The nurse reports that an infant is having abnormal movements of the extremities consistent with seizure activity. A seizure is an event defined as “a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.” Further categories of a neonatal seizures include:
Clinical-only seizure: “A sudden paroxysm of abnormal clinical changes that occur without a definite EEG [electroencephalogram] seizure.”
Electroclinical seizure: “Clinical signs that occur simultaneously with an electrographic seizure.”
Electrographic-only (subclinical) seizure: “Presence of a definite EEG seizure that is not associated with any clinical signs of a seizure.”
Epilepsy: Involves recurrent unprovoked seizures and is defined as “a disease of the brain defined by any one of the following conditions: at least two unprovoked seizures or reflex seizure occurring more than 24 hours apart, one unprovoked or reflex seizure and a probability of having another seizure similar to the general recurrence risk after two unprovoked seizures occurring over the next 10 years, or diagnosis of an epilepsy syndrome.”
Status epilepticus: Seizures appear in close succession or do not stop. Status epilepticus is a serious condition that requires prompt medical attention. There is no real definition of status epilepticus in neonates. Three definitions that have been used in the literature are as follows: (1) continuous seizures for a minimum of 30 minutes or seizures that recur over at least 30 minutes that do not return to a baseline neurologic activity; (2) at least 30 minutes of seizure activity over a 1-hour defined period; and (3) EEG seizure activity of >50% of the recording time of approximately 30 minutes.
The incidence of seizures in the neonatal age group is higher than at any other time in life, about 2 to 3 per 100 live births (up to 13 per 100 live births in preterm infants and up to 58 per 100 live births in very low birthweight infants). Studies have reported there is a higher incidence in preterm infants (vs term), low birthweight infants (vs normal weight), male infants (vs females), and African American infants (vs white or other races or ethnicities).
The etiology and semiology of seizures are quite different in neonates compared to older age groups. Most seizures in neonates are symptomatic of an acute illness and caused by an underlying condition. Most neonatal seizures occur during the first 24 hours of life. Developmental immaturity of the neonatal brain (immature inhibitory systems and the predominance of excitatory neurotransmitters) leads to unique seizure tendency and seizure patterns, altered drug pharmacodynamics, and increased susceptibility to developmental effects of anticonvulsants. This makes it imperative that we are able to recognize seizures and differentiate seizures from the movements that mimic seizures. It is now known that neonates with seizures are not only at a higher risk of death, but also at an increased risk of developmental delay, cerebral palsy, and epilepsy. Additional information on seizures can be found in Chapter 120...