysis showed an increased gray matter volume of the amygdala ipsilateral to the epileptogenic zone (EZ) in the ICA group compared to the noICA patients. Amygdala sub-segmentation analysis revealed an increased volume of the whole amygdala, ipsilateral to the EZ compared to controls [F(1, 76) = 5.383, pFDR = 0.042] and to noICA patients ([F(1, 76) = 5.383, pFDR = 0.038], specifically of the basolateral complex (respectively F(1, 76) = 6.160, pFDR = 0.037; F(1, 76) = 5.121, pFDR = 0.034). INTERPRETATION: Our findings, while confirming the key role of the amygdala in participating in ictal respiratory modifications, suggest that structural modifications of the amygdala and its subnuclei may be valuable morphological biomarkers of ICA.

Exploring the relationship between amygdala subnuclei volumes and cognitive performance in left-lateralized temporal lobe epilepsy with and without hippocampal sclerosis.

Cognitive disruption is a debilitating comorbidity in Temporal Lobe Epilepsy (TLE). Despite recent advances, the amygdala is often neglected in studies that explore cognition in TLE. Amygdala subnuclei are differently engaged in TLE with hippocampal sclerosis (TLE-HS) compared to non-lesional TLE (TLE-MRIneg), with predominant atrophy in the first and increased volume in the latter. Herein, we aim to explore the relationship between the volumes of the amygdala and its substructures with respect to cognitive performances in a population of left-lateralized TLE with and without HS. Twenty-nine TLEs were recruited (14 TLE-HS; 15 TLE-MRIneg). After investigating the differences in the subcortical amygdalae and hippocampal volumes compared to a matched healthy control population, we explored the associations between the subnuclei of the amygdala and the hippocampal subfields with the cognitive scores in TLE patients, according to their etiology. In TLE-HS, a reduced volume of the basolateral and cortical amygdala complexes joined with whole hippocampal atrophy, was related to poorer scores in verbal memory tasks, while in TLE-MRIneg, poorer performances in attention and processing speed tasks were associated with a generalized amygdala enlargement, particularly of the basolateral and central complexes. The present findings extend our knowledge of amygdala involvement in cognition and suggest structural amygdala abnormalities as useful disease biomarkers in TLE.

Impact of an optimized epilepsy surgery imaging protocol for focal epilepsy: A monocentric prospective study.

OBJECTIVE: To evaluate in a real clinical scenario the impact of the ILAE-recommended "Harmonized neuroimaging of epilepsy structural sequences"- HARNESS protocol in patients affected by focal epilepsy. METHODS: We prospectively enrolled focal epilepsy patients who underwent a structural brain MRI between 2020 and 2021 at Modena University Hospital. For all patients, MRIs were: (a) acquired according to the HARNESS-MRI protocol (H-MRI); (b) reviewed by the same neuroradiology team. MRI outcomes measures were: the number of positive (diagnostic) and negative MRI; the type of radiological diagnosis classified in: (1) Hippocampal Sclerosis; (2) Malformations of cortical development (MCD); (3) Vascular malformations; (4) Glial scars; (5) Low-grade epilepsy-associated tumors; (6) Dual pathology. For each patient we verified for previous MRI (without HARNESS protocol, noH-MRI) and the presence of clinical information in the MRI request form. Then the measured outcomes were reviewed and compared as appropriate. RESULTS: A total of 131 patients with H-MRI were included in the study. 100 patients out from this cohort had at least one previous noH-MRI scan. Of those, 92/100 were acquired at the same Hospital than H-MRI and 71/92 on a 3T scanner. The HARNESS protocol revealed 81 (62%) positive and 50 (38%) negative MRI, and MCD was the most common diagnosis (60%). Among the entire pool of 100 noH-MRI, 36 resulted positive with a significant difference (p < .001) compared to H-MRI. Similar findings were observed when accounting for the expert radiologists (H-MRI = 57 positive; noH-MRI = 33, p < .001) and the scanner field strength (H-MRI 43 = positive, noH-MRI = 23, p < .001), while clinical information were more present in H-MRI (p < .002). SIGNIFICANCE: The adoption of a standardized and optimized MRI acquisition protocol together with adequate clinical information contribute to identify a higher number of potentially epileptogenic lesions (especially FCD) thus impacting concretely on the clinical management of patients with focal epilepsy.