Delayed myelination

Introduction Delayed myelination is one of the myelin abnormalities, usually delayed in myelination of the white matter. Myelination is the final stage of white matter development. During the 3rd to 6th month of the uterus, the fetus develops from the spinal nerve root and the notochord, and from the caudal side to the cephalic side. At birth, a considerable amount of myelin has been located in the brain stem, the pons, the posterior limb of the sac and the radial crown of the semi-oval center. Its maturation process occurs mainly after birth and continues until the age of 20, and the white matter of the myelin sheath is remodeled throughout life.

Cause

Children may develop demyelinating diseases if they are affected by certain secondary factors such as viral infection, asphyxia, poisoning, autoimmune diseases, or certain primary factors such as multiple sclerosis and Schilder's disease. Demyelination has a major impact on the development of the nervous system in children, often leading to mental retardation, epilepsy, language barriers, limited mobility and other disabilities, MRI is helpful for diagnosis.

an examination

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Whole body soft tissue MRI examination CT examination

Diagnosis: The clinical manifestations of white matter malnutrition are characterized by progressive progression, and early symptoms are often overlooked. In normal infants or children, changes in muscle tone, posture, exercise, gait, language, eating movements, vision, memory learning, behavioral thinking, etc. can occur gradually. These signs can be gradually aggravated, and the rate of progression of the disease is faster in children.

Differential diagnosis

Differential diagnosis:

(a) metachromatic leukodystrophy (MLD)

MLD, also known as sulfatidosis, is autosomal recessive, and is a poor myelination caused by defects in arylsulfatase A. Due to the MLD mutation encoding the lysosomal arylsulfatase A (ASA) gene, MLD is located at 22q13.33, which has many types of mutations; it can be roughly divided into two groups: patients with type I mutations cannot produce Viable ASA can be measured in the cultured cells without ASA activity; patients with type A mutations can synthesize a small amount of viable ASA. The patient's phenotype depends on the type of genetic mutation: homozygous for type I mutations or two different type I mutations in clinical manifestations of late infants; one with type I and type A mutations is blue, juvenile Type; when both mutations are type A, they appear as adult. A small number of patients, especially adolescents, are not caused by MLD mutations, and their ASA activity is normal, which is caused by the lack of a lysosomal protein, sulphate sulphate activation factor (SAP1). This type of patient is also known as "activating factor-deficient metachromatic leukodystrophy."

(two) adrenal white matter malnutrition

Adrenal leukodystrophy can be divided into two types in hereditary ways. One is the more commonly X-linked adrenoleukodystrophy (XLALD or ALD for short); the other is autosomal recessive inheritance, which occurs in neonates, called neonatal adrenoleukodystrophy (neonatal adrenoleukodystrophy, NALD).

The diagnosis of adrenal leukodystrophy depends on the following examinations: 1 CT and MRI; 2 electrophysiological examination, early erectile potential and nerve conduction velocity in children. In adult AMN, the nerve conduction velocity is slowed down, and the brainstem auditory evoked potential is abnormal. 3 Cerebrospinal fluid, ALD is mostly normal, and the number of proteins and cells may be slightly increased. NALD common cerebrospinal fluid protein increased; 4 plasma and skin fibroblasts increased VLCFA, especially C26 fatty acid increased, C26 / C22 ratio increased, has diagnostic significance; 5 in the Adidas crisis of adrenal insufficiency, blood In the reduction of cortisol, the ACTH stimulation test also found a decrease in adrenal compensatory reserve in the absence of a crisis. For male Addison's disease, VLCFA should be tested even if no neurological symptoms are seen to avoid missed diagnosis.

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