Week 221 - Meningitis Flashcards Preview

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Flashcards in Week 221 - Meningitis Deck (56)
1

Of the 3 main causes of meningitis (bacterial, viral, fungal) which is the most common form?

Viral

2

Which has a worse prognosis bacterial or viral meningitis?

Bacterial

3

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

4

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

5

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

6

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

7

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?)

8

What conditions might predispose a child / someone to meningitis?

Ear or sinus infections
Hydrocephalous (foreign bodies in head used for Tx)
Immunosuppression

9

List some risk factors for meningitis

Immunosuppression; young; elderly; alcoholism; lack of vaccines; DM; renal / adrenal insufficiency; CF; splenectomy; malignancy; Thalasaemia major

10

What colour should CSF be normally?

Clear

11

What structure within the ventricles produces CSF?

the choroid plexus

12

What colour will CSF be if bacterial meningitis is present?

Cloudy

13

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

14

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

15

What is the risk associated with increased CSF protein?

Vascular obstruction (protein heavy CSF is thick and goopy) can cause thrombi etc

16

What will the CSF profile likely be in the presence of viral meningitis?

clear to turbid, lymphocytes high, protein normal to high, glucose normal

17

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

18

Where is CSF found?

In the subarachnoid space within the meninges - in the ventricles of the brain and the spinal cord

19

Where does all CSF drain to?

The internal jugular veins (via the sigmoid sinuses)

20

Which venous sinuses drain the anterior skull base?

The cavernous sinuses

21

Name the venous sinuses of the brain

The superior and inferior sagittal sinuses
The transverse sinuses
The cavernous sinuses
The sigmoid sinuses

22

Name the 4 septa of the dura mater

The falx cerebri
The falx cerebelli
The tentorium cerebelli
The diaphragm sellae

23

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

24

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)

25

What condition is caused by Herpes Simplex Virus?

Cold sores; genital herpes

26

What condition is caused by Herpes Zoster Virus?

Chicken Pox; Shingles

27

At what site do microorganisms cross the blood brain barrier?

The choroid plexus

28

How is it easier for microorganisms to cross the BBB through the choroid plexus than the brain microvascular endothelial cells (BMEC) of the brain parenchyma?

The BMECs have weaker tight junctions between them, the endothelium is fenestrate increasing permeability, thus intracellular flux is increased

29

What are the possible early signs and symptoms of meningitis?

severe headache, malaise, fever, lethargy, n&v, irritibility
Sometimes: photophobia, rash, drowsiness progressing to unconsciousness, convulsions, hamstring rigidity

30

What is Brudzinski's sign?

A test of meningeal irritation.
With pt supine flex the head towards their chest, involuntary flexion of hips and knees is a +ve Bradzinski's sign

31

What is Kernig's Sign?

A test of meningeal irritation.
With pt supine, flex their hip and knee and then try to extend their knee - back pain and resistance to extension is a +ve Kernig's sign

32

What combination of information / findings helps you diagnose meningitis?

signs, symptoms, CSF profiling, culture (perhaps with Kernig's / Brudzinski's signs tested for on examination)

33

What causes the petechial rash sometimes found with meningitis?

Septicaemia. Inflammation causes vessels to become leaky so subepithelial haemorrhage can occur

34

What terms are used to describe viral meningitis due to the CSF profile it produces?

"Aseptic" or "Lymphocytic"

35

What viruses usually cause meningitis?

Echoviruses; Coxackie Viruses (A + B); (polio rare now in UK)
Can be as a complication of other viral infections: Mumps; Herpes Simplex; Herpes Zoster; HIV

36

Anatomically how is encephalitis different to meningitis?

Encephalopathy occurs when the infection affects the brain parenchyma rather than the meninges

37

Where dose replication typically take place once an enterovirus has been ingested or inhaled?

Oro-pharynx or Peyer's Patches

38

In an individual between the ages of 3 months and 65 years what are the most likely organisms to cause BACTERIAL meningitis?

Neisseria meningitidis (meninigococcal)
Streptococcus pneumonia (Pneumococcal)

39

In neonates (<3 months) with bacterial meningitis what is the most likely causative organism?

Group B Streptococcus (Streptococcus agalactiae) (or E. coli according to GP)

40

What is the most common cause of bacterial meningitis in the UK?

Neisseria meningitidis (gram -ve, capsular)

41

What is the pathogenesis of Neisseria meningitidis?

nasopharynx > blood > meninges

42

What is the pathogenesis of Streptococcus pneumonia, Haemophilus influenza and Cryptococcus neoformans?

Resp tract > blood > meninges

43

List these bacterial pathogens: Hib, Pneumococcus, Meningococcus, in order of severity of meningitis they cause (generally) most to least severe

Pneumoccocus, meningococcus, Hib

44

How does meningitis develop if Mycobacterium tuberculosis is the causative organism?

Gradual onset, normally with a preceding focal infection elsewhere in the body e.g. lung

45

What is the pathogenesis of Mycobacterium tuberculosis meningitis?

Resp tract > Blood > meninges > burst from small abscesses then get symptoms

46

What is the best indicator of a fungal source of meningitis infection?

the India Ink Stain

47

What organism is responsible for causing most cases of fungal meningitis?

Cryptococcus neoformans (gradual onset of symptoms)

48

If symptoms are slow to develop what two organisms are likely to have caused the meningitis?

Mycoplasma tuberculosis or Cryptococcus

49

What is the main cause of encephalitis?

Herpes Simplex Virus (HSV type I)

50

Physically, what characterises encephalitis?

Extensive, asymmetric, necrosis of temporal lobes (resulting in altered mental status and personality and seizures )

51

How would you diagnose HSV encephalitis?

Head CT and MRI

52

What is the treatment for HSV encephalitis?

Aciclovir for 21 days

53

Reactivation of HSV infection in what area is most associated with HSV encephalitis?

Trigeminal ganglia
(mother can also pass to baby through birth canal)

54

Although 'pure encephalitis' (only affecting the parenchyma without meningeal involvement) is rare name a cause of it

Rabies Virus - infects the brain via the PNS

55

Describe briefly what a brain abscess is, how caused and how treated

Focal infection of brain parenchyma, most caused by bacteria (fungi + parasites can), often result of local extension of infection, blood transportation or direct implantation. CT / MRI, aspiration to diagnose (though difficult so high mortality). Tx: surgical drainage or at least 1month of ABx

56

Which form of meningitis causes the non-blanching rash and how?

Meningococcal AKA Neisseria meningitidis