Meningitis

  • adults - Bacterial meningitis in the Western world is most often caused by S pneumoniae
  • children - infection with Neisseria meningitidis is more common
  • classic triad of fever, nuchal rigidity, and altered mental status in adults
  • The sensitivity of the classic triad in adults presenting with community-acquired acute bacterial meningitis is low, and absence of specific clinical signs is not unusual. Neonates often not febrile
  • Kernig'sclose flexing the hip and extending the knee to elicit pain in the back and the legs & Brudzinski'sclose passive flexion of the neck elicits flexion of the hips signs - reported to be highly specific but low sensitivity. Absence of these signs should NOT exclude entertaining meningitis as Dx
  • Head jolt testclose considered positive if headache accentuated by horizontal rotation of head at frequency of 2-3x per sec variously considered more sensitive
  • seizures occur significantly more often in patients with pneumococcal meningitis than in meningococcal infection and are associated with increased mortality

Mollaret meningitis

  • due to a viral infection (aseptic meningitis) that occurs multiple times. Most often herpes simplex, HSV-2 but occasionally HSV-1
  • known by many other names including Recurrent benign lymphocytic meningitis (RBLM), aseptic meningitis etc
  • characterized by repeated episodes of meningitis, typically lasting 2-5/7, occurring weeks to years apart.
  • spontaneous full recovery usually after 5/7
  • neurological signs - not unlike migraine presentation
  • Almost 1/2 develop long-term CNS impairment eg. memory, balance, coordination, and/or hearing.

CT scan before LP if:

  • Altered mental status
  • New onset seizures
  • Immunocompromised
  • Focal neurology
  • Papilloedema
  • Hx of CNS disease - mass, infection, stroke)
  • CT is unreliable for identifying raised intracranial pressure

CSF findings

CSF findings Bacterial Viral Fungal
opening Press N
WCC 1k-10k <300 <500
Neutrophils >80% 1-50% 1-50%
Glu N
Protein N
g stain bacteria - -

Treatment

  • IV ceftriaxone.
  • children <3/12 IV cefotaxime + amoxycillin or ampicillin
  • consider herpes simplex encephalitis, consider other unusual pathogens eg Listeria, TB
  • IV dexamethasone
  • PCR should be taken for bacterial and viral studies

References include: