Infections of the CNS Flashcards by Lizzie Sellers

What is meningitis?

Inflammation of the meninges

Does not have to be infectious but usually is

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What is encephalitis?

Inflammation of the brain

Does not have to be infectious but usually is

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What is meningoencephalitis?

Inflammation of the brain and the meninges

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What is myelitis?

Inflammation of the spinal cord

Can be infectious (but not always)

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What is a cerebral abscess?

Collection of pus in the brain

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What is an epidural/ subdural abscess?

Pus in the epidural or subdural space

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Which bacteria commonly cause meningitis?

Neisseria meningitidis (Meningococcus) 
Haemophilus influenzae type B (HiB)
Streptococcus pneumoniae (Pneumococcus) 
Group B Streptococci 
Listeria monocytogenes
Mycobacterium tuberculosis

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What viruses can cause meningitis?

Enterovirus
Varicella Zoster virus (VZV) 
HIV
Mumps
Measles

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What fungi can cause meningitis?

Cryptococcus neoformans

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What viruses can cause encephalitis?

Herpes Simplex virus (HSV) 
Varicella Zoster virus (VZV)
HIV
Arboviruses
Rabies

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What can cause cerebritis?

Bacteria associated with immunodeficiency or abscesses

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What bacteria usually causes abscesses?

Streptococci

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What parasite can cause cysts?

Toxoplasmosis

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What viruses can cause myelitis?

Poliomyelitis

Rabies

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What is the most common form on meningitis in the UK?

MenB

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What are the common clinical features of all CNS infections?

Fever
Headache
Neck stiffness
Photophobia 
Rash 
Reduced GCS
Confusion 
Seizures

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What are the clinical features of meningococcal infections?

Acute
Sepsis
Purpuric rash 
Peripheral gangrene 
Often seen in children and young adults with possible outbreaks

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What are the clinical features of pneumococcal infections?

Less acute
No rash
High mortality/ morbidity

What form of CNS infection is generally associated with respiratory tract infections, trauma and immunocompromised patients?

Pneumococcal

What form of bacteria is more commonly picked up in neonates during birth?

Group B Strep

Low mortality but risk of CN damage

Who is most at risk of Listeriosis?

Neonates
Elderly
Immunocompromised
Pregnant women

What are the clinical features of bacterial meningitis caused by tuberculous?

Gradual onset of fever
Confusion
Coma
High CSF protein

What type of infection are brain abscesses commonly associated with?

Chronic URTIs (e.g. sinusitis or otitis media)

What investigations should be carried out to diagnosis a CNS infection?

Bloods (FBC + CRP, U+Es, coagulation tests - APTT/ PT)
Blood cultures
HIV test (possibly)
Lumbar puncture
Head CT (if risk of raised ICP/ brain lesions)

What is tested for in CSF for patients with suspected meningitis?

``` RCC/ WCC Organisms PCR test Protein Glucose (compare with blood glucose) ```

What are the contraindications for LP?

``` Raised ICP Infection at LP site Coagulation abnormality Septic shock/ convulsions Obvious/ extensive purpura ```

What features indicate a raised ICP?

``` GCS <12 (or >2 falls) Focal neurology Seizures Bradycardia / Hypertension Papilloedema ```

What can happen in a patient with raised ICP if a lumbar puncture is performed?

Coning (herniation of brain through the foramen magnum)

What should normal CSF look like?

Clear and colourless

Where is a lumbar puncture generally taken from?

Between L3 and L4 (although can be between L1 and L5) [L5/S1 in children]

Why can a purpuric rash be misleading?

Only occurs in meningococcal meningitis

Why is it important to take 2 sets of blood cultures?

Risk of contamination | Not reliable once antibiotics started

What are the indicators of a bacterial infection in CSF?

``` High WCC (esp. neutrophils) High protein Low glucose (compared to serum glucose levels) ```

What are the indicators of a viral infection in CSF?

Slightly high WCC (esp. lymphocytes) Slightly high protein Normal glucose (compared to serum glucose levels)

What are the indicators of a tuberculous infection in CSF?

``` High WCC (esp. lymphocytes) Very high proteins Low glucose (compared to serum glucose levels) ```

What are the priorities for immediate intervention when treating meningitis?

Early recognition ABC (then secure airway, high flow O2, IV access, fluid resuscitation) Urine output Mental state Neurology (focal neurological signs; persistent seizures; papilloedema)

What are the treatment guidelines for meningitis?

Assessment prior to LP Critical care (and postpone LP) if signs of raised ICP, shock or respiratory failure Monitor and stabilise circulation

What medication should be administered for suspected bacterial meningitis?

IV 2g Cefotaxime/ Ceftriaxone | IV 0.15mg/kg Dexamethasone

What medication should be administered for suspected listeriosis?

IV 2g amoxicillin

What medication should be administered for suspected viral encephalitis?

IV 10mg/kg aciclovir

What is used to prevent development of meningitis in those potentially exposed?

Chemoprophylaxis (500mg ciprofloxacin single dose or 600mg rifampicin for 2 days)

What viruses commonly cause peripheral nerve infections?

``` Herpes simplex (oral HSV1, genitals HSV2) Varicella Zoster (chickenpox/ shingles) ```

How does shingles track?

Along dermatome