pediatrics
Neonatal Seizure Disorders
Diagnosis of Neonatal Seizure Disorders
Electroencephalography (EEG) Laboratory testing (eg, serum glucose, electrolytes, cerebrospinal fluid [CSF] analysis, urine and blood cultures; sometimes genetic testing) Usually cranial imaging Evaluation begins with a detailed family history and a physical examination. Jitteriness (alternating contraction and relaxation of opposing muscles in the extremities) must be distinguished from true seizure activity. Jitteriness is usually stimulus-induced and can be stopped by holding the extremity still; in contrast, seizures occur spontaneously, and motor activity is felt even when the extremity is held still. EEG is essential, and at times recording may need to be prolonged, especially when it is difficult to determine whether the neonate is having seizures. EEG is also helpful for monitoring response to treatment. EEG should capture periods of active and quiet sleep and thus may require≥2 hours of recording. A normal EEG with expected variation during sleep stages is a good prognostic sign; an EEG with diffuse severe abnormalities (eg, suppressed voltage or burst suppression pattern) is a poor one. Bedside EEG with video monitoring for ≥ 24 hours may detect ongoing clinically silent electrical seizures, particularly in the first few days after a CNS insult. Laboratory tests to look for underlying treatable disorders should be done immediately; tests include pulse oximetry; measurement of serum glucose, sodium, potassium, chloride, bicarbonate, calcium, and magnesium; and lumbar puncture for CSF analysis (cell count and differential, glucose, protein) and culture. Urine and blood cultures are also obtained. The need for other metabolic tests (eg, arterial pH, blood gases, serum bilirubin, urine amino or organic acids) or tests for common recreationally used substances (passed to the neonate transplacentally or by breastfeeding) depends on the clinical situation. Genetic testing must be considered for children with recurrent or refractory seizures of undetermined cause. Imaging tests are typically done unless the cause is immediately obvious (eg, glucose or electrolyte abnormality). MRI is preferred but may not be readily available; in such cases, head CT is done. For very sick infants who cannot be moved to radiology, bedside cranial ultrasonography can be done; it may detect intraventricular but not subarachnoid hemorrhage. MRI or CT is done when infants are stable. Head CT can detect intracranial bleeding and some brain malformations. MRI shows malformations more clearly and can detect ischemic tissue within a few hours of onset. Magnetic resonance spectroscopy may help determine the extent of an ischemic injury or identify buildup of certain neurotransmitters associated with an underlying metabolic disorder. 