Epilepsy with electrical status epilepticus during slow-wave sleep

Prevalence
~0.2% to 0.5% of all childhood epilepsies.

Age at onset
Seizures 2 months to 12 years; peak at 4 to 5 years. EEG continuous spikes and waves during slow-wave sleep (CSWS), usually 1 to 2 years from seizure onset.

Sex
Males (62%) show preponderance.

Neurological and mental state
>1/3 abnormal.

Etiology
Symptomatic, probably symptomatic and idiopathic.

Clinical manifestations
Three stages of evolution:

• First stage before CSWS: infrequent nocturnal motor focal seizures, often hemiclonic status epilepticus, absences, atonic, complex focal seizures, and generalized tonic-clonic seizures occur.
• Second stage with CSWS: seizures more frequent and complicated with typical or more frequent atypical absences, myoclonic absences, absence status epilepticus, atonic or clonic seizures, and generalized tonic-clonic seizures. Tonic seizures do not occur. Eminent psychomotor decline and behavioral abnormalities.
• Third stage (after months to usually 2 to 7 years) with remission of seizures and general improvement.

Timing
Seizures are often nocturnal.

Diagnostic procedures
MRI is abnormal in more than half of patients. Unilateral or diffuse cortical atrophy, porencephaly, malformations of cortical development, and mainly polymicrogyria (18%).

Inter-ictal EEG
Initially multifocal and bisynchronous sharp waves (mainly frontal). CSWS = continuous (85% to 100%) mainly bisynchronous 1.5 to 2 Hz (and 3 to 4 Hz) spikes and waves during non-REM sleep.

Ictal EEG
Seizure dependent.

Prognosis
In all cases, seizures remit with global improvement of cognitive and behavioral abnormalities, but recovery is always slow and often partial; <1/4 resume acceptable social and professional levels; these are mainly of normal pre-morbid neuropsychological state and short CSWS life span.

Differential diagnosis
(1) Landau-Kleffner syndrome; (2) benign childhood focal seizures with atypical evolutions; and (3) Lennox-Gastaut syndrome.

Management options*
Seizures are not a major problem as their final prognosis is good. Valproate, lamotrigine, levetiracetam and sulthiame# may be the most appropriate treatments.

The treatment of CSWS, which is responsible for the neuropsychological impairment, is entirely empirical and usually of transient efficacy. The following schemes, alone or in combination, have been proposed.

In cases with severe linguistic impairment, subpial intracortical transections have been used with success.

*Expert opinion, please check FDA-approved indications and prescribing information
#Not approved by the FDA