sodium under 120 mEq/L may produce seizures. Hyponatremia occurs in neonates
with inappropriate antidiuretic hormone secretion syndrome, congenital
adrenal hyperplasia, and those receiving hypo-osmolar formula. Inappropriate
antidiuretic hormone secretion syndrome should be suspected in a neonate
with decreased urinary output and high urinary osmolarity. The immediate
treatment of hyponatremic seizures in neonates consists of providing enough
sodium in a 10-minute period to elevate the serum sodium level to 125
mEq/L by using 3% normal saline solution (contains 513 mEq of sodium/L).
The amount of sodium required is calculated using the following formula:
(125 -?) x (0.6) x (wt kg) = X mEq
where ? represents the patientís serum sodium, 0.6 is
the dilution constant, and X represents the number of mEq needed to correct
the sodium level to 125 mEq. Neonates with inappropriate antidiuretic
hormone secretion syndrome should also be given furosemide 1 mg/kg intravenously,
followed by replacing urinary sodium milliequivalent for milliequivalent
with 3% normal saline solution. Neonates with congenital adrenal hyperplasia
and neonates receiving diluted formulas do not require furosemide. Antiepileptic
drugs should be used if seizures persist after the infusion of 3% normal
saline solution or if it is not available.
pontine myelinolysis may occur due to rapid correction of hyponatremia.
Central pontine myelinolysis should be suspected in a neonate with hyponatremia
that in the course of correction of the hyponatremia develops cranial
nerve dysfunction and quadriparesis. Magnetic resonance imaging is the
study of choice (Figure 42.1).
Central pontine myelinolysis. [A] MRI of the brain (T1-weighted
image) demonstrating a round lesion in the central pontine area. [B] MRI
of the brain (T2-weighted image) demonstrating
an oval lesion in the central pontine area.
sodium above 150 mEq/L may produce seizures. Hypernatremia occurs in neonates
who have received excessive sodium orally (by mistakenly trying to sweeten
formula with salt) or intravenously (miscalculating the sodium in hyperalimentations
or not accounting for the sodium in sodium bicarbonate when it is used
to correct acidosis). Signs of dehydration may or may not be present.
The correct treatment of hypernatremic
seizures in a neonate is uncertain. Some advocate blood volume correction
using 5% albumin followed by forced diuresis (furosemide 1 mg/kg) and
replacement of the urine volume with a 10% dextrose solution. Others advocate
using D5W 0.2 normal saline solution at 100 to 150 cc/kg per day according
to the gestational age of the neonate. After seizures stop, serum sodium
should be measured and further correction should aim at decreasing serum
sodium by 10 mEq a day. Serum potassium and blood calcium should be monitored
Antiepileptic drugs may be necessary.
anesthetic intoxication should be considered as a possible cause of seizures
in neonates with scalp puncture wounds. Neonates with local anesthetic
intoxication may have fixed and dilated pupils,
and absence of extraocular movements during
the first 6 hours after the administration of local anesthetic. The usual
offenders are mepivacaine and lidocaine. The half-life of these drugs
is about 8 to 10 hours. Treatment consists of diuresis with acidification
of urine and support of vital signs. Antiepileptic drugs are of