Fungal Meningitis Causes And Symptoms

This article focuses on the causes of fungal meningitis, its symptoms and diagnosis, raising awareness on identifying the signs and symptoms if one has it. This article also provides information on the treatment and any complications caused by fungal meningitis.

Introduction

Definition of fungal meningitis

Meningitis is inflammation of the meninges. The meninges are three membranes that surround the brain and the spinal cord. The meninges provide protection and support to the central nervous system. The three layers of the meninges, going from the outer to the inner layer, are the dura mater, arachnoid mater, and pia mater. Meningitis can be caused by viruses, bacteria, fungi and parasites. However, fungal meningitis is caused by fungi.¹

Importance of understanding its causes and symptoms

Fungal meningitis can be caused by one of several fungal pathogens, including the following:

• Cryptococcus neoformans
• Aspergillus
• Candida

Those who are immunocompromised, such as those with HIV, AIDS or cancer are more susceptible to contracting fungal meningitis, as the immune system struggles to fight off invading fungal pathogens.¹

Symptoms of fungal meningitis include the following:

• Vomiting/nausea
• Fever
• Headache
• Stiff neck
• Photophobia (eyes being more sensitive to light)

Understanding the symptoms of fungal meningitis is important as this allows the infection to be detected, diagnosed, and treated early. This is especially crucial for those who are immunocompromised due to treatment possibly taking longer.

Causes offungal meningitis

Fungal pathogens

Common fungal species responsible

As previously mentioned, the most common fungal species responsible for fungal meningitis is Cryptococcus neoformans. However, other fungal species such as Aspergillus ,Candida, Coccidioides and Histoplasma may also cause fungal meningitis.^1,2 

How they enter the body

Fungal pathogens such as Cryptococcus enter the body via inhalation of spores into the lungs.³ Similarly, Aspergillus also enters the body via inhalation of spores into the lungs . Candida is part of the body’s natural flora, and usually exists on the surface of the skin without causing illness. However, Candida can cause infections such as fungal meningitis by entering the body.  For example, this can occur when a central venous catheter is inserted after surgery, and left in for a prolonged period of time or when the immune system has been weakened, such as after individuals with cancer have chemotherapy.

Risk factors

Immunocompromised individuals

Immunocompromised individuals have a weakened immune system and are more susceptible to catching infections. Those who are immunocompromised include those with cancer, AIDS, HIV and those who have diabetes.

Medical procedures

There can be healthcare associated breakouts of fungal meningitis. If you have received epidural anesthesia or corticosteroid injections, this can increase your risk of contracting fungal meningitis. 

Transmission

Person-to-person vs. environmental exposure

Fungal meningitis is not spread from person to person. In order to contract fungal meningitis, it must be contracted from environmental exposure. For example, fungal pathogens such as Cryptococcus and Histoplasma can be found throughout the environment. Candida exists on the skin, and Coccidiodes live in the soil in the United States, parts of Mexico, and both Central and South America. 

Modes of transmission:

• Environmental exposure in the environment
• Environmental exposure via the soil
• Candida entering the bloodstream 

Symptoms of Fungal Meningitis

Early Signs

Early symptoms of fungal meningitis include the following:

• Fever
• Headache 
• Nausea
• Vomiting

Later signs

Later symptoms include having confusion and being more sensitive to bright lights.

Specific symptoms based on causative fungi

Cryptococcal meningitis symptoms

Cryptococcal meningitis occurs when the cryptococcal infection spreads from the lungs to the meninges of the brain. The symptoms include:

• Headache
• Fever
• Sensitivity to bright lights
• Confusion 
• Vomiting 
• Nausea

Candida meningitis symptoms

Candida meningitis occurs when the fungus Candida enters the bloodstream or the internal organs. The symptoms include:

• Headache
• Stiff neck
• Fever

Diagnosis of fungal meningitis

Clinical evaluation

Physical examination

When being examined by the doctor, if they suspect fungal meningitis, the doctor may look for Brudzinski’s sign. The doctor will gently pull your neck forward, and any stiffness may indicate meningitis. Another sign a doctor may look for is Kernig’s sign. The doctor will bend your leg forward at the hip, and slowly straighten the leg. If you experience intense pain in either your thigh or back, this may be a sign that you have meningitis. However, these signs will not narrow down on the cause of meningitis, whether this be fungal, bacterial, viral, or parasitic in origin. 

