The latter either directly (potassium ions) or indirectly (albumin) affect neuronal firing

The latter either directly (potassium ions) or indirectly (albumin) affect neuronal firing. sub-threshold response or a single spike. Neuronal networks can oscillate between a resting and firing state activity in Gefitinib hydrochloride response to either intrinsic (pacemaker) properties or as a result from activity of many neurons. In individual neurons, oscillations can appear either as oscillations in membrane potential Gefitinib hydrochloride or as rhythmic patterns of action potentials. Synchronized activity of large numbers of neurons occurs during epileptic seizures. The summation of electrical signals from this large assemblies of neurons is the basis of the EEG appearance during a seizure, which is characterized by large amplitude (voltage) signals. == Seizure threshold == This term is used to describe how susceptible one is to seizures at a given time. Both internal and external factors and stimuli contribute towards this threshold. As described in this review, ions, transmitters, inflammatory mediators and body temperature are examples of Gefitinib hydrochloride internal factors that alter the epileptogenic threshold. External stimuli may be sensory, electrical or chemical. These are often used to trigger experimental seizures (kainic acid, electrical stimulation of the amygdala). A complex interaction between external and internal factors explains why precipitating events of comparable potency may or not trigger seizures. == Cryptogenic, idiopathic and symptomatic epilepsy == A cryptogenic or idiopathic disease is a disease with unknown etiology. In the case of epilepsy, these terms refer to patients where no genetic or metabolic disorder is identified and imaging (MRI) of the cortex and hippocampus does not reveal Gefitinib hydrochloride detectable abnormalities. The term symptomatic epilepsy is, by contrast, used to define an epileptic disorder due to a structural or metabolic condition, genetic or acquired, that has been demonstrated to be associated with a substantially increased risk of developing epilepsy. Gefitinib hydrochloride Lesional epilepsy is the antonym of cryptogenic and refers to patients with a distinct abnormality visible in MRI scans. == Interictal, ictal EEG == The EEG associated with epileptic seizures (referred to as ictal, fromictusLatin for a stroke or blow) is characterized by an abrupt change of the signal. Focal seizures are typically characterized by the appearance of local low-voltage fast activities progressively replaced by slower quasi-rhythmic activities often spreading to the neighboring regions. Between seizures, the EEG may appear normal or feature interictal epileptic abnormalities (e.g. spikes, sharp waves, slow waves) isolated or in brief discharges. == Ictogenic process, epileptogenesis == Seizures are symptoms of epilepsy, a cluster of neurological diseases. Ictogenesis refers to the events leading to the development of a seizure, including the prodromic features named auras and EEG changes that predict seizure onset (ripples, slowing,etc.). Epileptogenesis refers to the events occurring during the often silent (no seizures) period between an insult (e.g., traumatic brain injury) and the development of a first seizure. The epileptogenic process may last days to years. == Status epilepticus and super-refractory status epilepticus == According to the Glossary of Descriptive Terminology for Ictal Semiology of the International League Against Epilepsy (ILAE), the term status epilepticus (SE) refers to a seizure which shows no clinical signs of arresting after a duration encompassing the great majority of seizures of that type in most Tmem26 patients or recurrent seizures without resumption of baseline central nervous system function interictally. The most common SE is generalized tonic-clonic status epilepticus, a potentially fatal condition associated with neuronal injury and respiratory and metabolic dysfunction. Although the ILAE does not define the minimum duration for a seizure to be defined as status, the operational definitions propose to start treatment when seizure activity continues beyond 5 minutes. Refractory SE is defined as SE that has not responded to first-line therapy with a benzodiazepine or second-line therapy, and which requires the application of general anesthesia. Super-refractory status epilepticus.