Monochorionic Twin Pregnancy with Hydranencephaly and Co-Twin Death: A Case Report

Background: Hydranencephaly is a rare congenital brain malformation with an incidence estimated to be between 1 in 10 000 and 1 in 5 000 pregnancies. It is characterized by the absence of development of the cerebral hemispheres, which are replaced by cerebrospinal fluid. The diagnosis of hydranencephaly can be made from 15 weeks of amenorrhea via obstetric ultrasound, with antenatal nuclear MRI being the definitive test to establish the diagnosis. The condition results from an anomaly in embryogenesis after the formation of the neural plate, though the exact pathophysiology of hydranencephaly is not yet clear. There is no definitive treatment for hydranencephaly; treatment is symptomatic and supportive. The prognosis for children with hydranencephaly is generally poor, with death usually occurring within the first year of life.

Methods: We conducted a thorough clinical examination and neurological assessment. Imaging studies (CT, MRI) confirmed the diagnosis of hydranencephaly. Data were collected from medical records and interviews with the patient’s parents.

Results: We report a case of a female newborn, from a monochorionic twin pregnancy with an in utero fetal death of her twin, admitted for the exploration of congenital hydrocephalus and intrauterine growth restriction (IUGR) detected on prenatal ultrasound. Clinically, she had microcephaly, and postnatal imaging revealed hydranencephaly.

Conclusion and Recommendations: Hydranencephaly is a rare and serious malformation of the nervous system with a guarded prognosis. The etiopathogenesis is still poorly understood. During the antenatal period, it is important to discuss the possibility of medical termination of pregnancy if feasible. Otherwise, cephalocentesis might be considered to avoid a cesarean section. It is crucial to distinguish this condition, which has a poor prognosis, from extensive hydrocephalus, which has the potential for an improved prognosis with early shunting procedures.