Laboratory tests

Lumbar puncture (CSF analysis)

Fungal meningitis can be diagnosed via cerebrospinal fluid (CSF) analysis, which can include measuring glucose and protein levels, as well as conducting a white blood cell count. Protein and white blood cell counts are used to determine the degree of inflammation on the CSF when coming to a diagnosis.⁴  The CSF is obtained via a lumbar puncture, and the pressure is also measured from the lumbar puncture, helping to come to a diagnosis. This laboratory test can also allow additional tests to be conducted such as doing CSF fungal culture. For example, doing an Indian ink stain on the fungal culture can identify if the fungus causing the meningitis is Cryptococcus neoformans. Polymerase chain reaction can also be conducted on your CSF sample to identify the fungus causing the meningitis by looking at its genetic makeup.¹

Blood cultures

Fungal blood cultures are subject to antigen tests for Cryptococcus and Histoplasma. Antigens are unique proteins on the surface of a fungal species, allowing them to be identified. 

Blood cultures can also identify any antibodies that may have been produced due to the infection, helping to reach a diagnosis.

Fungal cultures

Culturing the pathogen allows aetiology to be determined, such as culturing from CSF and using Indian ink staining on the fungal culture, and observing the species under a microscope can determine if the cause of the meningitis is Cryptococcus neoformans.¹

Imaging studies

CT scans or MRI

Computer Tomography (CT) and Magnatic Resonance Imaging (MRI) scans may be used in conjunction with other diagnostic tests, but are not used solely when coming to a fungal meningitis diagnosis. They can help to detect how much inflammation there is of the meninges, and if any infections have been contracted. The downside to using MRI and CT scans is that the aetiology can not be detected. This means that meningitis can not be put down to a specific bacterial, viral or fungal species.⁴  

Treatment and management

Antifungal medications

If diagnosed with fungal meningitis, you will be treated with two antifungal drugs, which will be delivered intravenously (IV). These drugs are amphotericin B and voriconazole. After having these drugs delivered via IV for two weeks in a hospital, it may be possible to switch to oral medicines.

Supportive care

Pain management

Pain management is primarily centred around any headaches which you may get from having fungal meningitis and inflammation of the meninges in the brain. 

Managing complications

Hearing loss is a complication of meningitis, which may have to be treated with cochlear implants. There may also be seizures that may have to be managed medically, similar to epilepsy. Meningitis can result in disturbed sleep patterns, prompting individuals to seek counselling.

Monitoring and follow-up

Regular check-ups

Oral medication may be a treatment for up to 3 months after you contract fungal meningitis, which is why it is important to seek out regular checkups with your healthcare provider about the course of long-term treatment. 

Adjustments in treatment

Depending on the severity of the symptoms, your treatment may have to be adjusted to providing oxygen via a face mask or having a drip to help deliver nutrients to your body. In addition, if there is a high degree of meninges inflammation, steroids and diuretics may be given as part of your treatment. They can reduce the pressure buildup in the skull due to the brain meninges being severely inflamed.

Prevention

Vaccinations

Vaccinations do exist for bacterial meningitis. However, their protection does not extend to viral and fungal meningitis.

Reducing risk factors

Typically precautions do not need to be taken to prevent fungal meningitis. However, if you live in an area that has a higher rate of fungal infection, avoiding bird droppings, dusty environments, and digging in the soil are some advisory precautions.

Potential complications

Neurological deficits

If the patient begins to have neurological defects, an altered mental state, or their pupils stop showing response to a light stimulus, there may be a sign of increased intracranial pressure. In order to treat this, the head of the bed should be elevated to 30 degrees, and encourage the patient to mildly start hyperventilating. Osmotic diuretics may also be used.¹

Long-term cognitive issues

Long-term cognitive issues can include the following:¹

• Hearing and speech loss
• Blindness
• Behavioral changes

Prognosis 

Early diagnosis is of the utmost importance with fungal meningitis as symptoms can quickly escalate and result in brain damage and possibly even death. If treated quickly, the prognosis is much better, with high recovery rates.¹

Summary

• Fungal meningitis is caused by a fungal species and results in inflammation of the meninges in the brain/spinal cord
• Different fungal species can cause fungal meningitis, with the most common being Cryptococcus neoformans
• Early detection leads to the best prognosis, as symptoms can escalate very quickly
• Treatment centers around antifungal medication delivered intravenously, including Amphotericin B 
• Medical attention should be sought out as soon as symptoms arise
• Treatments are usually provided in hospital, and early detection prevents complications, such as hearing loss and seizures