How is encephalitis caused?

Written by Tang Li Li
Neurology
Updated on September 13, 2024
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Encephalitis generally falls into two categories: one is infectious inflammation caused by pathogenic infections, and the other is immune inflammation caused by abnormalities in immune mechanisms. Among these, the infectious type is the most common, including viral encephalitis, viral meningitis, tuberculous meningoencephalitis, purulent meningitis, and cryptococcal meningitis, which are associated with infections by viruses, bacteria, Mycobacterium tuberculosis, and Cryptococcus, respectively. Additionally, abnormalities in the immune system often cause autoimmune encephalitis, as well as multiple sclerosis and neuromyelitis optica when involving the brain, and acute disseminated encephalomyelitis, all of which are types of autoimmune encephalitis. The treatment approaches for these two types of encephalitis are different. For pathogen-induced cases, treatment primarily targets the pathogens: antiviral drugs for viral encephalitis, antibiotics for bacterial encephalitis, anti-tubercular therapy involving multiple drugs for Mycobacterium tuberculosis infection, and antifungal drugs, such as amphotericin B, for cryptococcal meningitis. For immune-mediated encephalitis, treatments generally involve immunosuppressants, high-dose corticosteroids, or intravenous immunoglobulins.

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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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Encephalitis belongs to which department?

Encephalitis is primarily a neurological disorder and is an infectious disease of the central nervous system, mainly diagnosed and treated in neurology. There are many causes of encephalitis, with viral encephalitis being the most common. For example, herpes simplex encephalitis is a typical type seen clinically. Patients may experience fever, even with very high temperatures exceeding 40°C, headaches, nausea, and vomiting. If the condition worsens, seizures, coma, and cognitive impairment may occur. These clinical manifestations require further investigations like electroencephalography, cranial MRI, and lumbar puncture. Additionally, there is a specific type of epidemic, known as Japanese encephalitis, which falls under the category of infectious diseases due to its contagious nature.

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Neurology
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What is checked for encephalitis?

The examination items for encephalitis mainly include, first, some basic hematological tests. These include routine blood tests, liver and kidney function tests, electrolytes, etc., to understand the status of the patient's white blood cells and whether there is any damage to liver and kidney functions. It is also necessary to test for cardiac enzymes, as some viruses can also affect the heart. Second, an EEG is required. Abnormal EEG patterns, such as increased diffuseness, can be observed in encephalitis, which is important for accurate diagnosis. Third, further examinations like lumbar puncture and cerebrospinal fluid tests are needed. The main focus in cerebrospinal fluid is to see if there is an increase in white blood cells and to check if there are any changes in protein and sugar levels in the fluid. This has great reference value for diagnosing whether it is encephalitis and what type of encephalitis it might be. Fourth, a cranial MRI can be performed to clearly identify if there are any organic lesions in the brain.

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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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How to relieve headache from encephalitis

Encephalitis is mainly divided into viral encephalitis, bacterial encephalitis, and tubercular meningitis, among others. Encephalitis usually causes patients to experience fever, headache, nausea, and vomiting. The cause of headaches includes the pain response due to inflammation stimulating the meninges. Moreover, these infections can cause an increase in intracranial pressure, leading to significant symptoms in patients such as headache, nausea, and vomiting. To alleviate headaches, it is important to actively treat the primary disease. This includes administering antiviral drugs for viral infections, and antibiotics for bacterial infections. If the headache is caused by increased intracranial pressure, it is crucial to actively administer dehydrating agents and drugs that lower intracranial pressure to reduce it, thereby relieving the headache. Additionally, the use of glucocorticoids can be combined to manage the treatment, suppress the inflammatory response, and alleviate pain. If the pain is significant, non-steroidal anti-inflammatory drugs may also be administered to relieve the pain. The treatment of pain in encephalitis is a comprehensive issue that requires addressing the pathogen, dehydration, reduction of intracranial pressure, and symptomatic treatment.