Abstracts

Rationale: The aim of this study is to investigate the clinical and polygraphic features of different types of ictal oro-alimentary automatisms in the attempt to describe their possible localizing value. Methods: Among the series of patients selected for presurgical investigation in the last 10 years at S. Paolo Hospital and Niguarda Hospital in Milan, two independent observers selected and analyzed seizures with oro-alimentary (OA) manifestations (67 patients,248 seizures). A study of video-EMG-EEG/SEEG correlations has been carried out, in order to subdivide and classify clinical OA subgroups and to investigate their possible localizing value. The study consisted with:(a)clinical analysis of features, sequence, latency and duration of ictal and postical OA manifestations;(b)analysis of the EMG features of the muscles of perioral and branchial regions (morphology, duration and period of single bursts);(c)evaluation of the EEG/SEEG correlate of each single OA pattern; (d)evaluation of the effects of intracranial electrical cortical stimulation (ECS). Results: We observed three main clinical-polygraphic subgroups of OA automatisms:(1)a chewing pattern,(2)a masticatory-deglutitory pattern,(3)complex ictal oro-alimentary automatisms. Different OA pattern could emerge at different time during the same seizure. Both OA patterns of type 1 and 2 were prolonged/rhythmic manifestations that differentiated for the EMG bursts, for their latency of appearance (longer in type 2) and for the topography of the concomitant ictal discharge. OA automatism of type 3 were an heterogeneous entity composed brief, monophasic and never postictal manifestation with variable latency and duration. OA type 1 were often preceded by epigastric rising aura (25%) or fear (25%), OA type 2 were preceded by epigastric not rising (20%) or acoustic aura (20%), whilst the aura preceding OA type 3 was variable. The ictal discharge during OA type 1 involved temporo-mesial regions, whilst during OA automatisms of type 2 and 3 the discharge was olo-temporal and extra temporal (insular and opercular regions). ECS confirmed the presence of different OA patterns with different cortical topography. The same pattern of chewing has been observed comparing ictal and postictal automatisms of type 1 and voluntary mastication in the same patient, while eating. Conclusions: We propose a clinical division in subgroups of oro-alimentary ictal patterns, suggesting the involvement of different motor circuits. Ictal chewing could result from the involvement of the antero-mesial temporal structures (epigastric or emotional aura), while a mild mastication with swallowing corresponds to a wider diffusion of the ictal discharge to T and extra-T (operculum, insula) structures. Both are probably expression of the liberation of the masticatory Central Pattern Generator (also post-ictal; same features of the voluntary mastication), possibly through the disinhibition of the amygdalo-pontine circuitry. Other complex OA automatisms probably reflects the activation of cerebral (fronto-insular) neocortical areas.