Meningitis

Question 1

Pathophysiology

Answer 1

Pathogen in SA space => meningeal inflammation
Cytokine production => increased vascular permeability
-leak of plasma proteins

Increased cerebral edema
Increased ICP
Reduced cerebral perfusion

Question 2

Source of infection => CNS

Answer 2

Hematogenous spread
-bacterial thromboemboli

Via skull

• ears
• sinuses
• osteomyelitis source

External

• penetrating cranial injuries
• cerebral, spinal surgery
• lumbar puncture

Question 3

Infective agent

• most common bacteria
• neonates U1wk
• neonates 1-6wks
• children, adults
• elderly
• post surgery
• IC

Answer 3

MOST COMMON CAUSE - VIRUSES
-often less severe, self limiting

Most common bacteria

• H inf
• N men
• S pneu

Neonates - GBS, listeria
1wk - E coli
1-6wks - G-ves

Post surgery - S aureus, S epidermidis, G-ves

Children, adults - N meningitis, S pneumoniae
Elderly - as above + listeria

IC - listeria

Question 4

Presentation - main features

Signs that you shouldn’t solely rely on

Answer 4

Headache
Fever
Neck stiffness
Confusion

Typical symptoms/signs can be absent in IC, young

Kernig - pain/resistance on passive knee extension
Brudzinski - neck flexion => hip, knee flexion

Question 5

Specific presentation of

• meningococcal meningitis
• pneumococcal meningitis
• H influenzae meningitis

Answer 5

MM - local outbreaks
-Rapid progression => toxic shock 
-Endotoxin release => multiorgan thrombosis,   bleeds, necrosis, limb loss
-Petechial/purpuric rash on lower body
-

PM - recent lung, ear, sinus, valve infection
-patients with increased infection risk

HI - recent URTI in child

Question 6

Investigations

-what is the criteria for head CT

Answer 6

Blood cultures - assess for cause

Gold standard for viral and increasingly for bacterial - CSF PCR

Criteria for head CT - exclude significant brain swelling, shift => contraindication to LP due to herniation risk

• focal neuro signs
• papillodema
• cont/uncontrollable seizures
• GCS U12

Question 7

Management

• preadmission
• admission
• close contacts

Answer 7

Preadmission - IV/IM benzylpenicillin

ABx ASAP IN SUSPECTED BACTERIAL
GIVE ABX ASAP IF BLOOD, CSF CULTURE DELAYED
Dexmeth => reduce inflammatory response => fewer complications

Prophylactic ciprofloxacin

Question 8

Vaccines currently used

Answer 8

MenB, C - routine baby imms

Men ACWY - teenagers, uni students