Choroid plexus coagulation in trisomy 9 mosaic-related hydrocephalus-a case report.

In trisomy 9 mosaicism, plexus hypertrophy has been described as a phenotypical feature and cause of hydrocephalus. We report on a 15-month-old child with hydrocephalus and trisomy 9 mosaicism primarily diagnosed in amniocentesis. After implantation of a ventriculoperitoneal shunt and subsequent revision, he presented with an exhaustion of peritoneal absorption leading to massive ascites. The implantation of a peritoneal drainage offered the unique opportunity to monitor cerebrospinal fluid (CSF) production indirectly via abdominal CSF drainage. In an individual trial, we performed endoscopic choroid plexus cauterization to reduce cerebrospinal fluid production, which failed to reduce excessive CSF production. In a second procedure, a ventriculoatrial shunt was implanted and succeeded to treat persistent hydrocephalus.