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HistoryA 20-year-old medical student presents to theEmergency Department feeling generallyunwell. He is wearing sunglasses andcomplains of a stiff neck with a ‘poundingheadache’. He has vomited twice.
On examination, he is Kernig's sign positive.
ObservationsHR 121, BP 101/77, RR 20, SpO2 98%, Temp38.3
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Case-based discussion: 1
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Question: 1
HistoryA 20-year-old medical student presents to theEmergency Department feeling generallyunwell. He is wearing sunglasses andcomplains of a stiff neck with a ‘poundingheadache’. He has vomited twice.
On examination, he is Kernig's sign positive.
ObservationsHR 121, BP 101/77, RR 20, SpO2 98%, Temp38.3
4
Case-based discussion: 1
DefinitionInflammation of the meninges due to infective (bacterial, viral, orfungal) or non-infective causes
• S. pneumoniae and N.meningitidis are the most common bacterial causes
• Enteroviruses are the most common viral cause
Epidemiology• 5 per 100,000 population (NICE)• Bacterial meningitis mortality: 25% in adults• Viral meningitis mortality: <1%
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Introduction
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Introduction
Risk factors• Age• Immunocompromised• Non-immunised• Smoking• Crowded environment
Bacteria• Haematogenous spread (most common) • Direct extension from a contiguous site• Release of inflammatory mediators in the CSF• Inflammation
• Cerebral oedema• Raised ICP
Virus• Enteroviruses spread via faecal-oral route• Enter the CNS through haematogenous spread• See above for the inflammatory response
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Pathophysiology
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Aetiology
Bacterial meningitis Viral meningitis Fungal meningitisRare, but potentially fatal
• Neonatal• Children• Adults• Elderly
More common, but self-limiting
• Enteroviruses: • Coxsackievirus• Echovirus
• Herpes simplex virus (HSV): • HSV-2• HSV-1
• Varicella-zoster virus (VZV)
Rarely affects immunocompetent patients
• Cryptococcus neoformans• Candida
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Question: 2
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Aetiology by age
Age Organism
0 to 3 months• Group B streptococcus• E. Coli• Streptococcus pneumoniae• Listeria monocytogenes
3 months to 6 years• Streptococcus pneumoniae• Neisseria meningitides • Haemophilus influenzae b
6 months to 60 years• Neisseria meningitidis• Streptococcus pneumoniae
> 60 years• Streptococcus pneumoniae• Neisseria meningitidis• Listeria monocytogenes
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Aetiology
Neisseria meningitidis(Meningococcal meningitis)• Colonises the nasopharynx – asymptomatic carriers• Droplet spread of respiratory secretions• Vaccination:
• Men B and Men C• Men ACWY
• Mortality: 10%• Typically causes a non-blanching purpuric rash
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Aetiology
S. pneumoniae(Pneumococcal meningitis)• Droplet spread • Poorer outcomes compared to N.meningitidis• Vaccination: PCV• Mortality: 25%
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Aetiology
Group B streptococcus (Streptococcus agalactiae)• Most common cause of neonatal meningitis,
pneumonia, and sepsis • Colonises the vagina and transmitted during birth• Currently not routinely screened for • Intrapartum antibiotics
Risk factors• Prolonged membrane rupture• Low birthweight
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Streptococci
Beta-haemolytic Alpha-haemolytic Gamma-haemolyticGroup A streptococcus• S.pyogenes
Group B streptococcus• S.agalactiae
S.pneumoniae
S.viridans
Group D streptococcus• Enterococcus
Classified according to pattern of haemolysis on blood agar• Alpha-haemolytic (partial haemolysis)• Beta-haemolytic (complete haemolysis)• Gamma-haemolytic (no haemolysis)
HistoryA 20-year-old medical student presents to theEmergency Department feeling generally unwell.He is wearing sunglasses and complains of a stiffneck with a ‘pounding headache’. He hasvomited twice.
On examination, he is Kernig's sign positive.
ObservationsHR 121, BP 101/77, RR 20, SpO2 98%, Temp 38.3
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Question: 3
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Question: 3
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Clinical features
Symptoms SignsMeningism• Headache• Photophobia• Neck stiffness
Kernig’s sign• When the hip is flexed and the knee is
at 90°, extension of the knee results in pain
Fever Brudzinski sign• Severe neck stiffness causes the hips
and knees to flex when the neck is flexed
Nausea and vomiting Purpuric non-blanching rash• Meningococcal disease
Seizures Pyrexia
Reduced GCS
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Clinical features
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Clinical features
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Differentials
Viral meningitis Bacterial meningitis Tuberculous meningitis Encephalitis
• Acute onset• Meningism• Usually self limiting
• Acute onset• Meningism• May be fatal
• Chronic onset• Prodromal malaise
and fever
• Abnormal cerebral function
• +/- meningism
• CSF interpretation • CSF interpretation • CSF interpretation• PCR and Ziehl-
Neelsen stain • CXR
• CSF profile may be similar to viral meningitis
HistoryA 20-year-old medical student presents to theEmergency Department feeling generallyunwell. He is wearing sunglasses andcomplains of a stiff neck with a ‘poundingheadache’. He has vomited twice.
