Meningitis

Question 1

Definition

Answer 1

Inflammation of the leptomeningeal (pia and arachnoid mater) coverings of the brain, most commonly due to infection

Question 2

Aetiology

Answer 2

· BACTERIAL
o Neonates (Group B streptococci, Escherichia coli, Listeria monocytogenes)
o Children (Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae)
o Adults (Neisseria meningitidis, Streptococcus pneumoniae, Tuberculosis)
o Elderly (Streptococcus pneumoniae, Listeria monocytogenes)

· VIRAL
o Enteroviruses
o Mumps
o HSV
o VZV
o HIV

· Fungal
o Cryptococcus (common cause of meningitis in HIV patients)

· Others
o Aseptic meningitis (not due to microbes)
o Mollaret’s meningitis (recurrent benign lymphocytic meningitis)

Question 3

Risk factors

Answer 3

o Close communities (e.g. college halls)
o Basal skull fractures
o Mastoiditis
o Sinusitis
o Inner ear infections
o Alcoholism
o Immunodeficiency
o Splenectomy
o Sickle cell anaemia
o CSF shunts
o Intracranial surgery

Question 4

Presenting symptoms

Answer 4

· Severe headache
· Photophobia
· Neck or backache
· Irritability
· Drowsiness
· Vomiting
· High-pitched crying or fits (common in children)
· Reduced consciousness
· Fever

Question 5

Important components of history

Answer 5

o Rodents (lymphocytic choriomeningitis virus)
o Ticks (Lyme borrelia, Rocky Mountain spotted fever)
o Mosquitoes (West Nile virus)
o Sexual activity (HSV-2, HIV, syphilis)
o Travel

Question 6

Signs on physical examination (meningism)

Answer 6

o Photophobia
o Neck stiffness
o Kernig’s Sign - with the hips flexed, there is pain/resistance on passive knee extension
o Brudzinski’s Sign - flexion of the hips when the neck is flexed

Question 7

Signs on physical examination (infection)

Answer 7

o Fever
o Tachycardia
o Hypotension
o Skin rash
o Altered mental state

Question 8

Investigations

Answer 8

· Bloods
o Two sets of blood cultures

· Imaging
o CT scan - exclude mass lesion or raised ICP before LP

· Lumbar Puncture
o MC&S

o Bacterial meningitis:

· Cloudy CSF
· High neutrophils
· High protein
· Low glucose

o Viral meningitis:
· High lymphocytes
· High protein
· Normal glucose

o TB meningitis:
· Fibrinous CSF
· High lymphocytes
· High protein
· Low glucose

Question 9

Management plan

Answer 9

· IMMEDIATE IV Antibiotics (before LP)
o First choice: 3rd generation cephalosporin (e.g. cefotaxime or ceftriaxone)
o Benzylpenicillin may be used as an initial blind therapy

· Dexamethasone IV
o Given shortly before or with the first dose of antibiotics
o Associated with a reduced risk of complications

· Resuscitation
o Manage in ITU
o Notify public health services

Question 10

Possible complications

Answer 10

· Septicaemia
· Shock
· DIC
· Renal failure
· Seizures
· Peripheral gangrene
· Cerebral oedema
· Cranial nerve lesions
· Cerebral venous thrombosis
· Hydrocephalus
· Waterhouse-Friderichsen Syndrome (bilateral adrenal haemorrhage caused by severe meningococcal infection)

Question 11

Prognosis

Answer 11

· Mortality rate from bacterial meningitis: 10-40% with meningococcal sepsis

· Viral meningitis is self-limiting