Neonatal Seizures Workup

Updated: Sep 06, 2017
  • Author: Raj D Sheth, MD; Chief Editor: Amy Kao, MD  more...
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Workup

Approach Considerations

Tests to ascertain the cause of neonatal seizures include the following:

  • Serum glucose and electrolytes - Transient neonatal hypocalcemia is a cause of neonatal seizures during the first 3 weeks of life; hypocalcemia associated with chromosome 22q11 deletion syndrome may also be a consideration
  • TORCH (toxoplasmosis, rubella, CMV, herpes) infection studies
  • Urine organic acids
  • Serum amino acid assay
  • Renal function tests - These tests rule out posthypoxic renal dysfunction; hypoxic damage to multiple organ systems may also be suggested by elevated liver transaminase levels.

Cerebrospinal fluid analysis

This should include tests checking for the following:

  • Pleocytosis
  • Xanthochromia - Suggestive of blood breakdown products, particularly if jaundice is not present
  • Lactic acid and pyruvate - For evidence of mitochondrial cytopathies
  • Herpes virus - Using a polymerase chain reaction (PCR) assay
  • Glucose concentration - Low glucose concentration is suggestive of bacterial meningitis

In the absence of bacterial meningitis, persistently low CSF glucose concentrations may suggest a glucose transporter defect.

Electroencephalography

Electroencephalography plays a vital role in properly identifying and differentiating neonatal seizures from nonepileptic events. [11, 12] Video EEG monitoring may be helpful when infrequent neonatal seizures persist. [13] (See the images below.)

Onset of neonatal seizure demonstrating a focal on Onset of neonatal seizure demonstrating a focal onset in the right frontal (FP4) region. At this point, the child had head and eye deviation to the left.
Twenty seconds into a seizure that had focal onset Twenty seconds into a seizure that had focal onset in the right frontal (FP4) region, the seizure shows a rhythmic buildup of activity in the right frontocentral region.
This seizure had focal onset in the right frontal This seizure had focal onset in the right frontal (FP4) region and subsequent buildup of activity in the right frontocentral region. As the seizure evolves, the electroencephalogram shows diffuse involvement of both cerebral hemispheres.

Continuous video-EEG (cEEG)

A recent large cohort of newborns with seizures treated at centers that use cEEG demonstrated that ~50% of those with high seizure burden received ≥2 antiseizure medications, and/or died or had abnormal examination at discharge. Greater seizure burden was associated with increased morbidity and mortality. The authors findings underscore the importance of accurate determination of neonatal seizure frequency and etiology and a potential for improved outcome if seizure burden is to be reduced. [14]

Neonatal hypothermia for hypoxic ischemic encephalopathy

Infants undergoing brain cooling for hypoxic ischemic encephalopathy via selective head cooling with the Cool-Cap system are unable to undergo continuous video EEG monitoring with a full electrode array for 48 hours or longer following initiation of brain cooling. This renders concern for not recognizing neonatal seizures during a particularly high-risk period. Amplitude-integrated EEG (aEEG) may be useful for monitoring such infants. [15, 16]

Therapeutic hypothermias (rectal temperature of 34C°) in infants older than conceptual age 36 weeks initiated within the first 6 hours following delivery may decrease mortality and neurodevelopmental disabilities. Hypothermia can also be achieved by whole body colling, which would enable cEEG to be performed. [17]

Consultations

Neurology consultation is recommended to help with the evaluation of seizures, electroencephalography, video EEG monitoring, and management of anticonvulsant medications.

Transfer

Mothers in premature labor ideally should be transferred to a facility with a tertiary neonatal intensive care unit. This is more desirable than transfer after birth, since later transfers more commonly result in morbidity.

Monitoring

Neurology outpatient evaluation and follow-up are needed to decide when to discontinue seizure medications. Orthopedic evaluations may be appropriate in infants with joint deformities.

Patients require developmental evaluation for early identification of physical or cognitive deficits. Enrollment in a "birth to 3" early intervention program may be indicated. Patients with tone abnormalities must be monitored carefully for development of contractures; strongly consider a physical medicine/physical therapy referral.

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Imaging Studies

Cranial ultrasonography

Cranial ultrasonography is performed readily at the bedside; it is a valuable tool for quickly ascertaining whether intracranial hemorrhage, particularly intraventricular hemorrhage, has occurred. A limitation of this study is the poor detection rate of cortical lesions or subarachnoid blood.

Cranial CT scanning

Cranial computed tomography (CT) scanning is a much more sensitive tool than ultrasonography in detecting parenchymal abnormalities. The disadvantage is that the sick neonate must be transported to the imaging site.

A distinct advantage is that with modern CT scan techniques, a study can be obtained in approximately 10 minutes.

Cranial CT scan can delineate congenital malformations. Subtle malformations may be missed on CT scan, requiring a magnetic resonance imaging (MRI) study.

MRI

Cranial MRI is the most sensitive imaging study for determining the etiology of neonatal seizures, particularly when electrolyte imbalance has been excluded as the seizures’ cause. [18] A major disadvantage is that MRI cannot be performed quickly and, in an unstable infant, it is best deferred until the acute clinical situation resolves.

Echocardiography

This study can rule out cardiac hypomotility as a result of more diffuse hypoxia.

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