How is encephalitis caused?

Written by Zhang Hui
Neurology
Updated on September 18, 2024
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Encephalitis generally occurs when pathogens invade the central nervous system of the brain, resulting in corresponding clinical manifestations. Patients may exhibit symptoms such as headache, fever, nausea, vomiting, and even paralysis of limbs and cognitive impairments. Patients become confused, with reduced computational and comprehension abilities. Some may also exhibit psychiatric symptoms and even experience seizures and other manifestations of epilepsy. Encephalitis is caused by pathogens, commonly viruses. Viral infections that lead to what is known as viral encephalitis can spread through the bloodstream to the brain and cause illness. Additionally, bacterial infections can also cause encephalitis. There are mainly two routes for bacterial infections: one is through bloodstream transmission leading to inflammation of the nervous system, and the other can occur directly, for example, from inflammation of the mastoids, tonsils, or cavernous sinus, where bacteria directly invade the brain, leading to the respective clinical manifestations. Furthermore, tuberculosis can also infect and cause tuberculous encephalitis, meningitis, and similar conditions.

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After-effects of encephalitis

Some more serious types of encephalitis may leave sequelae. For example, common ones like herpes simplex viral encephalitis and epidemic encephalitis B. A minority of patients may suffer from certain degrees of sequelae, which typically include the following aspects. Firstly, some patients may experience secondary epileptic seizures, which present with loss of consciousness, limb convulsions, incontinence, and frothing at the mouth. These symptoms might require long-term oral medication for epilepsy. Secondly, another consequence of encephalitis is cognitive impairment in patients, characterized by significant reductions in computational ability, memory, and executive function. Additionally, some forms of encephalitis might leave patients with psychiatric symptoms, such as speaking incoherently.

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Does encephalitis cause a runny nose?

Encephalitis can potentially cause a runny nose, as it is mainly caused by viral infections. These infections not only invade brain cells, leading to symptoms such as fever, headache, nausea, vomiting, and even seizures related to the nervous system, but can also affect the respiratory tract. If these viruses accumulate in the respiratory tract, particularly in the nasal mucosa, they will definitely cause symptoms such as a runny nose, cough, expectoration, and sore throat. Therefore, it is evident that patients with encephalitis can exhibit symptoms of upper respiratory tract infections. Moreover, some patients initially present with respiratory symptoms, such as a runny nose, before the viruses enter and infect the brain cells. Patients with encephalitis must receive timely treatment, primarily symptomatic treatment to prevent complications, along with antiviral medication for targeted treatment. Most patients have a good prognosis.

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Can encephalitis be cured?

Encephalitis is divided into many types. If it is a simple herpes virus encephalitis infection, this is a rather dangerous type of encephalitis. Before the advent of antiviral drugs, the mortality rate of this type of encephalitis was very high. Now, with improvements in diagnostic and treatment levels and the development of antiviral drugs, the prognosis for this type of encephalitis is generally quite good. As long as the initial condition is not particularly severe, the patient is not in a coma, or there is no obvious continuous epileptic state, the prognosis is still good, and many patients do not have any residual sequelae. However, if the initial condition is quite severe, there is usually some degree of cognitive impairment or weakness in the limbs. Other viral encephalitides, such as those caused by Coxsackie viruses and adenoviruses, tend to have milder symptoms, mainly fever, headache, nausea, and vomiting. These types of encephalitis can mostly be cured with appropriate symptomatic treatment and antiviral therapy.

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Is encephalitis hereditary?

Encephalitis is mostly caused by viral infections. For instance, Epidemic B encephalitis is caused by the B encephalitis virus, and herpes simplex encephalitis is caused by the herpes simplex virus. Therefore, encephalitis is not related to genetic mutations and is not hereditary, so there is no need for special concern. It is important to note that some cases of encephalitis are not directly related to viral infections and may be related to autoimmune responses. For example, autoimmune encephalitis can occur in patients experiencing immune system disorder, which may be accompanied by some tumors. A disordered immune system can produce antibodies that attack one's own brain tissue, leading to autoimmune encephalitis. This type of encephalitis also has no genetic tendencies.

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How to check for encephalitis?

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.