Congenital disorders of the nervous system
Introduction
Introduction to congenital diseases of the nervous system Congenitaldiseasesofnervoussystem, also known as developmentalomalyofnervoussystem, is an acquired neurological or developmental deficient disorder caused by multiple pathogenic factors during embryonic development. Embryonic phase, especially before pregnancy. The nervous system is in a period of vigorous development, and the fetus is vulnerable to pathogenic factors in the mother and the outside, causing developmental disorders, delays or defects in the nervous system, leading to postnatal neurological tissue and various malformations and abnormalities covering the capsule and skull. Congenital diseases of the nervous system are different from hereditary diseases. These pathogenic factors are determined by the outside world rather than by genetics. The incidence of this group of diseases is not high, but the degree of disease is different, and the disease types are various, Dyken and Krawiecki There are hundreds of species listed, some of which are very rare, some are obvious at birth, and some are gradually manifested during the development of the nervous system. Many of the causes and pathogenesis of these malformations are still unclear, and some are intrinsically linked to genetics, or they play a synergistic role. Therefore, it is difficult to draw a clear line with hereditary diseases. Embryonic nervous system structural defects can affect the brain, spinal cord, nerves and muscles and other tissues and organs, often accompanied by eye, nose, skull, spine, ear and heart. Some non-neural tissue deformities can also suggest nerves. System abnormalities are caused by developmental disorders. Some embryonic brain tissue abnormalities may not be accompanied by other tissue and organ defects. It may be due to the longest time required for the development and maturation of the nervous system in all organ systems, so during perinatal and childbirth. The influence of various factors is high. In theory, dysplasia caused by various reasons should be manifested at birth, but if the brain tissue that has not yet functioned at birth is abnormally involved, the fetus will not appear until a certain time after birth. basic knowledge The proportion of illness: 0.003% Susceptible people: no special people Mode of infection: non-infectious Complications: autonomic dysfunction
Cause
Nervous system congenital disease etiology
(1) Causes of the disease
The etiology of congenital dysplasia in the nervous system is not fully understood. It may be affected by teratogenic factors in the fetal early stage, especially in the first 3 months of embryonic development. The causes can usually be divided into 4 groups:
1 single gene mutation, accounting for 2.25 of live infants;
2 chromosomal abnormalities;
3 simple exogenous factors, such as viruses or other infectious agents, radiation or poisoning;
4 The cause is unknown, accounting for about 60% of the total number of cases.
Infants with abnormal nervous system develop obvious symptoms at birth, or gradually develop symptoms during the development of the nervous system after birth. If all pre-existing diseases can be classified into hereditary and non-hereditary (congenital), there will be Help clinicians and researchers to understand these diseases in depth. However, most diseases have no characteristic pathological changes in the early stage of embryonic development, so it is difficult to classify them. For example, the neural tube is not closed. The spine spine is in a There may be several cases in the family, but the current technical means can not be determined whether genetic factors work, or exogenous factors such as folic acid deficiency affect several fetuses during the mother's continuous pregnancy.
Congenital diseases of the nervous system are mainly divided into two categories according to the cause.
One is the developmental disorder of the brain and nervous system in the uterus, the production of some neurons, migration and tissue abnormalities, resulting in postnatal skull, nerve tissue and covering capsule malformation and mental retardation. The main reason may be hereditary and some environmental factors. Affect the embryo or fetus.
The other type is caused by birth injury and asphyxia during childbirth. Due to over-extrusion of the head or prolonged hypoxia, brain tissue damage and developmental abnormalities are eventually accompanied by damaged structures and dysfunctional brains. It is necessary to accept the wisdom and functional correction treatment for life. In addition, congenital factors are sometimes difficult to distinguish with acquired causes such as birth injury, asphyxia and neonatal metabolic disorders, but fetuses with congenital defects are more susceptible to poor delivery or postpartum period. The impact of environmental factors.
During the embryonic period, especially in the first 3 months of pregnancy, the nervous system is in a period of vigorous development. The fetus is susceptible to various pathogenic factors in the mother's internal and external environment, and the symptoms may occur at birth, or gradually appear during the development of the nervous system after birth. The difference between this group of diseases and hereditary diseases is that the cause is more of a self or environmental factor, while the latter is determined by genetics.
(two) pathogenesis
Congenital malformation is a developmental abnormality caused by some of the above-mentioned external or internal factors during embryonic development. In theory, it should be different from the developmental disorders caused by acquired damage, but the effects on infants and diagnosis are congenital. Sexual factors are sometimes difficult to separate from acquired causes (such as brain injury caused by childbirth, asphyxia, metabolic disorders in the neonatal period, etc.). Infants with congenital defects are more susceptible to environmental factors during birth and postpartum than normal infants. The effects, such as cerebral palsy, bilirubin encephalopathy, may be complicated by its pathogenesis.
