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 the parenchyma of the brain.

Question 4

Explain the aetiology/risk factors for meningitis?

Answer 4

Bacterial:

• Neonatal: GBS, E. Coli and Listeria monocytogenes
• Under 6 years: Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influnzae type B
• Over 6: Neisseria meningitidis, Streptococcus pneumoniae.

Viral:

• Enteroviruses, CMV, arbovirus (a virus caused by arthropods).
• TB – Most common between 6 months and 6 years.

Question 5

Explain the aetiology/risk factors for encephalitis.

Answer 5

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

Post measles: Subacute sclerosing panencephalitis

Question 6

What are general risk factors for CNS infection in children?

Answer 6

Immunodeficiency: Young age, HIV, defects of complement system leading to meningococcal susceptibility, asplenia secondary to sickle cell disease (Strep. pneumoniae and Hib susceptibility).

Environmental factors: Crowding, poverty and close contact with affected individuals (transmission by respiratory secretions), foreign travel, not being vaccinated.

Question 7

Summarise the epidemiology of meningitis?

Answer 7

• Viral meningitis: The most common meningitis. Incidence 3000/year in the UK.
• Bacterial meningitis: There are 2000/year new cases of bacterial meningitis in the UK. N. meningitidis (meningococcus) is the most common UK cause of bacterial meningitis.

Question 8

Summarise the epidemiology of encephalitis?

Answer 8

Prevalence: 1/100,000.

Peak age: 3–8 months. Most common in <4 years.

Question 9

What are the presenting symptoms of meningitis?

Answer 9

Neonates: A decrease in activity, irritability, lethargy, seizures, fever or hypothermia, poor feeding and high-pitched crying.

Children: Fever, headache, leg pain, neck stiffness, alteration in consciousness, nausea, vomiting, photophobia, anorexia, rash or seizures.

TB meningitis: Can occur 3–6 months after the initial TB infection.

Question 10

What are the presenting symptoms of encephalitis?

Answer 10

General: Lethargy, poor feeding, irritability, hypotonia, behavioural change, vomiting.

Neurological: Headache, drowsiness, confusion, photophobia, neck pain, seizures (focal fits suggestive of HSV encephalitis).

Question 11

What are the signs of meningitis?

Answer 11

Neck stiffness: From meningeal irritation.

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

Brudzinski’s sign

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 heart rate, irregular breathing).

Question 12

What are the signs of encephalitis?

Answer 12

Reduced GCS.

Positive Kernig sign; pain on extension of the knee with hips and knees flexed whilst in a supine position.

Cranial nerve and 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 and 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 increased ICP to avoid coning on LP.

LP: Contraindicated if focal neurological signs, increased ICP or petechiae/purpura.

CSF – Do PCR + serology for viral encephalitis.

Question 14

What are the features of normal CSF?

Answer 14

Appearance: 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

Appearance: 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

Appearance: 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

Appearance: 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 there is risk of increased ICP.

Commence intravenous ceftriaxone:

• In under 3 months add ampicillin or amoxicillin to cover Listeria.
• If there is recent travel to outside the UK or multiple exposure to antibiotics in the past 3 months add vancomycin.
• Ceftriaxone is contraindicated in premature babies and in babies with jaundice, hypoalbuminemia or acidosis – consider to cefotaxime

Confirm causative pathogen oIf gram-negative 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 above 3 months if there is bacteria on gram stain or frankly purulent CSF.

Question 19

What is the management for encephalitis?

Answer 19

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

Empirical sntibiotic therapy for meningitis cover.

Supportive.

Vaccination against measles, mumps and rubella.

Question 20

What are the complications for CNS infection in a child?

Answer 20

Both meningitis and encephalitis may cause hemiparesis, deafness, epilepsy, visual impairment, bilateral motor impairment, learning and language difficulties.

Specific to meningitis: Convulsions, cerebral oedema, circulatory shock, DIC.

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 this is dependent on age, aetiology and severity. There is a 70% mortality rate with untreated HSV encephalitis, and survivors often have severe neurological defects.