Seizures - Case 19-2: 10-Day-Old Boy
Seizures - Case 19-2: 10-Day-Old Boy: Excerpt from Pediatric Complaints and Diagnostic Dilemmas
I. History of Present Illness
A 10-day-old boy was well until the day of admission, when he was noted by his
mother to have the sudden onset of left arm and leg shaking while sleeping. The
episode lasted about 1 minute and was accompanied by eyelid fluttering. After
spontaneous cessation of the episode, the infant continued sleeping but aroused
easily. He was brought to the emergency department for evaluation. He did not
have fever or cyanosis. There was no recent vomiting or diarrhea. His oral
intake had been unchanged over the past several days and consisted exclusively
of cow milk-based formula every 2.5 to 3 hours. The parents were uncertain
about urine output because the maternal grandmother had cared for the infant on
the day before admission.
II. Past Medical History
The infant weighed 3,600 g at birth. He was born by spontaneous vaginal delivery
after an uncomplicated pregnancy. He required phototherapy briefly on the
second day of life for hyperbilirubinemia with a peak total bilirubin level of
15.5 mg/dL. The mother had vaginal colonization with group B
Streptococcus and received two doses of penicillin during labor. She also had a history of
genital HSV infection. Although no lesions were noted at delivery, she did
develop lesions on the seventh postpartum day.
III. Physical Examination
T, 37.5°C; RR, 40/min; HR, 124 bpm; BP, 75/45 mm Hg; SpO2, 100% in room air
Weight, 50th percentile; length, 25th percentile; head circumference, 25th
percentile
The infant appeared alert. There were no vesicles on the scalp or skin. His
anterior fontanel was open and flat. His conjunctivae were pink and anicteric.
Red reflex was present bilaterally. There was no murmur on cardiac examination,
and femoral pulses were strong. The spleen tip was just palpable, and there was
no hepatomegaly. The Moro reflex was symmetric. The remainder of the
examination was also normal.
IV. Diagnostic Studies
A complete blood count revealed 8,800 WBCs/mm3 (16% segmented neutrophils, 70% lymphocytes, 11% monocytes, and 3% atyptical
lymphocytes); hemoglobin, 13.4 g/dL; and platelets, 511,000/mm
3. Serum chemistry values included sodium, 139 mmol/L; potassium, 5.5 mmol/L;
chloride, 104 mmol/L; and bicarbonate, 28 mmol/L. The blood urea nitrogen and
creatinine concentrations were normal. Serum alanine and aspartate
aminotransferases were normal. Serum albumin was 3.3 g/dL. Examination of the
CSF revealed the following: WBCs, 12/mm
3; red blood cells, 1,834/mm3; glucose, 45 g/dL; and protein, 124 g/dL. There were no bacteria on Gram
staining.
V. Course of Illness
The infant was treated empirically with ampicillin, cefotaxime, and acyclovir
while the results of CSF bacterial culture and CSF HSV PCR were awaited. An ECG
(Fig. 19-1) suggested a cause of the seizures, which was confirmed by
additional blood tests in both the infant and his mother.
Discussion: Case 19-2
I. Differential Diagnosis
Many neonatal seizures are idiopathic. The most common definable etiologic
agents are asphyxia, intracranial infection, trauma, nontraumatic hemorrhage,
strokes, metabolic disorders, CNS malformations, and maternal drug abuse.
Seizures due to perinatal asphyxia typically occur within the first 24 hours of
life. Common infectious causes in the first week of life include bacterial
meningitis due to group B
Streptococcus and Escherichia coli. Neonates with HSV meningitis typically present during the second week of life,
but up to 40% develop symptoms within the first 5 days of life. Intracranial
hemorrhage of any cause can provoke seizures. Neonatal seizures related to
birth trauma with subsequent subarachnoid hemorrhage or subdural and epidural
hematomas usually occur within the first 72 hours of life. Nontraumatic causes
of intracranial hemorrhage, including ruptured arteriovenous malformations and
underlying disorders of coagulation, can occur at any time. Metabolic disorders
include hypocalcemia, hypoglycemia, and pyridoxine dependency. Neonatal
hypocalcemia occurring after the third day of life is usually caused by
transient relative hypoparathyroidism. The immature neonatal parathyroid may be
unable to handle an excessive phosphate load, particularly if the infant is fed
a formula with a relatively low ratio of calcium to phosphorus. Rarely,
prolonged phototherapy induces hypocalcemia. Phototherapy decreases melatonin
secretion, which decreases glucocorticoid secretion, which in turn leads to an
increase in bone calcium uptake with subsequent hypocalcemia. Multiple defects
in urea cycle and organic acid metabolism may cause seizures in the neonatal
period. Infants with these disorders usually have unexplained stupor, coma, and
vomiting in addition to seizures. Infants born to mothers who have used heroin
or methadone may have seizures, although other symptoms, such as poor feeding,
diarrhea, sweating, jitteriness, and irritability, are more common.
