Microcephaly and impotence–evaluating

Question 1

How is microcephaly defined?

Answer 1

An OFC or occipital frontal circumference of greater than 2 standard deviations below the mean which usually means less than 3rd percentile.

Question 2

When should an evaluation be initiated in the baby with microcephaly?

Answer 2

Upon the first measurement below 2 standard deviation or a progressive decrease in head size over time

Question 3

What is the definition for prenatal microcephaly that is found on ultrasound?

Answer 3

A head circumference that is less than 3 standard deviations below the mean or below the 2nd percentile for gestational age

Question 4

What is an average normal head circumference and what is the expected growth rate for the first 6 months and then for the subsequent 6 months to 12 months of age?

Answer 4

Average is 35 cm and the growth rate is 1 cm/month for the first 6 months and 1/2 cm/month from 6 to 12 months

Question 5

What is primary microcephaly?

Answer 5

Head circumference is abnormal at birth

Question 6

What history should be obtained for a baby with primary microcephaly?

Answer 6

Detailed family history, prenatal history including any genetic defects, maternal exposure to medications, maternal drug use, maternal alcohol use, maternal infections while pregnant, parental consanguinity, maternal health problems

Question 7

What is acquired microcephaly

Answer 7

Head circumference is normal at birth and then falls off the curve over months to years. crossing 2 major %

Question 8

What elements of the history should be obtained for acquired microcephaly?

Answer 8

Same elements as primary microcephaly with additional history including head circumference at birth, the head circumference trajectory, the patient’s developmental history, illnesses since birth, medications being taken.

Question 9

What are some of the common etiologies associated with microcephaly?

Answer 9

1. Autosomal dominant disorders
2. Autosomal recessive disorders
3. Trisomy 13, 18, and 21
4. Cornelia de Lange syndrome with features including upturned nose, eyebrows that meet in the middle, cleft palate, GERD
5. Smith-Lemli-Opitz syndrome: Defective chromosomal synthesis and possible 2-3 toe syndactyly
6. Rett syndrome
7. Inborn errors of metabolism
8. Hypothyroidism manifest by decreased activity, constipation, weight gain, slow growth
9. TORCH infections including toxoplasma, other (varicella, syphilis), rubella, cytomegalovirus, herpes simplex virus: look for neurologic deficits, calcifications on neuroimaging, eye abnormalities, blueberry muffin syndrome.
10. Maternal phenylketonuria
11. Fanconi anemia: Short stature, café au lait spots, renal abnormalities, hypogonadism, and upper limb/hand anomalies, aplastic anemia with macro cytosis
12. Cri du chat syndrome: High-pitched cry, developmental delays, wide set eyes, high palate, possible VSD
13. Familial microcephaly

Question 10

Describes some of the aspects of a physical exam with a child with microcephaly?

Answer 10

Evaluate shape of head
Assessing fontanelle patency
Assess milestones
Skin exam
Ophthalmologic exam
Neurologic exam
Assess for abnormalities of the digits and extremities
Weight and length trajectories
Organomegaly

Question 11

How is familial microcephaly diagnosed and on what curve are findings plotted and how is it managed?

Answer 11

Parents head circumference should be obtained and plotted on a Weaver curve, and can be managed and followed clinically.

Question 12

What are some diagnostic considerations?

Answer 12

Genetic testing for dysmorphic features or suspicions
Neuroimaging, MRI is preferred, however if TORCH infection or craniosynostosis is suspected a CT may be better for sutures and microcalcifications
Other testing and evaluations by multidisciplinary approach may be needed