Meningitis

Question 1

Define

Answer 1

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

Question 2

What are the causes?

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

Question 3

How can organisms reach the meninges?

Answer 3

• Reach the meninges either by direct extension from the ears, nasopharynx, cranial injury or congenital meningeal defect or by bloodstream spread

Question 4

What are the risk factors?

Answer 4

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 5

Epidemiology?

Answer 5

• UK: 2500 notifications/yr

Question 6

What are the presenting symptoms?

Answer 6

• Severe headache
• Photophobia
• Neck or backache
• Fever
• Irritability
• Drowsiness
• Vomiting
• High-pitched crying or fits (common in children)
• Reduced consciousness
• IMPORTANT: take a good travel history and exposure history and take note of exposure to any of the following
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 7

What are the signs?

Answer 7

o Photophobia
o Neck stiffness
o In meningococcal septicaemia – non-blanching petechial and purpuric rash and signs of shock
o Kernig’s Sign - with the hips flexed, there is pain/resistance on passive knee extension

Question 8

What are the appropriate investigations?

Answer 8

•	Bloods
o	Two sets of blood cultures
o	Blood glucose 
o	Viral and syphilis serology
•	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

How would you manage?

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

What are the 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

What’s the prognosis?

Answer 11

• Mortality rate from bacterial meningitis: 10-40% with meningococcal sepsis
• Viral meningitis is self-limiting

All cases of meningitis much be notified to the local public health authority.