How to check for encephalitis?

Written by Zhang Hui
Neurology
Updated on August 31, 2024
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To check for encephalitis, the main aspects of examination include the following. First, a complete blood count is necessary, which helps to determine if there is an increase in white blood cells and to assess the proportion of various types of white blood cells; this is a basic test. The second examination is an electroencephalogram (EEG), if the EEG shows abnormalities, it may suggest a diagnosis of encephalitis. The third examination involves cranial magnetic resonance imaging (MRI). If the encephalitis is severe, the MRI can reveal lesions, which also suggests a diagnosis of encephalitis. The fourth examination is invasive, involving a lumbar puncture. This test allows for the analysis of cerebrospinal fluid, assessing whether there is an increase in white blood cells and proteins in the fluid, which plays an important role in the diagnosis of encephalitis. In summary, diagnosing encephalitis necessitates a complete blood count, cranial MRI, analysis of cerebrospinal fluid, and a comprehensive EEG examination.

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Written by Tang Li Li
Neurology
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How is encephalitis in children diagnosed?

If a child presents with fever, headache, nausea, vomiting, or even convulsions and seizures, it is necessary to be vigilant about the possibility of encephalitis. It is advised to seek medical attention in pediatrics or neurology to conduct a thorough examination. First, an MRI of the brain should be carried out to observe if there are any abnormal signals in the meninges or any damage within the brain substance. Second, cerebrospinal fluid analysis via lumbar puncture is essential for diagnosing encephalitis, as encephalitis patients often show significant abnormalities in cell count and biochemistry of the cerebrospinal fluid, allowing for the identification of different types of infections. Third, an electroencephalogram (EEG) is conducted. While EEG specificity is not high, an affected cerebral cortex in encephalitis patients will show abnormal slow waves. Fourth, routine tests such as a complete blood count should be performed; an elevated blood count can indirectly indicate a potential infection in the patient.

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Written by Zhang Hui
Neurology
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How is encephalitis diagnosed?

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 Zhang Hui
Neurology
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Does encephalitis cause fever?

If the patient's encephalitis is caused by a viral infection, they usually exhibit fever, often a high fever with temperatures reaching above 39°C, accompanied by significant symptoms such as headache, nausea, and vomiting. Some patients may also experience cognitive dysfunction, epileptic seizures, and psychiatric symptoms. Therefore, it is crucial to seek medical attention promptly, complete examinations such as electroencephalography, lumbar puncture, and cranial magnetic resonance imaging, and timely apply effective antiviral medications. It should be noted that some encephalitis is caused by autoimmune reactions, referred to as autoimmune encephalitis, which is relatively rare clinically. This type of encephalitis generally does not present with fever. (Please use medications under the guidance of a doctor.)

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Written by Zhang Hui
Neurology
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What are the symptoms of encephalitis?

The clinical manifestations of encephalitis are complex and varied, primarily caused by infections from pathogens such as viruses and bacteria. There are numerous clinical symptoms, with fever being quite common; patients generally exhibit significant fevers, which can reach up to 38 degrees Celsius or even as high as 40 degrees Celsius. Headache is also a very common clinical manifestation of encephalitis, with some patients experiencing severe headaches accompanied by pronounced nausea and vomiting. Additionally, some patients may exhibit psychiatric symptoms, which mainly include incoherent speech, hallucinations, and failing to recognize family members. Some patients may experience cognitive impairments, such as diminished memory, and significant deficits in computational and judgment abilities. In severe cases, some patients may have epileptic seizures, characterized by convulsions of the limbs. Overall, the manifestations of encephalitis are diverse and can range from simple fever and headache to severe conditions such as psychiatric symptoms, cognitive impairments, and epilepsy.

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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.