Viral meningitis is a lesion of the membranes of the brain that proceeds according to the type of serous inflammatory process and is caused by a viral infection. Like meningitis of another etiology, viral meningitis is manifested by headache, nausea, repeated vomiting, and the presence of meningeal symptoms. Its distinctive features are an acute onset, a slight degree of disturbance of consciousness, a short course and a favorable outcome. Disease is diagnosed on the basis of clinical data, the results of analysis of cerebrospinal fluid and its PCR study. Treatment of patients consists in symptomatic therapy (antipyretics, analgesics), antiviral therapy is carried out according to indications.
A87 Viral meningitis
Viral meningitis is an inflammation of the membranes of the brain (meningitis) caused by the penetration of viruses into them. Unlike purulent meningitis caused by bacterial flora, disease is accompanied by a serous inflammatory process. Serous inflammation is characterized by the formation of a serous effusion, which permeates the membranes of the brain, leading to their thickening. Swelling of the meninges in viral meningitis causes a violation of the outflow of cerebrospinal fluid and leads to an increase in intracranial pressure. However, the serous type of inflammation is not accompanied by mass exudation of neutrophils and the death of cellular elements, so viral meningitis has a more favorable course than bacterial.
Viral meningitis is an infectious disease. Its pathogens can be various viruses that enter the meninges by hematogenic, lymphogenic or perineural pathways. Depending on the type of virus, viral meningitis can occur with contact or airborne infection. Once in the body, viruses penetrate into the subarachnoid space and infect the spider and soft meninges. The spread of viruses into the brain substance with the development of encephalitis is observed in extremely rare cases.
In 75-80% of cases, viral meningitis is caused by enterovirus infection (Coxsackie and ESNO viruses). Less often, the cause is the mumps virus, Epstein-Barr virus (the causative agent of infectious mononucleosis), arenaviruses, cytomegalovirus, herpes infection, adenoviruses. HIV infection can also lead to the development of pathology. However, more often with it, only changes in the cerebrospinal fluid are noted, and viral meningitis has an asymptomatic course. Viral meningitis has a seasonal incidence depending on the type of pathogen. Most cases of the disease occur in the summer, the mumps virus is characterized by a peak incidence in winter and spring.
Viral meningitis symptoms
As a rule, the incubation period takes from 2 to 4 days. It is characterized by an acute onset with a rise in body temperature to high numbers, general malaise and intoxication syndrome. There may be muscle pain, nausea and vomiting, anorexia, diarrhea and abdominal pain. The patient may complain of a runny nose, sore throat and/or cough. Infants have tension or swelling of the fontanel. With viral meningitis, mild disturbances of consciousness are often noted: drowsiness or deafness. In some cases, on the contrary, anxiety and excitement of the patient is possible. In the event of more severe disorders of consciousness (sopor, coma), it is necessary to re-examine the patient and revise the diagnosis.
Viral meningitis is accompanied by a pronounced meningeal syndrome, which can manifest from the first day of the disease or manifest on the second day. It is characterized by a constant excruciating headache, poorly relieved by taking analgesics, repeated vomiting, hypersensitivity of the skin (hyperesthesia) and painful perception of external stimuli (noise, harsh sounds, bright light, etc.). The patient’s position in bed is characteristic: lying on his side, head thrown back, knees brought to the stomach, hands pressed to the chest.
When examining a patient with viral meningitis, excessive tension (rigidity) of the extensor muscle group of the neck is noted, making it difficult to bring the chin to the chest; positive meningeal symptoms. Symptoms of Brudzinsky: upper — with passive bending of the head, involuntary bending of the legs occurs; lower — extension of the leg bent at right angles leads to bending of the second leg. Kernig’s symptom is difficulty passively extending the leg bent at right angles. In infants, the Lesage symptom (hanging symptom) is indicative: if the child is lifted, holding under the armpits, then there is a bending of the legs and pulling them up to the stomach.
Viral meningitis is characterized by a relatively short course. Already on 3-5 days, the body temperature drops to normal figures, although in some cases there is a second wave of fever. The entire period of the disease lasts from 7 to 14 days, on average about 10 days.
The neurologist can suspect viral meningitis by the characteristic complaints of the patient, the acute onset of the disease and the presence of meningeal symptoms. To establish the viral nature of inflammation of the meninges, a lumbar puncture is performed with a study of cerebrospinal fluid, PCR studies and isolation of the pathogen.
Analysis of cerebrospinal fluid in viral meningitis shows a slight increase in protein, normal glucose and leukocytosis. In the first 1-2 days, viral meningitis may be accompanied by neutrophilic leukocytosis of the cerebrospinal fluid, which is more typical for bacterial inflammation. However, the absence of the pathogen during microscopy of differently colored smears of cerebrospinal fluid indicates in favor of the viral etiology of the disease. To confirm it, it is necessary to re-examine the cerebrospinal fluid after 12 hours, in which, in the case of viral meningitis, there is a decrease in the number of neutrophils and an increase in the number of lymphocytes.
Analysis of cerebrospinal fluid allows differentiating viral meningitis from other types of inflammation of the meninges. Thus, with leptospirosis and tuberculosis etiology of meningitis, as well as with its tumor character, lymphocytosis observed in the cerebrospinal fluid is combined with a decrease in glucose levels.
Isolation of the virus is a very difficult task, since it is contained in a small amount in the cerebrospinal fluid, and in other sources (blood, urine, feces, a smear from the nasopharynx) may be present during carrier or after infection without the development of this disease. Therefore, the main modern method of diagnosing the pathogen in viral meningitis is PCR examination of cerebrospinal fluid. Serological reactions for the diagnosis are indicative only if their results are compared at the beginning of the disease and after 2-3 weeks. Due to the long duration of such a diagnosis, it can only be retrospective.
Patients with viral meningitis are additionally given a clinical blood test, biochemical liver tests, determination of the electrolyte composition of the blood, the content of glucose, creatinine, lipase and amylase in it. With an atypical course of viral meningitis and doubts about its diagnosis, it is possible to conduct electromyography, EEG, MRI and CT of the brain.
In relation to viral meningitis, symptomatic therapy is carried out in most cases. The patient is recommended rest, bed rest, being in a darkened room. Analgesics are prescribed to relieve headaches. But often it decreases significantly after a decrease in intracranial pressure as a result of diagnostic lumbar puncture. Body temperature above 38 ° C is an indication for taking antipyretic drugs (paracetamol, ibuprofen, etc.).
Specific and non-specific antiviral therapy is necessary in patients with a weakened immune system and in infants. In such cases, intravenous administration of immunoglobulin is carried out. If viral meningitis is caused by the herpes virus or Epstein-Barr virus, then the use of acyclovir is possible.
In adults, viral meningitis in most cases ends with complete recovery. In about 10% of cases, residual phenomena are noted in the form of asthenia, headache, minor coordination disorders, mild intellectual disorders (memory impairment, difficulty in concentrating, some inattention, etc.). However, they also pass after a few weeks, less often months. In infancy, viral meningitis can lead to severe complications in the form of persistent hearing loss, mental retardation, and intellectual disabilities.