Chiari malformations and syringomyelia are conditions affecting the central nervous system of as many as one in 300 people. In other words, it is about as common as Multiple Sclerosis (MS), yet it is still relatively unknown to the layman. The reason why the Chiari malformation and syringomyelia is relatively unknown is probably because of the great variety of symptoms that are related to these conditions, ranging from headaches to paralysis, but they often involve severe pain and decades of suffering. The condition is characterized by a displaced lower part of the brain. The abnormal anatomy of the central nervous system associated with these conditions causes abnormal flow of CSF and have led clinicians to consider the associated hydrodynamics. In fact, it is currently widely believed by both clinical researchers and interest organizations that these conditions are a "mechanics problem". In particular the condition leads to complex flow patterns such as jets, bidirectional flow, and in fact it might even be on the treshold to transition to turbulence.
For further info:
http://cbc.simula.no/pub/bfs/CSF.html