What Are the Causes of Demyelination?

Demyelination refers to the damage to the myelin sheath that occurs after the myelin sheath is formed. Demyelinating diseases are mainly a group of diseases characterized by the loss of neuromyelin sheaths and relatively less involvement of neuronal cell bodies and axons. Two categories of acquisition. Hereditary demyelinating disease mainly refers to white matter malnutrition, which is more common in children. Acquired demyelinating diseases are divided into two types: central and peripheral. The most representative of peripheral demyelinating diseases are acute and chronic inflammatory demyelinating polyneuropathy. Central demyelinating diseases include multiple sclerosis and acute disseminated encephalomyelitis.

Basic Information

English name

demyelination

Visiting department

neurosurgery

Multiple groups

20 40

Common symptoms

Multiple sclerosis, acute disseminated encephalomyelitis, acute inflammatory demyelinating polyneuropathy, chronic inflammatory demyelinating polyneuropathy

Contagious

no

Clinical manifestations of demyelinating

Multiple sclerosis

The age of onset is mostly between 20 and 40 years old, mostly in a subacute manner. Most patients show multiple lesions, and the course of the disease is remission-relapse.

(1) Limb weakness is the most common, and the first symptom of about 50% of patients is one or more limb weakness.

(2) Paresthesia manifests as acupuncture numbness in the limbs, trunk, or face, coldness in the limbs, and ants walking.

(3) Ocular symptoms Acute monocular vision loss and ophthalmoplegia.

(4) Some patients with ataxia can see nystagmus, intentional tremor, and bard-like language.

(5) Paroxysmal symptoms are short-lived and can be induced by special factors.

(6) Most of the mental symptoms are depression, irritability and irritability.

(7) Other symptoms include bladder dysfunction, and male patients may also have sexual dysfunction.

2. Acute disseminated encephalomyelitis

Occurs in children and young adults, and sporadic cases are common. Acute onset usually occurs 1 to 2 weeks after infection or vaccination. Encephalomyelitis usually appears 2 to 4 days after the rash, and often manifests as macular rash subsiding. When the symptoms are improving, there is a sudden recurrence of high fever, accompanied by headache, fatigue, and general soreness. In severe cases, convulsions and disturbances of consciousness occur. Hemiplegia, blindness, visual impairment and ataxia are also common.

3. Acute inflammatory demyelinating polyneuropathy

It can occur at any age, with similar incidence in men and women. Most patients have symptoms of a respiratory or gastrointestinal infection. The first symptom is symmetry weakness in the distal extremities, which quickly worsens and progresses proximally. Severe can cause respiratory paralysis. Flaccid paralysis. Paresthesia is manifested by paresthesia in the distal extremities and decreased gloves and socks. There may be tenderness in the muscles. Bilateral nerve palsy is most common.

4. Chronic inflammatory demyelinating polyneuropathy

Onset at any age, more common in middle-aged men. There is often no history of prodromal infection, mainly manifested as peripheral neuropathy involving sensory and motor involvement. Physical examination showed muscle weakness in the limbs, decreased muscle tone, disappearance of reflexes, and a decrease in peripheral limb sensation.

Demyelination

Multiple sclerosis

(1) The number of mononuclear cells in cerebrospinal fluid examination may be normal or slightly elevated. Intrathecal IgG synthesis or oligoclonal IgG bands are important indicators for the diagnosis of multiple sclerosis. In cytology, small lymphocytes are the most common in the acute phase; activated monocytes and macrophages are the remission phase.

(2) Electrophysiological examinations include visual, brainstem auditory, and somatosensory evoked potentials, which have no diagnostic specificity and assist early diagnosis.

(3) Routine CT scans of imaging studies are normal. MRI is the most effective aid for diagnosing multiple sclerosis. It is characterized by multiple long T ₁ and T ₂ signals in the white matter scattered around the ventricle, corpus callosum, brain stem, and cerebellum.

2. Acute disseminated encephalomyelitis

(1) The white blood cell count of peripheral blood is increased, and the erythrocyte sedimentation rate is increased.

(2) The number of cerebrospinal fluid cells is normal or slightly increased, mainly monocytes. Mild or severely increased protein.

(3) Extensive moderate abnormalities in EEG.

(4) The diffuse multifocal low-density area in the white matter of CT is intensified in the acute phase.

(5) MRI is mostly long T ₁ and long T ₂ abnormal signals.

3. Acute inflammatory demyelinating polyneuropathy

(1) The peripheral blood cell count increased slightly.

(2) The protein-cell separation phenomenon after 2 to 3 weeks of onset, that is, the increase in cerebrospinal fluid protein and normal cell number is a characteristic feature.

(3) The electromyogram shows that the F wave or H reflex is delayed or disappeared, and the nerve conduction speed is slowed down.

4. Chronic inflammatory demyelinating polyneuropathy

(1) The number of cerebrospinal fluid cells is normal, and the protein content is significantly increased.

(2) Electrophysiological examination showed that the movement speed was significantly slowed down and the F-wave latency was prolonged.

(3) Nerve biopsy showed loss of nerve fiber myelin segment with axonal mutation.

Demyelination

Multiple sclerosis

There are currently no effective curative measures. The main purpose of treatment is to inhibit the progression of inflammatory demyelinating lesions in the acute phase and to avoid factors that may promote recurrence. Symptomatic and supportive treatments are taken at a later stage.

(1) The main treatment for acute onset and relapse of corticosteroids is methylprednisolone or prednisone.

(2) -interferon.

(3) Immunosuppressants include azathioprine, methotrexate, cyclophosphamide and cyclosporine A.

(4) The mechanism of immunoglobulin in the treatment of multiple sclerosis has not yet been clarified, and many advocate high-impact therapy.

(5) The effect of plasma exchange therapy combined with hormone or immunosuppressive agent is better.

(6) Symptomatic treatment Painful spasm is best treated with baclofen. For urinary retention of bladder and rectum dysfunction, choose choline-like drugs such as carbamylcholine, and for urinary incontinence choose anti-choline drugs such as probencin fatigue can choose amantadine. Antan was selected for tremor at rest, and propranolol was used for intentional tremor.

2. Acute disseminated encephalomyelitis

Most advocate methylprednisolone or dexamethasone impact therapy, if it is not effective, you can use plasma exchange or immunoglobulin therapy.

3. Acute inflammatory demyelinating polyneuropathy

Treatment methods include immunosuppressive agents, intravenous IgG, plasmapheresis, and dexamethasone or methylponicone. Intensive care and early rehabilitation during bedridden. Keep the airway open, if necessary, perform tracheotomy or ventilator-assisted breathing early.

4. Chronic inflammatory demyelinating polyneuropathy

Immunotherapy includes intravenous immunoglobulin, plasma exchange and hormone therapy, which can achieve better results. Among them, intravenous immunoglobulin is the first choice, and the combination of immunoglobulin and hormone has the best effect.