Seizures in neonates are difficult to identify and often require aggressive therapy. All neonates experiencing seizures should be considered to be at serious risk from the underlying disorder and the effect of unremitting seizures and also to be at increased risk for epilepsy. Electroconvulsive activity should be of as much concern as the outward clinical signs of seizure. Prompt, effective anticonvulsant therapy and other specific therapies lessen the impact of short-term detrimental effect on long-term neurologic functioning. In many instances, the seizure itself is less important for its immediate effects than it is as an indicator of significant underlying disease (e.g., infection, metabolic disorder, or CNS malformation) that will ultimately have more effect on the morbidity and mortality rates.
The difference in seizure presentation is due to the lack of arborization of the immature brain, which prevents rapid propagation of electrical epileptic activity, and to the particular illnesses to which newborns are subject (hypoxic ischemic encephalopathy, and metabolic and dysplastic conditions). Multifocal or fragmentary seizures occur more commonly at this age, and clonic or tonic movements independently affect the limbs simultaneously or fleetingly.
Progressive migratory partial seizures (Jacksonian) are rarely seen at this age. Autonomic seizures manifest as variable changes in respiration (tachypnea, depression, or apnea), temperature, and color (cyanosis), and also as cardiac dysrhythmias and pupillary changes. Myoclonic seizures usually have hypoxic or metabolic causes and indicate a poor prognosis unless the cause is easily identifiable and readily reversible (e.g., hypocalcemia or hypoglycemia). Myoclonic seizures can, however, be refractory in metabolic disorders such as urea cycle defects and nonketotic hyperglycinemia. Unilateral (partial or focal) seizures may be associated with structural lesions, and permanent neurologic deficit may be associated with them. The causes of neonatal seizures are diverse, but the majority of the seizures are attributable to a few well-defined causes.
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