I. Overview
In the early stage of embryonic development, the lower abdominal peritoneum forms a protrusion into the groin and extends to the bottom of the scrotum, called the syringomyelia. The process of syringomyelia occlusion may be abnormal, so that there are different degrees of communication between the testicular sphincter cavity and the abdominal cavity, and the peritoneal fluid accumulates at a certain level through the occluded abnormal syringomyelia, which is clinically seen as syringomyelia (hydrocele). The types of syringomyelia are closely related to the occlusion of the sphincter ducts and are classified according to the location of the syringomyelia: testicular syringomyelia, spermatic cord syringomyelia, testicular spermatic cord syringomyelia, and traffic syringomyelia. The incidence of testicular syringomyelia in full-term male infants is 6%.
II. Etiology
In early fetal life, the testes are behind the peritoneum and in the 7th to 9th month of gestation, the testicular lead extends into the scrotum, guiding the testes as well as the sphincter to their final position. This process is associated with androgen stimulation, adequate terminal receptors, and the genitofemoral nerve. It descends through the inguinal canal into the scrotum, and the peritoneum attached to the testis also descends to form the peritoneal sheath. After birth, the sphincter gradually atrophies and closes over the entire section of the spermatic cord from the internal ring to the testis. In approximately 90% of infants, the sphincter will naturally occlude and degenerate, leaving a small portion of the sphincter attached to the testis, the sheath. The closure of the sphincter can lead to various abnormalities of the inguinal canal. Incomplete closure of the sphincter at different sites can in turn lead to various types of tetrasyringomyelia. There are four types of syringomyelia: testicular syringomyelia, spermatic syringomyelia, testicular spermatic syringomyelia, and traffic syringomyelia. Among them, testicular syringomyelia is the most common.
Pathology and typing
The basic change of syringomyelia is increased secretion or impaired absorption of the sphincter. The diameter of the sphincter is usually about 2mm and is located on the anterior medial side of the spermatic cord. The etiology of primary syringomyelia is unclear; Allen and Rinker found that in some primary syringomyelia the subplasmatic lymphatic plexus of the sphincter was absent, with only a few remnants of the deep lymphatic plexus, which is thought to be due to congenital abnormalities in the development of the sphincter tissue. If the lymphatic system of the sphincter develops late and the peritoneal sphincter closes prematurely before the lymphatic tissue of the sphincter is well developed, the fluid secreted by the sphincter cannot be absorbed and accumulates in the sphincter, resulting in congenital syringomyelia. When the lymphatic system is well developed, it can be absorbed on its own. Pathological examination often shows partial thickening of the sphincter and a chronic inflammatory reaction, so most scholars believe that it is related to chronic inflammation.
Primary non-infectious syringomyelia is an exudate, which is pale yellow, clear and transparent, resembling serum.
IV. Clinical manifestations
(a) It is seen in all age groups of pediatric patients, with newborns and infants being the most common, the majority being boys.
(B) There is generally no systemic condition. A pear-shaped or oval mass with clear borders and no obvious stalk tip into the abdominal cavity is seen in the scrotum or groin. In case of traffic syringomyelia, the size of the mass may change with the change of body position. A small amount of effusion may be asymptomatic; if the effusion is huge, there is discomfort of scrotal drop or urination disorder
(iii) The mass is cystic in nature and the transillumination test is positive.
V. Ultrasound diagnosis of perinatal fetus
Prenatal ultrasound has the potential to detect a cystic mass in the scrotum. pretorius DH et al. studied 123 fetuses and found that 19 fetuses had syringomyelia, 14 spontaneously normalized at postnatal follow-up, 1 had persistent syringomyelia, and 4 others were lost to follow-up. Based on the results, it is concluded that syringomyelia is relatively a common problem in fetuses in late pregnancy, and the advice to the parents-to-be is to reconfirm it after excluding other abnormalities at birth, and that syringomyelia itself is a physiological phenomenon that can resolve spontaneously. However, it needs to be differentiated from fetal hernia and other cystic disorders.
