This is a 2 month old male with a history of a VSD 
arriving in the ED for a possible seizure.  He has had 
some cold symptoms since yesterday.  This evening, 
his parents noted an episode of body stiffness, jerking 
of all extremities, and upward rolling of his eyes lasting 
one minute.  An ambulance was called.  His face was 
described as being blue toward the end of the episode.  
Paramedics noted him to be breathing spontaneously 
with no cyanosis.  He was transported to the ED.  An IV 
was attempted en route, but this was not successful.  
No fever was noted in the ambulance.  There was no 
history of fever prior to this episode.
     Exam:  VS T36.6 (rectal), P132, R60, weight 4.36 
kg.  He was alert and active.  Fontanelle soft and flat.  
Neck supple.  Heart regular, harsh grade III/VI systolic 
murmur.  Lungs clear.  Good color, perfusion, and tone.  
Shortly after arrival in the ED, another seizure was 
witnessed.  His upper extremities were flexed and
jerking.  His lower extremities were extended and 
jerking.  No one could recall what his eyes were doing.  
An IV was attempted during the seizure but this was not 
successful.  The seizure stopped on its own after five 
minutes.  His oxygen saturation was 100% throughout 
the seizure with an oxygen mask in place.  After the 
seizure, he was crying.  He was not drowsy.  He was 
moving around a lot during other IV attempts.  He was 
noted to be very strong.  An IV was started.  He was 
given 0.1 mg/kg of lorazepam and 10 mg/kg of 
phenobarbital.  He was more sedated at this point.  His 
respiratory effort and perfusion remained good.
     A CBC, blood culture, electrolytes, glucose, and 
calcium were drawn.  A quick glucose check was 175 
mg/dl.  He was given 50 mg/kg of cefotaxime IV.  A 
portable chest radiograph was obtained and a CT of the 
head was ordered.

View CXR.

     There is cardiomegaly with slightly prominent 
pulmonary vascularity suggesting a left to right shunt.  
Compare this CXR to his CXR taken at birth.

View CXR at birth.

     Birth history:  He was born to a 22 year old G3P2, 
O+, rubella immune, syphilis negative, hepatitis B 
negative mother at 40 weeks gestation via spontaneous 
vaginal delivery weighing 3.9 kg with apgar scores of 8 
and 9.  Membranes were ruptured at delivery.  Amniotic 
fluid was clear.  His newborn exam noted small ears.  A 
heart murmur was not noted initially, but two hours after 
birth a grade II/VI systolic murmur was noted.  A CXR 
taken at birth [Click on Birth] showed cardiomegaly 
without pulmonary edema.  An echocardiogram 
performed the next day showed a large VSD with an 
overriding aorta and a relatively narrow main 
pulmonary artery (consistent with a mild Tetralogy of 
Fallot; however, minimal pulmonic stenosis and no right 
to left shunting).  Despite the cardiomegaly noted on 
the CXR, the echocardiogram showed normal chamber 
sizes and contractility.  He was discharged on day 2 of 
life.  Several weeks later, he developed worsening 
congestive heart failure.  He was treated with digoxin.

     Returning to the E.D. and his current condition, his 
head CT study was normal.  Other lab results:  CBC, 
WBC 5,300, 59% segs, 20% lymphs, 17% monos, 4% 
eos, Hgb 10, Hct 30,  platelets 310,000.  Na 133, K 4.4, 
Cl 91, Bicarb 26, glucose 144, Ca 6.0, digoxin level 2.0, 
creatinine 0.4.  The calcium value is very low (normal 
8.0-10.0 mg/dl).  Mg and Phos levels were run when 
the low calcium was noted.  Mg 1.9 (normal), Phos 8.9 
(high, normal range 4.0-6.0).
     DiGeorge syndrome was suspected.  Review of his 
CXR's revealed the absence of a thymic shadow 
consistent with thymic aplasia (a feature of DiGeorge 
syndrome).  Review his CXR's again.  They are very 
similar.  Click on [Birth].  His newborn CXR shows a 
narrow superior mediastinum.  In normal newborns, the 
superior mediastinum is enlarged due to the presence 
of a normal large thymus.

