What is a brain infection. Explore the various types of brain infections, their causes, symptoms, diagnosis, and treatment options. Get insights into the complications and prevention strategies.

Understanding the Basics of Brain Infections

A brain infection, also known as a central nervous system (CNS) infection, is a potentially life-threatening condition that occurs when harmful microorganisms, such as bacteria, viruses, fungi, or parasites, invade the brain or its surrounding structures. These infections can lead to inflammation, tissue damage, and disruption of normal brain function. It is crucial to recognize the signs and symptoms of a brain infection and seek immediate medical attention to prevent serious complications.

Common Types of Brain Infections

The most common types of brain infections include:

• Brain abscess: A localized collection of pus and infected material within the brain tissue, often caused by bacteria or fungi.
• Meningitis: An infection of the protective membranes (meninges) surrounding the brain and spinal cord, typically caused by bacteria or viruses.
• Encephalitis: Inflammation of the brain itself, usually caused by viral infections.
• Neurocysticercosis: A parasitic infection caused by the larval stage of the pork tapeworm (Taenia solium), which can invade the brain and cause seizures and other neurological symptoms.

Causes and Risk Factors of Brain Infections

Brain infections can develop in several ways, including:

1. Spread from nearby infections: Infections in the ear, sinuses, or dental cavities can spread directly to the brain.
2. Bloodborne infections: Bacteria, viruses, or parasites can reach the brain through the bloodstream, often from an infection in another part of the body.
3. Traumatic injuries: Head injuries that breach the skull can allow bacteria or fungi to enter the brain.
4. Weakened immune system: Individuals with compromised immune systems, such as those with HIV/AIDS, cancer, or organ transplants, are at a higher risk of developing brain infections.

Symptoms and Diagnosis of Brain Infections

The symptoms of a brain infection can vary depending on the type of infection and the affected area of the brain. Common symptoms include:

• Severe headaches
• Changes in mental state, such as confusion or irritability
• Neurological deficits, such as muscle weakness or paralysis
• Seizures
• Fever
• Nausea and vomiting
• Stiff neck
• Vision problems

Diagnosing a brain infection typically involves a combination of medical history, physical examination, blood tests, and imaging studies, such as CT scans or MRI.

Treatment and Management of Brain Infections

The treatment of a brain infection depends on the underlying cause and the severity of the condition. Generally, brain infections are considered medical emergencies and require prompt treatment to prevent permanent brain damage or death. Treatment options may include:

1. Antibiotics or antifungal medications: These medications are used to target the specific microorganisms causing the infection.
2. Surgical intervention: In some cases, surgical procedures, such as draining a brain abscess or removing a tumor, may be necessary to alleviate the pressure and remove the source of the infection.
3. Supportive care: Measures to reduce intracranial pressure, manage seizures, and maintain hydration and electrolyte balance are essential components of the treatment plan.

Complications and Prognosis of Brain Infections

Complications of brain infections can include:

• Recurrence of the infection
• Permanent brain damage, ranging from mild to severe
• Seizures and epilepsy
• Meningitis, a life-threatening infection of the protective membranes surrounding the brain and spinal cord

The prognosis for individuals with a brain infection depends on the type and severity of the infection, the promptness of diagnosis and treatment, and the individual’s overall health and immune status. Early recognition and prompt treatment are crucial to improving the chances of a favorable outcome.

Preventing Brain Infections

Strategies to prevent brain infections include:

1. Maintaining good hygiene: Regular handwashing, proper wound care, and avoiding contact with sick individuals can help reduce the risk of infection.
2. Treating underlying conditions: Individuals with weakened immune systems or chronic medical conditions should work closely with their healthcare providers to manage these conditions and reduce the risk of infections.
3. Vaccination: Vaccines, such as those for certain types of meningitis, can help prevent some brain infections.
4. Seeking prompt medical attention: Recognizing the signs and symptoms of a brain infection and seeking immediate medical care can greatly improve the chances of successful treatment and recovery.

Understanding the various types of brain infections, their causes, symptoms, and treatment options is crucial for ensuring prompt and effective management of these potentially life-threatening conditions. By staying vigilant and seeking medical attention when necessary, individuals can take an active role in protecting their brain health and reducing the risk of serious complications.

Brain abscess – NHS

A brain abscess is a pus-filled swelling in the brain. It usually occurs when bacteria or fungi enter the brain tissue after an infection or severe head injury.

