Week 221 - Meningitis Flashcards
Of the 3 main causes of meningitis (bacterial, viral, fungal) which is the most common form?
Viral
Which has a worse prognosis bacterial or viral meningitis?
Bacterial
What is the initial treatment for suspected meningitis if it presents in the GP?
Antibiotics in case it is bacterial Call 999 (ambulance transfer to hospital) Call hospital to warn of a suspected meningitis case possibly give paracetamol, O2 if necessary / possible
What sort of antibiotics is the GP likely to give and why?
Whilst you would ideally treat with broad-spectrum antibiotics most GPs will have access to penicillin and so that narrow spectrum AB will be used
What it the management process once the patient is admitted to A&E?
ABCDE; Cannulate - Fluids (20mls/kg); bloods
Seizure control
LP when safe / not contraindicated
Get consultant involved and inform public health
What are the signs of shock that may present if sepsis/septicaemia sets in?
Drop in BP (although children hang on to BP longer than adults); reduced urine output (normal = ~1ml/kg/hr); slow cap refill, increase HR
What bloods are you going to want with suspected meningitis?
FBC (WCC up? and Hb down?), ESR, CRP, Cultures, U&E (low Na - inappropriate ADH?), LFT, glucose, coagulation, ABG (acidotic account for any confusion?)
What conditions might predispose a child / someone to meningitis?
Ear or sinus infections
Hydrocephalous (foreign bodies in head used for Tx)
Immunosuppression
List some risk factors for meningitis
Immunosuppression; young; elderly; alcoholism; lack of vaccines; DM; renal / adrenal insufficiency; CF; splenectomy; malignancy; Thalasaemia major
What colour should CSF be normally?
Clear
What structure within the ventricles produces CSF?
the choroid plexus
What colour will CSF be if bacterial meningitis is present?
Cloudy
What other changes, besides cloudiness of the CSF will be found on a CSF film?
High neutrophil count, High protein count, Low or absent glucose
What accounts for the low to absent glucose on a CSF film in the presence of bacterial meningitis?
The bacteria will be using it to replicate and survive
What is the risk associated with increased CSF protein?
Vascular obstruction (protein heavy CSF is thick and goopy) can cause thrombi etc
What will the CSF profile likely be in the presence of viral meningitis?
clear to turbid, lymphocytes high, protein normal to high, glucose normal
If mycobacteria is the cause of meningitis what will the CSF profile look like?
Clear to turbid, v high lymphocytes, v high protein, low glucose
Where is CSF found?
In the subarachnoid space within the meninges - in the ventricles of the brain and the spinal cord
Where does all CSF drain to?
The internal jugular veins (via the sigmoid sinuses)
Which venous sinuses drain the anterior skull base?
The cavernous sinuses
Name the venous sinuses of the brain
The superior and inferior sagittal sinuses
The transverse sinuses
The cavernous sinuses
The sigmoid sinuses
Name the 4 septa of the dura mater
The falx cerebri
The falx cerebelli
The tentorium cerebelli
The diaphragm sellae
What is the relationship between the septa of the dura and the venous sinuses?
The Inferior and Superior Sagittal sinuses follow the inferior and superior surfaces of the Falx Cerebri, and the anterior/posterior surfaces of the Falx Cerebelli
The Transverse sinuses follow the posterior line of the Tentorium Cerebelli
The Cavernous Sinus sits beneath the Diaphragma Sellae
What are the 4 route by which microbes enter the CNS?
via blood (most commonly) via direct implantation (traumatic, iatrogenic, congenital); via local extension of established infections (sinuses, teeth, middle ear) From PNS (rabies, herpes simplex, shingles)
