Table 2

Ultrasound characteristics of frontal horn cysts in 21 neonates

Subject	First scan (age)	Features and largest diameter	Other ultrasound findings	Scan progress
A	Day 1	Bilateral single L>R	SEH	Enlarged to 18 mm by 3 weeks, resolution by 3 months
B	Day 7 and 1 month	L side solitary 6 mm	Nil	FHC present day 30, resolution by 5 months
C	Day 5	L side 2 cysts 4 mm	R SEH
D	Day 3	L side single 10 mm	Nil	2 smaller cysts appeared at 3 weeks, all resolved at 4 months
E	Day 2	R side 2 cysts 3 mm	Nil	10 mm size by 4 weeks
F	Day 2	Bilateral 3L 2R 5 mm	R SEH/caudate nucleus dense at 2 m	FHC increased to 1.4 mm at 4 weeks, resolved by 5 months
G	Day 7	R side 2 cysts 20 mm	Nil	NA
H	Day 2	L side; single 13 mm	Nil	NA
I	Day 14	Bilateral, 10 mm	PM ultrasound	NA
J	Day 2	Bilateral, 2R 1L, 11 mm	Nil	No change at 4 weeks
K	Day 3	Bilateral, 2R, 1L	Nil	NA
L	Day 2	L side, single 16 mm	Nil	No change at 1 week, resolved 2 months
M	Day 3	L side, 23 mm	R SEH wide IHF, parietal subarachnoid space	NA
N	Day 1	Bilateral	Nil	NA
O	Day 1	Bilateral, 2L, 1R 2 mm	Nil	12 mm size at 2 weeks, regressed by 10 weeks
P	Day 3	L side, single, 3 mm	Not seen on day 2 scan	7 mm at 4 weeks, no further scans
Q	Day 3	L side, multiple, 5 mm	Bilateral. SEH	Bilateral PVL cysts after 2 weeks
R	Day 2	Bilateral, 2R, 1L	Nil	NA
S	Day 2	Bilateral, 1L, 2R, 9 mm	Nil	Resolved at 4 months
T	Day 3	R side, single 8 m	R SEH	Resolved
U	Day 1	L side, single 6 mm	Nil	Resolved

All scans, performed in the first week of life, confirmed typical features shown in fig 1[f1]. Fifteen subjects had frontal horn cysts, which enlarged by 34 weeks (range 28–40) gestation equivalent and resolved around 2 months corrected age (range 34 weeks to 4.5 months).
L, Left; R, right; SEH, subependymal haemorrhage; FHC, frontal horn cyst; NA, not available.