*5.1.3 Lennox – Gastaut syndrome*

*Updates in Sleep Neurology and Obstructive Sleep Apnea*

**5. Pediatric epilepsy associated with sleep**

and afternoon [22].

**5.1 Generalized epilepsies**

than during wakefulness [20].

*5.1.2 West syndrome*

*5.1.1 Absence epilepsy*

confined to nighttime sleep [18]. In most cases, seizures are characterized by sudden awakening from sleep with a sensory aura, which then progresses to a focal seizure with impaired awareness. The latter is often associated with amnestic automatisms that mimic a NREM parasomnia called confusional arousal. Most patients (around 70%) also have secondary generalized tonic-clonic seizures [18]. Regarding IEA, most studies have found an increase in interictal epileptiform activity during NREM sleep with decrement during REM sleep. The spike frequency was 85% in NREM and 12.5% in REM sleep [20]. Sammaritano found that the extent of the electrical field increased in more than 75% of the spikes in NREM compared with the wake state. Meanwhile, there was a restriction of the electrical field of the epileptiform activity during REM sleep. Desynchronization of EEG pattern during REM sleep reduces the likelihood of spatial and temporal summation of aberrant depolarizations [21]. One third of patients have bilateral IEDs that occur independently on both sides, especially during NREM. However, localization of the primary epileptogenic area is more reliable in REM sleep than in wakefulness, and in wakefulness more than in slow-wave sleep. Therefore, REM sleep provides an opportunity to better localized the epileptic focus. When seizures occur during daytime they are common in the afternoon or are bimodal, and peak in the morning

Absence seizures clinically present as a brief transitory behavioral arrest lasting a few seconds that is detectable while patient is awake and typically triggered by hyperventilation, and less often by photic stimulation [23]. Typical EEG shows a generalized 3-Hz spike-wave complexes. The activation of the IEA is most marked in the first sleep cycle [24]. Absence seizures are often inhibited by full wakefulness and REM sleep. During NREM slow-wave sleep the cell activity is more synchronous and allows the activation of spike-wave responses, whereas during REM, a traditional desynchronization state, spike and wave are uncommon [25]. The spike and waves present during NREM state differ also from wakefulness IEDs because they are briefer, more fragmented, more irregular, and slower

West Syndrome is characterized by the triad of infantile spasms, psychomotor retardation, and hypsarrhythmia in the EEG. Hypsarrhythmia is characterized by chaotic and disorganized background of high voltage, asynchronous spike and slow-wave activity [26]. Only 2-5% of the spams occurred during sleep despite increase in EEG abnormalities during NREM sleep [27]. The hypsarrhythmia pattern may become more apparent during sleep. During REM sleep, a marked attenuation or disappearance of the hypsarrhythmia pattern is noted [28]. Treatment of Infantile spasms includes ACTH, prednisone, and vigabatrin. Vigabatrin [gamma vinyl, gamma-aminobutyric acid (GABA)] is a specific, irreversible inhibitor of GABA-transaminase. Other treatment includes Zonisamide, Topiramate, Valproic acid, Nitrazepam, Pyridoxine, and Ketogenic diet. Surgery

**40**

Lennox-Gastaut's syndrome [LGS] usually begins in the first decade of life and is characterized by multiple types of primary generalized seizures, including prominent nocturnal tonic, astatic/atonic, atypical absence, myoclonic, and generalized tonic-clonic seizures with associated psychomotor and cognitive delay. It is often preceded by a history of infantile spasms with hypsarrhythmia in the EEG. Typical EEG shows slow spike-wave [SSW] complexes at 1.5-2.5 Hz, multifocal epileptiform abnormalities, paroxysmal fast activity, and diffuse background slowing. The quantity of the bursts of SSW complexes increases during NREM sleep [29]. Paroxysmal fast activity is a typical pattern of LGS characterized by diffuse bursts activity with a frequency of 15-20 Hz, mainly during NREM with an occurrence up to hundred times per night, but absent during REM sleep [23].