Common teratogenic factors in this group of diseases include:
1. Infection: The mother is infected by viruses (common to rubella virus), bacteria, spirochetes and protozoa. The pathogen invades the fetus through the placenta, causing congenital infection or malformation of the embryo, such as congenital heart disease, abnormal brain development, hydrocephalus, Cataracts and congenital deafness.
2. Drugs: androgen, adrenocortical hormone, benzodiazepines and nitrogen mustard have been confirmed to cause teratogenicity in the fetus, antithyroid drugs or iodine/P>
3. Radiation: 4 months before pregnancy, the mother's lower abdomen and pelvis receiving radiation therapy or strong -ray radiation can cause microcephaly and cerebellum, eyeball malformation.
4. Pregnant women with diabetes, severe anemia or carbon monoxide poisoning can cause fetal nervous system developmental malformation, ectopic placenta can lead to fetal nutritional disorders, excessive amniotic fluid causes excessive intrauterine pressure, causing fetal distress and hypoxia; Pregnant women with depression, anxiety, fear, nervousness and alcoholism, smoking, etc. all affect fetal development.
Pathological manifestations: the diseases caused by the above-mentioned pathogenic factors, some have specific signs, such as the tongue syndrome (Down syndrome); most diseases are anatomical malformations or dysfunction; or manifest as non-specific disorders, Such as hydrocephalus, spina bifida, congenital cataract, etc., different pathological manifestations may be related to harmful factors acting on different stages of embryonic development.
Prevention
Nervous system congenital disease prevention
Pay attention to maternal and child perinatal health care and neonatal feeding care to prevent premature babies, low birth weight, hypoxia and postpartum jaundice.
Complication
Nervous system congenital disease complications Complications, autonomic dysfunction
Most diseases often involve other malformations and/or have neurological dysfunction.
Symptom
Nervous system congenital disease symptoms common symptoms nodular intelligence disorder brain penetrating malformation dysphagia faint muscle myoclonus
Congenital diseases of the nervous system can be roughly divided into the following types. In addition to structural malformations, they are often associated with dysfunction and obvious mental (smart) developmental delay. The specific clinical manifestations can be found in related content.
1. Skull and spinal deformity:
(1) neural tube closure defects: skull fracture, spina bifida and related malformations, although more common, but the light does not show any symptoms, but not found.
(2) Cerebrospinal fluid system developmental disorders: midbrain aqueduct lock, fourth ventricle median hole, lateral hole atresia, etc., due to cerebrospinal fluid circulation disorders, leading to congenital hydrocephalus.
(3) Other cranial malformations: cranial stenosis, occipital macropore deformity, microcephaly, congenital skull defect, multiple bone development disorder (also known as fatty cartilage dystrophy, Hurler syndrome), due to congenital Caused by defects in mucopolysaccharide metabolism.
Clavicular skull ossification is a rare hereditary syndrome. The ossification of the midline of the skull is slow. The anterior iliac crest, the frontal and sagittal sutures are not closed for a long time; the bilateral clavicle is completely or mostly missing; the spine often has flexion deformity. The clinical manifestations are short stature, wide head and flat, increased shoulder adduction, squat limb paralysis, and mental retardation.
Eye hypertelorism is also a rare craniofacial deformity, the sphenoid winglet is widened, the sphenoid wing is narrowed, the clinical manifestation is wide and flat, the nose is flat, the distance between the eyes is increased, strabismus, intelligence Dysplasia and so on.
2. Nerve tissue development defects:
(1) cerebral cortical hypoplasia:
1 widening of the brain: the cerebral cortex has a simple texture, the sulci is reduced, the cerebral gyrus is widened, and the cortical structure is often only 4 layers.
2 The brain is narrow: some cortical textures are complex, the sulci is increased, and the sulcus is shallow, the cortex is scattered in the induration, the nerve cells are uneven in size, and the dendrites are reduced.
3 atrophic sclerosis of the brain: local or diffuse cerebral atrophy, hardening, neuronal degeneration, gliosis.
4 Nerve cell ectopic: embryonic nerve cell migration process is abnormal, nerve cell ectopic occurs, immature nerve cells appear in white matter, or the appearance is normal, but microscopic examination shows that the number of nerve cells is sparse, unevenly arranged, and glial fibers increase.
