A Brief Synopsis of AFP's "Diagnosis, Initial Management, and Prevention of Meningitis"

A brief synopsis of: Diagnosis, Initial Management, and Prevention of Meningitis, DAVID M. BAMBERGER, MD, University of Missouri–Kansas City School of Medicine, Kansas City, Missouri

Am Fam Physician. 2010 Dec 15;82(12):1491-1498.

http://www.aafp.org/afp/2010/1215/p1491.html

     Considering the recent outbreak in upstate New York, I thought it would be appropriate to review meningitis (i'll save bird flu for next week). Meningitis is usually bacterial or viral (aseptic).  Bacterial is more rare and way more dangerous. The most common types of aseptic meningitis are enterovirus, HSV, HZV and Borrelia burgdoferi.  Enterovirus and arbovirus are prevalent in the summer and fall months. 
     In adults, most patients with bacterial meningitis will have either fever, neck stiffness, altered mental status or headache. Some will present with a recent history of otitis, sinusitis, pneumonia, or an immunocompromised state. A petechial rash may also be seen in meningococcal meningitis. Seizures, focal neurological findings, and altered consciousness is more commonly seen in pneumococcal meningitis. Younger adults are less likely to present with seizures and hemiparesis, but more commonly with headaches, nausea, vomiting, and nuchal rigidity. Younger children will present with lethargy, irritability and a history of a recent URI. They may also "catch" a seizure at this young age. So you get the point, right? we have a serious disease with high mortality, but subtle clinical findings. Thus, if you can't come up with an explanation for all the symptoms, you better evaluate that CSF.
     A lumbar puncture is generally a safe procedure. We all have fear that we will cause a brain herniation when we hear the "pop", but as long as the patient the patient does not have any neurological issues (shunts trauma, papilledema, etc), you will be safe. Of course, if the patient had a seizure or is impaired, a CT will be necessary. Regardless, you still need to get blood cultures and start empiric therapy before the CT. Sitting on therapy for as little as 2 hours could affect the outcome poorly. Starting therapy before the LP will decrease the amount of bacteria available to culture, and may affect the glucose level, protein level , and ability to culture the bug for antibiotic sensitivity testing. It will not affect the gram stain of PCR results. 
     For empiric therapy, give vancomycin and ceftriaxone. Add ampicillin if the patient is over 50 years old  and an alcoholic. If the patient had a penetrating trauma, a CSF shunt or is post surgery, switch out the ceftriaxone for cefepime. If the patient is less than a month old, try ampicillin and cefotaxime. If you suspect M. Tuberculosis or S.pneumoniae , you can add dexamethasone.
     Aseptic meningitis is a less serious infection. It can be diagnosed by PCR of the CSF. An RPR, VDRL, or HIV antibody test may be done if the history warrants.  Fungal and TB meningitis can be diagnosed with PCR as well. Cryptococcal is the most common fungal cause and can be treated with amphotericin b and flucytosine.