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Clinical Neuroscience > Subarachnoid Haemorrhage & Meningitis > Flashcards

Subarachnoid Haemorrhage & Meningitis Flashcards

1
Q

Describe the epidemiology of SAH

A
  • 6% of all strokes
  • Slightly more females (x1.6)
  • 50% mortality, 60% have long term morbidity afterwards
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2
Q

List 8 risk factors for SAH

A
  • Hypertension
  • Smoking
  • Excess alcohol
  • Predisposition to aneurysm formation
  • Family history
  • Trauma
  • Cocaine
  • Associated conditions (CKD, Marfan’s, Neurofibromatosis)
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3
Q

SAHs usually occur after rupture of an Aneurysm in the Circle of Willis.

What is an Aneurysm?

A

A weakness in a vessel wall which can cause an abnormal bulge

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4
Q

Most SAHs come from Berry Aneurysms

List 3 common sites where these form, making up 75% of all aneurysms

A

Proximal ACA/ Ant. Comm. Artery;

  • 30%
  • (Can affect Optic Chiasm, Frontal Lobe, Pituitary)

Post. Comm. Artery;

  • 25%
  • (Can compress CNIII-> CNIII palsy)
MCA Bifurcation (as it splits into S + I divisions);
- 20%
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5
Q

List 6 Clinical Features/ Signs/ Symptoms of SAH

A
  • Thunderclap headache
  • Loss of consciousness + confusion
  • Meningism (Neck stiffness, Photophobia, Headache)
  • Focal neurology
  • Possible sentinel bleed/ headache
  • May present as cardiac arrest (Rapid rise in ICP-> Cushing’s response)
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6
Q

What 3 groups of things can happen after an SAH

A
  • Early brain injury
  • Cellular changes (Oxidative stress, inflammatory mediator release, platelet activation)
  • Systemic complications (Cushing’s response, Myocardial damage, Systemic inflammatory response)
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7
Q

What are 4 examples of Early brain injury due to SAH

A
  • Microthrombi (can occlude more distal branches)
  • Vasoconstriction (cerebral arteries)
  • Cerebral oedema (Inflammatory response)
  • Brain cell apoptosis
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8
Q

List SAH investigations

A
  • CT head
  • CT angiogram
  • Lumbar Puncture (if CT inconclusive but history strongly suggests)
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9
Q

Describe the CT appearance of a SAH

A
  • Filling of cisterns in a ‘5-pointed star pattern’

- Blood may be seen in ventricles

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10
Q

How long you should you wait after the onset of symptoms, before doing an LP to diagnose SAH?

Why?

A
  • At least 6 hours, preferably 12
  • Need time for lysis of RBCs in SA space, to allow Bilirubin to accumulate in CSF, giving it a yellow tinge (Xanthrochromia)
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11
Q

If SAH has happened describe the following results of a CSF sample;

  • Protein
  • WBCs
  • Glucose
  • RBCs
A
  • Protein: High (because blood constituents)
  • WBCs: Not rasied
  • Glucose: Normal
  • RBCs: Raised
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12
Q

Describe the technique of an LP

A
  • Find Iliac Crests (giving L4-L5 level)
  • Local anaesthetic
  • Insert needle between Spinous Processes and through InterS and SupraS ligaments
  • Feel ‘give’ as needle passes through Ligamentum Flavum and Dura
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13
Q

Outline the treatment of SAH patients

A
  • Airway monitoring, O2, Fluids (Nimodipine to alleviate cerebral vasospasm)
  • Neurological observations
  • Neurosurgery (Decompresive Craniectomy, Coiling, Clipping)
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14
Q

Describe the process of Coiling to treat SAH

A
  • Insertion of a Platinum wire into aneurysm sac

- Causes thrombosis of blood within aneurysm

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15
Q

Describe the process of Clipping to treat SAH

A
  • Clamping neck of the aneurysm with a spring clip

- Causes it to looses blood supply and shrivel up

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16
Q

Who does Coiling and Clipping procedures

A

Coiling: Done by Neuroradiologists

Clipping: Done by neurosurgeons

17
Q

Why do we operate on SAH patients with a good neurological status within 48 hours?