Although the risk of developing a brain abscess is extremely low in England, it is a life-threatening condition and should be diagnosed and treated as soon as possible.

Symptoms of a brain abscess

The symptoms of a brain abscess may develop quickly or slowly but can include:

• headache – which is often severe, located in a single section of the head and cannot be relieved with painkillers
• changes in mental state – such as confusion or irritability
• problems with nerve function – such as muscle weakness, slurred speech or paralysis on one side of the body
• a high temperature
• seizures (fits)
• feeling sick
• being sick
• stiff neck
• changes in vision – such as blurring, greying of vision or double vision (due to the abscess putting pressure on the optic nerve)

When to get medical advice

Any symptoms that suggest a problem with the brain and nervous system should be treated as a medical emergency. These include:

• slurred speech
• muscle weakness or paralysis
• seizures occurring in a person with no previous history of seizures

If you or someone you know experiences any of these symptoms, phone 999 immediately and ask for an ambulance.

Any symptoms that suggest a worsening infection, such as a high temperature or being sick, should be reported to your GP immediately.

If your GP is not available, contact your local out-of-hours service or call NHS 111.

Causes of a brain abscess

There are 3 main ways a brain abscess can develop. These are:

• an infection in another part of the skull – such as an ear infection, sinusitis or dental abscess, which can spread directly into the brain
• an infection in another part of the body – for example, the infection that causes pneumonia spreading into the brain via the blood
• trauma, such as a head injury – that cracks open the skull, allowing bacteria or fungi to enter the brain

However, in some cases, the source of the infection remains unknown.

Read more about the causes of a brain abscess.

Diagnosing a brain abscess

If a brain abscess is suspected, an initial assessment will be made based on your symptoms, medical history and whether you’ve had a recent infection or a weakened immune system.

Blood tests can also be carried out to check for an infection.

If you’re referred to hospital for further tests, you may have either:

• a CT scan – a series of X-rays are used to produce a detailed image of the inside of your body
• an MRI scan – which uses strong magnetic fields and radio waves to produce a detailed image of the inside of your body.

If an abscess is found, a procedure known as CT-guided aspiration may be used to remove a sample of pus for testing. This involves using a CT scan to guide a needle to the site of the abscess.

Treating a brain abscess

A brain abscess is regarded as a medical emergency. Swelling caused by the abscess can disrupt the blood and oxygen supply to the brain. There’s also a risk of the abscess bursting (rupturing).

If left untreated, a brain abscess can cause permanent brain damage and could be fatal.

A brain abscess is usually treated using a combination of:

• medicines – either antibiotics or antifungals
• surgery – either draining the pus through a hole in the skull (simple aspiration) or opening the skull and removing the abscess entirely (craniotomy)

Treatment with antibiotics often begins before a diagnosis is confirmed, to reduce the risk of complications.

Read more about treating a brain abscess.

Complications of a brain abscess

Complications of a brain abscess can include:

• a reoccurring abscess – seek immediate medical advice if you think there’s even a small chance your abscess has reoccurred; this is more common in people with a weakened immune system or cyanotic heart disease
• brain damage – mild to moderate brain damage often improves with time but severe brain damage is likely to be permanent; brain damage is more of a risk if diagnosis and treatment are delayed
• epilepsy – where a person has repeated seizures (fits)
• meningitis – a life-threatening infection of the protective membranes around the brain, which requires urgent treatment; this is more common in children

Page last reviewed: 18 October 2022
Next review due: 18 October 2025

Overview of Brain Infections – Brain, Spinal Cord, and Nerve Disorders

By

John E. Greenlee

, MD, University of Utah Health

Reviewed/Revised Mar 2022 | Modified Sep 2022

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Infections of the brain can be caused by viruses, bacteria, fungi, or, occasionally, protozoa or parasites. Another group of brain disorders, called spongiform encephalopathies, are caused by abnormal proteins called prions Overview of Prion Diseases Prion diseases are rare progressive, fatal, and currently untreatable degenerative disorders of the brain (and rarely of other organs) that result when a protein changes into an abnormal form… read more .

Infections of the brain often also involve other parts of the central nervous system, including the spinal cord. The brain and spinal cord are usually protected from infection, but when they become infected, the consequences are often very serious.

