Case Presentation

In #AMReport at @WCHospital this week, we discussed a case of a patient presenting with headache, confusion, fever and rash, who was found to have West Nile virus meningitis.  We reviewed an approach to headache, red flag features of headache as well as how to diagnose and manage meningitis.

Learning Points

1. Approach to Headache
2. Red Flag Features of Headache (SNOOPPPS)
3. Physical Exam Findings in Meningitis
4. Interpreting CSF
5. Key Things to Know about Bacterial Meningitis
6. Treatment of Bacterial Meningitis

Approach to Headache

When assessing a patient with headache, it is important to have a good differential of common primary causes and secondary, serious causes that you need to rule out:

Red Flag Features of Headache (SNOOPPPS)

Now that we have a good approach to headache,  it is important to ask about red flags associated with worrisome secondary causes of headache. Your history and physical will  then direct your investigations.

Physical Exam Findings in Meningitis

According to the JAMA Rational Clinical Exam:

• Kernig’s and Brudzinski’s signs have poor sensitivity and specificity (based on little data) for meningitis
• Jolt accentuation is very sensitive (97%) based on one study of 54 patients with fever and headache, making it a good rule-out test if it is negative.
  • To perform the test, ask the patient to shake their head from side-to-side at about 2-3Hz and ask them if their headache is better, the same or worse. If it is not worse, this significantly decreases the likelihood of meningitis.

CSF Interpretation

In terms of CSF interpretation, any of the following predict bacterial meningitis with 99% specificity: Glucose <1.9 mmol/L, WBC >2000, protein >2.2g/L, CSF: bluud glucose <0.23, PMNs>1180 cells/mL

Source: Spanos et al, 1989; Table modified from J. Hsu

Key Things to Know about Bacterial Meningitis

Check on this fantastic CMAJ Article on bacterial meningitis. We talked about the 5 things you should know from this article in morning report:

1. Bacterial meningitis is a medical emergency. Timely antibiotic therapy is critical.
   • Although early antibiotics might lower your chances of a obtaining a positive  CSF culture, they will reduce the chance or morbidity and mortality. If you are awaiting imaging or LP will be delayed, give antibiotics right away! Treat empirically if you unsure about viral vs bacterial meningitis while awaiting culture results.
2. Select patients may safely undergo LP without prior CT of the brain
3. Analysis of CSF can support the diagnosis of bacterial meningitis when gram staining and culture are negative because of prior antimicrobial administration
4. Clinical outcomes may be improved with adjuvant corticosteroid therapy
5. The choice of empirical antimicrobial therapy for bacterial meningitis must take the patient’s age and immune status into account

Treatment of Community-Acquired Bacterial Meningitis

If your patient is >50 years of age or immunocompromised (e.g., chronic alcohol use), you should provide coverage for Listeria with ampicillin (in addition to vancomycin and ceftriaxone).

*Remember to give chemoprophylaxis for close contacts of n. meningitidis meningitis

Source: Table from Moayedi & Gold, 2012

What about aseptic meningitis?

In the case at morning report, our patient had aseptic meningitis caused by West Nile Virus. There are many other viruses that can cause aseptic meningitis including herpesvirus, HIV, enteroviruses like coxsackie and mumps. CSF testing will depend on what organisms might be potentially causative. If you suspect HSV as a possible cause of aseptic meningitis, treat empirically with acyclovir. Otherwise, aseptic meningitis is usually self-limited and treatment is largely supportive (with some exceptions).

Additional Reading:

1. Moayedi Y, Gold WL. Acute bacterial meningitis in adults. CMAJ. 2012 Jun 12;184(9):1060-.
2. Van de Beek D, de Gans J, Tunkel AR, Wijdicks EF. Community-acquired bacterial meningitis in adults. New England Journal of Medicine. 2006 Jan 5;354(1):44-53.

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