CNS Infections Flashcards
1
Q
What are the functions of the meninges?
A
- Protect brain + spinal cord
- Blood supply to skull
- Space for flow of CSF
2
Q
What are the routes of CNS infections?
A
- Blood borne
- Peripheral nerves (rabies)
- Local invasion from ears, sinus
- Local injury - face, skull, spine
- Congenital defects
3
Q
Where does blood borne invasion take place across?
A
- BBB to cause encephalitis
- Blood-CSF barrier to cause meningitis
4
Q
How do microbes travel across barrier of CNS to cause infection?
A
- Growing across + infecting cells that make up barrier
- Passively transported across intracellular vacuoles
- Carried by infected WBCs
5
Q
Which microbes invade CNS via peripheral nerves and how?
A
- HSV, VSV, rabies
- HSV and VSV travel from mucosal and skin lesions up axons to dorsal root ganglion
- Rabies introduced into muscle via bite > peripheral nerves > glial cells + neurones
6
Q
What is meningitis?
A
- Inflammation + infection of meninges
- Bacterial (serious)
- Viral (more common, less severe)
- Notifiable disease
7
Q
What organisms cause bacterial meningitis?
A
- Strep pneumoniae
- Neisseria meningitidis
- Listeria monocytogenes
8
Q
What organisms cause viral meningitis?
A
- Enterovirus
- HSV
- CMC
- EBV
9
Q
What organisms cause fungal meningitis?
A
Cryptococcus neoformans
10
Q
What causes meningitis in newborns?
A
- Group B Strep
- Strep pneumoniae
- Listeria
- E.coli
11
Q
What causes meningitis in babies + children?
A
- Group B Strep
- Strep pneumoniae
- Neisseria
- Hib
12
Q
What causes meningitis in teens and young adults?
A
- Strep pneumoniae
- Neisseria
13
Q
What causes meningitis in older adults?
A
- Group B Strep
- Strep pneumoniae
- Neisseria
- Hib
- Listeria
14
Q
How are CNS infections spread?
A
- Mothers can pass group B strep + E.coli during labour and birth
- Hib + Strep spread by coughing/sneezing
- N.meningitidis spread by sharing resp or throat secretions
- E.coli + Listeria = by contaminated food
15
Q
What are the signs and symptoms of meningitis in babies?
A
- Fever, cold hands + feet
- Rapid breathing, grunting
- Unusual cry, moaning
- Stiff neck, dislike bright lights
- Refusing food, vomiting
- Drowsy, floppy, unresponsive
- Pale, blotchy skin spots/rash
- Tense, bulging fontanelle
- Convulsions/ seizures
16
Q
What are the signs and symptoms of meningitis in adults?
A
- Fever, cold hands + feet
- Drowsy
- Severe muscle pain + headache
- Dislike bright lights, stiff neck
- Vomiting
- Confusion + irritability
- Pale, blotchy skin spots/rash
- Convulsions/ seizures
17
Q
When is a head CT considered?
A
- Low GCS
- New focal neurology
- Other signs of increased ICP
- Papilloedema
- Immunocompromised
- Perform LP ASAP if no contraindication
18
Q
What are the contraindications of LP?
A
- Signs suggesting increased ICP
- Shock
- Extensive or spreading purpura (septic rash)
- Convulsions
- Cogagulation abnormalities
- Superficial infection @ LP site
- Resp insufficiency
19
Q
What CSF findings are found in bacterial meningitis?
A
- Yellow
- High polymorphs + protein
- Low glucose
20
Q
What CSF findings are found in viral meningitis?
A
- Clear
- High lymphocytes
21
Q
What CSF findings are found in TB
A
- Yellowish/ viscous
- High lymphocytes
- Low glucose
22
Q
What CSF findings are found in viral meningitis?
A
- Yellowish/ viscous
- High lymphocytes
23
Q
How is bacterial meningitis managed?
A
- Cefotaxime/ Cefriaxone
+/- Vancomycin - Newborns + elderly may require Ampicillin/ Amoxicillin
24
Q
What is viral meningitis characterised by?
A
- Headache
- Fever
- Photophobia
- Less neck stiffness
25
What are the causative agents of viral meningitis?
- HSV
- Mumps
- Enterovirus
- HIV
26
What is encephalitis and the clinical presentation?
- Acute inflammation + swelling of brain
- Caused by infection or immune response
- Presents with headache, fever, change in cognitive state
- Reduced GCS or seizures
27
What are the causative agents of encephalitis?
- HSV
- VSV
- CMV
- Mumps
- Poliovirus
- Rabies
- HIV
- Fungi, parasitic or bacterial = rare
28
How is encephalitis diagnosed?
- CSF for viral PCR + microscopy, culture + sensitivities
- Blood culture
- CT head, MRI brain or ECG to confirm
- Usually treat with Acyclovir
- Treating early before development haemorrhagic necrosis = critical to improve neurological outcome
29
What are the complications of encephalitis?
- High mortality if untreated
- Memory problems
- Personality + behavioural changes
- Speech + language problems
- Problems swallowing
- Seizures
- Emotional + psychological problems
- Problems with attention, concentrating, planning + problem solving
- Problems with balance, co-ordination + movement
- Persistent tiredness
30
What is a cerebral abscess?
- Infection in or around skull - sinuses, otitis media, dental abscess
- Severe head injury
- Infection elsewhere which spreads via blood
- Symptoms associated with expanding intracranial mass +/- sepsis FFFF (fever, fits, focal, fatal)
31
How is a cerebral abscess diagnosed?
- Contrast enhanced CT (or MRI)
- LP contraindicated
- Locate source
- Blood cultures
32
How is cerebral abscess treated?
- Antibiotics based on causative organism
| - Surgical defridement/ removal of abscess and distal infected area
33
What is the significance of danger triangle of face?
- Skin here is thin
- Facial veins = valveless + communicate directly with cavernous sinus
- Infection of are can spread intra cranially + cause septic cavernous sinus thrombosis
34
What can cause post-op CNS infections?
Mechanical shunts = regulate ICP
35
What is rabies encephalitis?
- Predominantly in Africa and Asia
- Most cases in children under 15
Infections spreads from bite > CNS
- Striking symptoms of furious rabies - removing inhibition + initiating aggression
- Virus shed in saliva
36
What is the prevention and treatment of rabies?
- Vaccine
- Hits poor + rural
- Following bite - rapid post bite wound washing with warm soapy water + rapid assessment has big impact
- Location important
- Post exposure vaccines
37
Which CNS infections are seen in immunocompromised patients?
- CMV encephalitis
- Mycobacterium tuberculosis + Cryptococcus neoformans meningitis
- Toxoplasmosis - parasitic
- Kaposi sarcoma
- Neurosyphilis