View normal newborn CXR.

     These two normal newborn CXR's show a normal 
thymus configuration.  The upper mediastinum is wider 
than our DiGeorge patient's CXR.  The normal thymus 
can be very large.  It may sometimes protrude to the 
side exhibiting a "sail sign".  The thymus may 
sometimes be elevated in a pneumomediastinum.
     The lateral view of the newborn CXR is most 
important in distinguishing these features.  The normal 
newborn CXR will have the space anterior to the heart 
filled by the thymus.

View normal lateral CXR.

     The arrows indicate a space anterior and superior to 
the heart.  In adults, this space should be filled with 
lung tissue (lucent).  Obliteration of this space in an 
adult indicates the presence of right ventricular 
enlargement or a mediastinal mass.  In newborns, this 
space should be filled with a tissue density (the 
thymus).  If this space is filled with air, it is indicative of 
a pneumomediastinum.  If this space is filled with lung 
tissue, it is indicative of thymic aplasia or hypolasia.

View DiGeorge patient's lateral CXR.

     In this lateral CXR, our patient with DiGeorge 
syndrome has no thymus.  Thus, the space anterior and 
superior to the heart is empty.  The radiologist who 
initially read his newborn CXR commented on the 
absence of a thymic shadow.  The thymus can also be 
hypoplastic in the presence of physiologic stress such 
as sepsis and shock.
     Further studies and clinical features confirmed the 
diagnosis of DiGeorge Syndrome.  His parathyroid 
hormone level in the presence of hypocalcemia was 
low.
     DiGeorge syndrome is predominantly a syndrome of 
hypoparathyroidism and T-lymphocyte deficiency due to 
thymic aplasia or hypoplasia.  The thymus and the 
parathyroid glands both arise from the same pharyngeal 
pouches (3rd and 4th) during embryogenesis.  Failure 
of these pouches to develop results in deficiencies of 
the thymus and parathyroids.  DiGeorge syndrome is 
classified as an immunodeficiency syndrome.  Patients 
with DiGeorge syndrome are susceptible to 
opportunistic infections.  However, patients with 
DiGeorge syndrome typically present initially with tetany 
and hypocalcemia (resembling seizures) due to 
hypoparathyroidism long before any immunodeficiency 
is appreciated.
     Other clinical features of DiGeorge syndrome 
include congenital heart and aortic defects, hypoplastic 
mandible, defective ears, and other subtle facial 
features.  The expression of all the clinical features of 
DiGeorge syndrome is variable.
     Although a serum calcium measurement is often 
included in the laboratory evaluation of a child with a 
first time seizure, it is rarely abnormal.  Febrile seizures 
are most common and are not associated with any 
electrolyte or calcium abnormalities.  DiGeorge 
syndrome is a rare occurrence when hypocalcemia is 
the cause of the "seizure" (tetany).  Children under five 
months of age are unlikely to have benign febrile 
convulsions.  Thus, a calcium measurement should be 
performed in all young infants (under 6 months) with an 
apparent seizure.  The yield of a serum calcium 
measurement in older children is much lower.  A 
seizure is difficult to distinguish from tetany in an infant.  
In this instance it appeared to be a true seizure as it 
was witnessed by an emergency pediatrician and many 
pediatric ED nurses.  

References
     Nypaver MM, et al.  Emergency Department 
Laboratory Evaluation of Children with Seizures:  
Dogma or Dilemma?  Pediatric Emergency Care 
1992;8(1):13.
     Turnbull TL, et al.  Utility of Laboratory Studies in the 
Emergency Department Patient with a New-Onset 
Seizure.  Annals of Emergency Medicine 
1990;19(4):373.
     DiGeorge Syndrome.  In:  Behrman RE, Vaughan 
VC.  Nelson Testbook of Pediatrics, 13th edition.  W.B. 
Saunders, Philadelphia, 1987, p464.