What is Status Epilepticus?
Status Epilepticus is characterized by prolonged or multiple seizures associated with a cascade of phenomenon that is fundamentally caused by the presence of an excitatory neurotransmitter that initiates the seizure and an absence of an agent to inhibit the abnormal and excessive excitation. Furthermore, the absence of a sub-unit receptor to cease excitation further maintains the hyperexcitable state.
Glutamate is the major excitatory neurotransmitter that is involved with Status Epilepticus. It acts on post-synaptic NMDA and AMPA receptors which recruit more pro-convulsant receptors. This increase in excitatory receptors encourages a stage for potentially prolonged seizure due to subsequent neuronal depolarization at the sodium and calcium channels.
From this initial maladaptive stage, Status Epilepticus is further lengthened as GABA receptors, which functions to inhibit hyperexcitability, and its sub-units undergo an endocytosis-mediated decrease wherein they move from the synapse to the cytoplasm where they are rendered inactive. The γ2 subunit contributes to benzodiazepine effectiveness and its decrease due to endocytosis causes benzodiazepine pharmacoresistance. With the absence of an agent to control the seizure, Status Epilepticus persists.
Further maladaptive changes that occur include alterations in neuropeptide expression as well as systematic alterations which affect the cardiopulmonary and nervous systems and the levels of glucose and insulin.
Therefore, uncontrolled and prolonged seizures can eventually cause neuronal cell death and injury due to a myriad of possibilities such as excitotoxicity and necrosis.
- 2nd most common neurologic emergency
- 1.2-5 million people worldwide
- 10-41 cases per 100,000 persons
- Mortality 20% but may be as high as 40% in certain populations
Causes of Status Epilepticus
Chronic epilepsy and low anti-epileptic drug levels are the most common causes of SE.
Other causes include delayed effects of previous lesions or injury such as tumors, stroke, and traumatic brain damage.