On the outer surface of the testes, epididymis and spermatic cord, there is a thin sheath that contains a small amount of plasma that allows the testes to slide within a certain range. This plasma can be absorbed at a constant rate through the veins and lymph, but if for some reason too much is secreted or too little is absorbed, a cyst can form, which we call a syringomyelia. Clinically, it is often manifested as a cystic mass in the scrotum or inguinal region, which is usually asymptomatic. In a dark room, the scrotal skin of the enlarged mass can be held against the scrotal skin with an electric rod and observed from the opposite side to see if light comes through. There are four main types of syringomyelia: testicular syringomyelia, spermatic cord syringomyelia, testicular and spermatic cord syringomyelia (infantile type) and traffic syringomyelia. Most syringomyelia in children under 2 years of age are self-absorbing and may be left untreated. Small asymptomatic syringomyelia in adults also does not require treatment. Surgery may be considered in cases of traffic syringomyelia above the age of 2 years or when clinical symptoms affect the quality of life. The basic principle of surgery is to destroy the original sphincter cavity, usually by sheath reversal or excision.