Pharmacoresistant temporal epilepsy: the relationship of epileptiform activity and structural changes in the hippocampus

Background. Hippocampal sclerosis is one of the most common structural lesions associated with epilepsy. The standard medical care in the treatment of drug-resistant temporal lobe epilepsy associated with hippocampal sclerosis is surgery with anterior temporal lobectomy. The extent of resection depends on the involvement of hippocampal sclerosis in the epileptic system. Objective. Determine the relationship between the involvement of the hippocampus in the epileptic system (on the basis of the results of intraoperative electrocorticography (ECoG)) and the presence of structural changes in it, found on the basis of MRI data. Materials and methods. The present article presents an original retrospective study of the dependence of the signs of hippocampal sclerosis according to neuroimaging data and the formation of epileptiform activity in 36 patients treated at the Polenov Neurosurgical Institute — branch of Almazov National Medical Research Centre in 2015–2018. Results. Depending on the presence of hippocampal sclerosis and epileptiform activity, patients were divided into 4 groups: 1) patients with the presence of both hippocampal sclerosis and epileptiform activity in the mesiobasal structures (n = 15); 2) patients with identified sclerosis of the hippocampus, without registration of specific activity according to the results of ECoG (n = 8); 3) patients with epileptiform activity, while MR-negative (n = 10); 4) patients without epileptiform activity and without signs of hippocampal sclerosis according to MRI (n = 3). After a statistical check of the distribution of patients, it was found that the distribution was random. Conclusion. The fact of the presence of structural changes in the hippocampus could not be a pathognomonic sign of the inclusion of the hippocampal-entorial complex in the epileptic system.

1. Guseva EI, Konovalova AB, Gekht AB. Neurology. National leadership. Brief Edition. Moscow: GEOTARMEDIA, 2018. p. 688. In Russian

2. Mukhin Kyu, Gataullina SH, Petrukhin AS. Paleocortical temporal lobe epilepsy with hippocampal sclerosis: clinical features, diagnosis and treatment (a review). Rossijskij zhurnal detskoj nevrologii=Russian Journal of Pediatric Neurology. 2008; 3(3):41–60. In Russian.

3. Arzimanoglou A. Temporal lobe epilepsy in children and cognitive dysfunction: comprehensive methodologies for comprehensive research and care. In: Arzimanoglou A., Aldenkamp A., Cross H. et al. Cognitive dysfunction in children with temporal lobe epilepsy. John Libbey Eurotext Ltd, 2005: 275–289.

4. Gataullinana SKh, Mukhin KYu, Petrukhin AS. Mesial temporal sclerosis and its role in the development of paleocortical temporal lobe epilepsy (a review). Rossijskij zhurnal detskoj nevrologii=Russian Journal of Pediatric Neurology. 2008; 3 (3): 31–40. In Russian.

5. Beaumanoir A, Roger J. Historical notes: from psychomotor to limbic seizures. In: Avanzini G, Beaumanor A, Mira L. Limbic Seizures in Children. Milan: John Libbey Eurotext, 2001: 1–6.

6. Bocti C, Robitaille Y, Diadori P, et al. The pathological basis of temporal lobe epilepsy in childhood. Neurology. 2003; 60 (2): 191–195.

7. Alexandrov MV, Ulitin AYu, Bersnev VP. Structural and functional organization of epileptic focus. Rossijskij nejrohirurgicheskij zhurnal im. professora A.P. Polenova=Russian neurosurgical journal named after Professor Polenov. 2017; 9 (2): 5–9. In Russian

8. Luders HO. Textbook of epilepsy surgery. London: CRC Press, 2008. p. 1648.

9. Aleksandrov MV, Toporkova OA, Chikurov AA. Neurophysiological intraoperative monitoring in neurosurgery: a guideline. 2nd ed. SPb.: SpetcLit, 2019. P.159. In Russian.

10. Tatum WO, Vale FL, Anthony KU. Epilepsy surgery. A practical approach to neurophysiologic intraoperative monitoring. New York: Demos, 2008: 283–301.

11. Akiyama T, McCoy B, Go CY, et al. Focal resection of fast ripples on extraoperative intracranial EEG improves seizure outcome in pediatric epilepsy. Epilepsia. 2011; 52 (10): 1802–1811.

12. Duvernoy HM, Cattin F, Risold P-Y. The human hippocampus: functional anatomy, vascularisation, and serial sections with MRI. 4 th edition. Berlin: Springer Verlag Berlin Heidelberg, 2013. p. 237.

13. Engel J. Surgical treatment of the epilepsies. 2nd edition. Philadelphia: Lippincott Williams & Wilkins, 1993. p. 786.