[Neonatal cystic structure adjacent to frontal horn--MRI features]

To evaluate the incidence and features of cystic structures adjacent to the frontal horns of neonates using MRI, and to assess the clinical features of the neonates.

Between April 2001 and January 2005, MRI examinations were performed at our hospital in 352 neonates and infants whose postconceptional age was less than 48 weeks. We retrospectively evaluated the MRI findings and the clinical records.

Seventeen babies (8 males and 9 females) showed cystic structures adjacent to frontal horns, hemilaterally or bilaterally. The incidence of the cysts was 4.8% in total, and was 1.4% (1/74), 9.2% (6/65), and 4.7% (10/213)in term infants, preterm infants born at 33-36 weeks of gestational age, and at less than 32 weeks, respectively. The cysts ranged from 1 to 8 mm in diameter, and were located in the white matter adjacent to ventricular walls and in the portion cephalad to the frontal horns. The cysts resolved in 5 cases (with follow-up ranging from 3 months to 2 years of age), causing slight dilatation of the frontal horn. Developmental disturbances were not observed in patients without other abnormalities.

Cystic structures near the frontal horns in neonates are detected by MRI at a rate of 4.8%. They will resolve spontaneously without causing developmental abnormalities.