II. Diagnosis
Bacterial cultures and HSV PCR of the CSF were negative. The ECG demonstrated
QTc prolongation (QTc = 0.47 seconds) characteristic of hypocalcemia (Fig.
19-1). The infant
's serum calcium concentration was 6.6 mg/dL (normal range, 8.8 to 10.1 mg/dL);
ionized calcium was 0.83 mmol/L (normal, 1.00 to 1.17 mmol/L); phosphate, 10.6
mg/dL (normal, 4.8 to 8.2 mg/dL); and magnesium, 1.1 mg/dL (normal, 1.5 to 2.5
mg/dL). Additional testing included intact parathyroid hormone (PTH), 9.7 pg/mL
(normal, 10 to 55 pg/mL); 25-hydroxyvitamin D (25-hydroxycholecalciferol
[25(OH)D
3]), 7 ng/mL (normal, 5 to 42 ng/mL); and active vitamin D
(1,25-dihydroxycholecalciferol [1,25(OH)
2D3]), 114 pg/mL (normal, 8 to 72 pg/mL). Although the mother was asymptomatic, her
calcium level was elevated to 12.8 mg/dL. The mother was subsequently diagnosed
with hyperparathyroidism related to a parathyroid adenoma.
The diagnosis is transient neonatal hypoparathyroidism secondary to maternal
hyperparathyroidism.
The infant was initially treated with intravenous calcium gluconate followed by
oral calcium and vitamin D supplementation, which were weaned over the
subsequent 3 weeks.
III. Incidence and Epidemiology
Hyperparathyroidism has a prevalence rate of 0.15%, with a peak incidence
between 30 and 50 years of age. Approximately 80% of cases are due to a
solitary adenoma that requires resection, and 15% are due to chief cell
hyperplasia. Maternal symptoms are not apparent until the serum calcium level
exceeds 12 to 13 mg/dL. However, even mild maternal hypercalcemia leads to
chronic fetal hypercalcemia, which in turn suppresses fetal production of PTH.
After birth, calcium levels decrease but PTH production cannot be rapidly
increased. In this condition, neonatal hypoparathyroidism is transient, lasting
only several days to several weeks. Eventually, as the parathyroids become more
active, increasing PTH levels stimulate vitamin D production and extra calcium
absorption from the plentiful supply in the gut. Clinically detectable
hypocalcemia develops in 15% to 25% of infants born to mothers with
hyperparathyroidism. As in this case, neonatal seizures or tetany often leads
to a search that identifies a maternal parathyroid adenoma.
IV. Clinical Presentation
Signs of hypocalcemia usually develop within the first 3 weeks of life. Signs of
neonatal hypocalcemia are often nonspecific and may be seen in a variety of
other conditions. Tremors and jitteriness are most commonly seen. Other signs
include irritability, hyperreflexia, facial twitching, carpopedal spasm,
seizures, cyanosis, and, rarely, laryngospasm. More importantly, other
disorders that can manifest with hypocalcemia should be considered. Features of
22q11 deletion syndromes include cleft palate, micrognathia, ear anomalies,
bulbous nasal tip, and conotruncal heart defects. Findings associated with
Albright hereditary osteodystrophy (pseudohypoparathyroidism type Ia) include
round face, short distal phalanges of the thumbs, subcutaneous calcifications,
and a family history of developmental delay and dental hypoplasia.
Sensorineural deafness, renal dysplasia, and mental retardation are also
associated with syndromes that include hypoparathyroidism.
V. Diagnostic Approach
Serum calcium and ionized calcium (Ca2+). Both calcium and Ca2+ levels are low with symptomatic hypocalcemia.
