What Are the Causes of Viral Meningitis?

Viral meningitis is a group of diffuse inflammatory syndromes of the pia mater (soft membrane and arachnoid) caused by various viral infections. It mainly displays fever, headache, vomiting, and meningeal irritation. It is the most common sterile meninges inflammation. Most are enterovirus infections, including polioviruses, coxsackieviruses A and B, and ecoviruses, followed by mumps virus, herpes virus, and adenovirus infections. Herpesviruses include herpes simplex virus and Varicella zoster virus. Cerebrospinal fluid is colorless and transparent, with white blood cells dominated by lymphocytes, and sugar and chloride are normal. The course of the disease is benign, mostly within 2 weeks, usually no more than 3 weeks, self-limiting, and the prognosis is good.

Basic Information

nickname: Nonbacterial meningitis
English name: viralmeningitis

Visiting department: Internal medicine
Common causes: Enterovirus infection
Common symptoms: Fever, headache, vomiting, meningeal irritation

Causes of viral meningitis

Most of the diseases are enterovirus infections, including polioviruses, coxsackieviruses A and B, and ecovirus. They are epidemic or scattered, and they are transmitted mainly through the fecal-oral route, and a few are transmitted through respiratory secretions. Followed by mumps virus, herpes virus and adenovirus infection. Mumps virus occurs frequently in winter and spring and is often self-limiting. Herpesviruses include herpes simplex virus, Epstein-Barr virus, cytomegalovirus, and varicella-zoster virus. Arboviruses are viruses that are conserved in nature through transmission between vertebrate and haemophilous arthropod hosts. They are distributed in multiple virus families, and at least 80 species can infect humans.

Clinical manifestations of viral meningitis

Usually acute onset, with severe headache, fever, vomiting, stiff neck, typical meningeal irritation such as Kernig sign, and general malaise, sore throat, photophobia, dizziness, mental fatigue, paresthesia, myalgia, abdominal pain, and Chills, etc. Some patients may have symptoms such as angina and blurred vision. Enterovirus infections can cause rashes, most of which occur concurrently with fever and last for 4 to 10 days. Coxsackie A5,9,16 and ECHO4,6,9,16,30 virus infections. The skin is typically damaged by maculopapular rash. The rash can be limited to the face, trunk, or limbs, including the palms and soles of the feet. Coxsackie B virus infections can include epidemic myalgia (chest pain) and myocarditis. Symptoms of clinical neurological damage are rare, and strabismus, diplopia, sensory disturbance, ataxia, asymmetry of tendon reflexes, and positive pathological reflexes are occasionally found. In severe cases, symptoms of neurological damage such as lethargy may occur.

Viral meningitis test

Peripheral blood white blood cell count and classification test, cerebrospinal fluid examination, craniocerebral CT examination, cranial MRI examination, electroencephalogram examination.

1. Peripheral blood white blood cell count and classification test

The white blood cell count is normal or decreased or slightly increased, the proportion of lymphocytes is increased, and atypical lymphocytes are often present.

2. Cerebrospinal fluid examination

Cerebrospinal fluid is colorless and transparent, pressure is normal or increased, and the number of cells is slightly increased, up to (10 1000) × 10 ⁹ / L. Polymorphonuclear cells are mainly in the early stage, and lymphocytes are mainly in 8 to 48 hours later. And the chloride content was normal, the protein was slightly elevated, and no bacteria were found in smears and cultures.

3. Virological examination

In some patients, the cerebrospinal fluid virus nucleic acid test was positive, the virus culture and the specific antibody test were positive, and the serum specific antibody titer in the recovery phase was more than 4 times higher than that in the acute phase.

4. Imaging examination

CT or MRI of the brain are usually normal.

5. EEG

It can only indicate abnormal brain function and cannot confirm the nature of viral infection. It is characterized by diffuse or localized abnormal slow wave background activity, with a few accompanied by spikes and slow-synthetic waves. EEG can also be normal in some patients.

Viral meningitis diagnosis

The diagnosis of this disease is mainly based on symptoms of acute onset of systemic infection poisoning, meningeal irritation, mild and moderate increase in CSF lymphocytes, and other diseases, etc. The diagnosis of CSF etiology is required.

Viral meningitis treatment

Mainly symptomatic treatment, supportive treatment and prevention of complications. Symptomatic treatment such as severe headache can be used with painkillers, cerebral edema can be appropriately applied with mannitol. Antiviral treatment can significantly shorten the course of the disease and relieve symptoms. Acyclovir is often used for herpes simplex virus and EB virus three times a day. Ganciclovir is the drug of choice for cytomegalovirus meningitis twice a day.