Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

S4 Neuro > Meningitis and subarachnoid haemorrhage > Flashcards

Meningitis and subarachnoid haemorrhage Flashcards

1
Q

4 important dural folds

A
  • falx cerebri (between cerebral hemispheres)
  • falx cerebelli (between cerebellar hemispheres)
  • tentorium cerebelli
  • diaphragm sella
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Role of CSF

A 
Physical support
Excretion of brain metabolites
Intracerebral transport (hormone releasing factors)
Control chemical environment
Volume changes - compensate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are cisterns?

A

Enlarged regions in subarachnoid space where brain moves away from skull - collect CSF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Flow of CSF

A

Formed by choroid plexuses and extra- choroidal structures

Lateral ventricles
3rd ventricle
Aqueduct of Sylvius
4th ventricle
Median and lateral apertures
Subarachnoid space (small amount into spinal cord)
Arachnoid granulations project into dural Sinuses -> circulation

Propelled by new fluid, ciliary action, ventricular ependyma, vascular pulsation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a subarachnoid haemorrhage? Risk factors, symptoms

A

Extravasated new of blood is to subarachnoid space - non-traumatic spontaneous (can also occur in trauma)

Risks: 6% of all strokes, female, black, Finnish, Japanese, 50-55yrs
Aneurysms risk: hypertension, smoking, alcohol, CT disorder, polycystic ovaries

Symptoms: headache 1/2, dizziness, orbital pain, diplopia, visual loss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Subarachnoid haemorrhage cause

A

Rupture of saccular (berry) aneurysms 80% of non-traumatic
(Rupture arterial/ venal malformations - 10%)

Usually at bifurcation points
Often large cerebral arteries circles of willis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Subarachnoid haemorrhage clinical signs

A

Signs of meningism
(Neck stiff, photophobia)
Right third nerve palsy - PCA aneurysm
Sentinel headaches in months preceding 40% - minor leaks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What can occur after the bleed in subarachnoid haemorrhage?

A

Micro thrombi which can occlude smaller distal arteries

Vasoconstriction from CSF irritant

Cerebral oedema (response to hypoxia & extravasated blood)

Sympathetic activation - myocardial damage (ECG ST elevation, troponin increased)

Earl rebleeding common

Acute hydrocephalus (blood in subarachnoid space may block drainage CSF)

Global cerebral ischaemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Subarachnoid haemorrhage investigations before diagnosis

A

1st lime - CT scan detects 93% if done within 24hrs or bleed (without contrast so not confused blood)

If convincing history but negative CT scan: lumbar puncture (should wait at least 6hrs, need time lysis RBCs - release bilirubin in CSF - yellow tinge (xanthochromia) in centrifuging, different from just blood from traumatic tap of procedure)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is xanthochromia

A

Yellow tinge to CSF that occurs >6hrs after bleed in subarachnoid space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Subarachnoid haemorrhage investigations post diagnosis

A

Angiography confirm location of aneurysm -

digital subtraction angiography (inject contrast-> vasculature, fluoroscope (x-ray) real-time)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Subarachnoid haemorrhage treatment

A

Stabilisation - May need airway support - monitor CVS parameters

✅CCB - nimodipine (selective cerebral vasculature- prevents vasospasms and secondary ischaemia)

✅operate within 72hrs if gd neurological status prevent re-bleeding

  • clipping (clamp aneurysm)
  • coiling (insertion wire into aneurysm sac-> thrombosis of blood)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What two broad categories can infections of the CNS be divided into?

A

Infections focused on parenchyma (encephalitis)

Infections focused on meninges (meningitis) - usually inflammation of leptomeninges (arachnoid, pia)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Signs and symptoms meningitis

A

Triad of meningism with a fever 44%

  • headache
  • neck stiffness
  • photophobia
  • flu like
  • joint pains
  • rash
  • reduced GCS/ seizures
Babies: 
Inconsolable crying/ high pitched
Reduced feeds
Floppy
Bulging fontanelle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the meningitis rash most common with, what causes it and what does it look like?

A

Most common with meningococcal meningitis

Caused by bleeding into skin/ mucosa (microvascular thrombosis)

  • non- blanching rash
    Larger lesions - purpuric
    Smaller lesions (1-2mm) - petechial (bbs can get from distress above clavicle)

Usually trunk/ legs/ mucous membranes/ conjunctivae/ palms/ soles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Causes of meningitis

A

Most often infectious bacterial/
viral (most common)

Common bacteria cause:
1st Streptococcus pneumonia (vaccine for 13 variants)
2nd neisseria meningitides
3rd haemophilus influenza (Hib vaccine)

  • occasionally from fungal disease or trauma/ surgery
17
Q

Risk factors for meningitis

A

Young and old <5 >65yrs

Crowding

Immune problems

Cochlear implants

18
Q

How does bacteria reach the CNS to cause meningitis?

A
  • colonisation nasopharynx
  • ascent through Eustachian tube -> middle ear (otitis media)
  • prolonged infection -> directly CSF (mastoid sinuses)

OR

  • colonisation nasopharynx
  • seeding to LRT (pneumonia)
  • lung inflammation bacteria enters blood (bacteraemia)
  • invasion of CSF via capillaries or subarachnoid space

Neonates can get pathogens from maternal source (placenta/ reproductive tract secretions)

19
Q

Effects of meningitis - pathophysiology & complications

A

Bacteria quickly multiply in subarachnoid space - inflammatory mediators induced - lots leukocytes enter CSF -> inflammatory cascade -> cerebral oedema ⬆️ICP

Complications:
Specific shock
Disseminated IV coagulation 
Coma
Seizures
Hearing loss 
Hydrocephalus
Focal paralysis
20
Q

Diagnosing meningitis

A

Symptoms/ signs
Physical examination

Kernig sign - supine patient with thigh flexed 90degrees -> extension knee met with resistance (more common children -53%)

Brudzinski sign - neck flexed involuntary flexion knees and hips (children 66%)

Due to meningeal irritation (stretching)

21
Q

Meningitis investigations and when to be cautious

A

Lumbar puncture - untreated bacterial CSF: cloudy, elevated protein, low glucose, positive gram stain
Viral CSF: clear or cloudy, normal/ raised protein, normal glucose

But performing Lp increases chance brain herniation (occurs 5% with acute bacterial meningitis anyway)
Signs:
Decreasing consciousness, Brainstem signs, recent seizure (delay LP)
CT head find contraindications to LP but normal may not mean safe

Can also do PCR:
Blood and CSF - helpful diagnose patients who received empirical antibiotic treatment, distinguish bacterial from viral causes

Blood culture - results can be inflicted previous antibiotic treatment

22
Q

Treatment meningitis

A

Admit to hospital

  • empirical antibiotics e.g. Vancomycin + (Ceftriaxone OR cefotaxime)
  • supportive therapy (intubation if altered consciousness, fluids if shocked, O2)
  • dexamethasone (prevent hearing loss)

If viral: aciclovir for herpes, supportive fluids, antipyrexial, painkillers, rest

S4 Neuro (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions