Meningitis

What is Meningitis?

Signs of brain and spinal cord inflammation, now known as ‘meningitis’, have been noted in numerous old writings throughout history. However, it wasn’t until surgeon John Abercrombie provided a clear definition for it in 1828 that the term ‘meningitis’ became widely used.

Despite advances in identifying, treating and preventing this disease, in 2015 alone, there were still around 8.7 million reported cases of meningitis around the globe, out of which 379,000 people sadly lost their lives.

Meningitis, an illness that poses severe risk to life, is usually caused by bacteria or viruses. Before antibiotics were discovered, everyone who got meningitis unfortunately passed away. Despite the healthcare improvements we’ve seen, meningitis continues to have a death rate of roughly 25%.

What Causes Meningitis?

Meningitis is a condition where the protective layers or membranes around the brain and spinal cord, known as meninges, become inflamed. These membranes act like cushions for the brain and spinal cord. In contrast, Encephalitis is a condition where the brain itself becomes inflamed.

Meningitis can be caused by various factors, both infectious and non-infectious. Non-infectious causes include autoimmune disorders, types of cancer, or reactions to certain medications. Infectious causes can include several kinds of microorganisms such as bacteria, viruses, fungi, and on rare occasions, parasites.

There are several risk factors that can increase the chances of developing meningitis:

* Chronic medical conditions such as kidney failure, diabetes, adrenal insufficiency, and cystic fibrosis
* Extreme ages – very young or very old
* Not being up-to-date on vaccines
* Weakened immune systems – this could be due to medication, organ transplant, congenital immune deficiencies, or AIDS
* Living in close quarters with a lot of people
* Certain exposures, like travelling to areas with higher prevalence of certain diseases (Southwestern U.S. for cocci, Northeastern U.S. for Lyme disease) or to certain vectors (mosquitoes, ticks)
* Alcohol use disorder
* Presence of a ventriculoperitoneal shunt – this is a surgical procedure often used to treat hydrocephalus (a condition where there is too much cerebrospinal fluid in the brain)
* Bacterial endocarditis – an infection of the inner lining of your heart chambers or valves
* Cancer
* Defects in the meninges
* Using intravenous drugs
* Sickle cell anemia – a genetic disease that affects red blood cells
* Splenectomy – surgical removal of the spleen.

Risk Factors and Frequency for Meningitis

In the United States, every year about 1.38 out of every 100,000 people get bacterial meningitis, a serious infection of the brain and spinal cord. About 14.3% of these cases end in death. Sub-Saharan Africa, spanning from Ethiopia to Senegal, has the highest number of meningitis cases in the world. This area is often referred to as “the meningitis belt”.

The bacteria most often causing meningitis in the U.S include:

• Streptococcus pneumoniae
• Group B Streptococcus
• Neisseria meningitidis
• Haemophilus influenzae
• Listeria monocytogenes

In some special situations, other bacteria might be responsible. For example, Staphylococcus aureus might be a cause in people who recently had surgery, injury, or have central lines. Mycobacterium tuberculosis should be considered in people with weakened immune systems. People who have been to areas where Lyme disease is common could get meningitis from Borrelia burgdorferi. Treponema pallidum can cause meningitis in people with HIV/AIDS and those with multiple sexual partners. Escherichia coli is a common cause in newborns.

Viruses can also cause meningitis. The most common ones are non-polio enteroviruses (including group B coxsackievirus and echovirus). Other viruses like mumps, Parechovirus, Herpesviruses (including Epstein Barr virus, Herpes simplex virus, and Varicella-zoster virus), measles, influenza, and arboviruses (like West Nile, La Crosse, Powassan, Jamestown Canyon) can also lead to meningitis.

