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Early infantile epileptic encephalopathies (EIEEs) are a heterogenous group of seizure disorders that begin in infancy. Some of them are present at birth whereas others arise later in infancy. In the recent years, advances in gene sequencing techniques have identified numerous genetic mutations that are thought to be responsible for many of the EIEEs.
It is known that the human brain has its own rhythmic activity. Some of these brain rhythms are relatively slow - occurring only a few times per second while others are faster and occur 30 to 80 times every second. However, with recent advances in electronic instrumentation it is now very clear that the brain produces even faster rhythms. Some of these rhythms are perfectly normal like “ripples” that occur 80-200 times per second. Others are even faster but most of these high frequency oscillations (HFOs), which sometimes occur 600 times per second, are thought to be abnormal.
Normal neuronal activity depends on the fine equilibrium between the actions of excitatory neurotransmitters (eg: glutamate) and inhibitory neurotransmitters (eg: gamma-aminobutyric acid, GABA). Usually, GABA, the major inhibitory neurotransmitter, counterbalances neuronal excitation in the brain, preventing neuronal hyperexcitabilty and seizures. At the same time, in order to ensure that neuronal activity continues at the optimal level, it is critical that GABA present in the space between neurons does not accumulate or linger.
Dravet syndrome is a rare and catastrophic form of incurable epilepsy that begins in infancy. Initially, these children develop normally but by the second year of life, they exhibit a progressive decline. It starts initially as febrile seizures i.e. seizures triggered by high fever but eventually progresses to severe spontaneous seizures. Over time, these children commonly exhibit developmental delays in cognitive and sensory abilities, and autistic traits. Moreover, the incidence of SUDEP (sudden unexplained death in epilepsy) is high among these patients.
Many pediatric cases of incurable epilepsy are attributed to a congenital defect, known as cortical dysplasia (CD) in which the neurons fail to migrate to appropriate locations in the brain during development. This results in abnormal brain architecture and neuronal miswiring that manifests as severe seizures. Currently, no treatments exist to prevent this condition and the only option is to reduce seizures using anticonvulsants or neurosurgery.
West syndrome is a rare epilepsy syndrome that affects about 1 in 3000 infants. It is diagnosed based on a triad of symptoms: infantile spasms, a high-voltage, chaotic electroencephalogram (EEG) pattern called hypsarrhythmia and cognitive impairment.
Infantile Spasms (West Syndrome) is a severe type of childhood epilepsy. Researchers in Dr. Swann's lab have developed a rat model of infantile spasms to identify underlying causes and to develop effective therapies. Watch this video to see the strikingly similar seizure patterns experienced by this rat model and a child with infantile spasms.