Congenital spina bifida encompasses a group of disorders that are manifestations of various abnormalities arising during the development of the pediatric spinal canal, defined as incomplete or non-fusion of mesenchymal, osseous, and neural structures in the midline of the trunk. It manifests itself in a variety of ways. Many types have been clarified due to the creation of MRI and the increasing understanding of the disease. At present, there are many domestic classification methods and different ways of saying things, which makes the diagnosis, treatment and communication difficult. For this reason, we review the relevant foreign literature, foreign congenital spina bifida recent classification and the current status of surgical treatment is introduced Congenital spina bifida: also known as “spina bifida”, “cryptic spina bifida”, for the spinal axis of the congenital malformation. The most common form is the absence of the spinous process and vertebral plate, and the spinal canal is open to the dorsal side, with the sacrococcygeal region being the most common, the cervical region being the second most common, and other parts being less common. The lesion may involve one or more vertebrae, and in some cases spinal curvature and foot deformities occur simultaneously. Spina bifida is often associated with spinal cord and spinal nerve abnormalities or other malformations, and rarely with craniosynostosis. A small number of patients may develop enuresis and urinary incontinence into adulthood. Some newborn babies have a bulging sac in the lumbar region, the wall is very thin and translucent, and when the baby cries, the tension of the sac increases, and if it ulcerates, it is easily infected and causes meningitis. This type is caused by the spinal strands expanding out of the spinal fissure and is called “spina bifida” or “cystic spina bifida”. If the spinal cord and nerve tissue in the spinal canal also bulge out, it is called “spinal cord spondylolisthesis”, which can produce weakness of the two lower limbs, muscle atrophy, children can walk later, but the gait is lame, the buttocks and the back of the thighs have dull sensation or numbness of the skin, the soles of the feet and the buttocks can be ulcers, urinary and fecal control is not possible, and in adults there are impotence and other symptoms. In a few patients, a section of the spinal cord may be completely exposed to the fissure, and in some cases there may be a thin fibrous membrane covering the surface. This type is called “spinal cord exposure” and has more severe symptoms and is more prone to infection, resulting in a very poor prognosis. Patients with spina bifida often have congenital developmental anomalies in other parts of the body, such as clubfoot, valgus foot, bowed feet, congenital hydrocephalus, and scoliosis. Cryptogenic spina bifida does not require treatment if it does not produce clinical symptoms. Cryptogenic spina bifida with clinical symptoms, spinal bulge and spinal cord spondylolisthesis need surgical treatment, and the earlier the surgery, the better the outcome. Before surgery, the bulging part should be protected to prevent rupture, and if rupture occurs, the bulging part should be sent to the hospital immediately for emergency treatment to avoid infection and meningitis. Congenital spina bifida is called dominant spina bifida according to the different degrees of lesions, and those with bulging out of the contents of the spinal canal are called recessive spina bifida. (1) Myelomeningocele: the spinal membrane protrudes through a large defect in the spinal canal and protrudes backwards. The bulging spinal sac contains neural tissue, soft spinal membrane, arachnoid membrane, and cerebrospinal fluid. This neural tissue includes the spinal cord, cauda equina, and malformed nerve branches. The spinal cord at the level of the bulging spinal sac resembles a primitive nerve plate, sometimes splitting into two, one in the vertebral canal cavity at the base of the bulging spinal sac and one herniated dorsally into the bulging spinal sac. This dysplastic spinal cord is also called a placode. The spinal cord is lowered and embolized by traction. This type has the appearance of a dorsal mass with a fenestrated cystic wall on the surface of the mass and no skin covering. In some cases, there is abnormal skin on the surface of the mass, which is greenish in color, with no subcutaneous tissue, and keloidal degeneration of the dermis, which is directly adherent to the cyst wall. If the cyst is not elevated above the skin surface, the surface shows a purplish-red granulation surface, also known as spinal cord ectasia (myelocele). If combined with the longitudinal split of the spinal cord type II, one or both of the split spinal cord can occur spinal cord expansion, this time called hemimyelomeningocele (hemimyelomeningocele). This type occurs in the lumbar and lumbosacral segments, the most serious neurological damage symptoms, often accompanied by double lower limb dysfunction, foot deformity, bladder-anal sphincter dysfunction, spinal deformities, etc. Chiari Ⅱ malformation and hydrocephalus has a high incidence (99%), followed by hydrocephalus (40% ~ 80%), longitudinal fracture of the spinal cord (30% ~ 40%), and arachnoid cysts (20%), and so on. Vertebral malformations and spinal curvature due to neuromuscular imbalance are also common. The incidence of this form is high, with about 2 out of 1,000 newborns in North America suffering from this condition. Because the disease is easy to diagnose, in order to prevent infection, foreign countries advocate that surgery should be performed within 24 to 48 hours of birth. (2) fat spinal cord spinal bulge (lipomye-lomeningocele): this type of manifestation of various forms, therefore, it can be divided into two subtypes. Type I: localized enlargement of the spinal canal cavity, protruding dorsally through the spinal canal defect to form a mass above the skin surface. The skin surface of the mass is intact and contains cerebrospinal fluid. The spinal cord (also known as the substrate), the cauda equina, and malformed nerve branches may also protrude into the cyst and become adherent to the wall of the cyst, and the spinal cord is thus stretched and embolized. This type is characterized by the presence of subcutaneous fat or lipoma on the surface of the mass, but may not enter the cyst. Type II: The appearance of this type is similar to that of type I, but the dorsal partially expanded dura mater is completely eroded by the subcutaneous lipoma. The normal structure is lost, and a large amount of fat pours into the cavity of the spinal canal through the vertebral canal defect, adheres to and mixes with the spinal cord to grow, and this spinal cord develops abnormally, loses the normal rounded vertebral structure, and becomes elongated and located in the cavity of the spinal canal, with its end located in the lumbosacral region or even in the sacrococcygeal region, and it is split dorsally, and the lipomas or adipose tissue grows into the split spinal cord. The spinal cord is stretched because the fat that has grown into the spinal cord is interconnected with the subcutaneous fat. Both types of lipomyelomeningocele have the appearance of a mass on the back covered with normal skin, some of which may start out small and grow rapidly with age or over a short period of time. The small size is usually rounded, the larger ones are irregular, some have a thin neck-like tip, and some have a broad base. On the surface of the bulge, some have sparse or dense long hairs or/and abnormal pigmentation on the skin, some show capillary hemangiomas, and some have skin depressions of varying depths on or near the bulge. Fatty spinal cord spondylolisthesis can occur in any segment of the spine, most commonly in the lumbosacral, lumbar, or thoracolumbar segments. Clinically, there may be different degrees of lower limb paralysis, foot deformity, gait abnormality and bladder-anal sphincter dysfunction. Some of them are combined with Chiari I malformation (10%), hydrocele (10%) and vertebral malformation. (3) Cystic herniation of the spinal cord (myelocystocele): refers to a cystic enlargement of the spinal cord, which expands dorsally through a defect in the spinal canal. The bulging cyst is essentially a cystic enlargement of the central canal and consists of the dura mater, cerebrospinal fluid, and the dysplastic spinal cord, which is stretched as a result. A cystic herniation of the spinal cord occurs in the lumbosacral region and is called a myelocystocele if it is not covered by skin, or a lipomyelocyst ocele if it is covered by skin and fat. The adipose tissue is only located in the subcutaneous, not into the cyst, and there is a clear demarcation with the cyst wall. Clinical manifestations include sensory-motor disorders of the lower limbs, sphincter dysfunction, and may be combined with gastrointestinal system, genitourinary system, spinal vertebral deformity, and Chiari II malformation. (4) Meningocele: characterized by outward expansion of the spinal membrane from the bone defect, the capsule contains cerebrospinal fluid, and there is no spinal cord or cauda equina. According to the different directions of spinal membrane extrusion, it can be divided into the following five types, of which the other four types can be attributed to occult spina bifida except for simple spinal membrane extrusion in the back. ① Simple posterior meningocele: the spinal membrane protrudes out to the back and is covered by skin. Mostly located in the lumbosacral region, sometimes also occurs in the neck or chest. ② sacral intrasacral meningocele (intrasacral meningocele): the dura mater and arachnoid membrane in the sacral canal protrudes outward toward the dura mater to form a small diverticulum, which communicates with the subdural cavity through the neck opening. Sometimes the high pressure inside the sac can compress the nerve root and produce symptoms. ③ Anterior sacral meningocele: The bulging dura mater and arachnoid membrane passes through the ventral sacral defect and bulges out to the anterior sacral area, which is called anterior sacral meningocele. The sac is usually free of nerve tissue, and sometimes nerve roots can herniate into the sac cavity, producing clinical symptoms. ④ Lateral spinal meningocele: the dura mater and arachnoid membrane protrude through the neural foramen, forming a cystic soft tissue mass on the side of the spine. The lesion can occur on one side or both sides of the spine, and can be single or multiple. 