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Epileptiform bursts

Epileptiform bursts are a specific EEG pattern characterized by a series of rapid, repetitive spikes or sharp waves that indicate abnormal electrical activity in the brain, typically associated with seizure activity. 1.       Definition : o     Epileptiform bursts consist of brief, high-frequency discharges that can appear as spikes or sharp waves. These bursts are indicative of underlying epileptic activity and can occur in various seizure types. 2.      EEG Characteristics : o     The bursts are often more monomorphic and stereotyped compared to non-epileptic bursts, exhibiting greater rhythmicity, especially in the faster frequency ranges. This distinct waveform helps differentiate them from other types of EEG activity, such as those seen in non-epileptic conditions. o     Epileptiform bursts can vary in duration and frequency, and they may evolve into more complex patterns, such as generalized spike-and-wave discharges or other ictal patterns. 3.      Clinical Significa
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Electrodecremental pattern

The electrodecremental pattern is a notable EEG finding associated with generalized-onset seizures and is characterized by a sudden and significant decrease in background amplitude. 1.       Definition : o     The electrodecremental pattern is defined by a sudden and generalized attenuation of the EEG signal, leading to a nearly isoelectric tracing across all channels. This pattern is often observed during seizures and can indicate significant cortical involvement. 2.      EEG Characteristics : o     The pattern typically begins with a high amplitude, generalized sharp wave, which is followed by a rapid and significant decrease in background amplitude (electrodecrement) that lasts approximately 1 second. After this initial decrement, fast (20 to 40 Hz) low-voltage rhythmic activity usually develops. o     The activity may gradually increase in amplitude and decrease in frequency over the subsequent few seconds, often evolving into generalized paroxysmal fast activity (GPFA).

Slow spike and (slow-) wave (complex)

  The slow spike and slow-wave complex (often abbreviated as SSSW complex) is an important EEG pattern associated with certain types of epilepsy, particularly those involving generalized seizures. 1.       Definition : o     The slow spike and slow-wave complex consists of a sequence of slow spikes followed by slow waves. This pattern is characterized by its relatively low frequency and is often seen in specific epilepsy syndromes. 2.      EEG Characteristics : o     The slow spikes typically have a frequency of less than 3 Hz, and the slow waves that follow are also of low frequency. The overall appearance is often irregular, and the complexes can be repetitive. o     This pattern may be maximal over frontal regions and can be associated with a variety of clinical manifestations, including seizures and interictal discharges. 3.      Clinical Significance : o     The presence of slow spike and slow-wave complexes is often indicative of underlying brain dysfunction and is

Generalized paroxysmal fast activity (GPFA)

  Generalized paroxysmal fast activity (GPFA) is an important EEG pattern associated with generalized seizures and certain types of epilepsy. 1.       Definition : o     GPFA is characterized by a sudden onset of fast-frequency activity, typically in the beta frequency range (15-25 Hz), that appears generalized across the EEG channels. This pattern is often seen during seizures and can indicate significant cortical involvement. 2.      EEG Characteristics : o     The GPFA pattern begins with low amplitude and fast frequency activity, which then evolves with an increasing amplitude and a decreasing frequency over a few seconds. This evolution can lead to a more complex pattern that may include spikes and slower waves. o     GPFA is distinct from other patterns like generalized spike and slow-wave complexes (GSW) due to its higher frequency and the nature of its evolution. It typically does not have the same triphasic appearance as GSW complexes. 3.      Clinical Significance

Generalized spike and slow-wave complex (GSW)

  The generalized spike and slow-wave complex (GSW) is a specific EEG pattern commonly associated with generalized seizures, particularly in certain epilepsy syndromes. 1.       Definition : o     The GSW complex consists of a sequence of spikes followed by slow waves, typically appearing as a triphasic waveform. This pattern is characterized by its repetitive nature and is often seen during both ictal (seizure) and interictal (between seizures) periods in patients with generalized epilepsy. 2.      EEG Characteristics : o     The GSW complex is usually maximal over the midline or frontal regions of the brain and can occur at a frequency that varies depending on the type of epilepsy. For example, in Lennox-Gastaut syndrome, the frequency may be less than 2.5 Hz, while in childhood absence epilepsy, it may be around 3 to 4 Hz. o     During an ictal event, the GSW complex occurs repeatedly without intervening background activity, and the duration of these complexes is typically