Neonatal Seizures

Neonatal seizures are frequently manifested by subtle movements that are referable to brain stem structure, ie, nystagmus, conjugate eye movements, posturing, sucking movements, and so forth. Electroencephalogram (EEG) confirmation of abnormal movements is essential in diagnosing seizures in the neonate. Clinical seizure signs are often a clue to etiology. Metabolic abnormalities must always be considered, and blood gases, calcium, magnesium, glucose, and ammonia obtained. Neonatal seizures are an indication for cerebrospinal fluid examination. Specific metabolic abnormalities are treated with metabolic approaches, not conventional anticonvulsant drugs. Hypertensive encephalopathy is treated by controlling blood pressure, and not through anticonvulsant drugs. Critically ill infants bind anticonvulsants in an unpredictable fashion, and unbound or free anticonvulsant drug concentrations should be used to guide therapy. Phenobarbital is the most commonly used drug in treating nonmetabolic seizures. Doses to achieve free concentrations of at least 35 mg/L should be used. Use in vitro binding determinations with this formula to calculate loading doses. Dose is 25 mg/kg multiplied by volume and distribution (1 L/kg) divided by % free. Phenytoin is the second most commonly used agent, and doses should be calculated to achieve, but not exceed, 3 mg/L. Dose is 3 mg/kg multiplied by volume and distribution (1 L/kg) divided by % free. Benzodiazepines, notably lorazepam and diazepam are used at doses of 0.15 mg/kg and 0.3 mg/kg, respectively.