Meningitis is the inflammation of the protective membranes covering the brain, the spinal cord, and the fluids between them.
Meningitis has many presentations that go from bacterial to non-infectious meningitis. Still, most of the cases are specifically due to a viral infection. Some meningitis cases may improve within a few weeks without treatment. On the other hand, others can be a life-threatening emergency.
Within this article, you will find some of the most common questions about this disease. Among these questions are the different types of meningitis, how frequent it is, and many more. But before reaching that point, there will be an explanation of basic concepts of the disease.
Consequently, by reading this article, you will obtain key insights about Meningitis, its causes, its symptoms, its complications, and many more. Please continue reading to get pearls on this specific topic by the hand of a Doctor.
What are the structures that Meningitis affects?
Meningitis is a syndrome that characterizes itself for causing the inflammation (swelling) of the meninges. The meninges are three layers of tissue that are designed to protect the brain and the spinal cord. Asides from this, the meninges have two major functions.
The first one is to provide a supportive framework for the cerebral and cranial vasculature. The second one is to work together with the cerebrospinal fluid to protect the Central Nervous System (CNS) from mechanical damage.
These layers are the following:
- Dura Mater: The outermost and toughest membrane of the meninges. It is an inextensible layer that is beneath the bones of the skull and vertebral column. It is a layer that receives its own blood supply and innervation.
- Arachnoid: It is the middle layer of the meninges, lying directly underneath the dura mater. It is a lacy and weblike layer that does not have any type of blood supply or innervation.
- Pia Mater: It is the most profound layer of the meninges and the thinnest of all. It is a layer that is tightly adhered to the surface of the brain and the spinal cord. As the dura mater, the pia mater is a layer with its own blood supply and innervation.
Between the Arachnoid and the Pia Mater, there is a space that receives the name of sub-arachnoid space. This space contains the cerebral spinal fluid or spinal fluid, which acts as a cushion to the brain and the spinal cord.
Anatomically, meningitis can be divided into inflammation of the dura mater (less common) and leptomeningitis. Leptomeningitis is the most common and includes the inflammation of the arachnoid layer and the sub-arachnoid space.
How does meningitis develop itself?
Most meningitis cases are caused by an infectious agent that has colonized or established a localized infection elsewhere in the host. Among the most common sites for infection includes the skin, nasopharynx, respiratory tract, gastrointestinal tract, and genitourinary tract. These infectious agents can gain access to the Central Nervous System (brain and spinal cord) following any of these 3 significant pathways.
- Invasion of the bloodstream and subsequent hematogenous seeding of the CNS. This includes bacteremia, viremia, fungemia, or parasitemia.
- Retrograde neuronal pathways like the olfactory and peripheral nerves, for example. One organism that takes this pathway is the Naegleria fowleri.
- Direct contiguous spread. For example, sinusitis, otitis media, trauma, or direct inoculation during intracranial manipulation.
The most common way of spreading the disease is the invasion of the bloodstream and its subsequent seeding. Accordingly, this pathway is characteristic of bacterial infections like meningococcal infection and pneumococcal meningitis.
The brain is naturally protected from the body’s immune system by a barrier between the bloodstream and the brain. This protection is an advantage as it prevents the immune system from attacking the brain. However, in meningitis, this barrier becomes disrupted. Once the bacterium or other organisms enter the brain, they become isolated from the immune system and spread.
When the body tries to fight the infection, the problem can become worse. The blood vessels become leaky and allow fluids, white blood cells, and other infection-fighting agents to enter the meninges and the brain. Therefore, this measure is counterproductive as it may cause swelling and decrease the blood flow, leading to worsening of the symptoms.
How frequent is Meningitis?
The frequency of Meningitis varies significantly depending on the cause or pathogen that causes it. There are different types of meningitis which are the following:
- Bacterial Meningitis
- Viral Meningitis
- Parasitic Meningitis
- Fungal Meningitis
- Non-Infectious Meningitis
Among these causes, the most common of all is Viral Meningitis, followed by Bacterial Meningitis and Non-Infectious Meningitis. Nevertheless, meningitis tends to be higher in developing countries because of a lack of preventive services like vaccination.
For bacterial meningitis, the two major organisms that cause acute bacterial meningitis are Streptococcus pneumoniae and Neisseria meningitidis. Importantly, in the United States, there are approximately 4100 cases annually and 500 deaths. There are 1.33 cases per 100.000 population.
Meningococcal disease is caused by Neisseria meningitides, and it was endemic (pretty common) in parts of Africa. Sadly, it is a recurrent problem as periodic epidemics in the sub-Saharan region receive the name of “Meningitis Belt.”
