[Syringomyelia and Arnold-Chiari syndrome].

Many hypotheses concerning pathogenesis of syringomyelia were abandoned because of evidence found in more recent investigations. We should rank among them the "classical" theories of Gardner and Williams based on the assumption that syringomyelic cavities result from directing the fluid from the fourth ventricle to the central canal of the spine in the case of disturbances of circulation of the cerebrospinal fluid in the region of the cranio-spinal junction. The theory of intraspinal pulsation pressure of Greitz may explain the pathogenesis of syringomyelia in the case of obstacles to fluid flow from the cranial cavity to the spinal canal as in patients with Arnold-Chiari syndrome. The origin of Arnold-Chiari syndrome is connected with narrowness in the posterior fossa, particularly with narrowing of the arachnoid spaces. Improvement of clinical condition after surgical restoration of the fluid spaces within the posterior cranial cavity and improvement of cerebrospinal fluid flow in the region of the cranio-cervical junction are factors supporting this opinion.