Insular seizures and epilepsies: Ictal semiology and minimal invasive surgery

Abstract

Purpose of review The increased identification of seizures with insular ictal onset, promoted by the international development of stereo-electroencephalography (SEEG), has led to the recent description of larger cohorts of patients with insular or insulo-opercular epilepsies than those previously available. These new series have consolidated and extended our knowledge of the rich ictal semiology and diverse anatomo-clinical correlations that characterized insular seizures. In parallel, some experiences have been gained in the surgical treatment of insular epilepsies using minimal invasive procedures. Recent findings The large majority of patients present with auras (mostly somatosensory and laryngeal) and motor signs (predominantly elementary and orofacial), an underlying focal cortical dysplasia, and an excellent postoperative seizure outcome. Many other subjective and objective ictal signs, known to occur in other forms of epilepsies, are also observed and clustered in five patterns, reflecting the functional anatomy of the insula and its overlying opercula, as well as preferential propagation pathways to frontal or temporal brain regions. A nocturnal predominance of seizure is frequently reported, whereas secondary generalization is infrequent. Some rare ictal signs are highly suggestive of an insular origin, including somatic pain, reflex seizures, choking spells, and vomiting. Minimal invasive surgical techniques have been applied to the treatment of insular epilepsies, including Magnetic Resonance Imaging-guided laser ablation (laser interstitial thermal therapy (LITT)), radiofrequency thermocoagulation (RFTC), gamma knife radiosurgery, and responsive neurostimulation. Rates of seizure freedom (about 50%) appear lower than that reported with open-surgery (about 80%) with yet a significant proportion of transient neurological deficit for LITT and RFTC. Summary Significant progress has been made in the identification and surgical treatment of insular and insulo-opercular epilepsies, including more precise anatomo-clinical correlations to optimally plan SEEG investigations, and experience in using minimal invasive surgery to reduce peri-operative morbidity.

Ictal semiology of epileptic seizures with insulo-opercular genesis

“…The left dendrogram shows features of the patients with insulo-opercular epilepsy and on the right features of the patients with mesiotemporal epilepsy [34]. The second most frequent seizure manifestation was somatosensory (including perioral and throat sensations) and autonomic symptoms (including bradycardia) [16,17,34]. Progression to bilateral tonic-clonic seizures was less frequent in other series than in our cohort, which may be partially related to tapering of antiepileptic drugs during video-EEG recordings in our patient sample.…”

“…2 Results of the cluster analysis. The left dendrogram shows features of the patients with insulo-opercular epilepsy and on the right features of the patients with mesiotemporal epilepsy [34]. The second most frequent seizure manifestation was somatosensory (including perioral and throat sensations) and autonomic symptoms (including bradycardia) [16,17,34].…”

Insular Involvement in Cases of Epilepsy Surgery Failure

“…Though none of the patients in this series underwent LITT, there is growing evidence that this technique may yield good outcomes. Our group recently published a review of minimally invasive techniques and found that 58% of patients having undergone LITT in the available literature (a total of 38 patients) had Engel class I outcomes [ 30 ].…”

Invasive Ableitung der Insel

“…Insuläre Epilepsien sind ein besonders herausforderndes Thema unter den pharmakoresistenten Epilepsien [4]. Ihre besondere anatomische Lage am Grund der Sylvischen Furche bedeckt vom frontalen, temporalen und parietalen Operculum sowie den Ästen der A. cerebri media (ACM) macht den Zugang zur Insel schwierig und morbiditätsbehaftet [18]. Trotzdem können ein gutes Ergebnis und eine hohe Rate an Anfallsfreiheit postoperativ erreicht werden, wobei häufig eine invasive Ableitung der Insel notwendig ist [2, 7-9, 14,18,21].…”

“…Ihre besondere anatomische Lage am Grund der Sylvischen Furche bedeckt vom frontalen, temporalen und parietalen Operculum sowie den Ästen der A. cerebri media (ACM) macht den Zugang zur Insel schwierig und morbiditätsbehaftet [18]. Trotzdem können ein gutes Ergebnis und eine hohe Rate an Anfallsfreiheit postoperativ erreicht werden, wobei häufig eine invasive Ableitung der Insel notwendig ist [2, 7-9, 14,18,21]. Hierfür werden verschiedenste Techniken beschrieben, welche in dieser Übersichtsarbeit beleuchtet werden.…”