Diagnosis of nonconvulsive status epilepticus

Non-convulsive status epilepticus (NCSE) is a neurologic emergency that affects a wide spectrum of patients. The diversity of clinical presentation and unconsciousness of patients due to primary insult, especially in intensive care units, make NCSE impossible to be diagnosed without using electroencephalography (EEG). There is no universally accepted definition of nonconvulsive status epilepticus, and there is no consensus on how to treat it. Not surprisingly, nonconvulsive status epilepticus is often a challenging diagnosis to make. EEG, although critical to the evaluation of nonconvulsive status epilepticus, can sometimes be equivocal. The American Clinical Neurophysiology Society (ACNS) had published proposals for a Standardized Critical Care EEG Terminology], which are now widely used and have a high interrater agreement. A consensus panel at the 4th London Innsbruck Colloquium on status epilepticus and acute seizures held in Salzburg (2013) proposed working criteria for the EEG diagnosis of NCSE (Salzburg Consensus Criteria for Non-Convulsive Status Epilepticus, SCNC). Once the diagnosis of nonconvulsive status epilepticus is made, there is often disagreement on how aggressively to treat it. Human data on the degree of injury associated with nonconvulsive status epilepticus can be difficult to interpret because the etiology of nonconvulsive status epilepticus often confounds the outcome data.