Meningitis Flashcards
Causes of meningism
Meningitis Subarachnoid haemorrhage Infections with bacteriaemia Severe viral infections, e.g. severe influenza, pneumonia, sinusitis Migraine
Capillaries of the brain and spinal
cord differ from those in other parts of
the vascular system in that they…
do not have fenestrations
Molecules therefore cross capillaries less by diffusion and more by active transport or lipid solubility
Pathogenesis of most cases of meningitis involves at least 5 steps
- Attachment to mucosal epithelial cells (eg, bacteria and mumps virus to nasopharyngeal and oropharyngeal mucosa, enteroviruses to intestinal mucosa).
- Transgression of the mucosal barrier.
- Survival in the blood stream.
- Entry into CSF.
- Production of overt infection in the meninges with or without brain infection (encephalitis)
Less common causes of meningitis
• Haemophilus influenzae type b
• Listeria monocytogenes
• Mycobacterium tuberculosis
• Leptospirosis
• Borrelia burgdorferi (Lyme Disease)
• Mycoplasma pneumoniae
• Cryptococcus neoformans (in AIDS)
• HIV
• Herpes Viruses other than Herpes simplex
- e.g. Varicella-Zoster virus (VZV)
- e.g. Epstein-Barr virus (EBV)
Distinction between meningitis and encephalitis is not absolute as enteroviruses can also cause
Meningo-encephalitis
Shunt associated meningitis (10-30% of patients with ventriculo-atrial/ peritoneal shunts develop ventriculitis and meningitis) is usually caused by what group of organisms
Coagulase negative staphylococci (eg, Staph. epidermidis)
What is aseptic meningitis (non-infective form of meningitis)
Syndrome in which the CSF shows an excessive number of lymphocytes and elevated protein but NO organism is cultured or detected by any assay.
Non-infective causes of meningitis
Tumour cells in CSF
Reactions to drugs or chemicals
Sarcoidosis
SLE
What should always be considered as a diagnosis in unexplained unconsciousness
Meningitis
Examination of meningitis
- general (4)
- cardio (2)
- neuro (2)
- traditional physical signs (2)
General
- pyrexia
- level of consciousness
- skin + conjunctival petechiae
- other rashes
Cardio
- pulse (tachy or brady)
- BP (hypotension; systolic <90 suggests sepsis)
Neuro
- focal neurological signs (esp CN palsies)
- papilloedema (unusual in meningitis; more suggestive of intracranial lesion)
Traditional physical signs
- Kernig’s sign: with the hip flexed, the patient’s leg cannot be straightened due to hamstring spasm in meningism.
- Flex the neck to attempt to touch the chin to the chest. This is dif cult with any degree of neck stiffness.
60% of people with meningococcal meningitis (neisseria meningitidis) have skin and conjunctival petechiae
What other cases may present with skin and conjunctival petechiae
other bacterial meningitides
viral meningitis
endocarditis.
CN palsies are focal neurological signs typical of which forms of meningitis
tuberculous or cryptococcal meningitis
Normal CSF contains up to how may white cells
5 white cells/ mm3 (all lymphocytes)
Bacterial meningitis due to Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae usually follows initial colonisation of where in the body
Nasopharynx
Acute meningitis is a medical emergency.
If the death rate is to be reduced, then the following are essential (5)
- Early clinical recognition.
- Rapid detection of pathogen.
- Rapid initiation of appropriate bactericidal antimicrobial therapy.
- Early recognition and treatment of sequelae of septicaemia
(eg, DIC with shock, hypoxia, acidosis and adrenal insufficiency) - Antibiotic prophylaxis (when appropriate) of close contacts