People with weakened immunity (such as those with HIV/AIDS, those taking long-term corticosteroid therapy, and cancer patients) are more likely to get fungal meningitis. Fungi that can cause meningitis include:

• Cryptococcus neoformans
• Coccidioides immitis
• Aspergillus
• Candida
• Mucormycosis

Mucormycosis is more common in patients with diabetes and organ transplant recipients, especially if the infection spreads from a sinus infection.

Signs and Symptoms of Meningitis

Meningitis is a condition that can present different symptoms depending on the age and immune system of the person. Common symptoms usually include fever, neck pain and stiffness, sensitivity to light, and more non-specific symptoms such as headaches, dizziness, confusion, restlessness, irritability and nausea or vomiting. Signs of increased pressure inside the skull, like changes in mental state, neurological losses, and seizures, can signify a severe illness.

The condition can be more suspected in the presence of certain risk factors. These include:

• Being in close contact with lots of people, like in military barracks or college dorms
• Not having complete vaccinations
• Having a compromised immune system
• Being a child younger than five years or an adult older than 65 years
• Having an alcohol use disorder

It can be beneficial to find out if there is a history of exposure to certain factors such as intimate contact, encountering animals, a brain surgery, recent travels, and the particular season as most viral instances tend to occur in warmer months.

For adults, doctors will typically focus on identifying any specific neurological deficits, irritation of the meninges (as signified by Brudzinski and Kernig signs), and especially in cases of meningococcal meningitis, characteristic skin lesions (small, flat, red or purple spots). Problems with cranial nerve function can be seen in 10% to 20% of patients.

Signs and symptoms may not be as evident in babies and infants. They could present with or without fever or low body temperature, reduced food intake, changes in mental state, irritability, and bulging fontanelle (the soft spot on a baby’s head). It’s important to gather thorough birth history and vaccination records, as some types of meningitis can be prevented by vaccines, such as those against Pneumococcus bacteria, Haemophilus influenzae type B, Meningococcus bacteria, measles and chickenpox.

Testing for Meningitis

Meningitis is diagnosed by analyzing a fluid from your spine called cerebrospinal fluid (CSF). Your doctor will take a sample of this fluid through a procedure called a lumbar puncture. Tests run on this fluid can include checking the white blood cell count, glucose and protein levels. They may also grow cultures and conduct a test called a polymerase chain reaction (PCR) if needed.

Depending on what your doctor suspects is causing your meningitis, other specific tests might also be done:

• For viral causes, multiplex and specific PCRs
• For fungal causes, a CSF fungal culture and a special stain to check for a fungus called Cryptococcus
• For tuberculosis causing bacteria, a CSF Acid-fast bacilli smear and culture
• For Syphilis, a CSF VDRL test will be performed
• For Lyme disease, they’ll test for a burgdorferi antibody in your CSF

Usually, doctors aim to collect the CSF sample prior to giving antibiotics, but if a patient with potential bacterial meningitis is severely ill, immediate administration of antibiotics might be necessary before taking time to do the lumbar puncture.

There is some debate about whether a lumbar puncture can cause brain herniation (a dangerous brain shift), particularly in patients with bacterial meningitis who already have increased pressure in their skulls. Therefore, if a doctor suspects increased intracranial pressure, they might decide to give you antibiotics immediately without waiting for the lumbar puncture.

Signs that you might have increased intracranial pressure or risk of brain herniation include a Glasgow coma scale (a brain functioning scale) score less than 11, being excessively tired, mental confusion, new seizures, or specific neurological symptoms like weakness or numbness in certain body parts.

Please remember: having a normal head CT scan does not definitely rule out increased skull pressure or brain herniation. If you show signs of brain herniation, avoid the lumbar puncture even if the head CT seems normal, and start treatment immediately.

Finally, various blood tests will be run as well, including blood culture, serum electrolytes to check for a condition called syndrome of inappropriate antidiuretic hormone secretion (SIADH) which can cause abnormal salt levels in your body, serum glucose, check your kidney and liver function, and a test for HIV.

