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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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 Zhang Hui
Neurology
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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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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 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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Written by Tang Li Li
Neurology
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How is encephalitis caused?

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.