subarachnoid hemorrhage

subarachnoid hemorrhage

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  SOEPEL – Subarachnoid haemorrhage (SAH) Abdul Waris Khan Dept: Internal medicine
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  SOEPEL • Subjective:A 35 years old male presents to ER with sudden severe headache and neck stiffness. His symptoms started when he was pruning flowers in the garden.
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  • Objective: Historytaking & Physical exam • Evaluation: SAH, migraine, subdural hemorrhage • Plan: CT • Elaboration: conservative and surgical treatment • Learning Goals: Subarachnoid hemorrhage
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  Subarachnoid haemorrhage (SAH) • SAH means spontaneous arterial bleeding into the subarachnoid space, and is usually clearly recognizable clinically from its dramatic onset.
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  Statistics SAH accountsfor some 5% of strokes Annual incidence of 6 per 100 000.
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  Risk factors •Hypertension • Smoking • Alcohol
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  Saccular (berry) aneurysms • Saccular aneurysms develop within the circle of Willis and adjacent arteries. Common sites are at arterial junctions: – Between posterior communicating and internal carotid artery – posterior communicating artery aneurysm – Between anterior communicating and anterior cerebral artery – anterior communicating and anterior cerebral artery aneurysm – At the trifurcation or a bifurcation of the middle cerebral artery – middle cerebral artery aneurysm.
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  • Aneurysms causesymptoms either by spontaneous rupture, when there is usually no preceding history, or by direct pressure on surrounding structures – For example, an enlarging unruptured posterior communicating artery aneurysm is the commonest cause of a painful IIIrd nerve palsy.
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  Arteriovenous malformation (AVM) • AVM are vascular developmental malformations, often with a fistula between arterial and venous system causing high blood flow through the AVM. • Once an AVM has ruptured, the tendency is to rebleed – 10% will then do so annually. • They maybe ablated with endovascular treatment (catheter injection of glue in the nidus)
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  Clinical features ofSAH • There is a sudden devastating headache, often occipital. • Headache is usually followed by vomiting and often by coma and death. • Survivors may remain comatose or drowsy for hours, days, or longer. • SAH is a possible diagnosis in any sudden headache. • Following major SAH there is neck stiffness and a positive Kernig’s sign.
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  Investigations • CTimaging is the immediate investigation needed. • Subarachnoid and/or intraventricular blood is usually seen. • Lumbar puncture is not necessary if SAH is confirmed by CT, but should be performed if doubt remains
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  • CSF becomesyellow (xanthochromic) several hours after SAH. • Spectrophotometry to estimate bilirubin in the CSF released from lysed cells is used to define SAH with certainty. • MR angiography is usually performed in all potentially fit for surgery, i.e. generally below 65 years and awake. • In some, no aneurysm or source of bleeding is found, despite a definite SAH.
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  Differential diagnosis •SAH must be differentiated from migraine. • Thunderclap headache is used (confusingly) to describe either SAH or a sudden (benign) headache for which no cause is ever found. • Acute bacterial meningitis occasionally causes a very abrupt headache, when a meningeal microabscess ruptures. • SAH also occasionally occurs at the onset of acute bacterial meningitis. • Cervical arterial dissection can present with a sudden headache.
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  Management • Immediatetreatment of SAH is bed rest and supportive measures. • Hypertension should be controlled. • Dexamethasone or mannitol is often prescribed to reduce cerebral oedema. • Nimodipine, a calcium-channel blocker, reduces mortality.
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  • Nearly halfof SAH cases are either dead or moribund before reaching hospital. • Of the remainder, a further 10–20% rebleed and die within several weeks. • Patients who remain comatose or who have persistent severe deficits have a poor outlook. • In others, who are less impaired, and where angiography demonstrates aneurysm, either a direct approach to clip the aneurysm neck or intravascular coiling is carried out. • For AVMs, surgery, and focal radiotherapy (gamma knife) are used, when appropriate.
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  References • Kumar& Clark's clinical medicine 7th edition