SKULL SHAPE IN TRISOMY 18    

  1. Normal Shaped Skull
    • Normal occiput due to the higher frequency of posterior fossa cysts.
    • Less pointing of the frontal bones due to a lesser degree of facial hypoplasia.
  2. Dolicocephaly
    • Decreased cephalic index.
    • Due to the severe oligohydramnios and lateral skull compression that may accompany the IUGR.
  3. Strawberry Skull
    • Brachycephaly with an increased cephalic index.
    • Flattening of the occiput (due to hypoplasia of the occipital lobes, brainstem and cerebellum).
    • Pointing of the frontal bones (distinguish from scalloping). Thought to be due to a vascular abnormality affecting the 1st and 2nd branchial arches.
      • Hypoplasia of face including facial artery muscles, maxilla, mandible, frontal and temporal bones.
      • Micropthalmia with narrow nasal bridge and palate.
      • Absent or rudimentary parotid and submandibular glands.
      • Hypoplasia of frontal lobes of brain.

 

·        Brahycephaly  and flattened occiput

·        Low set ears

·        Mild retrognathia

·        Narrow nasal bridge

·        Facial dysmorphism

Absent nasal bone on profile image

·        Depressed nasal bridge

·        Retrognathia

 

 

REFERENCES
  1. Nicolaides KH, Salvesen DR, Snijders RJM, Gosden CM. Strawberry-Shaped Skull in Fetal Trisomy 18. Fetal Diagn Ther 1992,7:132-137.