Infections can cause inflammation of the brain (encephalitis Encephalitis Encephalitis is inflammation of the brain that occurs when a virus directly infects the brain or when a virus, vaccine, or something else triggers inflammation. The spinal cord may also be involved… read more ). Viruses are the most common causes of encephalitis. Infections can also cause inflammation of the layers of tissue (meninges) that cover the brain and spinal cord—called meningitis Introduction to Meningitis Meningitis is inflammation of the layers of tissue that cover the brain and spinal cord (meninges) and of the fluid-filled space between the meninges (subarachnoid space). Meningitis can be… read more . Often, bacterial meningitis spreads to the brain itself, causing encephalitis. Similarly, viral infections that cause encephalitis often also cause meningitis. Technically, when both the brain and the meninges are infected, the disorder is called meningoencephalitis. However, infection that affects mainly the meninges is usually called meningitis, and infection that affects mainly the brain is usually called encephalitis.

Usually in encephalitis and meningitis, infection is not confined to one area. It may occur throughout the brain or within meninges along the entire length of the spinal cord and over the entire brain.

But in some disorders, infection is confined to one area (localized) as a pocket of pus, called an empyema or an abscess, depending on where it is located:

• Empyemas Intracranial Epidural Abscess and Subdural Empyema An intracranial epidural abscess is a pocket of pus that develops between the skull and the top layer of tissues (dura mater) covering the brain. A subdural empyema is a pocket of pus that develops… read more form in an existing space in the body, such as the space between the tissues that cover the brain (meninges) or the lungs.

• Abscesses Abscess of the Brain A brain abscess is a pocket of pus in the brain. An abscess may form in the brain when bacteria from an infection elsewhere in the head or in the bloodstream or from a wound enter the brain… read more , which resemble boils, can form anywhere in the body, including within the brain.

Fungi (such as aspergilli Aspergillosis Aspergillosis is an infection, usually of the lungs, caused by the fungus Aspergillus. A ball of fungus fibers, blood clots, and white blood cells may form in the lungs or sinuses. People… read more ), protozoa (such as Toxoplasma gondii Toxoplasmosis Toxoplasmosis is infection caused by the protozoan parasite Toxoplasma gondii. Infection occurs when people unknowingly ingest toxoplasma cysts from cat feces or eat contaminated meat… read more ), and parasites (such as Taenia solium, the pork tapeworm Tapeworm Infection Tapeworm infection of the intestine occurs mainly when people eat raw or undercooked contaminated pork, beef, or freshwater fish or, for the dwarf tapeworm, contaminated food or water. Adult… read more ) may cause cysts to form in the brain. These localized brain infections consist of a cluster of organisms enclosed in a protective wall.

Sometimes a brain infection, a vaccine, cancer, or another disorder triggers a misguided immune reaction, causing the immune system to attack normal cells in the brain (an autoimmune reaction Autoimmune Disorders An autoimmune disorder is a malfunction of the body’s immune system that causes the body to attack its own tissues. What triggers an autoimmune disorder is not known. Symptoms vary depending… read more ). As a result, the brain becomes inflamed. This disorder is called postinfectious encephalitis.

Bacteria and other infectious organisms can reach the brain and meninges in several ways:

• By being carried by the blood

• By entering the brain directly from the outside (for example, through a skull fracture or during surgery on the brain)

• By spreading from nearby infected structures, such as the sinuses or middle ear

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Infections of the brain | Neurology

All infections are dangerous to varying degrees, and even more so – neuroinfections. The most dangerous of neuroinfections are those that affect the brain. There can be no “non-serious” diseases here. Each pathogen that can overcome the blood-brain barrier poses a huge danger to human health and life.

Types of brain infections

The whole variety of neuroinfections affecting the brain can be divided into five groups:

• bacterial;
• parasitic;
• viral;
• prion;
• fungal.

Bacterial infections

A huge number of pathogens related to bacterial infections can affect the brain.
Diseases such as meningitis, encephalitis or brain abscess may well cause such “ordinary” pathogens as pneumococcus, staphylococcus, enterobacteria. But this can happen only when:

• damage to the bones of the skull, with a violation of the integrity of the meninges;
• the introduction of pathogens during a neurosurgical operation;
• the presence of a purulent focus in the body and weakened immunity.

However, the situation is different with other pathogens.

Meningococcal infection is a traditional neuroinfection that affects the brain. The peak incidence is observed in the autumn-winter period, when the immune system is reduced due to frequent hypothermia and lack of vitamins.

If the immune system is normal, then you will be limited to ordinary nasopharyngitis, otherwise, the likelihood of getting meningitis or meningoencephalitis increases.

