Subarachnoid Haemorrhage
Introduction
Subarachnoid haemorrhage (SAH) is the presence of blood in the subarachnoid space. The majority (about 75%) of non-traumatic subarachnoid haemorrhage, which is the subject of this blog, are caused by the rupture of intra-cranial aneurysms. However other intracranial vascular abnormalities can also result in subarachnoid haemorrhage and in about one 5th of cases no cause is identified(1).
While subarachnoid haemorrhage is not the most common cause of headache in patients presenting to the emergency department, the consequences of missing the diagnosis may be fatal for the patient and early recognition and intervention can significantly improve morbidity and mortality. 10 - 15% of patients who experience subarachnoid haemorrhage will die before they reach hospital and another 50% will die within 30 days (2). For the remaining patients the chances of recovery are good if they are transferred early to a specialist neurosurgical unit. Therefore it is important to always have a high index of suspicion for the diagnosis.
Clinical Features
Symptoms
Headache
Often described as thunderclap
Any headache which reaches maximal intensity within 1 hour should prompt a work up for subarachnoid haemorrhage(3)
Worst ever headache in a patient with previous headache history
Not everyone with SAH has their worst headache ever. In patients with a previous headache disorder any headache that is significantly different in quality to their normal headache should prompt consideration for alternative diagnoses including the possibility of SAH
Classically described as occipital but any severe headache should be considered as possibly an SAH
Other symptoms
Neck stiffness / pain
Photophobia
Syncope immediately preceding headache onset, at headache onset or immediately after headache onset
Nausea / vomiting
Some patients may describe an event that causes a rise in intracranial pressure immediately preceding headache onset such as;
Sexual intercourse
Exercise
Defecation
Signs
Patients may present with a variety of clinical signs or with no signs at all.
Signs patients may present with include;
Nuchal rigidity
Inability to flex the head forward - rigid neck muscles
Photophobia
Hypertension
Seizures
Altered consciousness
Focal neurologic deficits
Grading
There are a number of different grading systems used. One of the most widely used ones is the Hunt and Hess grading system which grades subarachnoid haemorrhage on a scale from 1 to 5
Mild headache and slight nuchal rigidity
Severe headache, stiff neck, cranial nerve palsy, no other neuro deficits
Drowsy or confused, mild neurological deficit
Stuporous, moderate or severe hemiparesis
Coma, decerebrate posturing
Risk Factors
Modifiable risk factors
Smoking
High blood pressure
Sympatheticomimetic drugs
Moderate to heavy alcohol consumption
Non-modifiable risk factors
Family history
Female gender
Inherited genetic disorders
Autosomal dominant polycystic kidney disease
Ehlers-Danlos syndrome
Marfan’s Syndrome
Neurofibromatosis type I
Differential Diagnosis
‘Herald bleed’
Aneurysms sometimes have small leaks in the weeks to months preceding aneurysmal rupture
Intra-cranial infections
Coital headache
First presentation of acute migraine
Space occupying lesion
Venous sinus thrombosis
Vertebral artery dissection
Clinical Investigations
Management and Disposition
Initial Resuscitation
Maintain O2 sats >94%
2 wide bore iv cannula
If GCS <8 / not maintaining own airway
Rapid sequence intubation prior to CT
Disposition
If diagnosis unclear patients should be referred to the on call medical team for further investigation
Once diagnosis confirmed
Refer to neurosurgical team on call
If altered consciousness ICU should be involved in the patients care
Symptomatic Treatment
Analgesia
oral if tolerated
iv if vomiting, paracetamol +/- opioid
Iv anti-emetic if vomiting
may or may not be effective
Specific Treatment
Control blood pressure while avoiding hypotension
The exact target is debated however systolic BP <160mmHg is accepted as a reasonable target(5)
Iv labetolol or iv GTN
Treat seizures
Initially with lorazepam 4mg iv
Load with anti-epileptic ie phenytoin or keppra
Reverse anti-coagulation
Warfarin - prothrombin complex concentrate
Vitamin K
NOAC’s - advice from haematology on reversal for specific agents
Refer to neurosurgeons for definitive treatment including coiling of causative aneurysms
References
Hackman JL, Johnson MD, John Ma O. Spontaneous Subarachnoid and intracerebral Haemorrhage. In Tintinalli JE, Stephan Stapczynski J, John Ma O, Cline DM, Cydulka RK, Meckler GD. Tintinalli's Emergency Medicine A Comprehensive Study Guide. New York: McGraw-Hill Education; 2010.
Health Service Executive. Bleeding in The Brain. [Online].; 2011 [cited 2020 Oct 25. Available from: https://www.hse.ie/eng/health/az/b/bleeding-in-the-brain/complications-of-subarachnoid-haemorrhage.html#:~:text=Every%20year%20around%20500%20people,to%20be%20affected%20than%20men.
Singer RJ, Ogilvy CS, Rofdorf G. UpToDate. [Online].; 2020 [cited 2020 Oct. Available from: https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-clinical-manifestations-and-diagnosis?search=sub%20arachnoid%20hemorrhage&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1.
Perry JJ, Stiell IG, Sivilotti MLA, Bullard MJ, Emond M, Symington C. Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study. BMJ. 2011 May; 343(4227).
Hemphill JC, Greenberg SM, Anderson CS, Becker K, Bendock BR, Cushman M, et al. Guidelines for the Management of Spontaneous Intracerebral Hemorrhage. Stroke. 2015 Jul; 46(7).
This blog was written by Dr. Emer Kidney and was last updated in November 2020