Infection of the CNS Flashcards
CNS infections can be classified anatomically or aetiologically. What are the 4 types of CNS infections under the anatomical classification? [4]
- Meningitis (Bacterial, Viral)
- Encephalitis/Meningo-encephalitis (Viral, Bacterial)
- Mass lesion (abscess)
- Myelitis C
Define meningitis [1]
inflammation of meninges +/- cerebrum (meningo-encephalitis) with inflammatory CSF
Define encephalitis and meningo-encephalitis [2]
- encephalitis = inflammation of the brain
- meningo-encephalitis = inflammation of the brain and meninges
Define myelitis [1]
infection of the spinal cord
What CNS syndromes are caused by bacteria [3] and what are the most common bacteria that cause these syndromes? [3]
- CNS Syndromes:
- meningitis
- meningo-encephalitis
- abscess
- Causative Bacteria:
- meningococcus,
- pneumococcus
- listeria
What CNS syndromes are caused by viruses [2] and what are the most common viruses that cause these syndromes? [5]
- CNS Syndromes:
- encephalitis
- meningitis
- Causative Viruses:
- herpes simplex virus (HSV)
- varicella zoster virus (VZV)
- enterovirus (D-68)
- HIV
- mumps
What CNS syndromes are caused by fungi [2] and what is the most common fungi that cause these syndromes? [1]
- CNS Syndromes:
- meningo-encephalitis
- mass lesion
- Causative Fungi:
- cryptococcosis
What CNS syndromes are caused by protozoa [2] and what is the most common protozoa that cause these syndromes? [1]
- CNS Syndromes:
- mass lesion
- eosinophilic-meningitis
- Causative Protozoa:
- toxoplasmosis
What are the signs & symptoms of meningitis? [4]
- 95% will have 2 of:
- headache
- neck stiffness
- reduced GCS
- fever
What is confusion indicative of in a patient with suspected meningitis? [2]
- cerebritis
- encephalitis
What kind of rash do you typically get with meningitis? [3]
purpuric and/or petechial but macular early on (meningococcal)
What are the 3 major bacterial causes of meningitis (including what type of bacteria each are)? [6]
- Gram positive diplococci → streptococcus pneumoniae
- Gram negative diplococci → neisseria meningitidis
- Gram positives rods → listeria monocytogenes
Meningitis in travellers tend to be caused by…? [1]
resistant, non-endemic disease
Meningitis in alcoholics and people with hearing aid transplants tend to be caused by…? [1]
pneumococcal disease
Meningitis in IVDUs tend to be caused by…? [2]
- staphylococcus aureus
- streptococcus
Meningitis in people coming back from pilgrimage (Hajj) tend to be caused by…? [1]
meningococcal disease
What factors put people at increased risk of developing pneumococcal brain meningitis? [5]
- Middle ear disease
- Head injury (CSF leak)
- Neurosurgery
- Alcohol
- Immunosuppression (HIV)
What factors put people at increased risk of brain meningitis caused by listeria? [2]
- immunosuppression
- pregnancy
Pneumococcal meningitis is more severe. What are the typical signs of pneumococcal meningitis? [6]
- Neurology
- focal signs (65%)
- seizures (24%)
- VIII palsy (22%)
- CAP - community acquired pneumonia
- ENT - ear, nose & throat infection
- Endocarditis
What factors predisposes people to have a worse outcome in a bacterial meningitis infection? [6]
- Pneumococcus
- Reduced GCS
- CNS signs
- Older age (>60 years)
- CN palsy (Pneumococcal)
- Bleeding (Meningococcal)
What investigations should be done on a patient with suspected meningitis? [6]
- History and exam
- typical presentation = headache and neck pain
- examine throat and examine for Cervical LNs
- if there is pus on the tonsils, it’s a group A strep infection, not meningococcus
- Blood cultures (blood PCR)
- Throat culture, Viral gargle
- FBC, UEs, LFTs, CRP
- Lumbar puncture (LP) - examining CSF
- Cell count, Gram stain, Culture and PCR
- Protein and Glucose
- Viral PCR
What is a CT scan used to exclude when investigating a patient with suspected meningitis? [2]
