Nonconvulsive status epilepticus (NCSE) comprises a group of syndromes that show great diversity in response to anticonvulsant preparations, from virtually self-limiting variants to refractory forms. NCSE is often unrecognized, leading to delays in its diagnosis and treatment, the main reason being the failure to consider and request an electroencephalogram. The etiology and clinical form of NCSE are strong predictors for the overall prognosis. NCSE treatment is simple in patients with pre-existing epilepsy, but poses major problems if it occurs in acute brain injury. Due to the lack of convulsive signs and / or minimal, subtle clinical manifestations, NCSE must be confirmed by EEGit is recommended to describe correlations using descriptors such as: paternal name, morphology, location, time-related characteristics, modulation, and effect of intervention and to use the terminology „Salzburg EEG criteria for NCSE” as a practical guide for diagnosis. Early recognition and treatment are essential to optimize the response to treatment and to prevent neurological and systemic complications. Management follows standard regimes for SE approach. There is still a need for further investigations into the mechanisms, definition, diagnostic criteria and optimal management options, especially in patients with coma and critical pathologies.