Date post: | 04-Aug-2015 |
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SOEPEL – Subarachnoid haemorrhage (SAH)
Abdul Waris Khan Dept: Internal medicine
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.
• Objective: History taking & Physical exam
• Evaluation: SAH, migraine, subdural hemorrhage
• Plan: CT
• Elaboration: conservative and surgical treatment
• Learning Goals: Subarachnoid hemorrhage
Subarachnoid haemorrhage (SAH)
• SAH means spontaneous arterial bleeding into the subarachnoid space, and is usually clearly recognizable clinically from its dramatic onset.
Statistics
SAH accounts for some 5% of strokes
Annual incidence of 6 per 100 000.
Risk factors
• Hypertension
• Smoking
• Alcohol
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.
• Aneurysms cause symptoms 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.
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)
Clinical features of SAH• 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.
Investigations
• CT imaging 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
• CSF becomes yellow (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.
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.
Management
• Immediate treatment 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.
• Nearly half of 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.
References
• Kumar & Clark's clinical medicine 7th edition