An electrical storm…in the head

‘The seizures observed in epileptic patients come from disorders within the cortex,’ points out Professor Grisar. ‘The cortex is made up of neuron circuits, in other words, nerve cells which communicate with each other through electrical signals, in an order guided by genes and the body’s environment.’ But these circuits, just like the electrical circuits which are all around us, can sometimes be flawed. ‘When the neurons lose certain of their capacities in a region of the brain, it can happen that 30 to 40 million neurons function in a synchronous fashion, and an electrical storm occurs!’ continues Thierry Grisar. It is at this moment that en epileptic seizure occurs, a clinical manifestation of this cerebral electrical storm. ‘If it takes place in a region in which visual projections are recorded, the patient manifests in particular visual hallucinations. If the disturbance affects the area responsible for motricity, the electrical storm will be translated as an uncontrollable jerking of the body.’ In this way, according to the region of the brain in which neuron synchronisation occurs, there exist a myriad of semiological possibilities. Furthermore, age, the presence of a tumour or cerebral lesions etc., can also influence the eruptions of such electrical storms.

Confronted with the multiple ‘faces’ of epilepsy, scientists have attempted to classify them. Two grand classes of epilepsies have thus seen the light of day: idiopathic epilepsies and lesional epilepsies. The former, whose causes are not really known, allow nothing to come to light when various tests are carried out, such as MRI, scanner or clinical examinations. They represent the majority of epilepsies and manifest themselves above all over the course of childhood. As for lesional epilepsies, they are those for which a cause is known, such as the presence of a tumour or lesion in the brain. ‘There are two occurrence peaks for epileptic seizures, one at the age of three and the other around the age of sixty-two,’ specifies Thierry Grisar. ‘Idiopathic epilepsies mainly concern children whilst lesional epilepsies above all affect people of pensionable age due to lesions or other cerebral commotions which can appear over the years.’