![]() In contrast, a clear separation appeared between Groups A and C, as only Group C (with complete AOC) displayed marked enhanced h 2 values, particularly pronounced for interactions outside the temporal lobe suggesting that the specific involvement of extratemporal structures increased synchrony in AOC. In comparison with the preictal (background) period, the groups did not differ in terms of neural synchrony within the temporal lobe at seizure onset. This was in agreement with the observations by Gloor [ Munari's team found a higher occurrence of loss of consciousness in seizures involving bilateral temporal structures. In contrast, patients who never lost consciousness were more likely to present subjective epigastric sensation at seizure onset in the context of a shorter discharge limited to unilateral temporal structures. Over half of the cases with AOC showed propagation to the contralateral hemisphere, especially contralateral temporal lobe. The presence of extratemporal ictal signs (such as lateralized tonic posturing or clonic jerks and subsequent generalization) was also associated with a longer duration of ictal discharge. The authors observed that patients with altered consciousness were also more likely to present complex semiology (such as dyspraxic automatisms) as well as extratemporal semiology, with, overall, a longer duration of ictal discharge (average seizure duration of 90 s when altered consciousness occurred, in contrast to 47 s for seizures with no loss of consciousness). Given the large size of the patient group, comparison was possible not only of individual seizures but also groups of patients (those who lost consciousness at the onset of every seizure versus those who never lost consciousness). This link between abnormal synchrony and AOC offers new perspectives in the treatment of the AOC since means of decreasing consciousness alteration in seizures could improve patients' quality of life. Changes in thalamocortical synchrony occurring during the spreading of the ictal activity seem particularly involved in the mechanism of altered consciousness. In particular, a nonlinear relation has been shown between excess of synchronization in the GW regions and the degree of AOC. Several lines of evidence support the view that partial seizures alter consciousness through disturbance of the GW. An emerging concept in neurology is the global workspace (GW) theory that postulates that access to consciousness (from several sensorial modalities) requires transient coordinated activity from associative cortices, in particular the prefrontal cortex and the posterior parietal associative cortex. Several theories have been proposed in the last fifty years. Alteration of consciousness (AOC) is an important clinical manifestation of partial seizures that greatly impacts the quality of life of patients with epilepsy.
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