Benign Neonatal Convulsions Workup

Updated: Feb 16, 2016
  • Author: Nitin C Patel, MD, MPH, FAAN; Chief Editor: Amy Kao, MD  more...
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Workup

Approach Considerations

The reason for ordering tests in benign familial and idiopathic neonatal convulsions is to exclude the presence of any etiology for the seizures. The diagnosis of benign infantile convulsions of either type requires that no other explanation exist for the seizures. Order tests for individual patients with a plan for that patient in mind.

Review of basic screening laboratory studies performed at delivery may also be helpful.

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Routine Laboratory Studies

The following studies may provide a starting point in the laboratory workup of benign neonatal convulsions:

  • Chemistry studies: Obtain a basic metabolic panel plus calcium, magnesium, phosphorus levels; thyroid function tests; and possibly B vitamin levels.
  • Basic hematologic tests: Obtain a complete blood cell (CBC) count, prothrombin time (PT), and activated partial thromboplastin time (APTT).
  • Lumbar puncture: A cerebrospinal fluid examination may be indicated to exclude neonatal meningoencephalitis or occult blood.

Any abnormalities found that are inconsistent with a diagnosis of benign neonatal convulsions require the appropriate further workup and treatment.

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CT Scanning and/or MRI of the Brain

Perform brain computed tomography (CT) scanning, magnetic resonance imaging (MRI), or both of these studies in every patient with neonatal seizures to exclude structural lesions and intracranial hemorrhage. An argument can be made that both studies are needed, because CT scanning yields better information on acute hemorrhage and skull fracture, and MRI shows better brain structural detail.

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Electroencephalography

The classic electroencephalogram (EEG) observed in 60% of patients with benign idiopathic neonatal convulsions (BINCs) is nonreactive, focal, rhythmic activity in the theta (4-7 Hz) frequency, which may be mixed with sharp waves. This activity is discontinuous and may alternate between hemispheres. This pattern is often termed theta pointu alternant. [3, 5, 36] Although clinical seizures may spontaneously resolve within a short time, it has been reported that the theta pointu alternant EEG pattern may persist for up to 2 weeks. [46]

The remaining patients with benign idiopathic neonatal convulsions have either a normal interictal EEG or focal abnormalities. The EEG during seizures is most often high-voltage (200-400 µV) generalized discharges, which may appear to have a focal onset.

In benign familial neonatal convulsions, the interictal EEG is most commonly normal (50-70% of patients). The theta pointu alternant pattern is also observed—but only in approximately 25% of patients. In a small percentage of patients, focal, often rolandic, discharges or spikes may be present. [3, 47, 48]

Video EEG

In selected patients, continuous video-EEG can be used to confirm behavioral events concordant with abnormal EEG and to confirm that treatment is effective. The state of the patient and improvement or deterioration can make decision making easier and facilitate accurate communication with an often anxious family. [5]

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