The names of sacral nerve root cysts are confusing, such as TARLOV cyst, nerve root cyst, perineural cyst, intra-sacral epidural cyst, intra-sacral arachnoid cyst, etc. In 1938, TARLOV first discovered sacral nerve root cysts in 30 autopsies, and in 1972, Osamu Kataoka referred to them collectively as sacral nerve root cysts. It is often misdiagnosed clinically as lumbar disc herniation, spinal stenosis or tumor. Due to the development of medical imaging, especially the application of MRI, the diagnosis rate of this disease has improved significantly. The clinical incidence of sacral nerve root cyst is about 1%-4.6%, and the disease often involves the posterior branch of sacral 2-3 nerve or dorsal ganglion, and MRI and spinal canal imaging can clarify its location and size. 70% of them are asymptomatic, and patients may have lower back pain, sciatica or urinary and fecal dysfunction as well as numbness and discomfort in the sacrococcygeal perineal area, and only 1/5 of them need surgical intervention. Clinical characteristics of sacral nerve root cysts Nerve root cysts mostly occur in S1~S3, and the clinical manifestations are more complicated due to the different nerves involved. Sacral nerve root cysts are mostly manifested as dull pain in the lumbosacral region, and the symptoms are related to the change of position. Since the cysts are mostly connected to the subarachnoid space, cerebrospinal fluid can enter the cysts when standing, causing the cysts to expand and the nerve fibers on the cyst walls to be stretched and compressed, and the symptoms are aggravated. The cerebrospinal fluid can flow out of the cyst in the recumbent position, and the volume of the cyst is reduced, which reduces the tension on the nerve roots, thus reducing the squeeze and pull on the nerve roots, and the symptoms are reduced. The symptoms are generally light in the morning and heavy in the afternoon, aggravated by standing or walking, and can be reduced by resting in bed. In the process of sitting or standing up for a long time, there is often pain in the back and lower limbs. With the growth of age, the cyst also gradually increases in size, and the compression symptoms also increase. There is often intermittent claudication, which is often misdiagnosed as lumbar spinal stenosis in clinical practice. If the sacral nerve roots are involved, the symptoms of compression and irritation of the cauda equina nerve are manifested, mainly abnormal sensation in the saddle area of the perineum, and some manifest urinary dysfunction or sexual dysfunction, burning pain in the anus, and some are misdiagnosed as cauda equina neuroma. The severity of clinical symptoms is related to the size of the cyst and the degree of compression. MRI has a high value in the diagnosis and differential diagnosis of this disease, not only can the site and morphology of the cyst be found, but also the size of the cyst can be measured directly. Minimally invasive CT-guided cyst puncture treated with fibrin adhesive injection Since most sacral nerve root cysts (about 70%) have mild clinical symptoms or no clear neurological symptoms, conservative treatment is feasible. Only a small percentage requires surgical intervention. The traditional treatment of sacral nerve root cysts is surgical occlusion of the lamina and spinous process, ligation and removal of the cyst. After surgical removal of the lamina, the local support of bone and soft tissue is lost, and when standing or abdominal pressure is increased, the influence of hydrostatic pressure can easily lead to cyst recurrence or cerebrospinal fluid leak formation. The procedure is more invasive, bleeding, long and expensive, and has the possibility of damaging nerve roots, and the surgical efficacy is not very satisfactory after years of clinical observation. In 1994, Paulsen et al. reported that CT-guided percutaneous puncture and drainage for sacral nerve root cysts could provide temporary relief of neurological symptoms. In 1997, Paul et al. reported 4 cases of sacral nerve root cysts treated with CT-guided percutaneous puncture bioprotein gel injection, which achieved good results after 7-11 months of follow-up. In 2003, Liu Yujie et al. of Beijing 301 Hospital reported 38 cases of sacral nerve root cysts treated by this method, with an excellent rate of 92%, no infection, nerve injury and cerebrospinal fluid leakage formation, and no recurrence after surgery. The principle of sacral nerve root cyst treatment by fibrin adhesive injection The fibrin adhesive fills the cyst space and blocks the cyst channel to prevent cerebrospinal fluid from entering the cyst cavity. This method can also reduce the tension and pressure of nerve fibers on the surface of the cyst and relieve the symptoms of nerve compression.