Subarachnoid haemorrhage Flashcards
What is meningism?
Meningism is resistance to neck flexion due to painful spasms of extensor muscles resulting from meningeal irritation.
What are causes of meningism? And what are the symptoms?
- Meningitis
- SAH
- Cervical spondylosis
- Parkinson’s disease
- Raised ICP
- Acute dystonic reaction
- Tetanus
Triad of symptoms:
- Headache
- Photophobia
- Neck stiffness
What is the pathophysiology of SAH?
It is most commonly caused by trauma and ruptured berry aneurysms.
Berry aneurysms occur by congenital weakness of vascular walls in Circle of Willis. They have thin or absent tunica media leading to saccular aneurysms. They commonly occur at branch points. When these rupture, blood enters subarachnoid space and into parenchyma and ventricles.
This increases ICP and blood products are toxic, leading to complications.
Where do berry aneurysms most frequently occur?
- ACA and anterior communicating artery
- Branch point of MCA
- Bifurcation of ICA
- Bifurcation of PCA
They are prone to rupture after a sudden increase in BP.
What are risk factors of SAH?
Family history Underlying HTN Smoking Coagulopathy Genetics
What are the complications of SAH?
Early: meningism, sterile meningitis, raised ICP and ischaemic event to brain tissue and hydrocephalus, herniation, re-bleeding, further haemorrhage,
vasospasm, hydrocephalus.
Late: hydrocephalus, delayed cerebral ischaemia (can give steroids or calcium gluconate), epilepsy
What is prognosis for SAH?
1/3 will die, 1/3 permanent neurological damage, 1/3 recovery.
What is venous drainage of the brain?
DEEP: Internal cerebral vein –> great cerebral vein –> straight sinus –> transverse sinus –> sigmoid sinus –> internal jugular vein
SUPERFICIAL: superior and inferior sagittal sinus –> transverse sinus –> sigmoid sinus –> internal jugular vein
What are clinical presentations of raised ICP?
Thunderclap headaches Papilloedema Nausea and vomiting Mydriasis: pupils dilation Deterioration of GCS Seizures Focal neurological signs Cushing's reflex/triad
What are the landmarks of CSF flow?
Lateral ventricles with anterior, posterior and inferior horns. Interventricular foramina of Monro. Third ventricles. Cerebral aqueduct (duct of Sylvius). Fourth ventricle. Central canal.
Where is CSF produced?
CSF is produced by ependymal cells in the choroid plexus in the lateral ventricles (mostly in the superior horn). It passes through the anatomy described previously.
How is CSF reabsorbed?
It enters subarachnoid space by lateral foramina of Luschka and medial foramen of Magendie, draining into superior sagittal sinus via arachnoid villi (functioning as one-way valve).
