Consequences of Nonconvulsive Status Epilepticus: Experimental and Clinical Evidence

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Nonconvulsive status epilepticus (NCSE), a prolonged seizure without prominent motor symptoms, occurs frequently in patients with critical neurological and medical illness. The merits of aggressive treatment of NCSE in the critically ill is a topic of serious debate given (a) the difficulty in delineating the prognosis of NCSE from the proximate cause of the illness and (b) the potential negative consequences associated with anesthetic therapies. In this chapter, we provide an update on the prognosis of NCSE as gleaned from preclinical and clinical studies. Although animal models fail to replicate all features of NCSE in the critically ill patient, available preclinical data indicates that NCSE per se can cause direct neuronal injury and neurological morbidity. Clinical data from a growing number of prospective studies in critical care settings including stroke, convulsive status epilepticus, traumatic brain injury, and sepsis are substantiating several retrospective observations that NCSE can both complicate the primary condition and independently worsen prognosis. The current state of knowledge emphasizes the urgent need for more preclinical and prospective studies to identify the long-term prognosis of NCSE. The adoption and increasing early use of Continuous EEG in neurological and medical critical care units can only aid in the development of definitive evidence-based guidelines to treat NCSE.