(2) Congenital brain penetrating malformation: it is a developmental defect of the local cortex, the ventricle is open to the surface like a funnel, and the wall is a cortex with a pia mater, which often occurs bilaterally symmetrically.
(3) Congenital brain hydrocephalus (hydrocephalus): cystic degeneration of the brain during development, complete or partial loss of the two hemispheres in the cranial cavity, and one or both sides of the single lobe missing, Such as the absence of temporal lobe, the site is replaced by arachnoid sac, the sac is filled with cerebrospinal fluid, the skull and brain stem are normal, but due to long-term pulsation of the cyst, compression, the local skull can be thin, deformed, the head of the child is large, before, After the sputum and the suture widened, more slumber, sucking, swallowing dysfunction, light transmission test can be seen in the cyst area.
(4) No brain malformation: the brain is completely absent, and the scalp and calvaria are also missing. Only the basal nucleus is covered by fibrous connective tissue. After birth, the baby cannot survive and soon die.
(5) Giant brain malformation: the performance of the head is large, the brain volume symmetry is increased, the number of neurons, the size increases, but the ventricles are correspondingly narrow, often accompanied by intelligent obstacles.
(6) corpus callosum dysplasia: complete or partial loss of corpus callosum, often accompanied by other malformations, such as hydrocephalus, microcephaly and intracranial congenital lipoma, clinically, no symptoms, can be expressed as epilepsy and / or Insufficient intelligence, air cerebral angiography showed a significant increase in the distance between the anterior horns of the lateral ventricles and an enlargement of the third ventricle.
(7) Congenital bilateral hand and foot hyperactivity disorder: also known as Vogt syndrome, the pathological features of the microscopic examination of bilateral caudate nucleus and coronary nucleus myelin fibers increased, nerve cell reduction and gliosis, called marble-like state ( Status marmoratus), occasionally basal ganglia fibrous insufficiency, called the status of myelin dysmyelinatus, the cause may be fetal developmental disorders, birth injury or neonatal asphyxia, children with developmental delay, muscle tone and rigidity, born weeks to After a few months, the involuntary movements of the parts of the body slowly squirming gradually appeared. The ends of the extremities were more obvious. They often had difficulty in eating and swallowing. A few children showed dance-like movements, twisting sputum, and myoclonic movements. Tremor or simple muscle tension, this disease can coexist with cerebral palsy and mental dysplasia, and can be progressively enhanced, stereotactic surgery may alleviate symptoms.
(8) Congenital cerebellar hereditary ataxia.
(9) Congenital mental retardation.
3. Congenital myopathy.
4. Neuroectodermal dysplasia: phakomatoss, also known as neurocutaneous syndrome, is a common neuroectodermal dysplasia, such as tuberous sclerosis, multiple neurofibromatosis, Sturge- Weber syndrome, ataxia-telangiectasia and retinal cerebellar hemangioma, others such as Wyburn-Mason syndrome (retinal hemangioma with cerebral or spinal hemangioma and syringomyelia), Bloch-Sulzberger syndrome (polymorphous skin pigmentation with microcephaly, epilepsy, mental dysplasia, limb paralysis, and congenital heart disease, glaucoma), Sjögren-Larsson syndrome (congenital psoriasis with cerebral palsy and mental dysplasia) Acanthosis nigricans (skin pigmentation and sputum lesions associated with epilepsy and mental dysplasia) are rare congenital neuroectodermal diseases.
5. Metabolic dysfunction.
6. Speech function development is incomplete:
(1) Congenital auditory aphasia: Although the patient's hearing and intelligence are normal, there are different degrees of understanding of the language that is heard. In severe cases, the speech cannot be understood at all. The cause is unknown, and there is often a family history.
(2) Congenital visual aphasia: The patient's visual acuity and intelligence are normal, but they can't be read. When copying, there are often anti-writing and miswriting, and there is often a family history.
7. Intelligent developmental insufficiency caused by various causes.
8. Cerebral palsy.
9. Bilirubin encephalopathy.
Examine
Examination of congenital diseases of the nervous system
Blood, urine, routine examination; cerebrospinal fluid examination; blood immunology.
1. Radiological examination: X-ray film, CT and MRI.
2. Prenatal diagnosis: fetal amniotic fluid chromosome, genetic examination.
Diagnosis
Diagnosis and diagnosis of congenital diseases in the nervous system
At present, there is a lack of specific diagnostic indicators for congenital diseases of the nervous system, which are mainly determined according to clinical symptoms, signs and laboratory auxiliary examination items after birth.
Note the differentiation from neurological damage caused by secondary diseases after birth.