- mass lesion/mass effect
- gross cerebral oedema
You should do a CT scan before lumbar puncture only if there are signs of…? [5]
- GCS 12
- CNS Signs
- Papilloedema
- Immunocompromised
- Seizure
What should you give before doing CT scan in a patient with suspected meningitis? [1]
antibiotics
Lumbar puncture is contraindacted if…? [7]
- Brain shift,
- Rapid GCS reduction,
- Resp/cardiac compromise,
- Severe sepsis,
- Rapidly evolving rash,
- Infection at LP site,
- Coagulopathy
- (incl INR 2 1.5, Platelets < 40, DOAC, therapeutic LMWH)
- Due to bleeding risk
How should you interpret results of a lumbar puncture? (the basic principles) [6]
- If white cell count is HIGH:
- Neutrophilic → bacterial infection
- Lymphocytic → usually viral infection
- If the protein is HIGH:
- Could be anything but more likely to be bacterial
- If glucose is LOW (less than 50% of blood):
- More likely to be bacterial
How do you treat suspected meningitis? [4]
- ANTIBIOTICS MUST NOT BE DELAYED
- if suspected meningitis, treat for all major bacterial causes, i.e. meningococcus, pneumococcus and haemophilus influenzae (HI) using ceftriaxone (2x a day)
- if age ≥60, listeria suspected or immunocompromised, add amoxicillin
- if pneumococcus is suspected, add steroids
How do you treat definitive meningitis caused by meningococcal infection and how long is the antibiotic therapy given for? [2]
- IV Ceftriaxone or Benzylpenicillin
- 5 days
How do you treat definitive meningitis caused by pneumococcal infection and how long is the antibiotic therapy given for? [3]
- IV Ceftriaxone or Benzylpenicillin
- 10-14 days (Increase duration if complications)
How do you treat definitive meningitis caused by listeria infection and how long is the antibiotic therapy given for? [2]
- IV Amoxicillin (stop Ceftriaxone)
- 21 days (Increase duration if complications)
What are the presenting clinical features of viral encephalitis? [3]
- confusion
- fever
- +/- seizures
What investigations should you order for a patient with suspected viral encephalitis? [4]
- Lymphocytic CSF (normal glucose)
- PCR
- EEG of Temporal lobe
- MRI
What is an EEG (electroencephalogram)? [1]
test used to find problems related to electrical activity of the brain
Which antibiotic is used to treat viral encephalitis and what does it target? [3]
- aciclovir (used for…)
- herpes simplex virus (HSV)
- vesicular stomatitis virus (VSV)
Intracerebral TB leads to lesions in which cranial nerves? [4]
- CN III
- CN IV
- CN VI
- CN IX
HIV brain disease is a consequence of what? [1] and what conditions can it lead to? [8]
- Consequence of unrecognised/untreated infection and marked immunodeficiency or lifestyle
- can lead to:
- Encephalitis (ARVs)
- Dementia
- Neuro-syphilis (secondary or tertiary)
- Opportunistic
- Tuberculosis,
- Cryptococcus,
- Toxoplasmosis
- JCV- Progressive multi-focal leuco-encephalopathy
What is progressive focal multifocal leuco-encephalopathy (PMLE)? [1]
neurological disorder characterized by destruction of cells that produce the myelin leading to progressive motor dysfunction
Who is more susceptible to progressive focal multifocal leuco-encephalopathy (PMLE)? [4]
- Immunocompromised patients
- HIV
- anti-TNF
- Transplant
What is intracerebral toxoplasmosis? [1]
infection caused by the virus T. gondii in the CNS and mainly affects HIV infected patients, particularly in developing countries
What are the typical presenting features of intracerebral toxoplasmosis? [3]
- Headache
- Seizures
- Focal CNS signs
What kind of pathology does intracerebral toxoplasmosis cause in the brain? [1]
Multiple enhancing lesions in the basal ganglia
How do you diagnose intracerebral toxoplasmosis? [2]
- Blood tests checking lgG and lgM
- PCR of CSF
What drugs are used to treat intracerebral toxoplasmosis? [2]
- Sulphadiazine
- Pyramethamine
