Craniosynostosis and Its Syndromic Associations

Craniosynostosis and Associated Conditions

• Craniosynostosis can lead to multiple syndromic associations, including syndactyly, characterized by the fusion of digits.
• Apert syndrome is detectable in the third trimester, presenting with bilateral syndactyly and additional abnormalities affecting cardiac, genitourinary (GU), and cerebral systems, particularly involving the corpus callosum.

Skeletal Anomalies

• Clubfoot (talipes) has a higher prevalence in males.
• Rocker-bottom foot is marked by a prominent heel and convex sole, often associated with trisomy 18 and other chromosomal anomalies.

Amniotic Band Sequence

• Also referred to as synechiae, this condition results from bands attached from one uterine wall to another, leading to various malformations.

Caudal Regression Syndrome/Sirenomelia

• Presents a spectrum of malformations at the caudal end of the neural tube, with sirenomelia specifically showing fused lower extremities.
• Associated factors include monozygotic twinning, presence of a single umbilical artery, and maternal cocaine use.

VACTERL Association

• VACTERL is a cluster of congenital anomalies that must include at least three features: vertebral defects, anal atresia, cardiac anomalies, tracheoesophageal fistula, renal anomalies, and limb dysplasia.

Doppler Assessment in Pregnancy

• Normal Middle Cerebral Artery (MCA) S/D ratio decreases with advancing gestational age.
• Abnormal ratios can indicate fetal anemia, intrauterine growth restriction (IUGR), hydrops, or isoimmunization.
• IUGR and hypoxic stress lead to a decreased MCA S/D ratio indicating brain-sparing effects.

Skeletal System Evaluation

• Normal sonographic appearance includes measurement techniques for fetal long bones; abnormal size or appearance raises suspicion for skeletal dysplasia.
• Micromelia refers to abnormally short limbs, mesomelia affects the middle portions (radius, ulna), rhizomelia involves shortening at proximal ends (femur, humerus), and acromelia affects distal ends (hands, feet).

Skeletal Dysplasia Management

• Family and paternal histories, along with serial growth images, are vital for assessment.

Lethal vs. Non-Lethal Skeletal Dysplasia

• Lethal forms often have severe prenatal appearances with accompanying pulmonary hypoplasia conditions.
• Common non-lethal forms include achondroplasia, which can manifest with rhizomelia and macrocephaly.

Common Skeletal Dysplasias

• Achondrogenesis, thanatophoric dysplasia, and osteogenesis imperfecta are notable lethal skeletal dysplasias.
• Non-lethal forms might present milder abnormalities, like in achondroplasia with frontal bossing and narrow thorax.

Anomalies of Specific Dysplasias

• Achondrogenesis:* Severe micromelia, hypomineralization, and absent ossification of structures.
• Thanatophoric Dwarfism:* Bowed long bones, macrocephaly, narrow thorax, severe hydrocephalus.
• Asphyxiating Thoracic Dysplasia:* Characterized by narrow thorax, rhizomelia, and lethal pulmonary hypoplasia.
• Ellis-Van Creveld Syndrome:* Involves polydactyly, short limbs, and heart defects, prevalent in the Amish community.
• Osteogenesis Imperfecta:* High variability, with types I and IV being non-lethal and type II noted for lethal outcomes.
• Camptomelic Dysplasia:* Presents with bowed long bones, cleft palate, and possible hydrocephalus.

Congenital Hypophosphatasia and Dysostosis

• Characterized by hypomineralization, curved long bones, and diagnosis confirmed through specific biochemical tests.
• Dysostosis involves abnormal ossification patterns, leading to craniofacial anomalies.

Maternal Portion of the Placenta

• Consists of the basal plate (decidua basalis) and the fetal surface (chorionic plate).
• The umbilical cord should insert centrally in the placenta.

Functions of the Placenta

• Responsible for fetal metabolism, nutrition, waste excretion, protection, and storage of nutrients.
• Produces key hormones including human chorionic gonadotropin (HCG), estrogen, and progesterone.

Placenta Localization

• Placement relative to the internal cervical os is important; low lying is defined as 1-2 cm from the os.
• Diagnosis of low lying placenta should not be made until after 32 weeks due to potential migration.

Biophysical Profile (BPP)

• High-risk factors necessitate additional examinations to monitor fetal health.
• BPP assesses fetal well-being or distress, focusing on signs of asphyxia including hypoxia and acidosis.
• Criteria for BPP:
  • Fetal breathing movements must last 30-60 seconds.
  • Gross body movements need to be noted (3 movements).
  • Fetal tone requires at least 1 episode of flexion/extension.
  • Amniotic fluid volume should have a pocket measuring at least 2 cm vertically.
• Scoring system: Each parameter can score 2 points, with a total possible score of 10 including non-stress test contributions.

Non-Stress Test (NST)

• Considered normal when fetal heart rate increases by 15 BPM or more at least twice over 20 minutes.
• Requires monitoring via Doppler for heart rate reactivity during contractions.

Fetal Growth Assessment

• Utilizes sonographic measurements to identify Intrauterine Growth Restriction (IUGR), defined as fetuses at or below the 10th percentile for gestational age.
• Most accurate assessment dates are determined early via menstrual dating and ultrasonographic methods.

Key Measurements

• Mean Sac Diameter (MSD) offers accuracy of ± 1 week, typically used when no embryo visible (4-5 weeks).
• Crown-Rump Length (CRL) is most accurate at 6-11 weeks with ± 5-7 days accuracy.
• Biparietal Diameter (BPD) measurements taken 11-40 weeks provide varying accuracies based on gestation timing.

IUGR Types

• Symmetric IUGR: Small size across the board, typically due to severe first trimester insults (e.g., congenital anomalies, infections).
• Asymmetric IUGR: Usually spares head size, indicative of later gestational insults, such as placental insufficiency.

Doppler Ultrasound Application

• Qualitative Doppler assessment evaluates flow resistance using ratios such as Systolic/Diastolic (S/D ratio).
• Increased vascular resistance indicates underlying issues in IUGR, with late signs including absent or reversed end-diastolic flow.

Macrosomia

• Birth weight greater than 4000 g or above the 90th percentile for a given gestational age.
• Associated risks include shoulder dystocia, fractures, and brachial plexus injuries.
• Risk factors include gestational diabetes, obesity, advanced maternal age, and excessive weight gain.

Conversion Note

• For converting grams to pounds, move the decimal three places left and multiply by 2.2 (e.g., 2000g = 4.4 lbs).