Pediatric emergency medicine trisk 1424 1424
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clonic seizure is now called bilateral tonic-clonic seizure (previously referred to
as a secondarily generalized seizure), to differentiate it from seizures that are
generalized from the onset.
It is important to recognize that generalized seizures with focal manifestations
are also considered focal. These manifestations may include lateral eye deviation,
head tilt, postictal Todd paresis (or paralysis), or psychomotor seizures (also
referred to as temporal lobe seizures).
Status epilepticus is a form of prolonged seizure. This is defined as seizures
lasting more than 5 minutes or repetitive seizure activity without recovery of
consciousness in between episodes. This is an operational definition used to guide
therapy. While only 25% of pediatric seizures last longer than 5 minutes, the
longer a seizure persists, the more difficult it becomes to control. If a child is seen
in the ED with a reported/witnessed generalized seizure that has resolved, a 30minute cutoff is used to define status, because 30 minutes is when the risk of
permanent neuronal injury increases significantly. Status epilepticus is the highest
form of seizure emergency.
A postictal (decreased responsiveness) period usually follows a seizure. During
this time, the patient may be confused, lethargic, fatigued, or irritable; also,
headache, vomiting, and muscle soreness may occur. In general, the length of the
postictal period is proportional to the length of the seizure. For brief seizures,
there may be few or no postictal symptoms. Transient focal deficits (e.g., Todd
paralysis) may occur during the postictal period, but one must first rule out a
focal central nervous system (CNS) deficit.
PATHOPHYSIOLOGY
The underlying abnormality in all seizures is the hypersynchrony of neuronal
discharges. Cerebral manifestations include increased blood flow, increased
oxygen and glucose consumption, and increased carbon dioxide and lactic acid
production. If a patient can maintain appropriate oxygenation and ventilation, the
increase in cerebral blood flow is usually sufficient to meet the initial increased
metabolic requirements of the brain. Brief seizures rarely produce any lasting
effects.
Multiple animal studies and a recent study in humans indicate that 30 minutes
of generalized convulsive status epilepticus increases the risk of permanent
neuronal injury.
Systemic alterations may occur with seizures and result from a massive
sympathetic discharge, leading to tachycardia, hypertension, and initially stress
hyperglycemia. Failure of adequate ventilation, especially in patients in whom
