Meningitis

Question 1

What is meningitis?

Answer 1

Infection of the meninges in the brain or spinal cord, that is most commonly viral or bacterial in origin, but may also be fungal, parasitic or due to non-infectious causes.

Question 2

What are the risk factors for meningitis?

Answer 2

o Close communities (e.g. college halls)
o For bacterial: being under 5 or over 60 yrs
o Male
o Immunosuppressed
o Basal skull fractures/ head trauma (causes CSF leak)
o Mastoiditis
o Sinusitis
o Inner ear infections
o Alcoholism
o Immunodeficiency
o Splenectomy
o Sickle cell anaemia
o Intracranial surgery/ neurosurgery
o Otitis media
o sepsis

Question 3

What are the 2 types of meningitis you can have?

Answer 3

1. Bacterial Meningitis (More Serious):
   - Neonates = Group B streptococcus
   - Children = streptococcus pneumoniae or neisseria meningitidis:
   *S.pneumoniae ⇒ gram positive diplococci
   *N.meningitidis ⇒ gram negative diplococci. Will also cause petechial non-blanching rash.
   - Elderly = streptococcus pneumoniae
2. Viral Meningitis (More Common) ⇒ enteroviruses (poliovirus, coxsackie A), HSV, VZV, mumps
   - Enteroviruses (Coxsackie, Poliovirus) → most common viral cause

Question 4

What presenting symptoms of meningitis can be found in the history?

Answer 4

● Early features:
⇒ Severe headache
⇒ Leg pain
⇒ Cold hands and feet
⇒ Abnormal skin

● Later:
⇒ Meningism: neck stiffness, photophobia, Kernig’s sign (see signs)
⇒ Fever
⇒ Irritability/altered mental state
⇒ Reduced consciousness
⇒ Vomiting
⇒ Children: High pitched crying/fits, hypothermia, irritability, poor feeding
⇒ Petechial rash – non-blanching (Glass test) (may only be ½ spots)
● 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 5

What signs of meningitis can be found on physical examination?

Answer 5

● Signs of MENINGISM:
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
● Signs of INFECTION:
o Pyrexia (fever)
o Tachycardia
o Hypotension
o Skin rash
o Altered mental state

Question 6

Summarise the epidemiology of meningitis

Answer 6

● UK: 2500 notifications/yr
● Tends to occur in elderly and in 15-30 yr old age group

Question 7

What investigations are used to diagnose/ monitor meningitis?

Answer 7

1. CT Head → Exclude mass lesion & perform before LP if increased ICP (intracranial pressure) is suspected (assess risk of brain herniation due to LP)
2. Lumbar Puncture → allows CSF analysis. Only if no signs of raised ICP.
3. Blood Cultures→ obtain two sets before starting antibiotic therapy
   - U&Es, FBC (low WCC = immunocompromised – needs help), LFT, glucose, coagulation screen

Question 8

How can you distinguish between the different types of meningitis from the investigations?

Answer 8

1. Bacterial meningitis:
   ● Cloudy CSF
   ● High neutrophils
   ● High protein
   ● Low glucose
2. Viral (‘aseptic’) meningitis – for this, also do CSF PCR
   ● Clear CSF
   ● High lymphocytes
   ● High protein
   ● Normal glucose
3. TB meningitis:
   ● Fibrinous CSF
   ● High lymphocytes
   ● High protein
   ● Low glucose

Question 9

How is meningitis managed?

Answer 9

Primary Care → as soon as bacterial meningitis is suspected, IV or IM Benzylpenicillin should be administered, then send to hospital.

1. Immediate IV antibiotics → first choice is third generation cephalosporin (eg. cefotaxime or ceftriaxone)
   - if penicillin allergy give IV Chloramphenicol
   - Prophylactic Antibiotics (close contacts of meningococcal meningitis) ⇒ oral ciprofloxacin or rifampicin
2. IV Dexamethasone → given shortly before or with first dose of antibiotics. Reduces risk of complications.
3. Viral → supportive measures, usually self-limiting, maybe anti-virals

Question 10

What complications can arise from meningitis?

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

Summarise the prognosis for patients with meningitis

Answer 11

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