A number of small studies have suggested that CSWS is the most common cause [47,59,60,61], due to the demonstration that there is a rise in plasma concentrations of both atrial natriuretic peptide (ANP) [59,60] and brain natriuretic peptic (BNP) concentrations [62] following SAH. This evidence concerns the gene NPPA and developmental and/or epileptic encephalopathy with spike-wave activation in sleep.