[Current surgical treatment of Chiari type I malformation and Chiari I-syringomyelia complex]

Chiari type I malformation and so-called Chiari-I/syringomyelia complex continue to inspire controversy. Disagreement on these malformations concern both etiopathogenesis and treatment. Our still poor understanding of the natural course of the disease, the lack of consensus regarding therapeutic indications and even disagreement on appropriate surgery all contribute to cause disagreement. Significant progress has been made in our understanding of contributing etiopathogenetic factors in recent years. The most widely accepted hypothesis is that anomalous embryonic development characterized by paraxial mesodermal insufficiency would put volumetric constraints on postnatal development of the posterior fossa. We review historical and current controversies regarding Chiari type I malformation and classic theories on causative and contributing factors. We also discuss the latest surgical treatments that have been suggested, as well as associated anomalies--mainly syringomyelia, hydrocephalus and malformed cranial-cervical articulation. Finally, we propose a protocol useful for the diagnosis and treatment of Chiari type I malformation associated with dilation of the ventricular system.