Literature Review On Absence Seizure

Absence seizures are a brief loss of awareness, sometimes mistaken for daydreaming. They can happen very often and can affect attention, learning and memory. There are a few different ways that scientists use to examine the brain while absence seizures are present. This article explored the insights of EEG-fMRI studies into the mechanisms of AS and considered how the DMN or default brain network ( which is a network of interacting brain regions known to have activity highly correlated with each other and distinct from other networks in the brain).The DNM is thought to be the major large-scale brain network central to both seizure generation and manifestation. EEG along with functional MRI is one such technique that provides an opportunity to explore interactions between different brain structures that are involved in AS generation.
Generalized epileptic seizures at some point originate in a rapidly engaging, bilaterally distributed networks. There’s a few types of absence seizures that are talked about in this article typical and atypical absence seizures. During a typical absence seizure a person usually stares into space for up to ten seconds, they are often mistaken for daydreaming. On the other hand during an atypical absence seizure a person will make some kind of movement while also staring into space. The movements could include blinking, chewing, or hand gestures. In order to understand the mechanisms of AS generation you have to think about the cellular networks involved in seizure generation.
In early experimental models of the spike-and-wave activity which gave rise to the centrencephalic theory of epilepsy which suggested that the thalamus is the likely central driver of of epileptiform activity. The thalamo-cortical network is the major network that generates seizures. The thalamus displays rhythmic firing and has reciprocal connections to the cortex it has excitatory neurons arising from the dorsal thalamus that conveys information to cortical and thalamic projections to the reticular nucleus of the thalamus. The role of thalamo cortical networks is to maintain the sleep-wake cycle, awareness, and cognition. Absence seizures occur during wakefulness or while drowsing off. The fMRI studies of different patients with absence seizures have been used successfully in order to understand the structural and functional mechanisms of seizure generation. EEG along with fMRI allows us to recognized BOLD (blood oxygen level dependant) changes that are associated with absence
seizures. A few imaging techniques have been employed which help to explore the different structures involved in AS generation. EEG and functional MRI are one of the dominant means of studying functional consequences of absence seizures in the brain. Also a few other techniques are used to study the blood flow in the brain and metabolic changes related to absence seizures. There is a type of exam that measures blood flow during an absence seizure it is called Doppler ultrasonography. Doppler ultrasonography of the middle cerebral artery indicates a reduction of blood flow as a result of absence seizures. fMRI uses the BOLD response as a replacement for neuronal metabolic activity to allow visualization of brain regions that respond to both physiological and pathological examples. The default mode network