Improvement tends to occur between 4 and 18 months after the event but even those who have independent living often have some cognitive defect. Younger patients do better.
Up to 60% of patients die in the first 30 days. 10% die immediately without any warning symptoms and an additional 25% die or become disabled.
Hospitalised patients have an average mortality rate of 40% in the first month. Rebleeding, a major complication, carries a mortality rate of 51-80%.
Delayed cerebral ischaemia due to vasospasm, the most deadly of all complications, affects 20% of angiographically visualised cases of vasospasm.
In a survey of 610 patients who were interviewed a mean of 8.9 years after subarachnoid haemorrhage (SAH), there was marked morbidity.

• Of the employed patients, 26% stopped working and 24% worked shorter hours or had a position with less responsibility.
• On average, patients returned to work 9.4 months after discharge (range 0-96 months).
• Related problems caused divorce in 7%.
• There were changes in personality in 59%, with the most common being increased irritability (37%) or emotionality (29%).
• Patients with SAH had a statistically significant higher mean depression score than the control population. Approximately 10% of the patients had a Hospital Anxiety and Depression Scale score in the range of a probable depressive or anxious state.
• Only 25% reported a complete recovery without psychosocial or neurological problems.
• • 5% or more of patients develop epilepsy after discharge.
  • After occlusion of the anterior communicating artery in particular, around 30% develop anosmia.

  A sudden deterioration in level of consciousness within the first few hours suggests further bleeding. This carries a mortality rate of 51-80%.

  SAH is a form of stroke and comprises 1–7% of all strokes

  Up to half of all cases of SAH are fatal and 10–15% of casualties die before reaching a hospital, and those who survive often have neurological or cognitive impairment.

  higher than normal levels of cholesterol. Approximately 4% of aneurysmal bleeds occur after sexual intercourse and 10% of people with SAH are bending over or lifting heavy objects at the onset of their symptoms.