Acute disseminated encephalomyelitis

Introduction to acute disseminated encephalomyelitis Acute disseminated encephalomyelitis is a cellular immune response to the central nervous system-specific sequence caused by viral infection or vaccination (such as rabies vaccine or vaccinia), resulting in a perivascular neurological immune response and causing Dilated inflammation of the brain and spinal cord. Acute disseminated encephalomyelitis, also known as encephalomyelitis after infection, encephalomyelitis after vaccination, refers to acute rash disease secondary to measles, rubella, chickenpox, smallpox, etc., or caused by immune dysfunction after vaccination Demyelinating disease in the central nervous system. basic knowledge The proportion of illness: 0.003% Susceptible people: no specific population Mode of infection: non-infectious Complications: urinary tract infections acne

The cause of acute disseminated encephalomyelitis

Virus infection (35%)

Especially measles or varicella virus, many patients with encephalomyelitis are secondary to common respiratory infections, such as EB virus, cytomegalovirus and mycoplasma pneumonia virus infection, the main pathological changes are brain, brain stem, cerebellum, spinal cord dissemination Sexual demyelination changes, white matter around the ventricles, temporal lobe, optic nerve, demyelination is often centered on the venules, inflammatory cells infiltrate the small veins, and the outer layer is dominated by mononuclear cells. Invasive, ie, vascular cuff, loss of white matter myelin around the vein, and scattered glial cell proliferation.

Drug factor (25%)

Encephalomyelitis is also seen in rabies. After vaccination with smallpox, it is occasionally reported after tetanus antitoxin injection. It is generally considered that acute disseminated encephalomyelitis is an immune-mediated demyelinating disease of the central nervous system.

Pathogenesis:

Immunization of animals with brain tissue and Freund's complete adjuvant can result in experimental animal model EAE, which has the same characteristic venous demyelinating and inflammatory lesions as human MS, presumably T cell-mediated immune response, and is considered to be ADE Acute MS or its variant.

The pathological features are scattered in the brain and a large number of demyelinating foci in the spinal cord. In some cases, the lesions are limited to the cerebellum and the spinal cord. These lesions range from 0.1 mm to several millimeters. They are located around the small and middle veins, and the lesions in the brain are multiple. Bilateral symmetry, fusion tendency, mainly affected by semi-oval center, affecting the amount, top, occipital and island leaves, optic nerve, optic chiasm and brain stem; severe loss of white matter and necrosis of the white matter, involving the neck, thoracic segment and The lumbar segment; the degree of old and new lesions is the same, which is different from multiple sclerosis. The axons and nerve cells are basically intact. When the lesions are severe, the axons are also slightly damaged, the inflammatory cells infiltrate obviously, and the surrounding small veins are inflammatory. There is a cellular response composed of pleomorphic microglia in the corresponding area of myelin deprivation; a perivascular sheath composed of lymphocytes and monocytes can be seen; multifocal meningeal exudation is another essential feature, but generally Nothing serious.

Acute disseminated encephalomyelitis prevention

Further improving the preparation process of the vaccine, so as to preserve the better antigenicity, reduce the effect of inducing or inducing vaccination encephalomyelitis, and change the prevention method can reduce the occurrence of encephalomyelitis after vaccination.

Acute disseminated encephalomyelitis complications Complications, urinary tract infection, acne

As the disease progresses, the symptoms and signs that appear may be the primary disease manifestations, and can also be regarded as complications (see clinical manifestations). In addition, secondary lung infections, urinary tract infections, hemorrhoids, etc. should be noted, and the mortality rate is high. Most of the survivors have different levels of disability, and some patients can fully recover.

Acute disseminated symptoms of encephalomyelitis common symptoms high fever irritability, restlessness, involuntary movement, radiation pain, convulsions

Most cases are children and young adults, acute onset 1 to 2 weeks after infection or vaccination, mostly sporadic, no seasonal, serious condition, some cases are dangerous, after the rash, encephalomyelitis is common after rash 2 ~ 4 days, the patient often disappeared in the rash, and suddenly there was high fever, seizure, lethargy and deep coma when the symptoms improved.

