Arnold-chiari malformation

[Rihanna]

a physical problem present from birth in which part of the brain is pushed through the opening for the spinal cord at the base of the skull, blocking the flow of fluid into the brain and spinal cord

[Tariq Zaki]

: a congenital abnormality in which the lower surface of the cerebellum and the lower brain stem protrude into the spinal canal through the foramen magnum She was born with Arnold-Chiari malformation, a rare and random birth defect that occurs, according to one study, in about 8 of 100,000 people.