85% of the lesions occur in the chest and can be complicated by multiple neurofibromas. ⑤ Terminal sacral meningocele: refers to a bulging spinal sac located in the region of the coccyx. This type is rare and is sometimes easily confused with cystic teratoma. Spina bifida occulta: Spina bifida often involves the 5th lumbar vertebra and the 1st sacral vertebra. The skin in the lesion area may be normal, or there may be hyperpigmentation, capillary hemangioma, skin depression, localized hirsutism and other phenomena. In infants and young children, the symptoms are often not obvious. If there is a congenital malformation in the vertebral canal cavity, the spinal cord is pulled abnormally during gradual growth in childhood to produce the spinal embolism syndrome. It has been reported that many children may not develop symptoms until adulthood. Occult spina bifida, according to the pathological type can be divided into: (1) longitudinal spinal cord dehiscence (diastematomyelia), which can be divided into two types: Ⅰ: double dural sac double spinal cord, that is, the spinal cord in the longitudinal dehiscence in two, with their own dura and arachnoid membrane, the two are separated by fibers, cartilage, or bony ridges, and the spinal cord is thus stretched. Clinical symptoms are produced. This type accounts for about 50% of cases. Type II: The spinal cord splits in two at the longitudinal fissure, but shares a dura mater and arachnoid membrane; there is no foreign body pulling on the spinal cord, and no clinical symptoms are produced. The most common sites are in the thoracic and lumbar segments, which may be accompanied by hydrocele, end-filament pulling sign and intradural lipoma. (2) Tight filum terminale syndrome. Normal end filaments are composed of ventricular membranes and glial cells. They emanate from the end of the spinal cord and travel downward through the bottom of the dural sac. Fixed to the sacrum, we usually refer to the end filaments within the dura mater as the inner end filaments. The portion of the endofilament that exits the dura mater is called the outer endofilament. In adults, the diameter of the end-filament is <2 mm, and when the end-filament is infiltrated with fatty fibrous tissue and becomes degenerated or even thickened (diameter can be greater than 2 mm), it pulls on the spinal cord and causes neurological symptoms [9]. At this time, the spinal cord may be low or in a normal position. (3) Intradural lipoma: a limited accumulation of fat in the subdural space that is not connected to the subcutaneous adipose tissue of the back. Lipoma usually grows on the surface of the spinal cord, but can also infiltrate into the spinal cord, causing pulling and compression on the spinal cord. (4) Dorsal subcutaneous sinus (dorsal dermal sinus): It can occur dorsal to the cerebrospinal axis, anywhere between the occipital and sacrococcygeal regions, with the sacrococcygeal region being the most common. The sacrococcygeal sinus rarely enters the spinal canal, but if it is located above the sacrococcygeal level, the sinus may cross the dura mater and enter the spinal canal or travel along the surface of the spinal cord. 50% of sinus tracts terminate in a dermatomatous cyst, which may be located at the end of the spinal canal or on the surface of the spinal cord, and the spinal cord may be compressed or stretched as a result. The skin appearance around the opening of the sinus tract is often abnormally hairy, hyperpigmented, or capillary hemangiomatous. Where the sinus tract passes through, there may be skull or spinal canal defects in the corresponding areas. 60% of the children may be secondary to cystic infections, cerebrospinal meningitis. (5) Dermoid or epidermoid tumors: they occur in the lumbosacral region, and about 25% of them are accompanied by dorsal cutaneous sinus tracts. The walls of the cysts are squamous epithelium with many sebaceous glands and hair follicles, and the cysts accumulate oily fluid, which is the secretion or breakdown product of sweat glands, sebaceous glands, and hair follicles. 40% of the cysts are intramedullary, and the rest are extramedullary subdural. Most cysts are present at birth, and because they grow slowly, they usually do not show symptoms until childhood. If a cyst ruptures, oily fluid can spread down the subarachnoid space, leading to chemical arachnoiditis. (6) Split notochord syndrome (SNS): This refers to an embryonic connection between the midgut and the skin of the back. This connection can occur dorsally from the esophagus, stomach, small intestine, and large intestine, and passes through the abdominal cavity or thoracic cavity, the posterior mediastinum in different directions, and crosses the spinal cord to reach the skin of the back. The duct can be interrupted at any location, forming a cyst, diverticulum, fistula, or fibrous fascicle. Depending on the location of the lesion, there are corresponding names, such as abdominal enterogenic cysts, intestinal diverticula and mediastinal enterogenic cysts, etc. If the cyst is in the lumen of the spinal canal, it is called intravertebral enterogenic cysts. The lesion occurs in the upper thoracic or cervical segments and may be located posteriorly in the vertebral body, adjacent to the vertebral body, or within the lumen of the spinal canal. The cyst wall usually has a single or pseudocomplex epithelium without muscular layers, and the morphology of the cyst, the thickness of the cyst wall, and the consistency and color of the cystic fluid are very variable. (7) Hydromyelia: Hydromyelia is an enlargement of the central canal of the spinal cord, which may be confined to the spinal cord alone or in multiple cases, or may occur in association with spinal bulging, longitudinal fissure of the spinal cord, and Chiari malformation. (8) Caudal regression syndrome: It refers to the developmental disorder of the end of the spine, which may be accompanied by neurogenic bladder, renal dysplasia, external genital malformations, anorectal malformations, ankylosing syndactyly, and foot deformities. Terminal bone defects are usually below the 9th thoracic segment. Depending on the level of the defect, there may be different degrees of clinical symptoms, the lower the level of the defect, the milder the clinical symptoms, and the terminal caudal bone defect may have no clinical symptoms. In addition, this disease can be combined with spinal cord bulge, longitudinal fissure of the spinal cord, end-filament pulling sign, latent hair sinus tract and intradural lipoma.