Spina bifida in children
Introduction
Introduction to pediatric spina bifida Spinal fold (spinabifida) is a condition of early pregnancy. When the embryo is developed, the process of neural tube closure is affected and part of the spinal canal is not completely closed. It is a common congenital malformation. Spinal fissure is the main cause of infant death and permanent disability. One of the reasons, therefore, the prevention and treatment of this disease is very important. basic knowledge The proportion of illness: 0.001% Susceptible people: infants and young children Mode of infection: non-infectious Complications: edema, hip dislocation, hydrocephalus, cleft lip
Cause
Pediatric spina bifida
(1) Causes of the disease
To study the cause of spina bifida, it is necessary to understand the normal process of neuronal embryo development. On the 16th day of human embryo development, the ectoderm above the notochord is thickened to form a nerve plate, then the nerve plates on both sides are increased to form nerve pleats and close to the midline, forming a fusion. The neural tube and neural tube fusion originally appeared on the 22nd day, at the level of the 3rd body segment, which is the future brainstem formation area. The fusion starts from the visual primordia and from the brain stem and the primordia to the head and tail. In the direction of development, the anterior neural tube is closed on the 23rd to 26th day of embryonic development. If the closure is not complete, the cranial fissure and no brain malformation are formed, and the posterior neural tube is closed on the 26th to 30th day of embryonic development. If the closure is not complete, the spina bifida is formed.
(two) pathogenesis
Spinal column is a neural tube defect (NTD). NTD is a polygenic genetic disease. Its pathogenesis is extremely complex and multifaceted. Interference with many factors can affect the pathogenesis, according to animal experiments, clinical observations and epidemics. Studies, that NTD is the result of a combination of genetic and environmental factors (intrauterine environment):
Genetic factor
In the study of the pathogenesis of NTD, it is difficult to distinguish multi-gene or multi-effects from complex environmental factors. For example, some families may be related to the environment in which they live together, so that some characteristics are usually attributed to the pathogenesis. As a result of genetic factors, such as changes in the incidence of NTD in different regions and ethnic groups, the incidence of close relatives with NTD is high, and the risk of recurrence within the NTD family is high.
Family studies have shown that pregnant women with a family history of NTD have a higher birth probability for NTD infants than the general population. Cater and Evans studies suggest that as long as one parent has a history of NTD, the incidence of NTD in his offspring is 3%, significantly higher. In the general population, the risk of NTD infants born to mothers who have had 2 or more NTD births increased by 10%. In addition, the incidence of NTD in twins is higher than that of the general population, and single-oval twins are more than double The incidence of NTD in ovarian twins is high, and these findings support the role of genetic factors in NTD.
The results of genetic studies on NTD cannot be explained by the single-gene mutation of Mendel's genetic law, but rather the basis of genetic inheritance, that is, the micro-effect gene, and there is no hidden or dominant difference between the micro-effect genes. It is cumulative, effect accumulation and environmental factors reach a certain threshold to cause disease, so the occurrence of NTD is caused by polygene inheritance. As for the effect of genetic factors on the occurrence of NTD, it has not been determined.
2. Environmental factors
Environmental teratogenic factors in the early pregnancy, usually within 3 months of the mother, resulting in malformations in the development of neural tube defects, common environmental factors associated with NTD including maternal early folic acid and other vitamin deficiency, Lack of zinc and other trace elements, severe pregnancy reactions, viral infections, taking certain medications, alcohol abuse, radiation exposure, and exposure to certain chemicals.
More research is related to the relationship between the deficiency of folic acid and other multivitamins (including vitamin A, B1, B2, C, D, E, niacin, etc.) and NTD in early pregnancy, especially the relationship between folic acid and NTD. Breakthroughs have been made since the 1980s, and it has been determined that early folate deficiency in women is the leading cause of NTD. Insufficient intake, malabsorption, metabolic disorders or increased need can lead to folate deficiency, leading to DNA synthesis. Obstacles, which affect cell division and proliferation, folic acid is a water-soluble vitamin, a nutrient essential for early fetal neurodevelopment, early pregnancy is the embryo differentiation, placenta formation stage, cell growth, division is very strong, if pregnant women folic acid Lack of it will affect the normal development of the fetal nervous system - the normal development of the neural tube, and later will cause poor fusion of the skull or vertebrae, NTD, and cause spontaneous abortion, stillbirth.
