Periodic limb movements during sleep vs seizures and epileptiform discharges: some supposedly shared pathomechanisms

Resumo

This is a narrative review that assesses some possible underlying abnormal mechanisms shared between periodic limb movements during sleep (PLMS) and interictal epileptiform discharges (IEDs) or epileptic seizures. The underlying abnormal mechanisms of PLMS are not clearly defined, but the hypotheses raised include a pure motor mechanism originating in the brainstem, spinal cord or a cortico-subcortical interaction, influenced by predisposing factors, through neural networks. PLMS rhythmicity appears to be closely linked to sleep
microarchitecture, and also to cortical arousals, as with some types of epilepsy, which involve both the underlying sleep rhythms and their intrinsic functions as well as the so-called central pattern generators that produce rhythmic motor patterns. However, the relationship between PLMS and epilepsy has not
yet been fully clarified. Rhythmicity and sleep fragmentation appear to be common denominators between them, at least more closely in sleep-related hypermotor epilepsy. To some extent, the electroencephalographic changes of PLMS would express an epiphenomenon of the involvement of some underlying brain networks common to epileptic seizures and IEDs.