AUDITORY STIMULATION DURING DEEP SLEEP IN CHILDHOOD EPILEPSIES MODULATES NOCTURNAL SPIKE ACTIVITY

Childhood epilepsies with spike–wave activation during sleep (SWAS) are a spectrum of epilepsies associated with cognitive, language, and motor impairments. A shared hallmark is the strong activation of epileptic spike–wave discharges during non-rapid eye movement (NREM) sleep. Physiological NREM sleep oscillations, specifically slow waves and spindles, are linked to sleep-related cognitive improvements and have been shown to be altered in SWAS. This suggests that interictal spikes interfere with sleep processes critical for cognitive functions, yet causal evidence is lacking.
Phase-targeted auditory stimulation during NREM sleep consists of playing short, non-arousing tones phase-locked to the ongoing slow waves. Depending on stimulation parameters the tones either interact with global or local brain networks. This offers a non-invasive approach to selectively manipulate sleep oscillations and probe their interaction with epileptic spikes.
Cluster-based permutation statistics across time showed that in 10 patients (age range: 7.3 – 16.2) isolated auditory stimuli induced global high-amplitude slow waves (p = .028) followed by spindles (p = .042) and were accompanied by a transient increase in spike rate (p = .035). In contrast, repetitive down-phase stimulation was associated with a significant local reduction in spike rate (p = .047) and showed no significant effect on slow waves and spindles.
These findings demonstrate an interaction between epileptic spikes and physiological oscillations during NREM sleep; globally induced synchronisation leads to a spike increase, whereas local desynchronisation leads to a spike reduction. This framework may provide a rational basis for targeted interventions aimed at reducing SWAS and its cognitive consequences.