VI. Clinical diagnosis and differential diagnosis
(A) Cystic mass in the scrotum.
(b) Physical examination reveals a spherical or ovoid testicular sphincter with smooth surface, elasticity and cyst-like sensation, no pressure pain, and no palpable testicles and epididymis.
(c) The spermatic cord cyst is often located in the groin or above the testis, and the sphincter of the effusion is clearly demarcated from the testis, pulling the spermatic cord down with it.
(iv) In testicular and spermatic cord sheath effusion, there is a pear-shaped swelling in the scrotum, and the testis is not palpable.
(e) In traffic sphincter effusion, the scrotum is enlarged in the standing position, and the effusion flows into the abdominal cavity when lying down, the sphincter shrinks or disappears, and the testes are palpable.
(vi) Positive transillumination test of the mass.
(vii) Ultrasound examination reveals a dark area of fluid in the mass.
Differential diagnosis
(i) Testicular tumor Testicular tumor is a substantial mass with a hard texture. Ultrasound is helpful for diagnosis.
(ii) Inguinal hernia In inguinal hernia, the upper pole of the enlarged mass is indistinct, and the mass can be retracted when lying down.
VII. Treatment
(I) Indications for surgery and age of surgery.
Some syringomyelia can be self-absorbed before 1 year of age, so syringomyelia that is not large in volume and tension, especially in children within 1 year of age, is generally not treated urgently by surgery. Surgical treatment is usually done after 1 year of age.
Among them, non-traffic testicular syringomyelia does not appear to change shape due to activity and can gradually degenerate spontaneously within 12 months after birth. In contrast, persistent syringomyelia beyond 12 months may be associated with inguinal hernia or open syringomyelia and require surgical treatment. And syringomyelia in older children can occasionally occur after trauma, infection or the presence of a tumor affecting the testis. So surgery’s a must.
For those with higher tension, it may affect the blood circulation to the testes, put pressure on the testicular parenchyma and increase the temperature in the scrotum, thus affecting the morphology and function of the testes and leading to testicular atrophy, so the surgery should be appropriately advanced.
(II) Surgical method
Sphincter high ligation. Needle aspiration and local drug injection are not advocated, nor are testicular syringomy or sphincterotomy. Unclosed syringomyelia can be found in almost all pediatric syringomyelia. In poorly closed cases, the syringomyelia has a white hernial sac-like appearance, and when the white sac-like tissue is cut open, a clear cavity is seen that communicates with the abdominal cavity, similar to an inguinal hernia. In some other cases, the syringomyelia was more translucent and contained fluid, which did not communicate with the cyst, and the fluid in the syringomyelia decreased after squeezing. A part of it showed white fine fibrous cord change.
VIII. Complications and prognosis
(a) Intraoperative damage to surrounding tissues, including: vas deferens, spermatic cord.
(b) The testicular tissue is loose, so scrotal hematoma, infection and pain may occur after surgery. If necessary, drainage strips should be placed at the base of the scrotum.
(iii) The sphincter ligation is not strong enough, and recurrence occurs after surgery.
(iv) Injection therapy: A variety of injection therapies have been proposed in the literature, and although clinically effective, complications due to improper treatment can result in extensive adhesions to the vas deferens and spermatic cord tissue, so the authors believe that such methods should be discarded. For example, pinyamycin is an antibiotic broad-spectrum antitumor drug, which can cause destruction of rapidly proliferating vascular endothelial cells followed by vascular embolism, which is milder than sclerosing agents and does not cause extensive necrosis, and can also inhibit endothelial cell and mesenchymal cell proliferation and promote fibrosis through chemical stimulation, which will inevitably cause extensive adhesions, sclerosis and other complications and make follow-up treatment difficult. Therefore, injection therapy can do more harm than good.