Symptoms of meningococcal infection

• fever,
• increase in body temperature up to 39-40 ° C.
• chills,
• headache
• weakness
• neck muscle tension
• nausea,
• vomiting,

specific symptoms

• Rashes of red-violet color protruding above the surface of the skin, the elements of which resemble a star in shape
• The disease begins very acutely (often you can specify a specific time (hour) when a person fell ill)
• Within 24 hours, while a person is conscious, treatment must begin, otherwise he may fall into a coma.

Mycobacterium tuberculosis , among other things, can also affect the brain.
Children, the elderly, and people with immunodeficiency are more likely to get sick.

Symptoms of the onset of the disease are not pronounced, more often it is general weakness, malaise, lack of appetite, headache and irritability, body temperature is subfebrile in nature (the temperature rises for a long time within 37. 1 – 38 ° C.). Subsequently, “usual” meningeal symptoms join.

After neurological disorders join – paresis and paralysis of the facial nerve, oculomotor muscles, dizziness. Against the background of neurological disorders, mental disorders occur.

Neurosyphilis, is now almost never found, but before the discovery of penicillin, it was the basis of the work of neurologists. There are several types of neurosyphilis:

1. Asymptomatic, proceeds without any special signs, the disease can be detected only by analysis.
2. Meningitis – often appears during the first year of the disease, manifested by disorders of the cranial nerves and increased intracranial pressure (ICP).
3. Cerebrovascular – occurs mainly in the 2-5th year of the disease and can lead to a stroke or transform into tabes dorsalis or progressive paralysis.
4. Progressive paralysis is a disease that is also called “paralysis of the lunatics.” It occurs 15-20 years after infection and first manifests itself with mental symptoms, then muscle paralysis occurs and progresses, which ultimately leads to death.
5. Congenital, which, strictly speaking, affects the entire body and is characterized by multiple defects in the development of the child.
6. Gumma of the brain – manifests itself as a volumetric formation. Symptoms include an increase in ICP and focal symptoms, depending on the localization of the gum.

An unpleasant feature of the disease is its difficult diagnosis.

Viral and prion infections

There are a huge number of viruses that cause acute encephalitis (mosquito, tick-borne, epidemic), in general, they differ in carriers and geography of distribution.

Focal symptoms occur against the background of “general infectious manifestations”, these are:

• paresis
• paralysis of the respiratory muscles
• paralysis of limbs,
• paralysis of the facial muscles, etc.

Rabies and slow infections can be a huge danger, and therefore, special attention is paid to them.

Rabies.
Almost all mammals can suffer from rabies. The source of infection is usually dogs, wolves, foxes, and it is through the bite of infected animals that this dangerous infection is transmitted to humans.
Symptoms:

• hydro and aerophobia
• convulsions
• bouts of aggressive behavior.

Emergency vaccination after a bite is the only way to recover, so waiting for the first symptoms of the disease to develop is prohibited, since this can only mean that the person can no longer be saved.

Slow infections – viral neuroinfections that have the ability to remain asymptomatically in the human nervous tissue for a long time, with the subsequent development of the disease.

Scientists have deduced four main features that distinguish slow infections:

• unusually long (months and years) incubation period;
• slowly progressive nature of the course;
• unusual damage to organs and tissues;
• inevitability of death.

The causative agents of the virus are rubella and measles. For reasons that are not completely clear, these viruses can remain in the brain cells after an illness and cause a disease after 4 or more years. Both viruses cause panencephalitis with similar symptoms:

personality change with dementia

Gradual paralysis of all striated muscles.

Unfortunately, even with treatment, the consequences of these neuroinfections are always the same – death.

Prions
Prions – proteinaceous infectious (particles).
Prions are defined as “a small protein infectious particle that is resistant to inactivating effects that modify nucleic acids”, in other words, prions are ordinary body proteins that, for some reason (which are not yet known), begin to behave “incorrectly”.

There are four types of prion neuroinfections, and only one of them has a clear mechanism of transmission. In some tribes of Papua New Guinea, cases of kuru-kuru have often been noted due to the previously common ritual cannibalism – eating the brains of relatives. Prions cause spongiform encephalopathy, that is, the brain turns into a kind of sponge.

Parasitic infections

Toxoplasmosis is a parasitic disease characterized by the possibility of intrauterine infection, damage to the nervous system, eyes, skeletal muscles and heart muscles, as well as an increase in lymph nodes, liver and spleen.

