Sleep-related hypermotor seizures of insulo-opercular origin: A review of 27 cases

Abstract

Introduction . Insular epilepsy is known to be a “great mimicker” of various types of focal epilepsy, including sleep-related hypermotor epilepsy (SHE) in about 15% of cases. Because SHE tends to have a frontal origin, misdiagnosis can result in a poor surgical outcome when epilepsy surgery is considered. In this study, we reviewed the existing literature to identify electro-clinical features suggestive of an insulo-opercular (IO) origin in SHE. Methodology . We found 11 case series of SHE or insular epilepsy with sufficiently detailed patient data. We identified 27 patients with IO SHE from 6 studies. When available, the semiology patterns (SP), early nonmotor manifestations, alteration of consciousness (AOC), EEG and MRI features and histopathology were collected. Results . SP analysis of the 27 identified patients showed a wide variety of indiscriminate SP, including hyperkinetic and/or dystonic features. Early nonmotor manifestations were observed in 80%, most commonly somatosensory auras (44%). Laryngeal constriction, pain, oral and widespread paresthesia were observed in IO SHE but not in frontal SHE. AOC was uncommon (20%). EEG was rarely suggestive of an IO origin (17%) and MRI was diagnostic in 48%. Focal cortical dysplasia was the most common diagnosis (78%). Following surgery, 83% were seizure-free (follow-up: 12–60 months). Conclusions . Few electro-clinical features, except early non-motor manifestations, are suggestive of an IO onset in SHE. Therefore, in MRI-negative patients, a heightened vigilance for subtle subjective or behavioral signs is warranted to avoid misdiagnosis and poor surgical outcome.