The insula is the fifth lobe of the brain and it is the least known. Hidden under the temporal, frontal and parietal opercula, as well as under dense arterial and venous vessels, its accessibility is particularly restricted. Functional data on this region in humans, therefore, are scarce and the existing evidence makes conclusions on its functional and somatotopic organization difficult. 5 patients with intractable epilepsy underwent an invasive presurgical evaluation with implantation of diagnostic invasive-depth electrodes, including insular electrodes that were inserted using a mesiocaudodorsal to laterorostroventral approach. Altogether 113 contacts were found to be in the insula and were stimulated with alternating currents during preoperative monitoring. Different viscerosensitive and somatosensory phenomena were elicited by stimulation of these electrodes. A relatively high density of electrode contacts enabled us to delineate several functionally distinct areas within the insula. We found somatosensory symptoms to be restricted to the posterior insula and a subgroup of warmth or painful sensations in the dorsal posterior insula. Viscerosensory symptoms were elicited by more anterior electrode contacts with a subgroup of gustatory symptoms occurring after stimulation of electrode contacts in the central part of the insula. The anterior insula did not show reproducible responses to stimulation. In line with previous studies, we found evidence for somato- and viscerosensory cortex in the insula. In addition, our results suggest that there is a predominantly posterior and central distribution of these functions in the insular lobe.Electronic supplementary materialThe online version of this article (doi:10.1007/s00429-010-0296-3) contains supplementary material, which is available to authorized users.
Summary This article critiques the International League Against Epilepsy (ILAE) 2015‐2017 classifications of epilepsy, epileptic seizures, and status epilepticus. It points out the following shortcomings of the ILAE classifications: (1) they mix semiological terms with epileptogenic zone terminology; (2) simple and widely accepted terminology has been replaced by complex terminology containing less information; (3) seizure evolution cannot be described in any detail; (4) in the four‐level epilepsy classification, level two (epilepsy category) overlaps almost 100% with diagnostic level one (seizure type); and (5) the design of different classifications with distinct frameworks for newborns, adults, and patients in status epilepticus is confusing. The authors stress the importance of validating the new ILAE classifications and feel that the decision of Epilepsia to accept only manuscripts that use the ILAE classifications is premature and regrettable.
Over the last few decades the ILAE classifications for seizures and epilepsies (ILAE-EC) have been updated repeatedly to reflect the substantial progress that has been made in diagnosis and understanding of the etiology of epilepsies and seizures and to correct some of the shortcomings of the terminology used by the original taxonomy from the 1980s. However, these proposals have not been universally accepted or used in routine clinical practice. During the same period, a separate classification known as the "Four-dimensional epilepsy classification" (4D-EC) was developed which includes a seizure classification based exclusively on ictal symptomatology, which has been tested and adapted over the years. The extensive arguments for and against these two classification systems made in the past have mainly focused on the shortcomings of each system, presuming that they are incompatible. As a further more detailed discussion of the differences seemed relatively unproductive, we here review and assess the concordance between these two approaches that has evolved over time, to consider whether a classification incorporating the best aspects of the two approaches is feasible. To facilitate further discussion in this direction we outline a concrete proposal showing how such a compromise could be accomplished, the "Integrated Epilepsy Classification". This consists of five categories derived to different degrees from both of the classification systems: 1) a "Headline" summarizing localization and etiology for the less specialized users, 2) "Seizure type(s)", 3) "Epilepsy type" (focal, generalized or unknown allowing to add the epilepsy syndrome if available), 4) "Etiology", and 5) "Comorbidities & patient preferences".
Aims. Seizure semiology provides information about the eloquent cortex involved during a seizure and helps to generate a hypothesis regarding the localization of the epileptogenic zone (EZ), a prerequisite for surgical management of epilepsy. We aimed to study the seizure semiology among all different age groups to better characterize semiological changes that occur with age. Methods. We performed a retrospective review of video‐EEG data in paediatric and adult patients admitted to the Epilepsy Monitoring Unit over a three‐year period. Authors independently reviewed and classified the seizure semiology while blinded to clinical, EEG, and neuroimaging data. A total of 270 patients were included in the study. Results. The most frequent EZ in patients who were one month to three years old was undetermined. Focal epilepsy became more frequent in patients older than 10 years. Among patients with focal epilepsy, a posterior quadrant EZ was most frequent in children younger than three years old, a temporal EZ between three and six years old, and a frontal EZ between six and 10 years old. The temporal lobe was the most frequent location for focal EZ in patients older than 18 years. Auras, automotor seizures, and generalized tonic‐clonic seizures were extremely infrequent in patients younger than 10 years old. The youngest patient with auras was 5.7 years old. The youngest patient with automotor seizures was 3.7 years old. We identified only three patients with generalized tonic‐clonic seizures who were younger than 10 years (aged six months, 6.6 years, and nine years, respectively). Patients younger than three years exhibited mostly generalized simple motor seizures and hypomotor seizures. Generalized epileptic spasms, generalized tonic seizures, and generalized clonic seizures were infrequent in patients older than 10 years. Conclusion. Seizure semiology and electroencephalographic changes most likely reflect the maturation of cortical functions.
In clinical practice, the diagnosis of focal vs generalized epilepsy dictates the management of the patient. The distinction between generalized and focal epilepsy is at times imperfect and some epilepsies have features that fall in between these two extremes. An example is the occurrence of focal interictal and focal ictal abnormalities in generalized epilepsies. As a part of the special issue on "The epileptogenic zone in pediatric epilepsy surgery", this focused narrative review will discuss different focal abnormalities seen in generalized epilepsy. An overlap of focal and generalized epileptiform abnormalities may support a continuum between focal and generalized epilepsy. When evaluating patients in the "gray zone", other factors such as ictal semiology, neuroimaging, genetic testing and functional deficits may need to be considered to reach an accurate diagnosis. Being aware of possible occurrence of focal clinical and EEG features in generalized epilepsy will help clinicians select more preferred AED (s), avoiding potential iatrogenic side effects and inappropriate consideration for epilepsy surgery.
Triphasic morphology GPDs confer less risk of seizures when compared with patients with GPDs without triphasic morphology. Features with a higher risk of seizures include focality on electroencephalogram, interburst suppression, a history of epilepsy, and an abnormal scan. The GPD score can be used to assess the risk of developing seizures in patients with GPDs.
Epilepsy should be suspected in patients with Stiff‐person syndrome and new onset paroxysmal episodes. Musicogenic epilepsy may be a manifestation of anti‐GAD‐Ab spectrum, supporting an autoimmune workup in these patients. Appropriate treatment is not well established, and immunotherapy should be considered in patients with only partial response to antiepileptic drugs.
Epileptic seizure semiology adds important information to the formulation of the hypothesis of the epileptogenic zone. Seizure semiology in infants and children are simple and elementary, becoming more complex with maturation of brain. Also in this age group, seizure semiology may be generalized in a setting of a focal lesion or may show focal signs with misleading localization values. We review seizure semiology of patients aged one month to ten years with respect to lateralization and localization of the epileptogenic zone. Benefits of semiological classificationThere are benefits of using the semiological classification (SC).
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