Meningitis and Encephalitis Flashcards
Define meningitis.
Primary inflammation of meninges.
Define neurotuberculosis.
TB infection most likely from haematogenous spread (milliary TB).
Define encephalitis.
Inflammation of brain parenchyma.
Explain the most common causative organisms for bacterial meningitis
Neonatal: GBS, E. Coli + Listeria monocytogenes
< 6 years: Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influnzae type B
> 6: Neisseria meningitidis, Streptococcus pneumoniae.
Explain the aetiology/risk factors for encephalitis.
Viral: Enteroviruses, HSV1, HSV2, VZV, arboviruses, adenoviruses, HIV, mumps, rubella + rabies.
Post measles: Subacute sclerosing panencephalitis
What are the immunodeficiency risk factors for CNS infection in children?
Young age
HIV
Defects of complement system (meningococcal susceptibility)
Asplenia secondary to sickle cell disease (Strep. pneumoniae + Hib susceptibility).
Summarise the epidemiology of meningitis?
Viral: most common. Incidence 3000/year in UK.
Bacterial: 2000/year in UK. N. meningitidis (meningococcus) is most common UK cause.
Summarise the epidemiology of encephalitis?
Prevalence: 1/100,000.
Peak 3–8m
Most common in <4 years.
What are the presenting symptoms of meningitis? (8)
Fever
Headache
Neck stiffness
Photophobia
Altered consciousness
N+V
Anorexia
Seizures.
6 generalised presenting symptoms of encephalitis?
Lethargy
Poor feeding
Irritability
Hypotonia
Behavioural change
Vomiting.
What are the signs of meningitis?
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).
What are the signs of encephalitis?
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).
Identify investigations for CNS infection in children?
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.
What are the features of normal CSF?
Clear
Leukocytes/ul: 0-8; lymphocytes
Protein (mg/dl): 15-45
Glucose (mg/dl): 50-80
What are the features of CSF in acute pyogenic meningitis?
Turbid
Leukocytes/ul: 1000-10,000; predominantly neutrophils
Protein (mg/dl): 100-500
Glucose (mg/dl): <40
What are the features of CSF of tuberculosis meningitis?
Straw coloured, with a “cobweb” appearance
Leukocytes/ul: 100-600; predominantly lymphocytes
Protein (mg/dl): 50-300
Glucose (mg/dl): <45
What are the features of CSF of viral meningitis?
Clear
Leukocytes/ul: 5-300; predominantly lymphocytes
Protein (mg/dl): Normal to mildly increased (usually <100)
Glucose (mg/dl): Normal
What is the management for meningitis?
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.
What is the management for encephalitis?
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.
What are the complications for both meningitis and encephalitis infection in a child?
Hemiparesis
Deafness
Epilepsy
Visual impairment
Bilateral motor impairment
Learning + language difficulties.
Summarise the prongosis of CNS infection in children.
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.
Explain the most common causative organisms for viral meningitis
Enteroviruses, CMV, arbovirus
TB: Most commonly 6 months- 6 years.
Give 3 Environmental risk factors for CNS infection
Crowding, poverty + close contact with affected individuals (transmission by respiratory secretions)
Foreign travel
Unvaccinated.
What are the presenting signs of meningitis in Neonates?
Fever or hypothermia
Poor feeding
High-pitched crying.
Decrease in activity
Irritability
Lethargy
Seizures
Describe the onset of TB meningitis
Can occur 3–6 months after initial TB infection.
Give 6 neurological Sx of encephalitis
Headache
Drowsiness
Confusion
Photophobia
Neck pain
Seizures (focal fits suggestive of HSV encephalitis).
Give 4 complications specific to meningitis
Convulsions
Cerebral oedema
Circulatory shock
DIC.
