[Diagnosis of syringomyelia and its classification on the basis of symptoms, radiological appearance, and causative disorders].

Although it is easier to accurately diagnose syringomyelia with the advent of magnetic resonance (MR) imaging, syringomyelia still poses challenges to clinicians because of its complex symptomatology, uncertain pathogenesis and multiple treatment options. Here, we propose criteria for classification of syringomyelia not related to those associated with spinal intramedullary tumors. The classification aims to distinguish between the presyrinx state and syringomyelia, between asymptomatic and symptomatic syringomyelia and to clarify the associated disorders such as Chiari malformations, spinal arachnoiditis and spinal cord trauma. Diagnostic criteria for Chiari I and II malformations with MR imaging were also defined. Several hypotheses proposed to explain the pathogenesis of syringomyelia associated with Chiari I malformation were reviewed. A questionnaire survey on syringomyelia based on the proposed criteria conducted between November 2009 and April 2010 in Japan revealed that 160 (22.6%) of the 708 patients were asymptomatic. Chiari I malformation was the most frequent causative disorder (48.3%), followed by spinal arachnoiditis (15.8%). The proposed criteria for classification of syringomyelia will facilitate a nationwide survey of syringomyelia in Japan. Such a survey will inform us of its prevalence and prognosis more precisely, and enable us to build a reliable database that may help determine the optimal treatment for the disease in the future.