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

  1. Mild headache and slight nuchal rigidity

  2. Severe headache, stiff neck, cranial nerve palsy, no other neuro deficits

  3. Drowsy or confused, mild neurological deficit

  4. Stuporous, moderate or severe hemiparesis

  5. 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

Dipstick+Urine+jpg.jpg

Bedside

  • Bedside glucose

  • ECG - usually normal but other possible ecg findings include;

    • Sinus tachycardia

    • ST elevation, may mimic myocardial ischaemia or pericarditis

    • Raised ICP

      • Widespread deep T wave inversion

      • QT prolongation

      • Bradycardia

bloods+%2B+pod.jpg

Laboratory

  • FBC, U/E, CRP, Coag screen

    • useful in ruling out other causes

  • Lumbar puncture

    • In cases with a normal CT scan a Lumbar puncture may show

      • xanthochromia - >12 hours after onset of the headache

      • Red cell count increasing across successive bottles

      • May show alternative diagnoses such as meningitis

      • Recent evidence suggests that a lumbar puncture may not be a useful test for diagnosing subarachnoid haemorrhage and if you are highly suspicious further imaging should be peformed.

SAH.png

Radiology

  • Non contrast CT brain (3rd generation CT)

    • Remains the initial diagnostic test of choice

    • Sensitivity and specificity depend on

      • Time since onset

      • Amount of blood

      • One study quotes a sensitivity and specificity of 92% and 100% respectively in neurologically intact patients(4)

    • Patients with a positive CT should undergo angiography to detect any underlying aneurysms

    • Patients with a negative CT’s management depends on the degree of suspicion for SAH

  • MRI has a high sensitivity and specificity within 12 hours of onset of headache however it is far less readily available

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

  1. 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.

  2. 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.

  3. 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.

  4. 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).

  5. 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

Before you go have another look at the clinical case and see have your answers to any of the questions changed and if so how?