Serum albumin. Because approximately 45% of serum calcium is protein bound, low serum albumin
levels lead to low serum calcium levels with normal Ca
2+ levels. Symptoms of hypocalcemia develop only when Ca2+ is low. The following correction factor is used to indicate whether a low
measured serum calcium level is due solely to hypoalbuminemia:
Corrected serum calcium = Measured serum calcium + [(Normal serum albumin
− Measured serum albumin) × 0.8]
If the corrected serum calcium is less than normal (i.e., less than 8.8 mg/dL),
the Ca
2+ may also be low, increasing the likelihood of symptomatic hypocalcemia. In this
patient described, the corrected serum calcium was calculated as follows:
Corrected calcium = 6.6 mg/dL + (4.0 mg/dL − 3.3 mg/dL) × 0.8] = 7.1 mg/dL
Serum magnesium. Magnesium deficiency can lead to neonatal hypocalcemia through functional
hypoparathyroidism and pseudohypoparathyroidism. In most cases, it is seen in
neonates born to magnesium-deficient mothers, such as those with poorly
controlled diabetes mellitus. In magnesium deficiency, magnesium replenishment
leads to increases in both calcium and PTH levels. In hypoparathyroidism of any
other cause, magnesium administration does not lead to changes in the calcium
and PTH levels.
Serum phosphorus. Phosphorus levels are elevated with both phosphate-induced neonatal hypocalcemia
and hypoparathyroidism.
Serum parathyroid hormone. PTH levels are low with hypoparathyroidism. However, in phosphate-induced
neonatal hypocalcemia, serum PTH is appropriately elevated.
Active vitamin D. Levels of 1,25(OH)2D3 are low with hypocalcemia due to vitamin D deficiency but normal or high with
underlying hypoparathyroidism.
Other tests. Infants who were treated with bicarbonate or other alkali to correct acidosis
can develop very significant hypocalcemia; therefore, an arterial blood gas
determination should be considered. A chest radiograph can document a normal
thymic shadow in neonates if 22q11 deletion syndromes are a concern. If
neonatal risk factors for hypocalcemia are absent, measurement of maternal
serum calcium, phosphorus, and PTH levels should be considered.
VI. Treatment
Emergency treatment for neonatal hypocalcemia consists of intravenous 10%
calcium gluconate infusion with continuous ECG monitoring. Additionally,
1,25(OH)
2D3 (calcitriol) should be given. Once the QTc interval on ECG is normal, therapy
can be continued with oral calcium and vitamin D
2 (ergocalciferol), which is less costly than calcitriol. Serum calcium levels
should be measured frequently in the early stages of treatment to determine the
appropriate dosing. If hypercalcemia occurs, therapy should be discontinued and
resumed at a lower dose after the serum calcium level has returned to normal.
When maternal hyperparathyroidism is the cause of neonatal hypoparathyroidism
and hypocalcemia, supplementation with calcium and vitamin D analogues is
required for only 3 to 4 weeks.
VII. References
1. Hsieh YY, Chang CC, Tsai HD, et al. Primary hyperparathyroidism in pregnancy:
report of three cases.
Arch Gynecol Obstet 1998;261:209–214.
2. Kaplan EL, Burrington JD, Klementschitsch P, et al. Primary
hyperparathyroidism, pregnancy, and neonatal hypocalcemia.
Surgery 1984;96:717–722.
3. Mimouni FB, Root AW. Disorders of calcium metabolism in the newborn. In:
Sperling MA, ed.
Pediatric endocrinology. Philadelphia: WB Saunders, 1996;95–115.
4. Morrison A. Neonatal seizures. In: Pomerance JJ, Richardson CJ, eds. Neonatology for the clinician. Norwalk, CT: Appleton & Lange, 1993;411–423.
5. Romagnoli C, Polidori G, Cataldi L, et al. Phototherapy induced
hypocalcemia.
J Pediatr 1979;94:815–816.
Pictures
Book Source Details
- Book Title: Pediatric Complaints and Diagnostic Dilemmas
- Author(s): Samir S Shah MD; Stephen Ludwig MD
- Year of Publication: 2003
- Copyright Details: Pediatric Complaints and Diagnostic Dilemmas, Copyright © 2003 Lippincott Williams & Wilkins.
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