Pediatric emergency medicine trisk 1438 1438
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collect an extra tube of CSF for later analysis. In any patient with signs of
increased intracranial pressure, an LP should not be performed until head imaging
can be done.
Electrolyte abnormalities may also cause seizures, with hyponatremia,
hypocalcemia, and hypomagnesemia being the most common. Unfortunately,
seizures caused by electrolyte derangements are often refractory to anticonvulsant
therapy and patients will continue to seize until the underlying abnormality is
corrected. In general, the routine screening for electrolyte abnormalities in a
patient with brief seizure is of low value. Serum electrolytes should be measured
in all patients with seizure with significant vomiting or diarrhea; patients with
underlying renal, hepatic, neoplastic, or endocrinologic disease; patients who are
taking medications that may lead to electrolyte disturbances; or patients who have
seizures that are refractory to typical anticonvulsant management. Another
clinical scenario involves hyponatremic seizures in infants, typically younger than
6 months, after prolonged feedings of dilute formula (“infantile water
intoxication”). Other patients may be evaluated on a case-by-case basis. IV
calcium, magnesium, and hypertonic (3%) sodium chloride should be used to
treat the appropriate abnormal condition. In the case of hyponatremia, 3% sodium
chloride should be infused rapidly until the seizure activity has been stopped;
subsequent to seizure resolution, a slower rate of sodium correction should be
used to avoid possible central pontine myelinolysis.
Rarely, other chemistries can be helpful in identifying specific organ
dysfunction, either as a cause of the seizure activity or as an assessment of
systemic injury. An elevated blood urea nitrogen or creatinine level suggests renal
insufficiency (with associated findings such as hypertension and electrolyte
disturbances) as a potential cause.
Elevated liver function tests (transaminases or coagulation times) can be a
reflection of hepatic failure. Metabolic acidosis or hyperammonemia can suggest
an underlying metabolic disorder. In patients with prolonged seizures, an arterial
or venous blood gas level can help in assessing adequacy of ventilation and a
creatine kinase level can identify possible rhabdomyolysis.
Toxicologic screening can also be helpful in the seizing patient because certain
ingestions are managed with specific antidotes or treatments. In general, the
toxicologic screen should be directed at agents known to cause seizures (Table
72.1 ) or those suggested by a clinical toxidrome.
Radiologic imaging of the patient with seizure generally consists of a
computed tomography (CT) scan for emergent imaging or, preferably, a magnetic
