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