Acute herpes simplex encephalitis

Introduction to acute herpes simplex encephalitis Acute herpes simplex encephalitis refers to the inflammatory response of the brain parenchyma caused by herpes virus infection. Most cases are caused by herpes simplex virus type I. Any age and season can occur (more common in 40 years old), multiple acute onset, incubation period 2 to 21 days (average 6d), prodromal symptoms may have fever, general malaise, headache, myalgia, lethargy, abdominal pain and diarrhea, etc. There is a history of herpes labialis (1/4 patient), and the course of disease is several days to 1-2 months. basic knowledge The proportion of illness: 0.001% - 0.008% Susceptible people: more than 40 years old Mode of infection: non-infectious Complications: brain edema, cerebral palsy

The cause of acute herpes simplex encephalitis

infection

Herpes simplex virus is a neurotropic DNA virus, which is divided into type I and type II. About 90% of human herpes simplex encephalitis is caused by type I. This virus usually causes primary infection of the oral cavity and respiratory tract. 3 weeks, along the trigeminal nerve branch through the axonal retrograde to the trigeminal ganglion, in the form of latent, can induce viral activation when the body's immunity is low, about 70% of herpes simplex encephalitis caused by endogenous virus activation, about 25% of cases were caused by primary infection.

pathology

The pathological changes are mainly edema, softening, hemorrhage and necrosis of the brain tissue. Both sides of the cerebral hemisphere can be diffusely affected, often with asymmetric distribution. The medial temporal margin, marginal system and frontal temporal lobe are most obvious, and the occipital lobe can also be involved. Among them, hemorrhagic necrosis in the brain parenchyma is an important pathological feature. A large number of lymphocytes infiltrate around the blood vessels to form a cuff, microglia proliferate, and diffuse degeneration and necrosis of nerve cells. Eosinophilic inclusion bodies are found in the nucleus of nerve cells and glial cells, and the inclusion of herpes virus particles and antigens in the body is the most characteristic pathological change.

Etiology

HSV is a neurotropic DNA virus surrounded by a stereo-symmetric protein capsid, which is surrounded by a lipid-like capsule. The virus has a diameter of about 150-200 nm and is rectangular under electron microscope. There are two serotypes of HSV, HSV-1 and HSV-2. Type 1 is mainly obtained from lip lesions, and type 2 can be isolated from genital lesions.

Acute herpes simplex encephalitis prevention

1. The past mortality rate is as high as 40%-70%. At present, the application of specific anti-HSV (herpes simplex virus) drugs enables most patients to receive early effective treatment, and the mortality rate decreases. Those under 30 years old and those who only show lethargy survive older or comatose patients. The possibility is great.

2. Strengthen physical exercise to effectively prevent the disease.

Acute herpes simplex encephalitis complications Complications brain edema cerebral palsy

Extensive necrosis and cerebral edema in severely cerebral parenchyma cause increased intracranial pressure and cerebral palsy formation and death.

Acute herpes simplex virus symptoms of common symptoms Common symptoms of meningeal irritation, abdominal pain, diarrhea, cerebral palsy, dysfunction, coma, ataxia, irritability, restless, cold sores, drowsiness

1. It can occur in any age and season (more common in people over 40 years old), multiple acute onset, incubation period 2~21d (average 6d), prodromal symptoms may have fever, general malaise, headache, myalgia, lethargy, abdominal pain and diarrhea Etc., history of herpes labialis (1/4 patient), the course of disease to several days to 1 to 2 months.

2. Common clinical symptoms:

1 headache, strong neck, vomiting, mild disturbance of consciousness and personality change, memory loss, loss of sense of smell, aphasia, hemiparesis, hemianopia, and ataxia, hyperactivity (tremor, dance-like movement, myoclonus) and meninges Stimulus sign.

21/3 patients developed systemic, partial seizures; 3 prominent mental symptoms (fiction, apathy, euphoria, irritability and hallucinations, etc.).

3. The disease progresses rapidly within a few days, and there are many disturbances of consciousness (sleepiness, coma or cortex). In the early stage, coma can also occur. In severe cases, extensive necrosis and brain edema cause increased intracranial pressure, and cerebral palsy is formed and died.

Examination of acute herpes simplex encephalitis

1. Increased cerebrospinal fluid pressure, increased white blood cell count and protein, mainly lymphocytes or lymphoid and polymorphonuclear cells, showing a large number of red blood cells, sugar, chloride normal.

2. EEG can be seen in the chronic high-wavelength slow wave, the temporal region is more obvious, and there may be periodic high-amplitude sharp waves.

3. Brain CT can be found in low-density lesions in the brain, usually in one or both temporal lobe, focal low-density area of hippocampus and limbic system, can be extended to frontal or parietal lobe, scattered in low-density lesions High-density indicates hemorrhagic necrosis of temporal lobe. NRI can be found in frontotemporal lobe lesions, T1WI low signal, and T2WI high signal lesion.

4. Virological examination: double-fold cerebrospinal fluid herpes simplex virus antibody titer increased by more than 4 times; single cerebrospinal fluid above antibody titer >1:80; single serum / cerebrospinal fluid antibody titer 40, serum neutralizing antibody or complement The binding antibody titer gradually increased to more than 4 times.

Diagnosis and diagnosis of acute herpes simplex encephalitis

diagnosis

Diagnosis can be based on medical history, clinical symptoms, and laboratory tests.

Differential diagnosis

1. Brain abscess: difficult to identify at the beginning, can be tested and treated, invalid biopsy.

2. Herpes zoster viral encephalitis: History of thoracolumbar herpes zoster, mild disease, good prognosis, and CSF detect the virus antibody, thereby identifying.

3. Enteroviral encephalitis: more common in summer and autumn, gastrointestinal symptoms at the beginning of the disease, PCR (polymerase chain reaction) detected viral DNA in CSF (cerebrospinal fluid).

4. Cytomegalovirus encephalitis: rare, common in immunodeficiency such as AIDS or long-term use of immunosuppressive patients, subacute or chronic disease, body fluid see giant cells, PCR (polymerase chain reaction) detected in CSF (cerebrospinal fluid) Viral DNA.

5. Acute disseminated encephalomyelitis: history of infection or vaccination, brain and spinal cord damage, corresponding signs.

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