CNS infections Flashcards
meningitis
Inflammation of meninges - tissues surrounding brain and spinal cord
encephalitis
inflammation of brain - in combination with meningitis it is meningoencephalitis
Clinical presentation of meningitis
Non-specific symptoms - fever, N&V, lethargy, irritable or unsettled mood, refusal of food and drink, headache, muscle ache or joint pain and rest symptoms such s a cough
More specific symptoms - stiff neck, altered mental state (confusion, delirium, drowsiness, impaired consciousness), non-blanching rash, bulging fontanelle in infants, photophobia, Kernigs (severe hamstring stiffness which gives inability to straighten leg when flexed) and Brudzinski’s (spontaneous knee and hip flexion) signs, coma, paresis, focal near defect and seizures
CSF CI’s
Cardioresp instability
Focal neuro signs
Signs of raised ICP e.g. coma, high BP, low HR or papilloedema
Coagulopathy
Thrombocytopenia
Local infection at site of LP
If it causes undue delay in starting antibiotics
CT scan?
Done before an LP in patients with suspected bacterial meningitis only if one of the following RFs present:
- Altered mentation
- Focal neuro signs
- Papilloedema
- Seizure within previous week
- Impaired cellular immunity
How is bacterial meningitis spread?
Close contact, droplets, direct contact with respiratory secretions
Inflammation during meningitis
When BBB disrupted by inflammation, proteins and cells enter the CSF. This permits a more effective immune response and allows rapid entry of drugs which do not penetrate the BBB in absence of infection
Inflamm can cause protein accumulation and fibrin deposition which can occlude the aqueduct and cause hydrocephalus
cerebral vein thrombosis
Intracranial HTN may incarcerate the brain against the skull leading to cerebral vein thrombosis or cerebral ischaemia
Meningitis tx
ABC Haemodynamiclly stable Fluid and electrolyte balance Seizures Empirical tx - cefotaxime and dexamath
Meningococcal meningitis
Tx - ben pen or cefotaxime
Prophylaxis - ciprofloxacin
Neonatal meningitis
Related to colonisation of maternal tract
Bacteraemia tends to occur in first week of life
meningitis at 2-3w
<3 months - group B streptococcus, e.coli
<6y - N.meningitis, S.pneumoniae, H.influenzae
>6 y - N.meningiits, S.pneumoniae
Tx of neonatal meningitis
Tx children younger than 3 months with suspected bacterial meningitis without delay using IV cefotaxime plus either amoxicillin or ampicillin
Tx Group B streptococcal meningitis with IV cefotaxime for at least 14 days
Tx gram -ve bacteria for at least 21 days
Brain abscess
Most common cause of intracerebral abscess formation is direct or indirect spread from infection in paranasal sinuses, middle ear and teeth
Frontal, ethmoid, sphenoid and maxillary sinusitis give rise to abscess formation in the frontal lobe
Brain abscess is a focal, in tracerebral infection evolving from an area of cerebrates into collection of purulent material enveloped in a vascularised capsule
Signs of neonatal brain abscess
Typically develop in second week of illness
Can be subtle - include vomiting, bulging fontanelle, inc head circumference, separation of cranial sutures, hemiparesis, focal seizures and inc peripheral WBC count
Encepaholppathy
Altered mental state - reduced consciousness or altered cognition, personality or behaviour
Has many causes including systemic infection, metabolic derangement, inherited, toxins, hypoxia, trauma, vasculitis
