How is encephalitis diagnosed?

Written by Zhang Hui
Neurology
Updated on September 02, 2024
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The diagnosis of encephalitis cannot rely solely on auxiliary examinations; it must depend on the patient's medical history, clinical manifestations, and corresponding physical examination. If a patient presents with fever, headache, nausea, vomiting, and signs of nuchal rigidity upon examination, the possibility of encephalitis should be considered. Additionally, severe cases of encephalitis may exhibit seizures, cognitive changes, and personality alterations. Auxiliary examinations mainly include three types: the first type is imaging studies, primarily brain MRI, which can clearly identify the specific areas of the brain affected and determine which brain lobe is damaged. The second important examination is an electroencephalogram (EEG), which can detect diffuse slow waves, especially a significant presence of delta waves, highly indicative of encephalitis. The third important auxiliary examination is lumbar puncture for cerebrospinal fluid analysis; an increase in white blood cells and protein in the cerebrospinal fluid also suggests inflammation within the skull. Therefore, the main auxiliary examinations for encephalitis include MRI, EEG, and lumbar puncture.

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Written by Tang Bo
Neurology
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How is a brain encephalitis puncture performed?

The encephalitis you mentioned is considered a central nervous system infection. In this case, a definitive diagnosis requires a lumbar puncture, which you referred to as a puncture. The lumbar puncture requires the patient to be in the lateral recumbent position, then the puncture is performed in the interspaces between L1-L3 or L4-L5 on the back to collect cerebrospinal fluid and conduct tests. This also allows for the examination of pathogens and pressure measurements. After the lumbar puncture, the patient needs to lie flat for six hours with a pillow removed to prevent headaches due to low cranial pressure.

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Written by Tang Li Li
Neurology
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How is encephalitis diagnosed?

The diagnosis of encephalitis relies on the following aspects. First, it is based on clinical manifestations. If the patient clearly exhibits symptoms such as headache, fever, nausea, vomiting, and signs of increased intracranial pressure, and physical examination shows positive signs of meningeal irritation, then there is a high suspicion of encephalitis. Second, various auxiliary tests can be conducted. Initially non-invasive tests such as electroencephalograms (EEG) and magnetic resonance imaging (MRI) of the skull can be completed. If the MRI reveals significant abnormalities, such as abnormal signals in the frontal and temporal lobes including the hippocampus, then viral encephalitis should be highly suspected. If the EEG shows moderate abnormalities or increased slow waves, it also indicates damage to the cerebral cortex, serving as an indirect indicator of encephalitis. Third, a lumbar puncture can be performed to ascertain any abnormalities in the cerebrospinal fluid (CSF) routine and biochemical tests. If the cell count is elevated beyond ten times the normal value, an inflammatory infection is considered. There is often a minor to moderate increase in protein. The levels of glucose and chloride may decrease in bacterial and tuberculous encephalitis, while they are generally normal in viral encephalitis.

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Written by Zhang Hui
Neurology
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Can encephalitis be cured?

The viruses that cause encephalitis are relatively common. Whether they can be cured depends mainly on the type of virus causing the encephalitis, the severity of the condition, and whether the treatment is timely. Generally, most cases of encephalitis, such as those caused by enterovirus infections, tend to self-heal to a certain extent. The focus should be on care to prevent complications, electrolyte disorders, overheating, and to provide appropriate antiviral treatment. Most patients can be cured. However, there are also some more dangerous types of encephalitis, such as encephalitis caused by the type B encephalitis virus, which can rapidly lead to disturbances in consciousness, seizures, and even respiratory involvement, resulting in respiratory failure. This type of encephalitis is more severe and can leave significant sequelae even if successfully treated. For herpes simplex virus encephalitis, as long as the initial symptoms are not particularly severe and antiviral medications are used in a timely manner, the prognosis is still good.

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Written by Zhang Hui
Neurology
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What tests are conducted for encephalitis?

First, it is generally necessary to conduct an EEG test. This test is very convenient and non-invasive for patients. If significant slow waves are detected, encephalitis cannot be ruled out. Secondly, an MRI of the brain should be performed. If the viral encephalitis is severe, abnormal signals can be observed in areas such as the frontal lobe, temporal lobe, and hippocampus on the MRI, which are of great diagnostic reference value. Thirdly, lumbar puncture is also very important. It allows for a direct observation of the color of the cerebrospinal fluid, to monitor the pressure of the brain fluid, and to test the cerebrospinal fluid for cell count, protein, sugar, and chloride levels. These tests are very important for the diagnosis and differential diagnosis of encephalitis.

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Written by Li Jiao Yan
Neonatology
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What to do with pediatric encephalitis

If a child develops encephalitis, it is definitely recommended that they be hospitalized for treatment. It is necessary to assess their condition and determine the cause of the encephalitis: is it viral? Bacterial? Or caused by other pathogens? If encephalitis occurs, aggressive treatment is certainly required. In such cases, if the child is discharged from the hospital, they must regularly revisit the hospital for follow-up examinations, and the development of the child's nervous system must be monitored, focusing on motor and cognitive development. Regular assessments at the hospital are definitely required.