Hyperkalemic periodic paralysis associated with multiple sleep onset REM periods

A 24-year-old man with sporadic hyperkalemic periodic paralysis (HPP) prese nted with moderate excessive daytime sleepiness and transitory episodes of weakness which occurred during and after sleep. Multiple sleep latency test (MSLT) demonstrated the presence of five sleep onset REM periods (SOREMPs) and a sleep latency of five minutes. Treatment with a diuretic which decrea ses serum potassium resolved all the clinical symtomps and a new MSLT showe d the absence of SOREMPs and a sleep latency of 13.5 minutes. To our knowle dge, the patient herein reported is the first case that associates sleep ab normalities and multiple SOREMPs with HPP. Furthermore, the present case su ggests that SOREMPs may be explained by an increased extracellular potassiu m conductance related to HPP.