The lack of zinc in the mother's early pregnancy is also an environmental factor that causes NTD in the fetus. Insufficient intake of other trace elements such as copper, calcium, selenium, etc. can also induce NTD, but its exact role is still unclear. As for the pregnancy response induced NTD The reason may be that severe vomiting causes loss of water to cause temporary dehydration, resulting in the deficiency of trace elements (such as zinc) or vitamins (such as folic acid).
Virological studies have shown that mothers infected with cytomegalovirus or influenza A virus during the first trimester of pregnancy can cause fetal central nervous system developmental disorders, NTD can occur, and toxoplasmosis infection in early pregnancy can also cause NTD, and the mother receives radiation from the abdomen or pelvis in early pregnancy. The development of the fetal central nervous system is often affected, and some NTD occurs.
Pregnant women with epilepsy take anti-epileptic drugs such as valproic acid, phenobarbital and phenytoin. Their offspring are prone to NTD, oral contraceptives in early pregnancy, and some anti-tumor drugs such as methotrexate and adenine (amino).) and , as well as large or continuous application of cortisone or prednisolone (prednisolone), can induce NTD, and its mechanism may be related to interfering folate metabolism.
Prevention
Pediatric spina bifida prevention
Neural tube defects (including spina bifida) are generally considered to be a polygenic genetic disease. Although the etiology is not fully understood, women taking 400 g of folic acid daily before pregnancy to 3 months of pregnancy can reduce the occurrence of neural tube defects. According to the "B" in pregnancy and the determination of alpha-fetoprotein in serum and amniotic fluid in pregnant women, neural tube defects can be screened in the early and middle stages of pregnancy, which greatly reduces the incidence of neural tube defects.
Complication
Pediatric spina bifida complications Complications, edema, hip dislocation, hydrocephalus, cleft lip
Spinal fissure complications
It can occur cyanosis and edema of the lower extremities, prone to nutritional ulcers, and even gangrene, often muscle contracture, sometimes hip dislocation, clubfoot deformity and so on.
2. Spinal fissure with malformation
Spina bifida may be accompanied by some other rare deformities such as:
(1) Hydrocephalus in the spinal cord: occurs mostly in the thoracic vertebrae, thoracolumbar or lumbosacral region. Many fluid volumes remain in the central canal of the spinal cord, and only atrophic spinal cord tissue is present in the cyst.
(2) No spinal cord: The spinal cord is not developed often with or without brain malformation, and it will die soon after birth.
(3) Dermoid cyst, lipoma or teratoma tissue: may invade the dura mater or spinal cord.
3. Simultaneous malformations
Common malformations with spina bifida are hydrocephalus, deformed foot, skull cavity, meningocele, brain swelling, cleft lip, congenital heart disease.
Symptom
Pediatric spina bifida symptoms common symptoms muscle contracture hip dislocation reflex disappear muscle atrophy spinal cauda equina involvement spinal gliosis proliferative spine edema
Clinical manifestation
Nervous system symptoms are related to the degree of involvement of the spinal cord and spinal nerves. The more common neurological symptoms are lower extremity paralysis, incontinence, etc., such as lesions in the lumbosacral region, lower limb paralysis and muscle atrophy, loss of sensory and tendon reflexes, lower extremities More performance temperature is lower, cyanosis and edema, prone to nutritional ulcers, and even gangrene, often muscle contracture, sometimes hip dislocation, lower extremity often shows clubfoot deformity, often incontinence, some mild cases, nervous system symptoms It may be very mild. As the age of the sick child increases, the nervous system symptoms often aggravate. This is related to the fact that the spinal canal grows faster than the spinal cord and the spinal cord and spinal nerves are gradually increased.
