Neuroimaging Cases 006

Subarachnoid haemorrhage

Latest instalment in our neuroimaging series. Images, text and cases collated by Teresa Crow MD (Emergency Medicine) and L. Erin Miller MD (Neurosurgery). First published on EMGuideWire.com and peer reviewed by Professor Michael Gibbs.

Key takeaways

Aetiology

• Trauma is the most common cause of SAH
• Aneurysmal rupture is the most common cause of spontaneous SAH
• Perimesencephalic non-aneurysmal SAH represents a unique anatomic subtype that is associated with a good prognosis

Diagnosis

• The Ottawa SAH Rule is highly sensitive for SAH, but has limited sensitivity
• A normal noncontrast CT in patients who present within 6 hours of symptom onset rules out SAH
• Patients who present after 6 hours of symptom onset should have either an LP or a CT-A if SAH is suspected

Evaluation

• Calculate the Hunt Hess Score
• Communicating this as part of your neurological exam adds precision and helps inform prognosis
• The Modified Fisher Score, based on the initial head CT helps predict the incidence of delayed cerebral ischaemia (DCI)
• Recognize CT signs of 3 ostructive hydrocephalus. When this is present there should be an increased urgency to consult Neurosurgery

Management

External ventricular drain indicated for:

• Obstructive hydrocephalus
• Patients undergoing aneurysm clipping

Blood pressure control:

• While AHA/ASA Guidelines do not specify a specific BP target, our institutional preference is to target a BPS <150 mmHg
• This can be achieved with a rapidly-acting IV antihypertensive, such as nicardipine or clevidipine

Seizure treatment & prophylaxis:

• The AHA/ASA recommends seizure prophylaxis in SAH patient with high-risk features (see: Slide 42)
• Our institutional preference is to load all SAH patient with levetiracetam

Definitive treatment of unsecured aneurysms:

• Endovascular embolization is generally preferred
• For MCA aneurysms there is evidence that clipping is associated with superior outcomes
• Treatment decisions are also influenced by surgeon preference and expertise

Prevention of cerebral vasospasm and delayed cerebral ischemia (DCI):

• Patients with aSAH should be given oral nimodipine promptly to reduce the incidence of vasospasm and DCI

