Meningitis and Encephalitis

Question 1

Aetiology of meningitis (children)?

Answer 1

• Viral infection commonest cause, and most self resolve.
• Enterovirus, EBV, adenoviruses, mumps.

Bacterial meningitis more serious (80% with it develop it <16 years):

1) Neonatal - Group B Strep, E.coli, Listeria monocytogenes
2) 1m-6years - Neisseria meningitides, Step pneumoniae, Haemophilus influenzae
3) >6yrs - Neisseria meningitidis, Streptococcus pneumoniae

Other causes: Autoimmune, Malignancy

Question 2

Pathophys of bacterial meningitis?

Answer 2

• Most of the damage is due to host response to infection rather than organism itself.
• release of inflammatory mediators, activated leukocytes leads to endothelial damage and oedema, raised ICP and decreased cerebral blood flow.
• Inflammatory response can cause cerebral infarction - fibrin deposits block villi from resorption of CSF - hydrocephalus.

Question 3

Clinical features of meningitis?

Answer 3

(Unspecific in infants who can’t talk)

1) fever
2) poor feeding, vomiting
3) irritable/lethargic
4) bulging fontanelle
5) seizures (late sign)
6) neck stiffness - (Kernig sign, brudzinski sign)
7) opisthotonus
8) headache and photophobia (older kids)
9) shock signs - tachycardia, tachypnoea, prolonged cap refill, hypotension
10) meningococcal sepsis - purpuric rash

Question 4

Investigations for meningitis?

Answer 4

1) Lumbar puncture
2) Bloods
3) Culture (blood, CSF, urine, throat swab, stool sample)
4) Rapid antigen screen (blood, CSF and urine)
5) PCR (blood and CSF)
6) If TB - Mantoux test, sputum, X-ray

Question 5

What are contraindications of LP?

Answer 5

1) Cardioresp instability
2) Focal neuro signs
3) Raised ICP (papilloedema, low HR, high BP, coma)
4) Coagulopathy
5) Thrombocytopenia
6) Local infections LP site

Question 6

Management of Meningitis?

Answer 6

1) Community - IM Benzylpenicillin
2) Antibiotics immediately:
Blind treatment - < 3m - IV Cefotaxime and Ampicillin (Listeria), OR >3m - IV Ceftriaxone

Pathogen - meningococcal - Ceftriaxone, pneumococcal - Vancomycin + Ceftrixacone/Cefotaxime.

3) Beyond neonatal period dexamethasone and Abs can reduce long term complications such as deafness
4) Meningococcal septicaemia - IM Benzylpenicillin and transferred to hospital

Question 7

What are the possible complications of meningitis?

Answer 7

1) Hearing loss (Needs audiological assessment)
2) Local vasculitis (CN palsies)
3) Local cerebral infarction (epilepsy + seizures)
4) Subdural effusion
5) Hydrocephalus (due to fibrin deposits in villi)
6) Cerebral abscess (confirm on CT if deterioration continues after Tx)

Question 8

Prophylaxis of meningitis?

Answer 8

1) Rifampicin to all household contacts for meningococcal and h.influenza OR IM ceftriaxone
2) Household contacts of pt with Group C meningococcal meningitis should be vaccinated with (Group C vaccine)

Question 9

Viral meningitis info:

Answer 9

1) Mumps meningitis rare due to MMR vaccine
2) Much less severe than bacterial
3) Diagnosis confirmed by culture/PCR of CSF, stool/uring culture, nasopharyngeal aspirate/throat swabs and serology.

Question 10

What is encephalitis?

Answer 10

Inflammation of cerebral tissue

Question 11

What are the causes of encephalitis?

Answer 11

1) Either direct invasion of cerebrum from neurotoxic virus (HSV)
2) Delayed brain swelling from immunological response to antigen usually a virus (post-infectious encephalopathy e.g. chicken pox)
3) Slow virus infection (HIV or SSPE)

Question 12

Pathogens causing encephalitis?

Answer 12

1) Enteroviruses
2) Respiratory viruses
3) Herpes virus (HSV, VZV, HHV6)
4) In world: mycoplasma, borrelia burgdorferi (lyme), cat scratch disease, rickettsial infections, arboviruses)

Question 13

Clinical presentation of encephalitis?

Answer 13

1) Fever
2) ALOC
3) Behavioural change
4) Seizures common
5) Hard to differentiate between encephalitis and meningitis so start Tx for both.

Question 14

Diagnosis for encephalitis?

Answer 14

1) PCR and CSF
2) Antibody in CSF
3) EEG
4) CT/MRI - focal changes particularly in temporal lobe (may be normal initially but should repeat)

Question 15

Treatment for encephalitis?

Answer 15

High Dose IV Aciclovir

Question 16

Toxic shock syndrome cause?

Answer 16

1) Staph Aureus

2) Group A streptococcus

Question 17

Symptoms of Toxic Shock syndrome?

Answer 17

1) Fever: >39 degrees
2) Flu-like symptoms
3) Hypotension
4) DIFFUSE (widespread) erythematous macular rash

Can cause multi systemic organ function:

1) Mucositis (conductive, oral, genital)
2) Liver impairment
3) Renal impairment
4) GI - vomiting and diarrhoea
5) Clotting abnormalities
6) CNS - altered consciousness

The toxin can be released from any infection at any site (small abrasion, burns which look minor)

Question 18

Management of TSS?

Answer 18

1) Intensive care for shock (artificial ventilation)
2) Areas of infection surgically debrided
3) IV Abx - 3rd gen cephalosporin (Ceftraiaxone and Clindamycin)
4) IVIg (to neutralise toxin)
5) 1-2 weeks later - desquamation of palms, soles, fingers and toes

Question 19

What is necrotising fasciitis/cellulitis?

Answer 19

Severe subcutaneous infection where area swells up leaving poorly perfused necrotic central areas of tissue.
Sx- Severe pain and systemic illness
Cause - Staph aureus and Group A Strep
Tx - Surgical debridement essential, Abs, may give IVIg