Clinically, it can be divided into the following types:

1. Encephalomyelitis after vaccination

The rabies vaccine, vaccinia, measles vaccine, and JE vaccine can occur. The incidence of rabies vaccine is the highest. Recently, due to improved vaccine preparation technology, the disease has been less common. The incidence of vaccination is obviously high, usually more common 2 to 15 days after vaccination, acute onset, sudden onset of fever, severe headache or spinal nerve root radiation pain, vomiting, convulsions, varying degrees of disturbance of consciousness, meningeal irritation positive, etc. Symptoms, followed by rapid emergence of quadriplegia (often flaccid, then converted to spasm) or hemiplegia, positive pyramidal tract, bladder and rectal sphincter disorders, may also be associated with pupillary changes, nystagmus, extraocular muscle paralysis , speech disorders, etc., the mortality rate is high, most of the survivors left different degrees of disability, and some patients can fully recover.

2. Encephalomyelitis after infection

The disease with the highest incidence is measles, followed by chickenpox, rubella, mumps and flu. It is more common after 7 to 14 days after viral onset or 2 to 4 days after rash. Acute onset is generally viral for patients. After the infection, the fever subsides again, and suddenly there is severe headache, convulsion, disturbance of consciousness, hemiplegia, and then there is obvious loss of intelligence, aphasia, blindness and cranial nerve damage; those with subarachnoid damage may have involuntary movement of extrapyramidal; with cerebellar damage There may be exercise ataxia; spinal cord lesions may have varying degrees of paraplegia, some of the survivors may have different disabilities, such as limb paralysis, mental retardation, personality change, blindness, aphasia and cranial Nerve paralysis and so on.

3, acute necrotizing hemorrhagic encephalomyelitis

Also known as acute hemorrhagic leukoencephalitis, it is considered to be ADE fulminant, rapid onset, dangerous condition, high mortality, high fever, blurred consciousness or coma, deep irritability, seizures, hemiplegia or quadriplegia; CSF pressure increased, the number of cells increased, EEG diffuse slow activity, CT sees the brain, brain stem and cerebellar white matter irregular low-density area.

Examination of acute disseminated encephalomyelitis

Laboratory inspection

1. Peripheral blood leukocytosis, erythrocyte sedimentation rate.

2. Cerebrospinal fluid pressure increased or normal, CSF-MNC increased, protein mild to moderate increase, mainly IgG increased, oligoclonal bands were found.

Film degree exam

1. EEG common and waves, also see the spike and spine slow complex.

2. CT showed diffuse multifocal large or patchy low-density areas in the white matter, which showed a significant enhancement effect in the acute phase. MRI showed multiple T1 low signals and T2 high-signal lesions in the white matter of the brain and spinal cord.

Diagnosis and differentiation of acute disseminated encephalomyelitis

Diagnose based on

According to diffuse lesions of brain parenchyma after acute infection or vaccination, meningeal involvement and symptoms of myelitis, increased CSF-MNC, extensive and abnormal EEG, CT or MRI showed multiple scattered lesions in the brain and spinal cord. clinical diagnosis.

Differential diagnosis

The disease needs to be differentiated from Japanese encephalitis and herpes simplex encephalitis. There is a clear epidemic season for Japanese encephalitis, and ADE is sporadic. Encephalitis and myelitis can be differentiated from viral encephalitis.

1. Herpes simplex virus encephalitis: can be sporadic, repeated herpes labialis before or during the onset of the disease, other prodromal symptoms are not obvious, with the most prominent mental symptoms, high fever and convulsions and high intracranial pressure, etc. In a coma, the mortality rate is extremely high, hemorrhagic changes can be seen in the cerebrospinal fluid, and specific IgM antibodies can be detected. The electroencephalogram is mainly caused by changes in the frontal and temporal lobe, which can be delayed or epileptiform, bilateral asymmetry It is more meaningful to have repeated lobes on one side. Both CT and MRI can show bleeding changes in the frontal and temporal lobes, which are different from acute disseminated encephalomyelitis.

2. Epidemic encephalitis: seasonal onset, mostly from July to September, insect-borne transmission, acute onset, manifested as high fever, headache, convulsions and high intracranial pressure symptoms, involving the brain, cerebellum, brainstem and spinal cord Such as multiple parts, can show symptoms of systemic poisoning, peripheral white blood cells increased, mostly neutrophils, cerebrospinal fluid in the early stage of neutral polymorphonuclear leukocytes, 4 to 5 days later can be converted to lymphocytes, the incidence Specific antibodies can be detected after 2 weeks, and MRI is a symmetric bilateral thalamus and basal ganglia lesion.

