Abstracts

Rationale: Autonomic arousal during seizures is frequent and may have localizing value (Baumgartner et al., 2001). Peri-ictal autonomic dysfunction is a likely contributory factor in SUDEP (see e.g. Lee & Devinsky, 2005; Vilella et al, 2019). This underlines the importance of better understanding the organization of the central autonomic network. Cortical stimulation is considered a “gold standard” test in determining the central organization of neurological function; this can extend to exploring the central autonomic network (e.g. Lacuey et al, 2018). Given the role of the cingulate in control of heart rate (Critchley et al., 2003) and findings that risk factors for SUDEP are associated with differential brain structure correlates in the mid-anterior cingulum (e.g. Ogren et al., 2018; Allen et al, 2019) in this analysis we explored the effect of cortical stimulation of this region on heart rate. Methods: A retrospective analysis of 50 patients who underwent cortical stimulation at the National Hospital for Neurology and Neurosurgery during intracranial electroencephalography with sterographically placed electrodes identified 21 patients in whom 50Hz cortical stimulation was performed at one or more sites within the mid-anterior cingulum. Concurrently recorded electrocardiographic (ECG) data were extracted, and preprocessed to convert into a continuous time series and yield evoked heart rate responses. Evoked heart rate responses from stimulation at the cingulate and non-cingulate sites were compared. Individual significance was calculated after correction for multiple comparisons using SPM12 and thresholded at p<0.05 after correction for family-wise error. Results: 9/21 patients (p<0.0001) showed individually significant transient heart rate increases (magnitude 4-10bpm) after 50Hz cortical stimulation at the cingulate compared to stimulation elsewhere. Heart rate increases were predominantly unreported by patients. A small average effect across patients (peak ~3bpm) was also evident (p<0.05) but this masks significant individual variation in response. Conclusions: 50Hz cortical stimulation at the mid-anterior cingulum can provoke mild transient heart rate increases. Funding: No funding