Meningitis and Encephalitis

Question 1

Define meningitis.

Answer 1

Primary inflammation of meninges.

Question 2

Define neurotuberculosis.

Answer 2

TB infection most likely from haematogenous spread (milliary TB).

Question 3

Define encephalitis.

Answer 3

Inflammation of brain parenchyma.

Question 4

Explain the most common causative organisms for bacterial meningitis

Answer 4

Neonatal: GBS, E. Coli + Listeria monocytogenes

< 6 years: Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influnzae type B

> 6: Neisseria meningitidis, Streptococcus pneumoniae.

Question 5

Explain the aetiology/risk factors for encephalitis.

Answer 5

Viral: Enteroviruses, HSV1, HSV2, VZV, arboviruses, adenoviruses, HIV, mumps, rubella + rabies.

Post measles: Subacute sclerosing panencephalitis

Question 6

What are the immunodeficiency risk factors for CNS infection in children?

Answer 6

Young age

HIV

Defects of complement system (meningococcal susceptibility)

Asplenia secondary to sickle cell disease (Strep. pneumoniae + Hib susceptibility).

Question 7

Summarise the epidemiology of meningitis?

Answer 7

Viral: most common. Incidence 3000/year in UK.

Bacterial: 2000/year in UK. N. meningitidis (meningococcus) is most common UK cause.

Question 8

Summarise the epidemiology of encephalitis?

Answer 8

Prevalence: 1/100,000.

Peak 3–8m

Most common in <4 years.

Question 9

What are the presenting symptoms of meningitis? (8)

Answer 9

Fever

Headache

Neck stiffness

Photophobia

Altered consciousness

N+V

Anorexia

Seizures.

Question 10

6 generalised presenting symptoms of encephalitis?

Answer 10

Lethargy

Poor feeding

Irritability

Hypotonia

Behavioural change

Vomiting.

Question 11

What are the signs of meningitis?

Answer 11

Neck stiffness: meningeal irritation.

Kernig sign: In supine position, extension of knee is painful when knee + hip are flexed.

Brudzinski’s sign: flexion of neck causes hips + knees to flex

Non-blanching rash: Purpuric or petechial (may initially be blanching). Characteristic of meningococcal infection.

Increased ICP: Papilloedema, reduced consciousness, focal neurology (e.g. 6th nerve palsy), Cushing reflex (increased BP, decreased HR, irregular breathing).

Question 12

What are the signs of encephalitis?

Answer 12

Reduced GCS.

+ve Kernig sign; pain on extension of knee with hips + knees flexed whilst in supine position.

Cranial nerve + motor abnormalities.

Ataxia (varicella-associated encephalitis).

Question 13

Identify investigations for CNS infection in children?

Answer 13

Bloods: Increased WBC, CRP. U&E, glucose, clotting studies, group + cross-match.

ABG/CBG

MC&S: Blood, stool, throat swab, mid-stream urine, urinary pneumococcal antigen.

PCR: For N meningitidis.

CT scan: If signs suggestive of raised ICP to avoid coning on LP.

LP: CI if focal neurological signs, raised ICP or petechiae/ purpura.

CSF – Do PCR + serology for viral encephalitis.

Question 14

What are the features of normal CSF?

Answer 14

Clear
Leukocytes/ul: 0-8; lymphocytes
Protein (mg/dl): 15-45
Glucose (mg/dl): 50-80

Question 15

What are the features of CSF in acute pyogenic meningitis?

Answer 15

Turbid
Leukocytes/ul: 1000-10,000; predominantly neutrophils
Protein (mg/dl): 100-500
Glucose (mg/dl): <40

Question 16

What are the features of CSF of tuberculosis meningitis?

Answer 16

Straw coloured, with a “cobweb” appearance
Leukocytes/ul: 100-600; predominantly lymphocytes
Protein (mg/dl): 50-300
Glucose (mg/dl): <45

Question 17

What are the features of CSF of viral meningitis?

Answer 17

Clear
Leukocytes/ul: 5-300; predominantly lymphocytes
Protein (mg/dl): Normal to mildly increased (usually <100)
Glucose (mg/dl): Normal

Question 18

What is the management for meningitis?

Answer 18

Treat shock: Fluids unless risk of raised ICP.

Commence IV ceftriaxone:

• < 3 months add ampicillin or amoxicillin to cover Listeria.
• If recent travel to outside UK or multiple exposure to abx in past 3 months add vancomycin.
• Ceftriaxone is CI in premature babies + babies with jaundice, hypoalbuminemia or acidosis: consider to cefotaxime

Confirm causative pathogen

If gram-ve bacilli (N. meningitidis): IV Cefotaxime for 21 days.

• If H influenzae: IV ceftriaxone for 10 days
• If Strep pneumoniae: IV Ceftriaxone for 14 days.
• If GBS: IV cefotaxime for 14 days
• If Listeria: IV Cefotaxime with ampicillin or amoxicillin for 14 days + gentamicin for the first 7 days.

Give dexamethasone for children >3 months if there is bacteria on gram stain or frankly purulent CSF.

Question 19

What is the management for encephalitis?

Answer 19

IV acyclovir within 6 hours of admission. Should be continued for 14-21 days.

Empirical abx therapy for meningitis cover.

Supportive.

Vaccination against measles, mumps + rubella.

Question 20

What are the complications for both meningitis and encephalitis infection in a child?

Answer 20

Hemiparesis

Deafness

Epilepsy

Visual impairment

Bilateral motor impairment

Learning + language difficulties.

Question 21

Summarise the prongosis of CNS infection in children.

Answer 21

Overall mortality 5–10%; neurological complications 10–20%.

Meningococcal meningitis: mortality 5%.

Pneumococcal meningitis: mortality 16%, 50% adverse neurological sequelae

E. coli meningitis: neonatal mortality is 20%, high adverse neurological sequelae.

TB meningitis: mortality 15–30%, 25% adverse neurological sequelae.

Many cases of encephalitis make a full recovery, but is dependent on age, aetiology + severity.

70% mortality rate with untreated HSV encephalitis, + survivors often have severe neurological defects.

Question 22

Explain the most common causative organisms for viral meningitis

Answer 22

Enteroviruses, CMV, arbovirus

TB: Most commonly 6 months- 6 years.

Question 23

Give 3 Environmental risk factors for CNS infection

Answer 23

Crowding, poverty + close contact with affected individuals (transmission by respiratory secretions)

Foreign travel

Unvaccinated.

Question 24

What are the presenting signs of meningitis in Neonates?

Answer 24

Fever or hypothermia

Poor feeding

High-pitched crying.

Decrease in activity

Irritability

Lethargy

Seizures

Question 25

Describe the onset of TB meningitis

Answer 25

Can occur 3–6 months after initial TB infection.

Question 26

Give 6 neurological Sx of encephalitis

Answer 26

Headache

Drowsiness

Confusion

Photophobia

Neck pain

Seizures (focal fits suggestive of HSV encephalitis).

Question 27

Give 4 complications specific to meningitis

Answer 27

Convulsions

Cerebral oedema

Circulatory shock

DIC.