3. Acute hemorrhagic viral encephalitis: Most scholars believe that the type of acute disseminated encephalomyelitis is a sudden onset, the disease is dangerous, the mortality rate is extremely high, more than a few days after the onset of the disease, the spinal cord is affected. Symptoms are less common than brain symptoms, or masked by brain symptoms. Peripheral blood and cerebrospinal fluid can be significantly increased in white blood cells, mainly neutrophils, reflecting the abnormal activity of the immune system. Imaging can be in softening and necrotic foci. Hemorrhagic foci are seen inside or around, and are also diffuse, mostly lamellae. Some cases have been reported to progress from ADE to acute hemorrhagic leukoencephalitis by magnetic resonance. The possible cause is in Hurst's earliest pathological report. Described as venules and perivascular red blood cell exudation, vascular wall necrosis, polymorphonuclear leukocyte infiltration and glial cell response, may be in more serious cases, while demyelination, microvascular surrounding damage, vascular matrix Edema, the lesion gradually merges to form a relatively large lesion, which leads to the occurrence of hemorrhage. The findings of magnetic resonance prove that acute hemorrhagic leukoencephalitis is Acute dissemination.

4. Multiple sclerosis: acute dissemination is the main difference between the disease and MS. MS is theoretically scattered, multiple lesions, not diffuse, and multiple occurrences, recurrence-remission course, clinically Some patients with MS can be more acute, and lack of recurrence-remission characteristics, and the course of disease is relatively short, showing a single-phase course. This type of patient is associated with pathology and pathophysiology as well as ADE. It is difficult to identify, some scholars believe that this is a transitional type. From the perspective of clinical practice, demyelinating diseases are their common points, and for patients with rapid onset and rapid progress, specificity is adopted in time. The treatment is the most important to save the endangered organization.

The differential diagnosis of ADE and MS is very important for the judgment of prognosis. It is also very difficult. In terms of the first onset, ADE often has a relatively diffuse central nervous system disorder, accompanied by coma, lethargy, convulsions and involvement of the brain, spinal cord. And multiple lesions of the optic nerve, and MS often presents a single symptom, or optic nerve damage, or subacute myelopathy, optic nerve damage in ADE is bilaterally involved at the same time, spinal cord lesions are mostly complete, reflex loss; and in MS Optic nerve damage is often unilateral, and spinal cord lesions are often incomplete. ADE is often infected or vaccinated before ADE, and MS does not necessarily have such a precursor, but these factors make MS symptoms recur, so it is not There is an absolute difference. Cerebrospinal fluid index is not specific for differential diagnosis. Cell elevation can also occur in MS. Although oligoclonal bands are a feature of MS, ADE can also occur. However, the oligoclonal region of MS can be more persistent. By follow-up observation, there is a certain significance in the identification of the two, so an episode of clinical symptoms and cerebrospinal fluid alone cannot Effectively distinguishing between the two, ADE is often a multifocal asymmetric model on magnetic resonance images, which is difficult to distinguish from MS. Typical ADE is a relatively symmetrical lesion involving the brain and cerebellar white matter, and also involving the basal nucleus. It is reported that the latter is extremely rare in MS. The lesions of MS are asymmetrical. The size of the lesions is different from that of old and new. If the old and new lesions coexist in imaging, the diagnosis of MS is supported. The difference between ADE and MS is that it is a single. Time-phase, so multiple magnetic resonance examinations in the period of improvement and sequelae can help to differentiate the diagnosis. According to Poser's standard, MS reappears for more than 1 month, and the symptoms are recurrence. Therefore, in demyelinating diseases, it is best to at least Clinical and magnetic resonance follow-up was performed every 6 months for 2 consecutive years.

It is also necessary to consider the extensive invasion of the central nervous system such as multiple metastases and hematological tumors, as well as rare diseases such as acute encephalopathy caused by vitamin deficiency, and consider the possible effects of medical diseases while considering neurological diseases.

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