A hypothesis for how non-REM sleep might promote seizures in partial epilepsies: a transcranial magnetic stimulation study.

ABSTRACT

PURPOSE: To investigate alterations of inhibitory and excitatory cortical circuits during non-rapid eye movement (NREM) sleep in drug-naive patients with partial epilepsies and sleep-bound seizures only. METHODS: A paired-pulse TMS paradigm was used to test intracortical inhibition (ICI) and facilitation (ICF) in the hemisphere of the epileptic focus in three untreated patients with nonlesional, nongenetic frontal lobe epilepsy in NREM2 (three patients), NREM3/4 (one patient), and wakefulness (three patients). RESULTS: All three patients exhibited a major decrease of ICI in NREM sleep as opposed to the physiological enhancement of ICI with the progression of NREM sleep. CONCLUSIONS: Decreased ICI might reflect a substrate for the association of epileptic processes with thalamocortical networks that propagate sleep. Thus our findings contribute to a hypothesis of how NREM sleep could promote seizures.