WHAT IS STATUS EPILEPTICUS?
- 1WHAT IS THE MEANING OF STATUS EPILEPTICUS?
- Status epilepticus (SE) is any seizure lasting more than 30 minutes, whether or not consciousness is impaired or recurrent seizures without an intervening period of consciousness. SE is a medical emergency, and aggressive treatment of seizures that last 5 minutes or more is strongly recommended. Seizure duration of greater than 30 minutes is associated with increasing risk of long-term consequences. Table 1–1 shows the classification of SE. This chapter focuses on generalised convulsive status epilepticus (GCSE), the most common and severe form.
(SE, status epilepticus.)
aMost common in older children.
bMost common in adolescents and adults.
cMost common in infants and young children.
dMost common in neonates.
- The four stages of GCSE are (1) impending, (2) established, (3) refractory, and (4) super refractory.
- 2WHAT ARE THE CAUSES OF STATUS EPILEPTICUS?
- Seizure initiation is likely caused by an imbalance between excitatory (e.g., glutamate, calcium, sodium, substance P, and neurokinin B) and inhibitory (γ-aminobutyric acid [GABA], adenosine, potassium, neuropeptide Y, opioid peptides, and galanin) neurotransmission.
- GCSE is largely caused by glutamate acting on postsynaptic N-methyl-d- aspartate (NMDA) and α-amino-3-hydroxy-5-methylisoxazole-4- propionate (AMPA)/kainate receptors. Sustained depolarisation can result in neuronal death.
- GABAA receptors may become less responsive to endogenous GABA and GABA agonists.
- During phase I of GCSE, each seizure produces marked increases in plasma epinephrine, norepinephrine, and steroid concentrations that may cause hypertension, tachycardia, and cardiac arrhythmias. Muscle contractions and hypoxia can cause acidosis, hypotension, shock, rhabdomyolysis, and secondary hyperkalemia, and acute tubular necrosis may ensue.
- In phase II, beginning 30 minutes into the seizure, the patient begins to decompensate and may become hypotensive with compromised cerebral blood flow. Serum glucose may be normal or decreased, and hyperthermia, respiratory deterioration, hypoxia, and ventilatory failure may develop.
- In prolonged seizures, motor activity may cease, but electrical seizures may persist.
- 3WHAT ARE THE SIGNS AND SYMPTOMS OF STATUS EPILEPTICUS?
- Symptoms: impaired consciousness (e.g., ranging from lethargy to coma); disorientation (once GCSE is controlled); and pain associated with injuries.
- Early signs: generalised convulsions; acute injuries; central nervous system (CNS) insults that cause extensor or flexor posturing; hypothermia or fever suggestive of intercurrent illnesses, e.g., sepsis or meningitis); incontinence; normal blood pressure or hypotension; and respiratory compromise.
- Late signs: clinical seizures may or may not be apparent; pulmonary oedema with respiratory failure; cardiac failure (dysrhythmias, arrest, or cardiogenic shock); hypotension or hypertension; disseminated intravascular coagulation or multisystem organ failure; rhabdomyolysis; and hyperpyrexia.