The central nervous system (CNS) consists of the brain and the spinal cord. Three connective tissue membranes called meninges cover and protect the CNS. Meningitis occurs when the meninges become infected and swell. Of the three types of meningitis, viral, bacterial and fungal, fungal is not contagious and is rarely the focus of any health news. As the name fungal meningitis implies, it is usually caused by a fungus that spreads from the blood to the CNS. It is usually diagnosed in people taking high dose steroids that get an infection in their nasopharynx that can spread up into the meninges of the brain. It can also be contracted from inhalation of spores from soil that is heavily contaminated with bird or bat droppings. However, fungal meningitis has recently flooded the news but it is not from a traditional path but from contaminated epidural medication.
In October 2012, the Center for Disease Control and the Food and Drug Administration began investigating a fungal meningitis outbreak that has occurred in many states from contaminated steroid injections given to patients with severe back pain. In these cases, the steroid medication methylprednisolone inadvertently containing the fungus Exserohilum rostratum, a common black fungus typically associated with grass and rotting wood, was injected directly into the epidural space, the space between the spinal cord and the backbone. In humans, this space houses lymphatics (drainage vessels that collect excess interstitial fluid and return it to the bloodstream), loose fatty tissue, spinal nerve roots, small arteries and a network of large, thin walled blood vessels called the epidural venous plexus.
Patients with severe neck and/or back pain are commonly given these injections in the epidural space so the medication has direct access to nerves causing the pain. The epidural space is continuous all the way up the spine to the brain stem and connects to the brain. Therefore the contaminated injection potentially allows the fungus that seems to be particularly aggressive in attacking tissues in the spine and brain stem to spread all the way up the epidural space to the brain. As the fungus multiplies and spreads the meninges become infected and inflamed.
As a result of this outbreak, fatalities have occurred from stroke like complications in patients who for the most part were healthy except for back pain. A stroke typically occurs when blood vessels in the brain are either blocked by a clot or burst. When the meninges become inflamed, the many blood vessels supplying the brain with oxygen and nutrient rich blood also become inflamed. Inflammation causes the artery wall to become narrow which slows blood flow and can result in clot formation in the brain. The loss of blood flow limits the supply of blood to brain tissue which causes the tissue to die. Artery inflammation can also lead to artery wall rupture in the brain causing a hemorrhage, bleeding in the brain and the loss of brain tissue.
Fungal meningitis is treatable with intravenous antifungal drugs but early detection is critical. Patients who have received steroid injections in their back or peripheral locations (elbow, knee, shoulder, etc.) should monitor themselves vigilantly for signs of meningitis. Symptoms include: headache, fever, sensitivity to light, stiff neck, weakness or numbness in any part of the body, slurred speech, increased pain, redness or swelling at the injection site. If any of these symptoms are noticed you should contact your doctor immediately.
References
http://www.fda.gov/Drugs/DrugSafety/FungalMeningitis/default.htm
http://www.humanillnesses.com/Infectious-Diseases-He-My/Meningitis.html
Marieb, E. (2010). Human Anatomy and Physiology.San Francisco: Pearson.
