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