On examination, he is Kernig's sign positive.
ObservationsHR 121, BP 101/77, RR 20, SpO2 98%, Temp38.3
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Question: 4
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Question: 4
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Investigations
Bedside• Blood glucose: required to compare to CSF glucose
Bloods• FBC: leukocytosis• CRP: raised inflammatory markers• Coagulation profile: sepsis and DIC• Blood culture• PCR for N. meningitidis
Imaging• CT head: meningeal enhancement. May be conducted prior to an LP
Specialist tests• Lumbar puncture (LP): MCS and PCR
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Investigations
Question: 5
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CSF interpretation
Viral Bacterial Fungal/TB
Pressure Normal/elevated Elevated Elevated
Appearance Clear Cloudy CloudyFibrin web
WCC <1000/mm3
Lymphocytes10-5000/mm
3
Neutrophils <1000/mm
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Lymphocytes
Glucose >60% serum glucose <50% serum glucose <50% serum glucose
Protein <1g/L >1g/L >1g/L
HistoryA 20-year-old medical student presents to theEmergency Department feeling generallyunwell. He is wearing sunglasses andcomplains of a stiff neck with a ‘poundingheadache’. He has vomited twice.
On examination, he is Kernig's sign positive.
ObservationsHR 121, BP 101/77, RR 20, SpO2 98%, Temp38.3
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Question: 6
Question: 6
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Management
Antibiotics• Secondary care: IV cephalosporin (cefotaxime or ceftriaxone) +/- amoxicillin• Primary care: IV or IM benzylpenicillin if there is evidence of a non-blanching rash
Steroids• Dexamethasone: administered before or at the same time as antibiotics
• Should be given within 12 hours of antibiotics• If pneumococcal meningitis is confirmed, continue steroid
Anti-viral• Aciclovir: if viral meningitis is suspected. Used to treat HSV and VZV
Adjunct• IVF• Analgesia and anti-pyretic
HistoryA 20-year-old medical student presents to theEmergency Department feeling generallyunwell. He is wearing sunglasses andcomplains of a stiff neck with a ‘poundingheadache’. He has vomited twice.
On examination, he is Kernig's sign positive.
ObservationsHR 121, BP 101/77, RR 20, SpO2 98%, Temp38.3
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Question: 7
Question: 7
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Contact tracing
Meningitis is a notifiable disease
Meningococcal meningitis• Prolonged close contact in a household setting in the preceding 7 days before onset of
illness• Exposure to respiratory droplets • Ciprofloxacin 500mg one off dose to anyone who meets the above criteria• Rifampicin is an alternative
Pneumococcal meningitis• Prophylaxis is not usually required
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Complications
System Complication
Neurological • Sensorineural hearing loss • Seizures• Cerebral oedema• Long-term cognitive and behaviour
deficit• Abscess• Hydrocephalus
Endocrine • Waterhouse-Friderichsen syndrome
Other • Sepsis
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Top-decile question
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Top-decile question
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Recap
• Meningitis is relatively rare but carries a high mortality
• The most common cause are enteroviruses
• S.pneumoniae and N.meningitidis is the most common bacterial cause
• The definitive investigation is with CSF analysis
• Management depends on the aetiology and involves:• Antibiotics• Antivirals• Corticosteroids
• Ciprofloxacin prophylaxis is indicated for contacts of patients with meningococcal disease
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References
1. SVG by Mysid, original by SEER Development Team [1], Jmarchn / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)
2. Microman12345 / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)
3. Doc. RNDr. Josef Reischig, CSc. / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)
4. CDC / CC BY (https://creativecommons.org/licenses/by/2.5)
5. GrahamColm / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)
6. R. G. Wiener, Harlem Hospital / Public domain
7. Pam Cleverley, Perry Bisman, http://babycharlotte.co.nz / CC BY-SA (http://creativecommons.org/licenses/by-sa/3.0/)
8. Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014". WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. / CC BY (https://creativecommons.org/licenses/by/3.0)
9. Amadalvarez / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)
All other images were made by BiteMedicine or under the basic license from Shutterstock and not suitable for redistribution
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