C N S S A H 5th Class

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CNS SAH 5th med students lecture.

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C N S S A H 5th Class

  1. 1. SUBARACHNOID HAEMORRHAGE
  2. 2. Epidemiology : <ul><li>3/4 are < 65 years. </li></ul><ul><li>Women are more frequently affected than men. </li></ul><ul><li>It typically presents with a sudden, severe 'thunderclap' headache (often occipital) which lasts for hours or even days, often accompanied by vomiting. </li></ul><ul><li>Physical exertion, straining, sexual excitement are common antecedents. </li></ul><ul><li>There may be loss of consciousness at the onset, so it should be considered if a patient is found comatose. </li></ul><ul><li>Since it is rare (incidence 6/100 000) & only 1/8 with a sudden severe headache has had a SAH, clinical vigilance is necessary to avoid a missed diagnosis. </li></ul><ul><li>All patients with a sudden severe headache require investigation to exclude a SAH. </li></ul>
  3. 3. EXAM : <ul><li>The patient is usually distressed & irritable, with photophobia. </li></ul><ul><li>There may be neck stiffness due to subarachnoid blood but this may take some hours to develop. </li></ul><ul><li>Focal hemisphere signs (hemiparesis, aphasia etc.) may be present at onset if there is an associated intracerebral haematoma. </li></ul><ul><li>A 3rd nerve palsy may be present due to local pressure from an aneurysm of the posterior communicating artery, though this is rare. </li></ul><ul><li>Fundoscopy may reveal a subhyaloid haemorrhage, which represents blood tracking along the subarachnoid space around the optic nerve. </li></ul>
  4. 5. Pathology : <ul><li>85% are caused by saccular ('berry') aneurysms bulging out from the bifurcations of the cerebral arteries, particularly in the region of the circle of Willis. </li></ul><ul><li>These rarely present before the age of 20 years. </li></ul><ul><li>There is an increased risk in first-degree relatives of those with saccular aneurysms& with polycystic kidney disease & congenital collagen defects, e.g. Ehlers-Danlos syndrome. </li></ul><ul><li>Of the remainder, 10% are non-aneurysmal haemorrhages (so called peri-mesencephalic haemorrhages), which have a very characteristic appearance on CT& a benign outcome in terms of mortality&recurrence. </li></ul><ul><li>Some 5% of SAHs are due to rarities including arteriovenous malformations & vertebral artery dissection. </li></ul>
  5. 14. Management & prognosis: <ul><li>The immediate mortality of aneurysmal SAH is about 30%. </li></ul><ul><li>Survivors have a recurrence, or re-bleed, of 40% in the first 4 weeks & 3% annually thereafter. </li></ul><ul><li>Insertion of platinum coils into an aneurysm (via an endovascular procedure) or surgical clipping of the aneurysm neck reduces the risk of both early & late recurrence. </li></ul><ul><li>Coiling may be associated with fewer perioperative complications &better outcomes. </li></ul><ul><li>A re-bleed is not the only cause of early deterioration. </li></ul><ul><li>The clinician should also consider obstructive hydrocephalus, delayed cerebral ischaemia due to vasospasm, hyponatraemia & systemic complications associated with immobility, e.g. chest infection or pulmonary embolism. </li></ul><ul><li>Nimodipine (60 mg) is given to prevent vasospasm in the acute phase. </li></ul>

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