Seminars in epileptology: How to diagnose status epilepticus in adults and children.

Status epilepticus (SE) can be regarded as the most severe expression of seizure activity characterized by a low probability of spontaneous cessation and mechanisms leading to metabolic and inflammatory derangements with increased risk of brain damage, alterations of neural networks, and potentially life-threatening systemic complications. Time-based criteria are fundamental in diagnosing SE as response to treatment and outcomes worsen with increasing duration in terms of neurological impairment and mortality. Classification of status epilepticus includes four axes: semiology, EEG correlates, etiology, and age. Semiology, especially when evolving from SE with prominent motor phenomena (SE-PM) to nonconvulsive status epilepticus (NCSE) with impaired consciousness, is associated with drug resistance and poor prognosis. The Salzburg EEG criteria define four subcategories of NCSE. The umbrella term ictal-interictal continuum (IIC) includes a wide spectrum of EEG changes ranging from almost non-epileptic situations to conditions that just fail to fulfill the criteria of NCSE. From a pathophysiologic point of view, EEG patterns on the IIC might be generated by both the underlying etiology and the superimposed hypersynchronous epileptic activity. It is impossible to disentangle their relative contributions by visual inspection of the EEG. However, it is essential to identify the contribution of ictal activity in an individual patient as it may be amenable to treatment with antiseizure medication (ASM). The main approach is to perform a diagnostic intravenous ASM trial (diagnostic IV-ASM trial) during EEG recording and to assess for both EEG and clinical response. Furthermore, CT- and MRI-perfusion studies help to clarify the diagnosis. Early and consequent treatment is necessary to minimize the total time spent in status, also called seizure burden. This educational review focuses on the diagnosis of status epilepticus in children and adults, excluding neonatal status.