To identify which cortical regions are associated with direct electrical stimulation (DES)-induced alteration of breathing significant enough to impair pulse oximetry (SpO ₂ ).
Evolution of SpO ₂ after 1,352 DES was analyzed in 75 patients with refractory focal epilepsy who underwent stereo-EEG recordings. For each DES, we assessed the change in SpO ₂ from 30 seconds prior to DES onset to 120 seconds following the end of the DES. The primary outcome was occurrence of stimulation-induced transient hypoxemia as defined by decrease of SpO ₂ ≥5% within 60 seconds after stimulation onset as compared to pre-DES SpO ₂ or SpO ₂ nadir <90% during at least 5 seconds. Localization of the stimulated contacts was defined according to MarsAtlas brain parcellation and Freesurfer segmentation.
A stimulation-induced transient hypoxemia was observed after 16 DES (1.2%) in 10 patients (13%), including 6 in whom SpO ₂ nadir was <90%. Among these 16 DES, 7 (44%) were localized within the perisylvian cortex. After correction for individual effects and the varying number of DES contributed by each person, significant decrease of SpO ₂ was significantly associated with the localization of DES (p = 0.019).
Though rare, a significant decrease of SpO ₂ could be elicited by cortical direct electrical stimulation outside the temporo-limbic structures, most commonly after stimulation of the perisylvian cortex.