References

• 2023 Guideline for the Management of Patients With Aneurysmal Subarachnoid Hemorrhage: A Guideline From the American Heart Association/American Stroke Association. Stroke. 2023 Jul;54(7):e314-e370.
• Hunt WE, Hess RM. Surgical risk as related to time of intervention in the repair of intracranial aneurysms. J Neurosurg. 1968 Jan;28(1):14-20. 
• Frontera JA, Claassen J, Schmidt JM, Wartenberg KE, Temes R, Connolly ES Jr, MacDonald RL, Mayer SA. Prediction of symptomatic vasospasm after subarachnoid hemorrhage: the modified fisher scale. Neurosurgery. 2006 Jul;59(1):21-7; discussion 21-7.
• American College of Emergency Physicians Clinical Policies Subcommittee (Writing Committee) on Acute Headache:; Godwin SA, Cherkas DS, Panagos PD, Shih RD, Byyny R, Wolf SJ. Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting to the Emergency Department With Acute Headache. Ann Emerg Med. 2019 Oct;74(4):e41-e74.
• Mark DG, Horton BH, Reed ME; Kaiser Permanente CREST Network Investigators. Shifts in Diagnostic Testing for Headache in the Emergency Department, 2015 to 2021. JAMA Netw Open. 2024 Apr 1;7(4):e247373.
• Perry JJ, Stiell IG, Sivilotti ML, Bullard MJ, Hohl CM, Sutherland J, Émond M, Worster A, Lee JS, Mackey D, Pauls M, Lesiuk H, Symington C, Wells GA. Clinical decision rules to rule out subarachnoid hemorrhage for acute headache. JAMA. 2013 Sep 25;310(12):1248-55.
• Perry JJ, Sivilotti MLA, Émond M, Hohl CM, Khan M, Lesiuk H, Abdulaziz K, Wells GA, Stiell IG. Prospective Implementation of the Ottawa Subarachnoid Hemorrhage Rule and 6-Hour Computed Tomography Rule. Stroke. 2020 Feb;51(2):424-430. 
• Buscot MJ, Chandra RV, Maingard J, Nichols L, Blizzard L, Stirling C, Smith K, Lai L, Asadi H, Froelich J, Reeves MJ, Thani N, Thrift A, Gall S. Association of Onset-to-Treatment Time With Discharge Destination, Mortality, and Complications Among Patients With Aneurysmal Subarachnoid Hemorrhage. JAMA Netw Open. 2022 Jan 4;5(1):e2144039. doi: 10.1001/jamanetworkopen.2021.44039. Erratum in: JAMA Netw Open. 2022 Feb 1;5(2):e222124. 
• Lindgren A, Vergouwen MD, van der Schaaf I, Algra A, Wermer M, Clarke MJ, Rinkel GJ. Endovascular coiling versus neurosurgical clipping for people with aneurysmal subarachnoid haemorrhage. Cochrane Database Syst Rev. 2018 Aug 15;8(8):CD003085.
• Smith TR, Cote DJ, Dasenbrock HH, Hamade YJ, Zammar SG, El Tecle NE, Batjer HH, Bendok BR. Comparison of the Efficacy and Safety of Endovascular Coiling Versus Microsurgical Clipping for Unruptured Middle Cerebral Artery Aneurysms: A Systematic Review and Meta-Analysis. World Neurosurg. 2015 Oct;84(4):942-53.
• Berro DH, L’Allinec V, Pasco-Papon A, Emery E, Berro M, Barbier C, Fournier HD, Gaberel T. Clip-first policy versus coil-first policy for the exclusion of middle cerebral artery aneurysms. J Neurosurg. 2019 Sep 20;133(4):1124-1131.
• Sturiale CL et al Clipping versus coiling for treatment of middle cerebral artery aneurysms: a retrospective Italian multicenter experience. Neurosurg Rev. 2022 Oct;45(5):3179-3191.
• Metayer T et al. Clipping Versus Coiling for Ruptured MCA Aneurysms Associated with Intracerebral Hematoma Requiring Surgical Evacuation. Neurocrit Care. 2023 Aug;39(1):162-171.
• Woodruff MM, Edlow JA. Evaluation of third nerve palsy in the emergency department. J Emerg Med. 2008 Oct;35(3):239-46.
• Fang C, Leavitt JA, Hodge DO, Holmes JM, Mohney BG, Chen JJ. Incidence and Etiologies of Acquired Third Nerve Palsy Using a Population-Based Method. JAMA Ophthalmol. 2017 Jan 1;135(1):23-28.
• Emerling A, Goldenberg WD, Taysom D, Buckalew E. Headache and Cranial Nerve III Palsy. J Emerg Med. 2020 Jan;58(1):e31-e32.
• Vaphiades MS, Roberson GH. Imaging of Oculomotor (Third) Cranial Nerve Palsy. Neurol Clin. 2017 Feb;35(1):101-113.
• Hou K, Yu J. Current status of perimesencephalic non-aneurysmal subarachnoid hemorrhage. Front Neurol. 2022 Sep 1;13:960702. 
• Griswold DP, Fernandez L, Rubiano AM. Traumatic Subarachnoid Hemorrhage: A Scoping Review. J Neurotrauma. 2022 Jan;39(1-2):35-48. 
• Lawton MT, Vates GE. Subarachnoid Hemorrhage. N Engl J Med. 2017 Jul 20;377(3):257-266.

This neuroimaging interpretation series is proudly sponsored by the Emergency Medicine Residency Program at Carolinas Medical Center. The goal is to promote widespread mastery of CXR interpretation. There is no personal health information [PHI] within, and ages have been changed to protect patient confidentiality.