Abstracts

Rationale:
Motor manifestations of insular seizures have been described in some stimulation studies as well as in studies looking at insular onset seizures. These motor manifestations that have been reported are myoclonic phenomena, tremor, gestural movements (brief pedaling, swinging along the vertical axis of the body), spectacular motor phenomena (choreo-dystonic movements such as dystonia or involuntary movements, hypermotor). It has been proposed that motor manifestations are likely due to the spread of these seizures from the insula to the respective cortex. Task based fMRI studies have shown that the anterior cingulate cortex (ACC) and anterior insula (aINS) co-activate in diverse tasks , conditions, emotional autonomic and executive functions including thirst, hunger pain, bladder distention, embarrassment and uncertainty to those eliciting amusement, compassion, tenderness and humor.  Few other studies have reported the emergence of motor manifestations with insular onset seizures as a result of the connection between the insula and the mesial frontal regions with the help of stereo-EEG. As motor manifestations are rarely isolated in insular seizures but associated with arousal, autonomic symptoms and signs and somatosensory symptoms we undertook to study the clinical semiology emerging from the coactivation of insula and cingulate cortex with insular onset seizures. To this end, we selected a population of patients investigated with SEEG. These patients had an ictal discharge primarily limited to these two regions at the onset of motor semiology. Our secondary aim is to segregate these motor manifestations based on semiology and correlate them with the part of the cingulate cortex (anterior, anterior-mid, mid or posterior cingulate) they spread to.
Method:
A Retrospective analysis of SEEG patients was conducted from January 2013 to May 2020. Ten patients which fit the inclusion criteria were selected for the study. All patients had atleast two electrodes in the cingulate cortex (anterior, middle or posterior) and two or more electrodes in the insula (one each in the anterior and posterior insula). A visual analysis of the seizure onset was conducted as well as time frequency maps using brainstorm and MATLAB software’s were analyzed for patients who had fast activity (slow gamma, gamma) at onset of motor symptoms. Linear regression analysis will be conducted on these seizures to look for correlation between the time from EEG onset to motor onset and time from cingulate onset to motor onset.
Results:
The cohort included 6 females(60%) and 4 males(40%). Median age at seizure onset was 11 years and median age at SEEG was 20.5 years. Five of ten patients had integrated gestural motor behavior (shuffling in bed, urge to move, rocking). Two out of ten patients had non-integrated gestural motor behavior (dystonia, choreo-athetoid). Six out of ten patients had a facial grimace or chapeau gendarme). Two of the ten patients had arms going up at seizure onset. More than one motor feature could be present at seizure onset. Four out of ten patients had aura’s and/or no-clinical signs seizure without progression to motor seizure with EEG showing involvement of only the insular contacts without involvement of the cingulate contacts. 2/10 patients had spread to the posterior cingulate. 4/10 had spread to the anterior cingulate and 4/10 had spread to the anterior mid or mid cingulate.
Conclusion:
The semiology generated from insular seizures is likely due to spread to other regions. Here we have explored the spread of the insular seizures to the cingulate cortex.
Funding:
:none