Nervous System Infection

Question 1

What is meningitis?

Answer 1

Inflammation/infection of the meningies (leptomeninges : arachnoid and pia mater)

Question 2

Clinical features of meningitis

Answer 2

Triad: neck stiffness, fever, headaches
Phonophobia, photophobia

Question 3

What are the meningeal irritation tests?

Answer 3

Kernig’s test
Brudzinski test

Question 4

Gold standard investigation for meningitis

Answer 4

Lumbar puncture for CSF

Question 5

When should a lumbar puncture be delayed in the context of bacterial meningitis

Answer 5

signs of severe sepsis or a rapidly evolving rash
severe respiratory/cardiac compromise
significant bleeding risk
signs of raised intracranial pressure

Question 6

What is encephalitis?

Answer 6

Inflammation of the brain parenchyma

Question 7

Aetiology of encephalitis

Answer 7

Viral (m/c)
HSV-1 is responsible for 95% of cases in adults
typically affects temporal and inferior frontal lobes

bacteria
Fungal

Non-infective

Question 8

Clinical features of encephalitis

Answer 8

cerebrospinal fluid
lymphocytosis
elevated protein
PCR for HSV, VZV and enteroviruses
neuroimaging
medial temporal and inferior frontal changes (e.g. petechial haemorrhages)
normal in one-third of patients
MRI is better
EEG
lateralised periodic discharges at 2 Hz

Question 9

Aetiology for brain abscess

Answer 9

extension of sepsis from middle ear or sinuses
trauma or surgery to the scalp
penetrating head injuries
embolic events from endocarditis

Question 10

Pathogens responsible for brain abscess

Answer 10

Bacteria (strep. Anginosus, staph. For penetrating injuries)
HIV

Question 11

Clinical features of brain abscess

Answer 11

headache (often dull, persistent)
fever (may be absent and usually not the swinging pyrexia seen with abscesses at other sites)
focal neurology (e.g. oculomotor nerve palsy or abducens nerve palsy secondary to raised intracranial pressure)

other features consistent with raised intracranial pressure
nausea
papilloedema
seizures

Question 12

features seen on MRI for brain abscess

Answer 12

‘Ring enhancing mass’ with considerable surrounding oedema

Question 13

Management for brain abscess

Answer 13

surgery : a craniotomy is performed and the abscess cavity debrided, the abscess may reform because the head is closed following abscess drainage.

IV antibiotics: IV 3rd-generation cephalosporin + metronidazole

intracranial pressure management: e.g. dexamethasone