Continuous spike-and-wave activity during slow-wave sleep: syndrome or EEG pattern?

Area of Science:

• Neurology
• Clinical Neurophysiology

Background:

• Continuous spike-and-wave activity during slow sleep (CSWS) is a recognized electroencephalogram (EEG) pattern.
• The CSWS syndrome, as defined by the International League Against Epilepsy (ILAE), is associated with specific age-related characteristics.
• The relationship between the EEG pattern of CSWS and its clinical manifestations requires further clarification.

Purpose of the Study:

• To investigate the electroclinical features of 32 patients with CSWS.
• To determine the association of the CSWS EEG pattern with the defined CSWS syndrome versus other clinical settings.
• To understand the variability in clinical conditions associated with CSWS.

Main Methods:

• Retrospective review of clinical and EEG data from 32 patients diagnosed with CSWS.
• Analysis of patient characteristics, including age, epilepsy type, and neurological status.
• Classification of patients based on ILAE criteria and observed clinical presentations.

Main Results:

• CSWS detection coincided with neurological status worsening in all patients.
• Only 34% of patients met the typical criteria for the CSWS syndrome.
• Other diagnoses included Landau-Kleffner syndrome (4 patients), acquired opercular syndromes (3 patients), and symptomatic epilepsy (15 patients).
• Unilateral CSWS was observed in three patients with epilepsy, associated with contralateral motor worsening.

Conclusions:

• Multiple factors contribute to the genesis of CSWS, leading to diverse clinical presentations.
• The EEG pattern of CSWS is not pathognomonic for the CSWS syndrome.
• The CSWS syndrome represents a specific subgroup, while the CSWS EEG pattern is observed across various clinical conditions.