Treatment Options for Meningitis

If you are diagnosed with bacterial meningitis, your doctor will primarily focus on utilizing antibiotics and offering supportive care to manage the condition. This generally involves making sure you can breathe properly, administering intravenous fluids to prevent dehydration, and taking steps to control your fever.

The specific type of antibiotic prescribed will heavily depend on your age group, your medical history, and the suspected bacteria causing the infection. It is crucial to choose the right antibiotic to effectively tackle the bacteria causing the illness.

For newborns up to 1 month of age and for adults between 18 to 49 years of age, the desired treatment generally involves a combination of specific antibiotics. People older than 50 and those with weakened immune systems may require a different combination of antibiotics. Similarly, meningitis associated with a foreign body (such as after surgery or an injury) or severe penicillin allergy needs medicines tailored to each situation. For fungal meningitis, one of the rarer types, doctors usually prescribes a specific type of antibiotics used to treat such infections.

It’s important to understand that there are different types of antibiotics to treat various kinds of bacterial infections. Without getting too much into medical jargon, some work better in handling certain types of bacteria whereas others penetrate the central nervous system more effectively. Your doctor will choose the best one based on your specific situation.

In terms of steroid therapy, the consensus among medical professionals is less clear. Some believe that steroids can reduce mortality in specific kinds of meningitis, whereas others argue that the evidence supporting their use is not robust. Steroids might be used in children to prevent severe hearing impairment caused by a particular type of bacteria.

If you show signs of increased intracranial pressure–such as changes in consciousness, neurologic deficits, non-reactive pupils, or a slow heart rate–the doctor might elevate your head or administer diuretics that can reduce pressure in the brain.

In addition to treating you, it’s also important to prevent the spread of meningitis to people close to you. In some types of meningitis, household members, partners, those sharing utensils, and healthcare professionals who have been in contact with your secretions without protective masks may need preventive treatments, which in medical terms is known as ‘chemoprophylaxis’. This process could involve a specific set of antibiotics that are effective against the bacteria causing your infection.

What else can Meningitis be?

Here are several medical conditions that may result in brain dysfunction and could be confused with meningitis:

• Stroke
• Subdural hematoma – a condition where blood collects on the brain’s surface
• Subarachnoid hemorrhage – a type of brain bleed
• Metastatic brain disease – spread of cancer to the brain
• Brain abscess – which might occur at the same time as meningitis

What to expect with Meningitis

The outcome or recovery from bacterial meningitis can depend on various factors such as the patient’s age and how strong their immune system is. It is also affected by the type of bacteria causing the meningitis. In the US, the annual death rate from all types of bacterial meningitis was at 14.3% in 2010.

The death rate can vary greatly depending on the specific bacteria involved. Here are some figures:

• For meningitis caused by the bacteria Streptococcus pneumoniae, the death rate was about 17.9%.
• For meningitis caused by Neisseria meningitidis, the death rate was about 10.1%.
• For meningitis caused by Group B Streptococcus, the death rate was about 11.1%.
• For meningitis caused by H. influenzae, the death rate was about 7%.
• For meningitis caused by Listeria monocytogenes, the death rate was about 18.1%.

Possible Complications When Diagnosed with Meningitis

A study in 2010 examining children found that nearly 20% of patients experienced health problems after leaving the hospital. The top two germs found were H. influenzae, followed by S. pneumoniae. The most common issue post-hospital stay was hearing loss (6%), followed by behavioral (2.6%) and cognitive difficulties (2.2%), motor skills problems (2.3%), seizures (1.6%), and vision issues (0.9%).

Other Complications Include:

• Raised pressure in the skull from brain swelling due to high intracellular fluid in the brain. This could be caused by multiple factors such as increased permeability of the blood-brain barrier, toxicity from substances released by immune cells and bacteria.
• Hydrocephalus, which is the buildup of fluid in the cavities deep within the brain.
• Complications involving the blood vessels in the brain.
• Localized neurological problems.