Status epilepticus: Risk factors and complications

Status epilepticus is common and associated with significant mortality and complications. It affects approximately 50 patients per 100,000 population annually and recurs in >13%. History of epilepsy is the strongest single ri sk factor for generalized convulsive status epilepticus. More than 15% of p atients with epilepsy have at least one episode of status epilepticus and l ow antiepileptic drug levels are a potentially modifiable risk factor. Othe r risks include young age, genetic predisposition, and acquired brain insul ts. Fever is a very common risk in children, as is stroke in adults. Mortal ity rates are 15% to 20% in adults and 3% to 15% in children. Acute complic ations result from hyperthermia, pulmonary edema, cardiac arrhythmias, and cardiovascular collapse. Long-term complications include epilepsy (20% to 4 0%), encephalopathy (6% to 15%), and focal neurologic deficits (9% to 11%). Neuronal injury leading to temporal lobe epilepsy is probably mediated by excess excitation via activation of The N-methyl-D-aspartate (NMDA) subtype of glutamate receptors and consequent elevated intracellular calcium that causes acute necrosis and delayed apoptotic cell death. Some forms of nonco nvulsive status epilepticus may also lead to neuronal injury by this mechan ism, but others may not. Based on clinical and experimental observations, c omplex partial status epilepticus is more likely to result in neuronal inju ry similar to generalized convulsive status epilepticus. Absence status epi lepticus is much less likely to result in neuronal injury, and complication s because it may be mediated primarily through excess inhibition. Future re search strategies to prevent complications of status epilepticus include th e study of new drugs (including NMDA antagonists,new drug delivery systems, and drug combinations) to stop seizure activity and prevent acute and dela yed neuronal injury that leads to the development of epilepsy.