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Subarachnoid haemorrhage

A subarachnoid haemorrhage is an uncommon form of stroke and can be a life-threatening medical emergency. Early diagnosis and treatment are essential to limit complications.

Article by Jane Gooch

First published: Last updated:
Definition

A subarachnoid haemorrhage is defined as bleeding on the surface of the brain into the subarachnoid space, between the arachnoid and pia mater. It is an uncommon form of stroke and can be a life-threatening medical emergency. A subarachnoid haemorrhage increases the risk of mortality and disability. Patient presentation varies widely, and delayed or missed diagnosis is common. Early diagnosis and treatment are essential to limit complications.

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Symptoms

People affected by a subarachnoid haemorrhage typically present with a severe, sudden onset headache. This is known as a ‘thunderclap headache’ that peaks in intensity within 1–5 minutes, and is often described by patients as the worst headache of their life. The headache can be accompanied by:

  • nausea
  • vomiting
  • photophobia
  • neck pain or stiffness
  • focal neurological deficits
  • loss of consciousness (National Institute for Health and Care Excellence (NICE), 2022)

A subarachnoid haemorrhage can occur at any time, without warning, even when sleeping. However, it is more likely to occur during episodes of physical effort, such as:

  • coughing
  • exercise
  • lifting a heavy object
  • sexual intercourse (NHS, 2021)

The person can also develop slurred speech and weakness down one side of the body, in keeping with stroke symptoms, although this may not manifest in everyone.

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Aetiology

The most common cause of a subarachnoid haemorrhage is a ruptured cerebral aneurysm, although trauma and non-traumatic rupture of vascular malformations, such as arteriovenous malformations, may also be responsible. Unfortunately, many people are unaware that they have an aneurysm until it ruptures. Non-aneurysmal subarachnoid haemorrhages occur when there is bleeding into the subarachnoid space with no identifiable cause, while traumatic subarachnoid haemorrhage occurs near the site of a skull fracture (Cooper et al, 2019).

Subarachnoid haemorrhage accounts for up to 9% of all strokes (Krishnamurthi et al, 2020). Although cerebral aneurysms can develop in anyone at any age, they are more common in people over the age of 40 years. Women tend to be more commonly affected than men (Claassen and Park, 2022).

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Risk factors

Although it is not completely understood why brain aneurysms develop in some people, certain risk factors have been identified such as:

  • hypertension
  • severe head injury
  • smoking
  • excessive alcohol consumption
  • cocaine use
  • autosomal dominant polycystic kidney disease
  • bleeding disorders
  • taking anticoagulants
  • a family history of brain aneurysms or subarachnoid haemorrhage (NICE, 2022)

Aneurysms are considered familial when two or more first-degree blood relatives have had a brain haemorrhage from an aneurysm. There is no routine screening for aneurysms in the UK, so people who are concerned about this should ask their GP to refer them to a neurosurgical specialist (NICE, 2022).

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Diagnosis

A non-contrast computed tomography scan should be performed to rule out or confirm a diagnosis. Diagnostic accuracy is highest when the scan is performed within 6 hours of symptom onset (NICE, 2022). Where an aneurysm is suspected, computed tomography angiography should be performed. NICE guidelines should be followed for diagnosis and management (NICE, 2022). A lumbar puncture should be considered in a negative computed tomography scan.

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Treatment

Following a diagnosis of subarachnoid haemorrhage, urgent discussion with a specialist neurosurgical centre should be made for transfer of care of the patient and decisions to appropriate management. The severity of a subarachnoid haemorrhage is graded on a scale based on symptoms at presentation (Hunt and Hess, 1968). Neurological observations may be required, depending on the level of the patient’s consciousness. Effective pain relief should be given to the patient, including opioid analgesia if needed.

Other medications that may be required are nimodipine and anticonvulsants. Nimodipine is a calcium-channel blocker with a neuroprotective effect, and is used to prevent cerebral vasospasm and reduce mortality and morbidity (NICE, 2022). Adult patients with a confirmed subarachnoid haemorrhage should be started on 60 mg of oral nimodipine every 4 hours and continued for 21 days (Joint Formulary Committee, 2021). Intravenous nimodipine should only be given in a specialised setting. Maintenance of normal blood

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NMC proficiencies

Nursing and Midwifery Council: standards of proficiency for registered nurses

Part 1: Procedures for assessing people’s needs for person-centred care

1. Use evidence-based, best practice approaches to take a history, observe, recognise and accurately assess people of all ages:

1.1.3 signs of cognitive distress and impairment

2.12 undertake, respond to and interpret neurological observations and assessments

Part 2: Procedures for the planning, provision and management of person-centred nursing care

3.5 take appropriate action to reduce or minimise pain or discomfort

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Resources

Brisman JL, Song JK, Newell DW. Cerebral aneurysms. N Engl J Med. 2006;355(9):928–939. https://doi.org/10.1056/NEJMra052760 

Chen S, Luo J, Reis C, Manaenko A, Zhang J. Hydrocephalus after subarachnoid hemorrhage: pathophysiology, diagnosis, and treatment. Biomed Res Int. 2017;2017:8584753. https://doi.org/10.1155/2017/8584753 

Claassen J, Park S. Spontaneous subarachnoid haemorrhage. Lancet. 2022;400(10355):846-862. https://doi.org/10.1016/S0140-6736(22)00938-2 

Cooper SW, Bethea KB, Skrobut TJ et al. Management of traumatic subarachnoid hemorrhage by the trauma service: is repeat CT scanning and routine neurosurgical consultation necessary?. Trauma Surg Acute Care Open. 2019;4(1):e000313. https://doi.org/10.1136/tsaco-2019-000313 

Göcking B, Biller-Andorno N, Brandi G, Gloeckler S, Glässel A. Aneurysmal subarachnoid hemorrhage and clinical decision-making: a qualitative pilot study exploring perspectives of those directly affected, their next of kin, and treating clinicians. Int J Environ Res Public Health. 2023;20(4):3187. https://doi.org/10.3390/ijerph20043187 

Hunt, WE, Hess, RM. Surgical risk as related to time of intervention in the repair of intracranial aneurysms. J Neurosurg. 1968;28(1):14-20. https://doi.org/10.3171/jns.1968.28.1.0014 

Joint Formulary Committee. Nimodipine. 2021. https://bnf.nice.org.uk/drugs/nimodipine/#drug-action (accessed

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