Electrical status epilepticus during slow-wave sleep (ESESS). Continuous spike-wave during slow sleep syndrome (CSWSS syndrome)
Incidence
It is an sporadic condition. From the analysis of a series of more than 12,000 cases of infantile epilepsy examined over 10 years, CSWSS syndrome affects approximately 0.5% of these patients, with slight preponderance of boys.
Clinical Characteristics
This is a rare epilepsy syndrome. When it does happen, it usually appears in mid-childhood. It is also called \"continuous spike-wave of slow sleep\". The cause of this syndrome is not known. It usually happens in children who already have epilepsy. The syndrome of continuous spike and waves discharges during slow sleep (CSWSS) is a rare form of age-related epilepsy. It is considered an epileptic syndrome. CSWSS syndrome onset occurs between 3 and 7 years, rarely before 2 years, in children who previously have a normal neurocognitive development. However, some authors have mentioned pre-existing delayed acquisition of language or mental retardation in one-fourth of cases. Epileptic seizures occur usually and are not always the first manifestation of the disease. In some cases (between 8 % to 30 %), seizures may be absent. They can be partial or generalized and most often occur while the child is falling asleep or awakening. At the same time, the family and teachers note a behavioral change associated with a sharp drop in cognitive capacities. A distinction must be made between the idiopathic forms of CSWSS syndrome, which occur in children with no prior neurological history and normal initial development, and the lesional forms, which are associated with a cerebral lesion. In the latter forms, the neuropsychological deficits that precede epilepsy are associated with a motor deficit, often hemiparesis. No etiology is known for the idiopathic forms, which represent two-thirds of the CSWSS syndromes. According to ILAE, epilepsy with CSWSS covers different types of seizures, partial or general, which occur during sleep, and atypical absences during wakefulness. Tonic seizures are absent. Electroencephalogram (EEG) alterations are continuous diffuse spikes and waves during slow sleep. The CSWSS syndrome can last several months up to several years. Despite the usually benign evolution of the epilepsy, seizures and EEG alterations improve at the beginning of adolescence whatever the effect of anti epileptic drugs. However, prognosis is guarded because of the associated neuropsychological disorders.
Precipitants
Partial or generalized seizures are rare and occur while the child is falling asleep. Some agents, such as carbamazepine or phenobarbital worsens the condition.
Provocation Tests
Sleep EEG should always be done to make the diagnosis. During slow sleep, spikes and waves become generalized and continuous, occupying over 85% of sleep.
Diagnostic Procedures
It is basically an EEG diagnosis. The electroencephalogram (EEG) shows continuous spike and wave epileptic activity during sleep – and especially during part of the sleep called ‘slow wave’ sleep. The EEG is often abnormal when the child is awake but may also be normal. It is the EEG finding that gives the syndrome its name.