syringomyelocele /siring′gōmī″əlōsēl′/ [Gk, syrinx + myelos, marrow, kele, hernia] , a hernial protrusion of the spinal cord through a congenital defect in the vertebral column. The cerebrospinal fluid within the central cavities of the cord is greatly increased so that the cord tissue forms a thin-walled sac that lies close to the membrane of the cavity. See also myelomeningocele, neural tube defect, spina bifida.