Excess cerebrospinal fluid in the central canal of the spinal cord is called [[hydromyelia]]. This term refers to increased cerebrospinal fluid that is contained within the ependyma of the central canal. When fluid dissects into the surrounding white matter forming a cystic cavity or syrinx, the term [[syringomyelia]] is applied. As these conditions coexist in the majority of cases, the term syringohydromyelia is applied