Temporal relationship between awakening and seizure onset in nocturnal partial seizures

Clinical awakening can be seen just before or after seizure onsets. In this study we determined the time between onset of seizures and awakening in patients with frontal lobe epilepsy (FLE) and temporal lobe epilepsy (TLE). Sixty-eight patients who underwent video-EEG monitoring with simultaneous PSG were retrospectively examined. TLE or FLE patients having seizures during sleep were included. Seizure onset and awakening onset were marked according to clinical and electrophysiological features. The duration between awakening and seizure onset was compared in patients with TLE and FLE. Twenty-five patients who had been diagnosed with TLE (17) or FLE (8) had a total of 75 seizures during sleep. All seizures except one, occurred during NREM sleep in both TLE and FLE patients. The seizure onsets were before awakening in 49 seizures (FLE: 20, TLE: 29) and the awakening preceded the seizure onsets in 12 seizures (FLE: 3, TLE: 9). The duration between seizure onset and the awakening was shorter in FLE, either in seizures with preceding awakening or not (p=0.014, p=0.015). Awakening was mostly seen after onset of seizures rather than before, especially in TLE. But in patients with FLE the duration between seizure onset and awakening was shorter. The localization of epileptic activity may play a role for the timing of awakening mechanisms during nocturnal partial seizures.