Subarachnoid Haemorrhage

Subarachnoid haemorrhage (SAH) is usually the result of bleeding from an aneurysm in the Circle of Willis, most often from a berry aneurysm. They are called berry aneurysms because of their shape. They were once thought to be congenital but there is now evidence that they are acquired, increase in incidence with age and that most do not rupture.¹

• Subarachnoid haemorrhage affects 6 to 12 people per 100,000 of the population per year and constitutes about 6% of first strokes.
• Approximately 85% of patients bleed from intracranial arterial aneurysms, 10% from a non-aneurysmal peri-mesencephalic haemorrhage and 5% from other vascular abnormalities including arteriovenous malformation.²
• Subarachnoid haemorrhage (SAH) represents a mere 5% of cases of stroke but it is relatively far more important as it tends to affect younger people of whom about half die in that episode.
• Half are under 55 years old.³
• 10 to 15% fail to reach hospital.

Risk factors

• The bigger the aneurysm, the more likely it is to bleed. However, as about 90% of aneurysms are small, the majority that bleed are less than 1cm in diameter.⁴
• Hypertension.
• Smoking.
• Excessive alcohol intake..

The last 3 each roughly double the risk and these modifiable risk factors account for around two thirds of SAH.⁵

• Although no single gene has been isolated, genetic factors also play a part and account for around 10%.⁶
• Patients with a positive family history tend to have their first SAH at a younger age.
• They are also more likely to have large and multiple aneurysms.

However, as this group accounts for only 10%, most patients with large or multiple aneurysms are sporadic rather than familial.

Berry aneurysms are found in 10% of patients with autosomal dominant adult polycystic kidney disease but they represent only 1% of cases of SAH.

The most characteristic feature is a sudden headache. This may last a few seconds or even a fraction of a second.⁷ The patient may even look round and accuse someone of hitting him on the back of the head. In general practice, it may be the only symptom in a third of patients.⁸ Of patients who present in general practice with a sudden headache, around 10% have subarachnoid haemorrhage.⁸

• The headache is often diffuse.
• The dominant feature is the severity rather than the suddenness of the headache, often being described as the most severe ever experienced.
• It usually lasts a week or two.

Other features include:

• Vomiting may occur but this does not distinguish it from other causes of headache including thunderclap headache without haemorrhage.
• Seizures occur in only about 7% but when they do, they are highly suggestive of a haemorrhage.

Examination

• On admission to hospital two thirds have a depressed level of consciousness of whom half are in coma but beware - SAH patients have been known to walk into the surgery complaining of sudden onset of headache.
• Neck stiffness may occur due to meningeal irritation by the blood but it is not invariable.
• Ophthalmoscopy will show intraocular haemorrhages in around 15% and especially those with depressed level of consciousness.
• There may be focal neurological signs, suggestive of a stroke. Complete or partial palsy of the oculomotor nerve is well recognised, especially with rupture of aneurysms of the internal carotid artery at the origin of the posterior communicating artery.
• Hypertension is a risk factor for the condition but a marked rise in blood pressure may occur as a reflex following haemorrhage.

• Other causes of stroke
• Meningitis
• Trauma
• Thunderclap headache

Thunderclap headache is an idiopathic condition. Headache is intense but benign but it can resemble the headache of SAH. Onset is acute, possibly within 30 seconds, and CT or even angiography may be required to rule out SAH. The angiogram may be normal or show focal cerebral vasoconstriction. Most patients with thunderclap headache never have a second episode, nor are they at higher risk for haemorrhage. However, the term thunderclap headache is often used to describe the headache that is associated with SAH.

• Arterial blood gases may show hypoxia.
• An ECG may show changes. If these are wrongly interpreted as acute myocardial infarction and thrombolysis is given, the result is disastrous.
• Every patient should have a CT scan at the earliest opportunity if subarachnoid haemorrhage is suspected. This should be done immediately if the patient presents with sudden severe headache and as soon as possible in all other cases.
• CT angiography should follow immediately if acute SAH is confirmed.
• If the CT scan is negative lumbar puncture should be undertaken providing the scan shows no contraindications. A small number of patients with a negative CT scan will prove to have had a SAH on lumbar puncture.
• Spectrophotometry should be used to permit detection of small amounts of xanthochromia.

Early management

Initial management of subarachnoid haemorrhage aims to prevent further bleeding and to reduce the rate of secondary complications such as cerebral ischaemia or hydrocephalus.

• Every patient should be started on nimodipine 60 mg four hourly. A Cochrane review confirms that calcium antagonists help to reduce spasm and cerebral ischaemia.¹⁰
• Patients should not be given an antifibrinolytic agent or steroids.
• Every patient should be referred to a specialist unit, usually neurosurgical, for investigation and if appropriate definitive treatment. This transfer should take place within 24 hours if appropriate.
• All necessary supportive care should be provided.
• If the patient has not already had a CT angiogram they should have imaging of all cerebral arteries.
• Any aneurysm associated with the haemorrhage should be treated by surgical clipping or endovascular embolisation as appropriate.¹¹
• All patients should be monitored for the development of treatable complications, especially hydrocephalus, cerebral ischaemia, electrolyte imbalance and hypotension.

Further management

• All surviving patients should be advised on secondary prevention, especially on treatment for hypertension and the need to stop smoking.
• Any patient with residual impairment after investigation and treatment should be referred to an appropriate specialist rehabilitation service.
• Patients with a strong family history (one other affected first degree relative and/or with a history of polycystic kidney disease) should be advised that their family may be at greater risk of subarachnoid haemorrhage and a referral made to a neurovascular specialist for up-to-date information and advice.

• In about 3%, cardiac arrest occurs at the onset but of those successfully resuscitated, about half can leave hospital to an independent existence.
• A delayed complication is cerebral ischaemia. The risk is reduced with oral nimodipine and probably by maintaining circulatory volume. The peak time for occurence is 5 to 14 days after the haemorrhage.
• Hydrocephalus might cause gradual obtundation in the first few hours or days. It can be treated by lumbar puncture or ventricular drainage, depending on the site of obstruction.
• Abnormalities of biochemistry are common and need appropriate management in intensive care.
• 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.

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.
In a survey of 610 patients who were interviewed a mean of 8.9 years after SAH, there was marked morbidity.¹²

• 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.

As hypertension, smoking and excessive alcohol consumption are risk factors, individuals need to address such issues.

The question of management of aneurysms falls into 3 groups.

• Patients may be found to have incidental aneurysms.
• Patients with subarachnoid haemorrhage might have one or more unruptured aneurysms.
• There is the question of screening for aneurysms in patients who survive an episode of subarachnoid haemorrhage, and in first-degree relatives of patients with subarachnoid haemorrhage.

The management of incidental findings will depend upon many aspects. The risk of rupture increases with age but so does morbidity of the procedure and younger people stand to gain more years. It is a difficult decision and family history and patient wishes must be considered.

Those who have already had a SAH are usually offered treatment although if it is small or difficult to reach it may be left alone.

The results of screening first degree relatives of patients for aneurysms are not promising and few apparently dangerous lesions are found. Even routine screening of people with adult polycystic kidney disease is not recommended.