Epilepsy in children with Down syndrome.
DS is the most common genetic cause of mental retardation (MR) with a reported prevalence of epilepsy of 1-13%.
Infantile spasms (IS) or West syndrome (WS) is the most frequent epilepsy syndrome in children with DS. IS occur in 0.6-13% of children with DS, representing 4.5-47% of seizures in these children.
Curiously, these patients have electroencephalographic (EEG) characteristics of idiopathic rather than symptomatic WS. Despite a lack of consensus on therapeutic approach, no significant difference has been reported among the different regimens with regards to achieving clinical remission or EEG normalisation.
It appears that DS patients have better seizure control compared to other patients with symptomatic IS, and early initiation of appropriate treatment may contribute to the prevention of late seizure development and better developmental outcome.
Lennox-Gastaut syndrome (LGS) also exhibits some distinctive features in children with DS including later onset and high incidence of reflex seizures. Other seizure types including partial and generalised tonic clonic seizures have also been described in children with DS.
There is a high rate of EEG abnormalities in children with DS, even among children without epilepsy, however, no patterns specific to DS have been identified and EEG does not correlate with outcome.
Various cellular and molecular mechanisms contribute to epileptogenesis in DS and offer an interesting field of study.