15) Subarachnoid Haemorrhage and Meningitis Flashcards
What is a Subarachnoid Haemorrhage ?
Bleeding into the space between the Arachnoid and Pia Layer
List some risk factors of having a Subarachnoid Haemorrhage
> Trauma > Aneurysm > Hypertension > Smoking > Cocaine > Alcohol > FHx > Associated conditions
Why do Aneurysms develop ?
Develop due to abnormal weakness in vessel wall and large changes in pressure
Where in the Circle of Willis is an Aneurysm most likely to develop ? and Why ?
Anterior and Posterior Communicating Arteries .
B/c They have a much smaller lumen size than the main cerebral artery therefore there is a large change in pressure
Also intracranial lack, External Elastic Lamina and have a thin adventitia
What is an early warning sign that someone may have an aneurysm in the PCA ?
Painful CN III Palsy
Outline the presentation of Subarachnoid Haemorrhage ?
> Thunder clap headache, worse one they’ve ever head
- Last 1 hour to a week
Loss of Consciousness and Confusion due to compression of the brain affecting the neurones
Dizzy
Stiff Neck
Meningism (irritation of the meninges due to irritation of the arachnoid and pia by the blood)
Focal Neurology
Visual problems, diplopia, loss
Sentinel Bleeding
What investigations are to be carried out with a suspected SAH ?
> CT Head (Blood is bright)
IF confirmed CT angiogram
IF negative CT but convincing history carry out Lumbar Puncture
=> But wait for at least 6 hours because need time for lysis for RBC to take place, the release of bilirubin gives CSF a yellow tinge - Xanthochromia
What is the treatment for SAH ?
Stabilisation
> Assessment whether they need airway support
> Monitor cardiovascular parameters
> CCBs - Nimodipine prevent vasospasm and secondary ischaemia
> Operate if they have good neurological status within 72 hours to prevent re bleeding
> Clipping
> Coiling
What happens after a Subarachnoid bleed ?
Early - Late (3 days)
Mechanical Effect and Acute Global Ischaemia : Early
> Early Brain Injury
- Microthrombi which can occlude smaller distal arteries
- Vasoconstriction of Cerebral Arteries
- Cerebral Oedema as a response to hypoxia and extravasated blood and Inflammation
> Systemic Complications
- Activation of Sympathetic System => Myocardial Damage
> Cellular changes
- Oxidative stress
- Inflammatory mediators
- Platelet Activation
Late
> Delayed Cerebral Ischaemia
- Vasoconstriction and Vasospasm of cerebral vessels
What complications can occur following a SAH ?
> Global Cerebral Ischaemia > Early rebleeding > Acute Hydrocephalus if blood blocks normal drainage of CSF >Seizure > Disability > Death
What is Meningitis ?
Inflammation of Leptomeninge, especially arachnoid tissue and subarachnoid space
What are the S/S of Meningitis ?
> Meningism - Headache - Neck Stiffness - Photophobia > Flu Like > Joint Pains > Rash > Reduced GCS > Physical Examination -> Kernig Sign - Patient bends knee and hip into chest, neck should extend naturally - Then extend knee but there is resistance because there is Nuchal Rigidity
- > Brudzinski sign
- Involuntary neck flexion with involuntary flexion of knee and hip
Babies: > Inconsolable crying > Reduced Feeds > Floppy > Bulging Fontanelle
Why does a Non Blanching Rash arise in Meningitis ?
Microvascular thrombi caused by endotoxins released by Neisseria.
=> Cascade activated causing sluggish circulation (Increased Viscosity)
=> Impaired fibrinolysis therefore more likely to get clot and when pressing down it won’t disappear
=> Increased tissue factor expression and impaired antithrombi mechanisms
This occurs most commonly in Meningococcal Meninigitis
What are the most common micro organisms which can cause Meningitis ?
1) Strep. Pneumonia
2) Neisseria Meninigitides
3) Haemophilus Influenzae
What are some risk factors of acquiring Meninigitis ?
> CSF defects > Spinal procedures > Endocarditis > Diabetes > Immunosuppressed patients > Crowded Areas