Nonetheless, the cases have greatly dropped since the introduction of the Hib vaccination. This is a vaccine specifically for the Haemophilus influenzae, another cause of meningitis due to bacteria (infection).
Since introducing the latter vaccine, this pathogen is almost inexistent as a cause of meningitis in developed countries. Accordingly, the cases in the United States are now in 1.33 per 100.000 population against 2.00 per 100.000 population previous to the introduction of the Hib vaccine.
Meningitis also greatly affects infants and newborns. There are approximately 4 cases per 100.000 children between 1 to 23 months of Neisseria meningitis. And the rate of meningitis by S. pneumoniae is 6.5 cases per 100.000 children between 1 to 23 months.
Interestingly, it is essential to note that most viral meningitis cases, which are the most common cause of the disease, occur in children younger than 5 years old.
What are the risk factors?
Meningitis is a disease that is not so common among people. Yet, certain factors tell that a patient has an increased risk of developing the disease. Among the risk factors are the following:
- Age: Although it may not seem, age is an important risk factor for developing meningitis. Most cases of viral meningitis occur in children younger than 5 years old. Bacterial meningitis is more common in patients younger than 20 years old.
- Skipping vaccinations: The current development of meningitis vaccines like the meningococcal vaccine and the pneumococcal vaccine are preventive measures that lower the risk. Therefore, if a person skips, the meningitis vaccination is at more risk of developing the disease.
- Living in a community setting: People living in conglomerates such as college students, military bases, and children at daycares are at greater risk of meningococcal meningitis. The meningococcal bacterium is spread through the respiratory route. This enables the bacterium to spread quickly through large groups of people.
- Pregnancy: Pregnant women are at higher risk of acquiring listeriosis. Listeriosis is a disease due to an infection caused by Listeria monocytogenes; this also causes meningitis. Sadly, listeriosis increases the risk of miscarriage, stillbirth, and premature delivery.
- Compromised immune system: There are certain conditions and other factors that compromise the immune system. Among the conditions are AIDS, alcoholism, and Diabetes Mellitus. Moreover, other factors include the use of immunosuppressant drugs and having your spleen removed that lower your immune system. This puts the patient at higher risk of developing meningitis; these patients should consider vaccination to minimize that risk.
What are the different types of meningitis?
Meningitis has several causes that may root the disease; they go from being infectious to non-infectious. Importantly, the most common of these causes are viral; however, bacterial infections can be life-threatening, so it is important to determine the specific causal agent. Among the different types of meningitis are the following.
- Bacterial Meningitis: Bacterium that enters the bloodstream may travel to the brain and the spinal cord and cause acute bacterial meningitis. Yet, there is also the possibility that the bacteria invade the meninges. Among the most common strains of bacteria that cause acute bacterial meningitis are the following:
- Streptococcus pneumoniae (pneumococcus)
- Neisseria meningitides (meningococcus)
- Haemophilus influenzae (Haemophilus)
- Listeria monocytogenes (Listeria)
- Viral Meningitis: Although these are the most common types of meningitis, viral meningitis is usually mild and often clear on its own. Importantly, most of the cases directly correlate to a group of viruses that receive the name of Enteroviruses. Other viruses that can cause meningitis are HIV, mumps virus, and West Nile Virus.
- Chronic Meningitis: Chronic meningitis is related to slow-growing organisms that take over two weeks to develop the disease. The most common organism is Mycobacterium tuberculosis and other types of fungi.
- Fungal meningitis: It is a very uncommon type of disease. People can contract fungal meningitis by breathing fungal spores in the soil, decaying woods, and bird droppings. It is important to note that an infected person cannot transmit the fungal infection to a healthy one.
- Parasitic meningitis: Another rare type of meningitis can be caused by tapeworm (neurocysticercosis) or cerebral malaria. The parasites typically cause parasitic meningitis in animals.
- Other meningitis causes: Other causes include chemical reactions, drug allergies, cancer, and inflammatory diseases like sarcoidosis.
What are the symptoms of meningitis?
The meningitis symptoms at the beginning may mimic the simple flu. However, the symptoms may develop over several hours or a few days. The symptoms may vary on the age of the patient. For people 2 years or older, the symptoms are the following:
- Sudden high fever (39°C-40°C)
- Neck stiffness
- Severe headache that is different from a normal or common headache
- Confusion or difficulty concentrating
- Photalgia (photophobia) – discomfort when the patient looks into bright lights
- Sleepiness or difficulty walking
- No appetite or thirst
- Skin rash (Most common in meningococcal meningitis)
- Headache with nausea or vomiting.
