Meningitis

Question 1

How common is it?

Answer 1

Incidence 2-5 per 100,000

Question 2

What causes it?

Answer 2

Inflammation of the meninges as a result of bacterial infection.

Neisseria meningitides, Streptococcus pneumoniae, and Haemophilus influenza type B (Hib) are the most common causative organisms of acute bacterial meningitis in children aged 3 months and older.

Meningitis resulting from infection with Neisseria Meningitides is known as meningococcal disease, meningitis resulting from infection with Streptococcus pneumoniae is known as pneumococcal disease.

In neonates (younger than one month of age), Streptococcus agalactia, Escherichia coli, S. pneumoniae, and Listeria monocytogenes are the most common causative organisms.

May also be idiopathic, viral, parasitic, fungal or autoimmune

Question 3

What risk factors are there?

Answer 3

Young age, most important factor. 
Winter season
an absent or non-functioning spleen
older than 65
immunocompromised state
organ dysfunction
smoking
living in crowded housing or barrack
Basal skull fractures with leakage of CSF
cochlear implants
otitis media
sinusitis
sick cell disease.

Question 4

How does it present?

Answer 4

NON BLANCHING RASH. 
Fever
vomiting/nausea
lethargy
irritability/unsettled behaviour
ill appearance
refusing food/drink
headache
muscle ache/joint pain
respiratory symptoms/signs or breathing difficulty.
Less common signs: Chills/shivering, diarrhoea, abdo pain, sore throat, or other ENT symptoms.

Question 5

Signs on examination?

Answer 5

Non blanching rash.
Stiff neck.
Cap refill >2 seconds + cold hands and feet.
Unusual skin colour.
Shock and hypotension.
Leg pain.
Back rigidity.
Bulging fontanelle (children).
Photophobia. Kerning’s sign (person unable to fully extend at the knee when hip is flexed).
Brudzinski’s sign (persons knees and hip flex when neck is flexed.
Unconscious or toxic/moribund state.
Paresis.
Seizures.
Focal neurological deficit including cranial nerve involvement and abnormal pupils.

Question 6

Investigations

Answer 6

Head CT should be performed if there is any suspicion of an intracranial mass lesion such as focal neurological signs, papilledema, LOC or seizures.

Lumbar puncture.

Urgent CSF microscopy, white cell count and differential, and analysis for protein and glucose concentration.

Also blood cultures, glucose, chest x-ray, viral and syphilis serology.

Question 7

Treatment

Answer 7

Other infective meningitis and meningoencephalitis, for example: Viral meningitis, common and can occur at any age (Enteroviruses e.g. Cocksakie and echoviruses) and HSV. Fungal meningitis (e.g. Cryptococcus). Viral encephalitis.

Brain and nervous system malignancy.

Brain or spinal epidural abscess.

Parameningeal infection (such as osteomyelitis and subdural empyema).

Other non-infective causes of meningitis such as autoimmune disorders such as SLE and Bechet’s syndrome.

Petechiae may have other causes: enterovirus, Epstein-Barr virus, adenovirus and respiratory virus.

Non-infective causes: clotting factor or platelet deficiencies.

Petechiae in the eyes or on the face may also result from non-infective causes (sneezing, coughing, vomiting and trauma)