Meningitis ☺️ Flashcards
What are some of the causes of meningitis
Bacterial
Viral - HSV, HIV, MMR, entero
Protozoal
Non infectious - NSAIDS, ABx, SLE, sarcoid
Pathogenesis
Contact with infected people/travel to endemic areas
Bacteria enter meninges => SA inflammation
Increased CSF outflow resistance => hydrocephalus, increased ICP => cerebral ischemia
3 most common causative bacteria -up to 1 week old -1-6 weeks old -elderly -post surgery 2 most common causative bacteria -infants, children, adults 1 most common causative bacteria -IC
Neonates - GBS, listeria
- 1wk - E coli
- 1-6wks - G-ves
Post surgery - S aureus, S epidermidis, G-ves
Infants, children, adults - N meningitis, S pneumoniae
Elderly - as above + listeria
IC - listeria
What is the most common cause of acute bacterial meningitis in general
What type of meningitis is the most common in 20-40s
-prognosis
S pneumonia
20-40s => viral meningitis, generally self limiting
Classic triad
Presentation in arise in adults
-signs
What is a drawback of identifying these symptoms
Fever, confusion, neck stiffness
Headache N+V Non blanching rash Photophobia, phonophobia Fatigue, irritability
Due to meningeal irritation
Kernig - unable to extend knee when hip flexed
Brudzinski - knees, hip flexed when neck is flexed
Cannot distinguish between viral and bacterial meningitis
What are the CSF findings when healthy
- opening pressure
- appearance
- WCC
- differential count
- protein
- CSF/plasma glucose ratio
Opening pressure => 12-20 Appearance => clear WCC CSF => <5 Differential count => N/A CSF protein => < 0.4 CSF/plasma glucose => >0.66
What are the CSF findings if you have bacterial meningitis
- opening pressure
- appearance
- WCC
- differential count
- protein (indicator of the no of inflammatory cells)
- CSF/plasma glucose ratio
Opening pressure => high
Appearance => turbid
WCC => raised (may be normal in early infection)
Differential count => neutrophils
Protein => raised (protein leak into fluid)
CSF/plasma glucose => v low (bacteria using glucose)
ALWAYS INTERPRET FINDINGS IN CLINICAL CONTEXT
What are the CSF findings if you have viral meningitis
- opening pressure
- appearance
- WCC
- differential count
- protein
- CSF/plasma glucose ratio
Opening pressure => normal/high Appearance => clear WCC => raised Differential count => lymphocytes Protein => mildly raised CSF/plasma glucose => normal
ALWAYS INTERPRET FINDINGS IN CLINICAL CONTEXT
What are the CSF findings if you have TB/fungal meningitis
- opening pressure
- appearance
- WCC
- differential count
- protein
- CSF/plasma glucose ratio
Opening pressure => high Appearance => clear/cloudy WCC => raised Differential count => lymphocytes Protein => markedly raised CSF/plasma glucose => v low
ALWAYS INTERPRET FINDINGS IN CLINICAL CONTEXT
Diagnosis and investigations
Bloods
- FBC, U&E, CRP, clotting, culture - organ function and sepsis
- meningococcal PCR
- glucose
- ABG
CT - if there are focal neurological deficits/specific underlying cause suspected
GOLD STANDARD - LP CSF
-within hour of arriving at hospital before ABx started
CSF analysed for cell count, gram stain. glucose, protein, lactate, culture, bacterial/viral PCR
-analysis
-analyse alongside paired blood glucose
How would you treat acute bacterial meningitis
- primary care
- secondary care
- management of viral meningitis
- prophylaxis of close contacts
IV, IM benzylpenicillin => ADMIT TO A&E
Supportive - fluids, nutrition, analgesia, antipyretics, antiemetics
Treat causative organism - TREATED EMPIRICALLY AS BACTERIAL UNTIL PROVEN OTHERWISE
- U3 months IV amox+cefotaxime
- 3 months+ IV ceftriaxone
- IV dexmeth in certain situations
Viral - supportive only
-aciclovir if HSV encephalitis
Prophylaxis within 24hrs - cipro
What is the difference between purpura/petichiae in septicaemia and vasodilation of blood vessels
What do you need to consider in a patient with purpura/petichiae?
Purpura/petichiae => bleeding into skin, no blanching
Not specific to meningits, not always found in early disease
Vasodilation => compression of vessels => blanching
What are the red flag signs and symptom in
-young children
Why is it important to identify these symptoms?
The younger the child, the less likely they are to present typically
-typical signs are often late due to greater physiological reserve
All ages => first specific clinical features = signs of sepsis
Cold, painful limbs Pale, mottled skin Rash (often a late sign) Changes in HR, RR Drowsy Diarrhea Thirst
Why does meningococcal septicaemia kill/permanently damage survivors?
-complications?
Endotoxins => inflammatory response
Septic shock
-widespread VD
-myocardial damage
- intravascular coagulation => distal areas blocked, gangrenous, needs amputation
- vessel damage => petichiae, purpura
DISRUPTION OF NORMAL CV FUNCTIONING
Complications
- hearing loss
- seizures
- cognitive, motor, visual impairment
- hydrocephalus
- amputations
What vaccines are currently being offered
MenB, ACWY
Pneumococcal vaccine
