As the testis descends from the retroperitoneal space, the sphincter, which is composed of two layers of peritoneum, also enters the scrotum through the inguinal canal. Normally, around the time of birth, the upper 2/3 of the sphincter is completely closed and the testicular sphincter forms a blind pouch that surrounds the testicle and is called the testicular sheath. A small amount of fluid accumulates in the testicular sheath, which acts as a lubricant for the testicle to move around. If there is an abnormally large amount of fluid in the congenital sphincter or if the sphincter closes abnormally, causing fluid to accumulate in the sack, an effusion is formed. In addition, syringomyelia can also occur when the sheath closure is normal, due to an increase in the amount of fluid within the sheath caused by an infection of the testis or epididymis, an acquired factor such as a tumor, filariasis or trauma. Pediatric syringomyelia is different from that of adults. A careful anatomical study of the pathology of syringomyelia reveals that pediatric syringomyelia almost always has an unclosed syringomyelia duct that communicates with the abdominal cavity. The syringomyelia is usually about 2 mm in diameter, located on the anteromedial aspect of the spermatic cord, and is thin and translucent. Some syringomyelia are thicker, up to 0.5 cm in diameter, and if the syringomyelia is thick enough to allow the intestines to enter, a hernia is formed. Some sphincter ducts are as thin as a hair and can only be identified by careful dissection. In female fetuses, the syringomyelia is called the NüCK duct and descends along the round ligament. The unclosed NüCK duct can also form a syringomyelia, also known as a NüCK duct cyst. Clinical manifestations Syringomyelia can be seen in all age groups of the pediatric population. The vast majority are boys and present as a mass in the groin or on one or both sides of the scrotum. The size of the mass does not vary significantly, but if the diameter of the unclosed sphincter is thicker, the mass may shrink in the morning. Girls occasionally have syringomyelia, which is called Nuck’s cyst. Neonatal syringomyelia is quite common and may be due to continued occlusion of the syringomyelia after birth, which may gradually resolve on its own in some cases. According to the location of the abnormal closure of the syringomyelia, there are basically four types of syringomyelia: (1) spermatic cord syringomyelia: the syringomyelia near the testis is occluded, but the syringomyelia of the spermatic cord is not closed, and the fluid in the abdominal cavity flows through the inner ring into the syringomyelia of the spermatic cord, also known as spermatic cord cyst; (2) testicular syringomyelia: fluid accumulates in the syringomyelia of the testis, and there may be a thin syringomyelia that communicates with the abdominal cavity, but sometimes a live flap-like structure is formed and the fluid cannot flow back, resulting in (3) spermatic cord and testicular syringomyelia: the fluid is located in the spermatic cord and testis, and there is a fine sphincter between the lumen and the abdominal cavity; (4) traffic syringomyelia: the entire sphincter is not closed, and the fluid in the abdominal cavity flows through the sphincter. Diagnosis A mass in the scrotum or groin with clear borders and no obvious continuity with the abdominal cavity; the mass is cystic in nature and has a positive transillumination test. In some cases, its tension can be reduced after repeated compression, but there is no significant volume reduction. If the mass is limited to the spermatic cord, it is usually small, about the size of a finger, and ovoid in shape. The testicle can be clearly retrieved under the mass, and the mass can move with pulling on the testicle. Testicular syringomyelia drapes over the bottom of the scrotum and is oval or round. If the mass is in high tension, the testicle is usually not palpable. If the mass is not in high tension, the testicle can be palpated within the cystic mass. In a few cases, the syringomyelia mass protrudes retroperitoneally and a cystic mass may be palpated in the lower abdomen. Treatment If the sphingomyelomeningocele is not large and the tension is not high, surgery may not be urgent, especially in infants under 1 year of age, as it has a chance to subside on its own. If the tension is high, it may affect the blood circulation of the testis and lead to testicular atrophy, which should be treated by high sphincter ligation. The distal syringomyelia can be left untreated, and it usually regresses on its own 2 to 3 months after surgery, or the syringomyelia can be opened to release the fluid to make it more acceptable to parents. Surgical procedures previously used to treat adult syringomyelia, such as syringomyelia reversal or syringomyelia, have been abandoned for pediatric syringomyelia. Although there are other methods used to treat pediatric syringomyelia, surgical treatment is the safest and most reliable, with a very low recurrence rate. Puncture and drainage alone is difficult to achieve a cure because the unclosed syringomyelia is not treated. After puncture and drainage, injection of certain drugs such as uradan, hydrocortisone, urea, wine, tetracycline, and carbolic acid into the sphincter cavity is also partially effective, but these drugs may cause chemical peritonitis by flowing into the peritoneal cavity through the incompletely occluded syringomyelia, and it is not clear whether the histological reaction caused by the drugs will cause long-term damage to the developing pediatric testis.