Clin Neurophysiol. 2022 Feb 4;136:150-157. doi: 10.1016/j.clinph.2022.01.132. Online ahead of print.
ABSTRACT
OBJECTIVE: To investigate whether barques can be localized across the hippocampal longitudinal axis with sufficient specificity.
METHODS: We identified 51 focal epilepsy patients implanted with a minimum of two electrodes – unilateral anterior and posterior – in either hippocampus. We used visual inspection of the intracranial electroencephalogram (iEEG) and 3D brain volume spectrum-based statistical parametric mapping (SPM) to localize barques.
RESULTS: In 18/51 patients (35.29%), barques were identified in 22/70 (31.42%) hippocampi. In all hippocampi (100%), barques were present in the posterior hippocampus, while 9 (40.90%) showed concurrent non-independent barque activity anteriorly (P < 0.0001). Statistical parametric mapping confirmed the posterior barque localization, with significant differences in t-values (t(27) = 8.08, P < 0.0001) and z-scores (t(24) = 6.85, P < 0.0001) between anterior and posterior hippocampal barque activity. Posterior lateral extrahippocampal contacts demonstrated phase reversals of positive polarity during barque activity (P = 0.0092, compared to anterior extrahippocampal contacts).
CONCLUSIONS: This study highlights the posterior hippocampal predominance of barques. Our findings are concordant with the posterior distribution of the scalp manifestation of barques as “14&6/sec positive spikes”. The posterio-lateral hippocampal barque phase reversal can explain the positive polarity of scalp 14&6/sec spikes.
SIGNIFICANCE: Understanding the properties of barques is critical for the iEEG interpretation in epilepsy surgery evaluations that include the hippocampus.
PMID:35168029 | DOI:10.1016/j.clinph.2022.01.132
