Videos
Figures
Figure 1
Invasive EEG recording of somatosensory evoked seizure in Patient 1. The recording sites are shown on a 3-D representation of the patient's brain in insets (C) and (D). In the upper EEG recording, rubbing the patient's right hand (*indicates onset of stimulus; horizontal bracket shows the duration of stimulation) triggers low-amplitude preictal spikes (↑) in the left posterior long insular gyrus (triangulated in the insets: [E] coronal view, [F] axial view, and [G] sagittal view) and frontal operculum, transitioning into a low-voltage fast activity ictal pattern (↑↑). Clinically, the patient feels right hemibody pain and lifts his right arm (**) until the end of the ictal discharge (***lower EEG recording). The latency between the trigger and the first epileptiform discharge was 2.850 seconds. PMA: premotor area; Pre-CG: precentral gyrus; Post-CG: postcentral gyrus; pINS: posterior insula; CG: cingulate gyrus; Tp: temporal pole; MTG: middle temporal gyrus.
Figure 1
Figure 2
Invasive EEG recording of reflex audiogenic operculoinsular spikes (A) and seizure (B) in Patient 2. The recording sites are shown on a 3-D representation of the patient's brain in inset (C). In the upper EEG recording (A), an auditory stimulus to the left ear (2000 Hz, 85 dB) (*indicates onset of auditory stimulation; horizontal bracket indicates duration of stimulus) triggers, within a second, asymptomatic rhythmic spike-and-wave discharges (↑), maximum over the left posterior insula (as triangulated in the insets: [D] sagittal view, [E] axial view, and [F] coronal view) and parietal more than temporal opercula. High-pass filter: 0; low-pass filter: 35 Hz. In the lower EEG recording (B), listening to a piece of classical music gradually raised to maximum volume (*indicates onset; horizontal bracket shows stimulus duration) triggers a similar burst of spikes (↑) transiting into a seizure (↑↑) with the appearance of a high-frequency discharge in the posterior insula, parietal and temporal opercula. Clinically, the patient suddenly feels his aura, quickly removes his headphones (**), but is unable to abort subsequent evolution into complex motor behaviours (***). High-pass filter: 0 and low-pass filter: 20. IFG: inferior frontal gyrus; STG: superior temporal gyrus; MTG: middle temporal gyrus; aINS: anterior insula; pINS: posterior insula; P-op: parietal operculum; Tp: temporal pole.
Figure 2
Authors
1 Division of Neurology, CHUM Notre-Dame, Université de Montréal, Montreal, Canada
2 Department of Internal Medicine, Hue University of Medicine and Pharmacy, Hue University, Hue, Vietnam
3 Department of Psychology, Université de Montréal, Montreal
4 Division of Neurology, IWK Health Center, Dalhousie University, Halifax
5 Division of Neurosurgery, CHUM Notre-Dame, Université de Montréal, Montreal, Canada
* Correspondence: Dang Khoa Nguyen
CHUM Notre-Dame,
1560 Sherbrooke Street East,
Montreal, Quebec,
Canada H2L 4M1
Activation of specific cortical territories by certain stimuli is known to trigger focal seizures. We report three cases of well documented operculo-insular reflex seizures, triggered by somatosensory stimuli in two and loud noises in the third. Limited operculoinsular resection resulted in an excellent outcome for all. We discuss these observations in regard to the literature on reflex epilepsy and known functions of the insula. [Published with video sequences online ]