1. Aseptic Meningitis
Rasheda EL-Nazer PGY1

2. Aseptic Meningitis - Definition
Exam, history, lab studies suggest meningeal inflammation. But, routine bacterial cultures are negative.

3. Meningitis
Symptoms: may have photophobia, neck stiffness (30%), headache (most common). But no signs of cerebral dysfunction (motor / sensory / speech / personality / behavior changes).
Kernig and Brudzinski (5%): poor sensitivity, good specificity
Seizures may occur with meningitis alone
Overlap may be present with encephalitis

4. CSF analysis* Bacterial Viral WBC count >1000
<500 (more than 50% lymphocytes)
Glucose
<40
Normal
Protein
>100
< 100
*Gross generalization. There is significant overlap.
Use this as a starting point.
60-70% of the concentration in the blood

5. Classification Viral (most common) Other infections
Enteroviruses - Summer, fall months. Most common. Associated with rash, diarrhea, URI.
HIV: may be associated with primary mononucleosis-like syndrome. Suspect HIV in high-risk populations.
HSV: ~ 85% of patients with HSV meningitis have genital lesions that precede CNS symptoms by 7 days.
Other infections
Syphilis: During secondary syphilis. Headache, malaise, disseminated rash.
Lyme disease: (fall / summer months). Can cause CN 7 palsy. Erythema chronicum migrans. History of tick bites.

6. Classification Fungal Infections: Cryptococcal: Coccidioidal:
Infection spreads from respiratory tract to CNS.
In immunocompromised patients, particularly in AIDS
CSF studies are usually only slightly abnormal.
WBC < 50, glucose and protein slightly abnormal
Coccidioidal:
Southwest US, Central / South America.
Slow infection. Takes weeks to months after primary(usually respiratory) infection.
Most common symptom: persistent headache- making this difficult to diagnose
Significant number of eosinophils may be present in CSF

7. Classification Tuberculosis:
Basilar meningeal enhancement, hydrocephalus seen on MRI
CSF findings: normal to mildly elevated protein, normal glucose, WBC 5-100
Spillage of tubercular protein into the subarachnoid space produces an intense hypersensitivity reaction1
Proliferative arachnoiditis at base of brain – “fibrous” encapsulation of cranial nerves, vessels
Vasculitus / aneurysms
Hydrocephalus from impedance of CSF circulation / absorption

8. TB meningeal enhancement

9. Classification Neoplasms of leptomeninges Drug induced meningitis
Hematologic malignancies and solid tumors can cause meningeal signs.
Drug induced meningitis
Dx of exclusion
NSAIDS, bactrim, IVIG, antiepileptic drugs

10. Diagnosis Physical exam: CSF analysis: CSF PCR, culture for viruses
Rash: HIV, syphilis, RMSF, meningococcal infection
Vesicules: HSV
Oropharyngeal thrush, cervical lymphadenopathy: HIV
CSF analysis:
Early viral meningitis may have PMN predominance, but later switches to lymphocytic predominance.
CSF WBC < 250, CSF protein < 150, glucose levels normal
CSF PCR, culture for viruses
CSF Bacterial culture, gram stain
VDRL, HIV antibody / HIV RNA testing

11. Treatment Suspected Viral: Suspected Bacterial:
If elderly, immunocompromised. Empiric antibiotic therapy.
Acyclovir for HSV
Suspected Bacterial:
Empiric antibiotic therapy.
Typically Vancomycin (gram +) + Ceftriaxone (Gram -)
Health care associated meningitis requires pseudomonas coverage. Vancomycin + Ceftazidine / cefepime / meropenem
Add dexamethasone 10mg Q6H x 4 days to reduce hearing loss, other complications if bacterial pathogen is suspected or unkown, or S. Pneumoniae.
Cochrane meta analysis performed in 2013 looked at over patients in 25 randomized trials. GC reduce mortality only in patient with S. pneumo meningitis. Reduction in hearing loss and short term neurologic sequelea were only prevented with dexamethasone in high income countries

12. References
Patriquin G, Hatchette J, Forward K. Clinical presentation of patients with aseptic meningitis, factors influencing treatment and hospitalization, and consequences of enterovirus cerebrospinal fluid polymerase chain reaction testing. Can J Infect Dis Med Microbiol Spring;23(1):e1-5.
Brouwer MC, McIntyre P, Prasad K, van de Beek D. Corticosteroids for acute bacterial meningitis. Cochrane Database Syst Rev Jun 4;6:CD
Sáez-Llorens X, O'Ryan M. Cefepime in the empiric treatment of meningitis in children. Pediatr Infect Dis J Mar;20(3): Review.
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