The Responder’s Guide to Meningitis

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Objectives

• Define what is meningitis
• Discuss the epidemiology of meningitis
• Review evaluation of the meningitis patient
• Discuss prehospital management of the meningitis patient

The meningitis outbreak of late 2012 began in September when a patient in Tennessee was diagnosed with Aspergillus fumigatus meningitis 46 days after being injected with an epidural steroid.¹ A subsequent investigation led by the Tennessee Department of Health, CDC and North Carolina Department of Health and Human Services identified 8 more patients. Fast-forward to November 1, and we’ve now confirmed 414 patients in 19 states, 30 of whom have died.

What happened is still being determined. However, what is known is that more than 17,500 vials of preservative-free methylprednisolone acetate, from three different drug lots, were packaged in volumes of 1, 2 and 5 mL and shipped to 75 distribution sites in 23 states. These vials were later found to be infected with the fungus Exserohilum rostratum, which has been associated with patients developing:^1,2

• Fungal meningitis or nonbacterial and nonviral meningitis;

• Basilar stroke following epidural injection;

• Septic arthritis or osteomyelitis of a peripheral joint following injection;

• Spinal osteomyelitis or epidural abscess.

Of patients aged 23–91 years, 91% of those experiencing ill effects from their steroid injections have been diagnosed with fungal meningitis, which is considered a very rare complication from epidural injections.¹ As meningitis is a serious and life-threatening illness often not easily distinguished from other emergencies, this outbreak has real and potential impacts on EMS systems all over the country.

What Is Meningitis?

Anytime -itis is seen at the end of a part of anatomy, think inflammation. Meningitis is the inflammation, or swelling, of the meninges. The meninges are three layers of connective tissues that surround and protect the brain and spinal cord. In order from outer to inner, the meningeal layers (see Figure 1) are the:

• Dura—The tough and relatively inelastic outermost membrane;

• Arachnoid—The middle layer, thin and spider web-like;

• Pia—The innermost, vascularly rich layer that tightly hugs the brain and spinal cord.

EMS providers most often remember the dura, as it is the separating membrane for epidural and subdural hematomas. However, as seen in Figure 1, the meninges extend down the length of the spinal cord. Cerebrospinal fluid takes up the space between each layer to maintain near-frictionless movement of the membranes against one another and help the central nervous system move electrolytes and nutrients, maintain acid-base balance, transport hormones and neurotransmitters, and maintain a balance of intracranial pressure.

Additionally, the meninges make up a significant part of the blood-brain barrier, and this barrier extends throughout the CNS. Most of the time it helps protect the CNS by making infection difficult. However, once an infectious material passes the blood-brain barrier, infection can spread rapidly.

Epidemiology

In the United States the annual incidence of meningitis is 4,100 cases, with 500 deaths.³ While this number appears small, meningitis remains a major source of morbidity and mortality in developing countries. The worst outbreak occurred in 1996 in West Africa: 250,000 persons were infected, and 25,000 died.⁴ While not important for daily medicine in the United States, it is important to remember that locations throughout the developing world still have outbreaks, and EMS providers traveling on medical mission trips may visit locations where meningitis remains an epidemic problem.