The Bottom Line: Nonconvulsive status epilepticus (NCSE) refers to a group of highly heterogeneous clinical conditions lasting more than 30 minutes, in which continuous or recurrent electrographic seizure activity results in nonconvulsive clinical features. NCSE in adults represents a constellation of conditions producing ongoing ictal impairment with myriad clinical presentations (Fernandez-Torre et al, 2015).
- seizure activity seen on electroencephalogram (EEG) without clinical findings associated with convulsive status epilepticus
- changes in behavior and/or mental processes from baseline associated with continuous epileptiform discharges on EEG
- subtle status epilepticus
- severely impaired mental status, with or without subtle motor movements
- coma with or without subtle convulsive movements developing in patient with untreated or inadequately treated generalized convulsive status epilepticus
- complex partial status epilepticus
- characterized by agitation or confusion, nystagmus, or stereotypic motor activity (such as lip smacking or picking at items in air or on clothing)
- National Institute for Health and Care Excellence (NICE) recommends use of “focal seizure” instead of partial complex seizure
- absence status epilepticus
- relatively benign form of status epilepticus identified by 3 hertz spike-wave discharges on EEG
- characterized by behavioral arrest associated with generalized spike wave activity on EEG
- subtle status epilepticus
(DynaMed Plus, 2017)
References: DynaMed Plus [Internet]. Ipswich (MA): EBSCO Information Services. 1995 – 2017. Record No. 115329, Status epilepticus in adults; [updated 2017 Feb 06, cited 2017 July 20].
Fernandez-Torre JL, Kaplan PL, Hernandez-Hernandez ML. New understanding of nonconvulsive status epilepticus in adults: Treatment and challenges. Expert Review of Neurotherapeutics. 2015; 15(12):1455-73. doi:10.1586/14737175.2015.1115719.
Summary: NCSE is responsible for diverse clinical manifestations including altered mental state, abnormal and bizarre behavior, language disorders, perception disturbances and/or consciousness impairment. All these symptoms occur without overt tonic, clonic or tonic-clonic motor activity. Nevertheless, NCSE does not always imply absence of all motor activity. Subtle motor manifestations such as palpebral myoclonia, limb and oroalimentary automatisms, dystonic posturing, twitching of the face or limbs and rhythmic nystagmus may occur (Fernandez-Torre et al, 2015).
Because the presentation is pleomorphic, a high index of suspicion and knowledge of the precipitating clinical underpinnings are essential in making a prompt diagnosis and treatment plan. Electroencephalography (EEG) is a mandatory test and constitutes the cornerstone for diagnosis and classification. EEG interpretation may be difficult and requires clinical and electrophysiological expertise, particularly with comatose or critically ill patients in ICUs (Fernandez-Torre et al, 2015).