For newborns or children under two years old, the symptoms are the following:
- High fever
- Constant crying
- Excessive sleepiness
- Not wanting to eat
- Inactivity or sluggishness
- Stiffness in the body and the neck
- The bulge in the soft spot on the top of a baby’s head (fontanel)
What are the complications of meningitis?
Advanced meningitis can lead to serious complications, brain injury, coma, or even death. Nonetheless, these are common in septic meningitis with weeks of evolution. Many patients can even develop long-term sequelae that vary with the disease’s etiologic agent, age, and clinical course. Among the complications are the following:
- Hearing loss or deafness
- Cortical blindness
- Learning disabilities
- Memory difficulty
- Kidney failure
- Subdural effusions
- Cerebral atrophy
- Focal paralysis
- Muscular hypertonia
- Delayed cerebral thrombosis
- Peripheral gangrene
- Other cranial nerve dysfunctions
Among this list of complications, one of the most common is seizures. Seizures become an essential complication of the disease as it occurs in one out of five patients who suffered meningitis. Sadly, it becomes more troublesome in patients younger than 1-year-old as it affects 40% of these children.
How is meningitis diagnosed?
To make an assertive diagnosis, the doctor must perform a complete history and a physical examination looking for signs or symptoms of the disease. During the physical examination, your doctor may look for signs of infection on your body. Your doctor may check your head, ears, throat, or your skin. Therefore, your doctor will ask for the following diagnostic tests to make a diagnosis.
- Blood cultures: This study takes a blood sample and places it in a special dish that allows the growing of microorganisms, if there are any. Among these microorganisms are bacteria. Later the sample goes under a microscope to see if there is a presence of them.
- Imaging: Several studies may reveal if there is the presence of inflammation around the brain or the spine. Among them are Computerized tomography and magnetic resonance imaging (MRI). The CT scan also may show alongside the X-Ray if there are signs of infection in the sinuses or the chest.
- Lumbar Puncture: Also receives the name of Spinal Tap, and it is the gold standard of the diagnostic tests. It allows making a definitive diagnosis by taking a sample of the Cerebrospinal Fluid. It goes through several studies to determine what type of meningitis is.
What is the treatment?
The treatment will vary depending on the type of meningitis. For example, viral meningitis cannot receive antibiotics as they only work in bacteria. Hence, the following are the different types of treatment.
- Bacterial Meningitis: This type of meningitis should receive immediate treatment as it can be a life-threatening disease. These patients will receive intravenous antibiotics and corticosteroids depending on the case. It ensures the recovery of the patient and the reduction of the risk of possible complications. The antibiotics will vary depending on the type of bacteria.
- Viral Meningitis: Most viral meningitis cases improve on their own in several weeks. Still, it will also depend on the virus that causes it; if it is a Herpes Virus, antiviral medication is available. For other types of viruses, the treatment can be straightforward. It includes bed rest, plenty of fluids, and over-the-counter medications to reduce pain and fever. Also, the doctor may indicate corticosteroids to reduce brain swelling.
- Other types: Among the different types are fungal infections, chronic meningitis, non-infectious diseases, or related to cancer. The treatment will vary for each one of them. So, chronic meningitis will receive specific treatment for the underlying cause. Fungal meningitis should be correctly diagnosed first as the antifungal treatment can have serious side effects. Non-infectious causes like allergic reactions or autoimmune diseases receive corticosteroids. Cancer-related meningitis should receive treatment for the specific type of cancer.
What are the different types of Vaccines?
There are different types of a vaccine specifically for bacterial meningitis that can help to prevent the disease. The following are the available vaccines.
- Haemophilus influenzae type B (Hib) vaccine: Several organizations such as the World Health Organization (WHO) and the Center for Disease Control and Prevention (CDC) recommend this vaccine for children at about 2 months old. It also includes adults with HIV, sickle cell disease, or those who don’t have a spleen.
- Pneumococcal conjugate vaccine (PCV13): WHO and the CDC also include this vaccine in their vaccination scheme. Children under 2 years old should receive this vaccine and reinforcement between 2 and 5 years old.
- Pneumococcal Polysaccharide Vaccine (PPSV23): This is a vaccine for older children and adults that may need protection from these bacteria. Therefore, it is recommended for adults over 65 years old and children older than 2 years old with a weak immune system.
- Meningococcal conjugate vaccine: This is a vaccine designed for children over 11 years old. Depending on the age of administration, a booster shot may be necessary. Importantly, it is also recommended for children between 2 months and ten years old who are at high risk of bacterial meningitis or exposed to an infected person.
Do you have symptoms of this disease?
This tool is a Meningitis Symptoms Checker. It gathers the most important signs, symptoms, and risk factors for the disease. Therefore, the tool will tell anybody who uses it the likelihood of having meningitis. Using the tool is free and would only take a few minutes.