2. Classification
The posterior spina bifida can be divided into the following categories:
(1) recessive spina bifida (spina bifida occulta): This type of malformation is common, only the spinal canal defect, the spinal cord itself is normal, so there is no neurological symptoms, no effect on health, the past thought that the disease and enuresis or other urinary Pathologically related, but the incidence of recessive spina bifida is similar in normal children and children with urinary tract disorders. There are often abnormalities on the skin of the defect site, such as a mane, nest, sputum, pigment. Sinking, subcutaneous fat thickening, etc., there may be congenital cysts or lipomas on the defect, which can be confirmed by X-ray examination.
(2) Spinal fissure with meningocele: There are cysts in the spinal defect, more in the lumbosacral region, the tumor is round, may grow very large, only the meninges inside And cerebrospinal fluid, without spinal cord and other nerve tissue, the disease of the simple meningocele is not paralyzed or other neurological symptoms, the outer wall of the capsule is normal skin, the tumor is rarely secondary infection, such as the wall is very thin or has When ruptured, it often forms cerebrospinal fluid leakage or co-infection.
(3) Spinal fissure with meningomyelocele: mostly occurs in the lumbosacral region, can also be seen in the back, the tumor is round, may be as large as orange, except for the meninges and cerebrospinal fluid, There is also nerve tissue, which is covered with a thin skin. In the central area, it may only be covered with a translucent meninges. In newborns, sometimes only granulation tissue, it is easy to have ulcers, and the spinal cord tissue enters the upper part of the mass. The nerve fibers are widely distributed in the tumor, and then the lower part is returned to the spinal cord part of the spinal canal. The dysplastic spinal cord, nerve, spinal membrane, and vertebral muscles are often connected with the skin. Some children have no spinal cord protrusions. Membrane, without skin covering, is a valgus deformity. These patients have almost all lower extremity spasm and incontinence. Some patients have hydrocephalus, and the sacral spinal meningocele bulges under the outlet of the lumbosacral plexus. There is no sputum in the lower limbs, but the incontinence is still incontinent. When the newborn is crying, it can be seen in the urine. In the case of the baby, the urine cannot be urinated normally.
Examine
Pediatric spina bifida examination
Pediatric spina bifida examination project:
Blood routine, cerebrospinal fluid routine test (CSF), spinal MRI, spinal vertebral body scan, urine routine, spinal mobility, spinal examination, spinal tenderness and sputum pain.
Blood image refers to the general test of blood (formerly known as blood routine examination), which refers to the laboratory test of the number and quality of blood cells in peripheral blood.
Peripheral blood leukocytes were significantly increased in concurrent infections, and cerebrospinal fluid white blood cells were significantly increased during intracranial infection.
The X-ray film of the spine showed the absence of laminar spine, the pedicle spacing was widened, and the bone defect was connected with the soft tissue mass. CT and MRI also showed the cyst contents.
Diagnosis
Diagnosis and diagnosis of pediatric spina bifida
diagnosis
Diagnosis can be made based on typical symptoms. In older children, after better ossification of the vertebrae, X-ray examination can determine whether or not there is spina bifida. CT and MRI are also helpful for diagnosis.
Differential diagnosis
Different from the lower extremity spasm and other causes of hydrocephalus, it is easy to differentiate the diagnosis according to clinical features and auxiliary examination.
1. Lower extremity spasm refers to a disease in which the nervous system is damaged, and the lower limbs of the body are completely or partially lost in motor function after the occurrence of sensory disturbance, and the movement of the free movement is reduced or disappeared.
2. Hydrocephalus is a general term for cerebrospinal fluid production or circulatory absorption process, resulting in excessive cerebrospinal fluid volume, increased pressure, and enlarged space occupied by normal cerebrospinal fluid, which leads to increased intracranial pressure and enlarged ventricles.
