Primary acalvaria with open-lip schizencephaly in indigenous South Papuan surviving newborn: a rare case report.

Background: Acalvaria, or acrania, is a rare congenital cranial vault defect with neurocranium absences, including complete or part of calvaria flat bones, dura mater, and associated muscles, but with a still present in the central nervous system, skull base, facial bones, and skin-covered the defect. It is a sporadic incidence without apparent genetic factors confirmed. Acalvaria is often misdiagnosed as anencephaly; the distinguishable difference is that anencephaly has an absence (partial or complete) of the brain tissue, including the skull and scalp. Acalvaria is considered a fatal anomaly with a low survival rate, and only a few cases of extended survival have been reported until now. To the best of the author's knowledge, no acalvaria case has been published in Papua, and only one reported case of the coexistence of acalvaria with schizencephaly in Brazil (2018).

Case report: Herein, we present a case of an indigenous South Papuan living newborn with primary acalvaria and open-lip schizencephaly in a frontoparietal region. A male newborn baby was born from a 39-year-old female Marind-Anim tribe patient with a 38th week of gestation, with no previous history of miscarriage, is not a consanguineous marriage, and had an unremarkable medical history during this pregnancy. Post-natal physical examinations showed an irregularly shaped head with 11.5 cm diameter concave of the right side, with a soft brain-like consistency palpable and the absence of half right frontoparietal calvarium covered with a presence of scalp and hair. Cranial 2-dimension ultrasonography shows an absence of half right frontoparietal calvaria bone with a complete presence of scalp and periosteum covering the defect with a fluid accumulation (anechoic) below the periosteum. A transverse axis view shows a complete structure but hypoplasia of brain cortex with visible slightly dysgenesis of gyrus and sulcus in both hemispheres convincing the acalvaria condition not anencephaly. A fluid accumulation above brain parenchyma of the frontoparietal region happened to be a cerebrospinal fluid coming from a wide-open cleft extending from the left lateral and fourth ventricles to the cerebral cortex, suggesting a typical condition of open-lip schizencephaly. Further health follow-ups until 6 months old showed still normal physical and behavioral development with no sign of complications.

Conclusions: No standard acalvaria treatment is being established; conservative and supportive therapy is mostly taken considering their low survival rate. With the advancement of medical technology nowadays, surgical approaches, including scalp defect closure, bone graft, and 3D-printed defect filling, are being performed and have succeeded in a few cases. Long-term follow-up is required to monitor their neuro-psychological development and complication incidences that need further intervention.