The Anatomical Basis of Seizures

Excerpt

Paroxysmal alteration of neurological function caused by an excessive hypersynchronous neuronal discharge in the brain is known as seizure. Non-epileptic seizure is short-lived while epilepsy is a neurological condition characterized by two or more provoked seizures. The hippocampus, amygdala, frontal cortex, temporal cortex, and olfactory cortex are the common areas involved in seizures. According to the ‘dormant basket cell’ theory, loss of excitatory input from the dentate mossy cells makes inhibitory basket cells dormant while according to the ‘mossy fiber’ theory, mossy fibers induce the formation of excitatory circuits resulting in hyperexcitability. Amygdala is present at the anterior end of the inferior horn of the lateral ventricle; basolateral part plays an important role in temporal lobe epilepsy. The thalamus is an ovoid mass of grey matter; midline nuclei of the thalamus is involved in memory function and arousal, while it plays a crucial role in controlling seizures. Dendrites are short post-synaptic neural processes; in pathological conditions dendrites can cause hyperexcitability in neuronal circuits and lead to decreased seizure thresholds and progressive epileptogenesis. Regions specialized for learning/memory are most prone to seizures, particularly, the neocortical regions and the hippocampus.