Meningitis

Meningitis is the inflammation of meninges surround the brain. It is important to recognize early as can have significant morbidity and mortality. It is important to consider on the differential in any patient with a non-specific febrile illness, especially in patients at higher risk.

Risk factors

 * Immunocompromised (HIV, DM, steroid use, ETOHs, asplenia)
 * Recent infection (otitis media, sinusitis)
 * Head trauma
 * Recent neurosurgical procedures/shunts
 * Neonates
 * Non-immunized
 * History of contacts with meningitis
 * Recent abdominal surgery


 * Aboriginal groups
 * Students living in residency

Clinical

 * Signs: HA, fever, neck stiffness, altered mental status, N/V
 * Neonate: fever/hypothermia, lethargy, irritable, poor feed
 * (no fever, neck stiffness and N mental status = sensitive 99%)


 * Physical examination:
 * Neonate: toxic, bulging anterior fontanelle, resp distress, purpuric rash
 * Complete neurological examination
 * Older child/adult: toxic, decrease LOC, nuchal rigidity, +/- papilledema, +/- petechial rash
 * Kernigs: flex hip/knee --> when try to extend knee = pain (sensitivity 5-10%, specificity 95%)
 * Bruzinski: flex patients neck--> involuntary flexion of knee/hip (sensitivity 5-10%, specificity 95%)
 * Jolt accentuation: exacerbation of a baseline headache with horizontal rotation of the neck at a rate of 2 rotations/second
 * (97% sensitive, 54% specific)

Investigations

 * CBC, lytes (for SIADH), blood cultures
 * If fever NYD - complete remainder of septic w/u
 * Lumbar puncture
 * Need to do CT prior to LP if suspect elevated ICP as an LP would put patient at risk of herniation
 * CT first: decrease LOC, seizure, >60 years of age, immunocompromised, focal neurological findings, papilledema, known CNS diseases
 * When meningitis is suspected ensure a timely lumbar puncture. Do not delay Abx for LP.
 * Send LP for: 1. cell count + differential 2. Chemistry (glucose/protein) 3. gram stain R+M/ C+S 4. Cytology 5. RBCs
 * Consider sending for acid fast bacilli, fungal C+S, cryptococcal antigen in immunocompromised, travel history, TB exposure history
 * Consider PCR HSV, VZV, EBC, enteroviruses, west nile if viral etiology suspected
 * Note: RBC in tube #1 >>>tube #4/5= traumatic tap. If equal = Subarachnoid hemorrhage
 * The CSF is normally acellular, although up to 5 white blood cells (WBCs) and 5 red blood cells (RBCs) are considered normal in adults when the CSF is sampled by lumbar puncture (LP); newborns, in contrast, may have up to 20  WBCs/microL  in the CSF
 * ensure to interpret the data in light of recent antibiotic use

Common organisms


Other:
 * Viral: HSV1/@, VZV, enterovirus, west nile, measles, infleunza
 * Fungal: cryptococcus
 * Other: TB, lyme disease, neurosyphillis

Complications

 * Hearing loss
 * Chronic headache
 * Learning disabilities
 * SIADH
 * Neuro deficits/hydrocephalus/seizure
 * Death

Treatment

 * Viral meningitis:
 * Supportive care. Often resolve in 7-10 days
 * Antivirals for HSV and influenza
 * Bacterial meningitis: MEDICAL emergency
 * Dexamethasone prior to antibiotics (adults 10mg IV q 6hours x 4 days, children 0.6mg/kg/day)- decrease mortality in patients with s.pneumo. Initiate 15-20 minutesprior to abx.
 * Broad spectrum coverage then narrow based on gram stain
 * Neonate - 3 months: ampicillin + cefotaxime +/- gentamycin/tobramycin (if source not definitive)
 * Note: ceftriaxone safety not established in neonates. Therefore only recommended >1 month.
 * Infants, children: same as age 18-50- dose based on weight
 * Age 18-50: 3rd gen cephalosporin (ceftriaxone 2 grams IV q 12 hours x 24 hours then q24 hours) + vancomycin 1.5 grams IV q12
 * >50, ETOH or immunocompromised) add ampicillin 2grams q4hours (listeria coverage)
 * Alternative: IV chloramphenicol 1 gram q6hours + IV vancomycin 1.5 grams q12 hours +/- septra 5mg/kg q6hours
 * If concern r.e. HSV --> add acyclovir
 * Post trauma/neurosurgery: ceftazidime + vanco
 * Duration of therapy is uncertain. General guide: meningococcal/ h.influenza 7-10days. S. pneumo 10-14days.

Prevention

 * See immunizations page
 * Vaccines: H.influenza, meningococcal, pneumococcal
 * Reportable if invasive to public health

Close contacts

 * Contact public health to ensure appropriate prophylaxis for family, friends and other contacts of each person with meningitis. Chemoprophylaxis only indicated in h.influenza type B and menongoccal infections.
 * Prophlylaxis may be indicated for household/close contacts (if unimmunized) of a child with inasive H. Influneza type B: rifampin 20mg/kg orally (mx 600mg/day) once daily x 4 days

Resources
http://www.cdc.gov/meningitis/bacterial.html

http://www.uptodate.com/contents/treatment-and-prevention-of-meningococcal-infection?source=machineLearning&search=propylaxis+of+meningitis&selectedTitle=1~150§ionRank=3&anchor=H23#H23