Relation between arousal and focal epileptic seizure during sleep: Evaluation by CAP analysis

The Cyclic Alternating Pattern (CAP) is a physiological oscillatory activity consisting of repetitive sequences of activation phase (A) and inhibitory phase (B) during NREM sleep, expressing a state of sleep instability (arousal), which was documented to modulate most of the paroxysmal epileptic events during sleep. Macro- and microstructure (CAP) of sleep was analized in 14 laboratory or ambulatory Polysomnographic (PSG) recordings of 12 adult patients affected by symptomatic or cryptogenic localization-related epilepsy. Forty-four out of the 56 seizures recorded (78%) occurred during a CAP sequence, in close relation to A (namely A2) phase. Fifty-five per cent of the seizures was followed by awakening; 62% of the seizures occurring during non-CAP sleep was followed by CAP. The A phase of CAP appears to be a trigger for most of the seizures recorded independently of the macrostructural stage of NREM sleep. In turn the seizure occurrence results in sleep fragmentation.