Available online 27 July 2022

Suprasellar Arachnoid Cysts (SAC) are rare heterogeneous entities. Though prenatally diagnosed, they are rarely treated pre-birth. Symptomatic cases are mainly seen in infants.

We describe a case of a prenatally symptomatic suprasellar arachnoid cyst treated postnatally.The cyst was diagnosed on a routine ultrasound at 22 weeks, was rapidly evolving in the ultrasounds and the MRI of the 29th week.

It then became symptomatic at 30 weeks with episodes of fetal bradycardia, independent to the uterine contractions. Antenatal treatment was discussed but delivery decided in emergency despite the prematurity via C-section. Though well tolerated postnatally, the cyst continued to grow. Endoscopic ventriculo-cysto-cisternostomy was performed on the 5th day of birth. Despite progressive reduction of the cyst, residual brainstem compression and evolving ventriculomegaly lead to a transient extrathecal internal shunting.

Our case suggests that prenatally diagnosed cysts require a close follow-up. Treatment options and timing should be adapted to anatomy, cyst evolution and symptoms whether it is before or after birth.

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