demyelination
Introduction
Introduction Demyelination refers to a class of diseases in which the myelin is lost or thinned and the axon is relatively intact. The pathological change is the loss of myelin of nerve fibers and the relative maintenance of nerve cells, which affects the transmission of nerve impulses. The acute demyelinated myelin sheath can be regenerated and is more rapid and complete, with little effect on functional recovery. In chronic demyelinating neuropathy, the regenerative nerve membrane cells of repeated demyelination and myelin sheath proliferate, the nerves become thick and axonal, and the functional recovery is incomplete.
Cause
Cause
The cause of demyelination:
The cause is unknown and may be related to the following factors:
1 Genetic factors: HLA-A3, -B7 and -DW2 antigen positive in white and white patients.
2 Human geography factors: The disease is more common in the cold temperate zone and less in the tropics. The incidence of Europeans is high, while the prevalence of the East and Africa is low.
3 Infectious factors: It has been suspected that measles virus, herpes virus and HIV virus are associated with this disease, but even if molecular biology methods are used to detect viral genomes in and around brain tissue, no clear conclusion can be drawn.
Animal experiments have shown that injection of brain tissue components or rabies vaccine can cause demyelinating lesions, suggesting that the disease may be an allergic disease induced by a variety of factors. CD4T (adjuvant) and CD8T (suppressor) cells can be detected in demyelinating lesions, but the exact pathogenesis remains unclear.
Examine
an examination
Related inspection
Neurological examination, nervous system, cytology, spinal MRI
Demyelination diagnosis:
1. Demyelinating disease occurs when the myelin sheath of the cranial spinal cord is lost. There are two types of causes: myelin destruction; myelin formation disorders. Myelitis inflammatory demyelinating disease is currently considered to be an immune-mediated disease, and its clinical features are:
1 patients are children and young adults;
2 acute onset, 1 month before the illness often have a cold, fever, infection, rash, vaccination, cold, childbirth or surgery history;
3 comprehensive neurological examinations can often find evidence of other central nervous system involvement outside the signs of spinal cord symptoms;
4 cerebrospinal fluid examination oligoclonal zone positive;
5 electrophysiology and mri can be found in some subclinical lesions in the brain; mri found white matter abnormal signals in the brain. Some spinal cord inflammatory demyelinating lesions have a "false tumor-like" appearance, and their mri exhibits a mild mass effect, with mild edema around, may have a flaky hemorrhagic signal, and is easily misdiagnosed as a spinal cord tumor. At present, the medical treatment of internal medicine is not effective.
2. Demyelinating myelitis disease symptoms and signs: demyelinating myelitis mostly acute multiple sclerosis (ms) spinal cord type, clinical manifestations and post-infection myelitis similar, but the progress is slow, often in 1-3 It reached its peak within the week. Pre-infection can be inconspicuous, mostly incomplete transverse injury, manifesting weakness or paralysis of one or both lower extremities, with numbness, impaired sensory level or two planes, and urinary dysfunction. Evoked potentials and mri examination may reveal lesions in other parts of cns.
Diagnosis
Differential diagnosis
Differential diagnosis of demyelination:
Demyelinating lesion of cervical spinal cord: It is a disease in which the cervical spinal cord is compressed and damaged by the nerve center. When the disease is serious, it can invade the spinal cord anterior horn cells and brainstem nucleus and brain motor cortex pyramidal cells, which is life-threatening.
First, the history and symptoms: more young and healthy, the symptoms of respiratory infections, or vaccination history within two weeks before the disease. There are causes of cold, overwork, trauma and other causes. The first symptom was numbness and weakness in the lower limbs, back pain and banding in the corresponding parts of the lesion, urinary retention and fecal incontinence.
Second, auxiliary inspection:
1. The white blood cell count in the peripheral phase of the acute phase is normal or slightly higher.
2. Cerebrospinal fluid pressure is normal, some patients have mildly increased white blood cells and protein, and normal sugar and chloride content.
3. Spinal MRI showed thickening of the spinal cord and abnormal signal.
Demyelination of the white matter: Normal myelin, which is already mature, is destroyed, that is, demyelination of the white matter. It mainly includes: multiple sclerosis, progressive multifocal leukoencephalopathy, acute sporadic encephalomyelitis, subacute sclerosing panencephalitis, central pontine myelinolysis, corpus callosum degeneration, subcortical arteriosclerotic encephalopathy and concentricity Round hardening, etc. Onset can be urgent or slow, manifested as: (1) mental symptoms: such as irritability, strong crying, strong laughter, memory loss, etc.; (2) dysarthria or voice differences; (3) visual impairment; (4) ) feelings of fainting or paresthesia; (5) unfavorable or paralyzed limb movements; (6) urinary dysfunction, impotence, etc. The disease has volatility, that is, the symptoms can be relieved by themselves after one attack or relieved after treatment, and can relapse after a period of time. However, each relapse can leave a certain degree of functional impairment, and the general trend is that the condition gradually deteriorates. The prognosis of this disease is generally not very bad, the average survival period after onset is 25-30 years.
Delayed myelination: a type of myelin abnormality, usually delayed by myelination of the white matter. The clinical manifestations of white matter dystrophy are characterized by gradual 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.
