Mechanism of the Epileptic Seizures:A Pathophysiologic Correlation of Clinical and EEG Findings with a Review of the Recent Literature.

Kim, Yoon Bum

Original Article

Journal of Korean Neurosurgical Society 1975;4(1): 73-82.

Yoon Bum Kim

Kim Yoon Bum Neurosurgical Hospital, Busan, Korea.

ABSTRACT

To increase the understanding of the pathophysiologic mechanisms present in epileptic seizures, and to correlate the clinical features with the EEG findings, a review of the recent literature has been made. Epileptic seizures are classified into three types:focal(or partial), generalized and unilateral seizures. In the first type, the focal seizure, there are two sites which have been thought to have one or the other of an initial discharge. The first site is the cortical pole, and the second is the end pole of the interconnected subcortical nuclear system. the cortical pole, and the second is the end pole of the interconnected subcortical nuclear system, the cortical pole is more accessible and vulnerable to seizures. The end pole of the interconnected subcortical nuclear system has two sectors which may be involved. the first sector, the cortico-thalamic system, includes filstly the specific cortico-thalamic system in which the focal stimulation is related to relatively simple somato-motor, sensory and autonomic nervous functions. Secondly, in this first sector, is the non-specific corticothalamic systems which includes the body integrative functions which underlie psychic elaboration of primary sense data. The second sector in the subcortical nuclear system is the amygdalo-brain stem sector. In this non-thalamic system there are the deep temporal structures of the brain such as the amygdalahippocampal complex. These structures are involved in the regulation of emotions, in memory functions and in the maintenance of consciousness. A schematic diagram is prepared to explain the mode of propagation of the epileptic discharge from the initial focus along pathways in the brain structures. This diagram is explained and discussed. The second type of seizure is the generalized seizure. This type is subdivided into two groups:convulsive and non-convulsive. The convulsive group of seizures includes tonic clonic(grandmal), tonic, clonic, infantile spastic, and bilateral myoclonic seizures. These are discussed. The non-convulsive group of seizures includes the following kinds:typical absence(petitmal), atypical absence(petitmal varient), absence status, and atonic seizures. In this group of seizures the initial discharge occurs at the centrencephalon(diencephalo-mesencephalo-rhombencephalon). The intricate mode of propagation of this type of discharge, which involve the recruiting and inhibitory systems, was discussed and also presented schematically.