For the causative agent of this disease, a person is an intermediate host, and the main one is cats. In a normal state of immunity, the disease does not manifest itself in any way, but if a person suffers from immunodeficiency, then there may be such variants of the disease:

• encephalopathy, with the development of delirium, confusion up to coma;
• meningoencephalitis, with all its classic manifestations;
• toxoplasma abscess of the brain, which is manifested by general infectious symptoms, focal disorders, depending on the location, convulsions, impaired consciousness.

The most severe consequences of toxoplasmosis are in pregnant women, as it causes underdevelopment of the fetal brain.

Diagnostics

In order to diagnose a neuroinfection, including the brain, a set of measures is used:

• general analysis of blood and urine;
• blood chemistry;
• blood test for antibodies to viral, bacterial and other agents;
• visualization methods – MRI;

Treatment

Despite the difference in pathogens, some aspects of treatment are the same in all cases.

Patients must be prescribed bed rest (for acute infections), anti-inflammatory drugs, detoxification therapy.

When it is a subacute or chronic process, patients are also given “vascular” drugs that promote better blood supply to the brain, nootropic, anti-inflammatory drugs.

Precautions
Do not eat raw or undercooked meat, wash hands thoroughly after contact with cats.

Viral infections of the brain (Encephalitis, Encephalomyelitis, Viral meningitis)

Main Viral infections of the brain (Encephalitis, Encephalomyelitis, Viral meningitis)

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Encephalitis is inflammation of the brain, usually caused by a virus (viral encephalitis). Encephalomyelitis is an inflammation of both the brain and spinal cord, also more commonly caused by a virus. Viral meningitis is an inflammation of the meninges (the membranes surrounding the brain and spinal cord) caused by a virus.

Symptoms

Viral diseases of the brain are accompanied by three types of symptoms. Some diseases are mild, causing an increase in body temperature and a feeling of general malaise, often without specific symptoms. Others, such as viral meningitis, usually cause fever, headache, vomiting, weakness, and stiff neck. Still others, such as encephalitis, disrupt normal brain function, leading to personality changes, seizures, weakness of one or more muscle groups, confusion, drowsiness that can develop into a coma, and symptoms of meningitis. Some viruses cause additional symptoms. For example, the early stages of encephalitis caused by the herpes simplex virus are often accompanied by convulsions, and the patient’s cerebrospinal fluid contains erythrocytes in addition to leukocytes, which is not typical for other, more easily occurring viral diseases. This virus also leads to swelling of the temporal lobe of the brain, which can be diagnosed quite early using magnetic resonance imaging (MRI). Computed tomography (CT) can detect changes only after severe damage has occurred.

All symptoms: confusion, headache, weakness, stiff neck, increased drowsiness, coma

Causes

The brain and spinal cord can be affected by various viruses, including the herpes virus and the mumps virus. Some diseases are caused by contact with sick people, while others are caused by the bite of infected insects. Some viruses do not directly damage the brain or spinal cord, but provoke immune responses that lead to inflammation of these organs. This kind of encephalitis (para-infectious or post-infectious encephalitis) can develop after measles, chicken pox or rubella. Inflammation usually occurs 5 to 10 days after the onset of a viral infection and can cause severe damage to the nervous system. In very rare cases, brain inflammation appears weeks, months or years after a viral infection. An example is subacute sclerosing panencephalitis, an inflammation of the brain that sometimes occurs after measles and is more common in children.

Diagnostics

At first, it can be difficult for a doctor to distinguish viral or aseptic meningitis from bacterial, and encephalitis can resemble many other diseases that cause brain dysfunction. At the first sign of any of these conditions, the doctor seeks to pinpoint the cause of the disease. To do this, a lumbar puncture is almost always done to assess changes in the cerebrospinal fluid: with viral infections, the number of leukocytes in it increases, but there are no bacteria. The identification of viruses in cerebrospinal fluid is difficult and takes many days. Doctors also use immunological tests that detect antibodies against viruses, but even with their help, the virus can be identified in less than half of the cases. Your doctor may order a CT or MRI to make sure your symptoms are not caused by a brain abscess, stroke, or hematoma, aneurysm, or tumor.

List of diagnostic methods: computed tomography (CT), magnetic resonance imaging (MRI), blood antibodies, spinal puncture

Treatment

Viral infections that do not cause specific symptoms usually do not require treatment, but more severe infections require antiviral drugs. Leave a Reply Cancel reply Your email address will not be published. Required fields are marked * Comment * Name * Email * Website