Mystery case: sawtooth waves: another normal variant not to over-read as epileptiform discharges.

A 20-year-old-woman demonstrated sawtooth waves but no epileptiform discharges while undergoing EEG-video monitoring for new-onset generalized tonic-clonic seizure-like activity and staring spells (figures 1 and 2). Sawtooth waves are an uncommon EEG pattern of REM sleep. They have a unique morphology, first described in 1937 by Alfred Lee Loomis, are maximum in the central regions, and typically occur in repetitive bursts. They are seen in REM sleep, typically in the vicinity of eye movements, but at times they can be found seconds or minutes away from REM. The identification of sawtooth waves is important to avoid their misinterpretation as epileptic discharges and the (common) misdiagnosis of epilepsy.