A

To prevent re-bleeding (a risk of previous SAH)

18
Q

Describe the typical presentation of Meningitis

A
  • Fever + Meningism (Neck stiffness, Photophobia, Headache)
  • Flu like symptoms
  • Rash (non-blanching, Petechiae and Purpura)
  • Joint pain/ stiffness
  • Seizure
  • Drop in GCS
  • Shock
19
Q

How can meningitis present in babies?

A
  • Inconsolable crying
  • Rigidity/ floppiness
  • Bulging fontanelle (late sign)
20
Q

Compare the development of Meningitis if due to a Bacterial and Viral cause

A

Bacterial cause: Over hours

Viral: Over days

21
Q

List 6 risk factors for Meningitis

A
  • Cochlear implants (easier route of bacterial entry into brain)
  • Crowding
  • Young and old
  • Immunosuppression
  • Spinal procedures
  • CSF defects
22
Q

Describe 2 ways bacteria can reach the CNS

A
    • Bacteria ascend Nasopharynx-> Middle ear
    • Prolonged infection here allows them to spread directly into CSF
    • Bacteria accumulate in LRT
    • Lung inflammation allows entry into blood
    • Invasion of CSF via capillaries allows entry into CSF

(Neonates can get bacteria from their mothers)

23
Q

Describe the pathophysiology of Meningitis

A
  • Cause damage to vessel walls in Brain and Meninges, allowing pathogen to enter SA space
  • In here, they cause Meningeal inflammation and CSF becomes purulent
  • Inflammatory cascade-> Cerebral Oedema and Raised ICP
24
Q

Suggest complications of Meningitis

A
  • Septic shock
  • DIC
  • Coma (raised ICP)
  • Seizures
  • Death (herniation, sepsis)
  • Hydrocephalus
  • SIADH
  • Hearing loss
  • Focal paralysis
  • Intellectual deficits
25
Q

Meningitis can appear with Kernig and Brudzinski signs

Describe these 2 signs (more common in children)

(Kernig- Upto 53% of cases, Brudzinski-Upto 66% of cases)

A

Kernig sign;

  • Supine, thigh flexed to 90 degrees
  • Extension of knee met with resistance

Brudzinski sign;
- Neck flexion-> Involuntary flexion of Knees and Hips

26
Q

List investigations for Meningitis

A
  • Sepsis screening, maybe CXR or Mid Stream urine

- LP most important

27
Q

Compare Bacterial and Viral Meningitis with regards to the following CSF results;

  • CSF appearance
  • Protein count
  • WBC count
  • Glucose content
A

Bacterial (Can get a positive gram stain);

  • Cloudy CSF
  • High protein
  • High WBCs (mainly Neutrophils)
  • Low glucose (bacteria and WBCs metabolise it)

Viral;

  • Clear, can be cloudy
  • Normal or raised
  • High WBCs (mainly Lymphocytes)
  • Normal
28
Q

Describe the Supportive treatment of Meningitis

A
  • Analgesia
  • Antipyretics
  • Fluids if went through shock
  • Oxygen
29
Q

Describe the Specific treatment for Meningitis

A
  • Broad spectrum/ Empirical antibiotics initially (E.g Vancomycin)
  • IV Ceftriaxone
  • Dexamethasone

If Viral;

  • Aciclovir for Herpes
  • Ganciclovir for CMV
30
Q

Why give Dexamethasone when treating Meningitis?

A

To prevent hearing loss (due to swelling of CN VIII OR effect on Cochlea)

31
Q

Where does blood mostly accumulate in a subarachnoid haemorrhage?

A

In the Basal Cistern, in the area of the Sella Turcica

Clinical Neuroscience (19 decks)

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