Neuroimaging Mastery Project: Presentation #6 Subarachnoid Hemorrhage

Dr. Teresa Crow is an Emergency Medicine Residents at Carolinas Medical Center and is interested in medical education. Dr. Erin Miller, MD is a Neurosurgical resident at Carolinas Medical Center. Along with the guidance of Dr. Michael Gibbs (Chair of Emergency Medicine), Dr. Jonathan Clemente (Chief of the Department of Radiology and Neuroradiology specialist), Dr. Christa Swisher (Neurocritcal Care Intensivist), and Dr. Scott Wait (Chief of Pediatric Neurosurgery) they aim to help educate us on Neuroimaging. In this presentation they will address Subarachnoid Hemorrhage. Follow along with the EMGuideWire.com team as they post the CMC Neuroimaging Case Studies.

- Subarachnoid Hemorrhage

1. Subarachnoid Hemorrhage L. Erin Miller, MD 1 and Teresa Crow, MD 2 Carolinas Medical Center & Levine Children’s Hospital Carolina Neurosurgery & Spine Associates 1 Department of Emergency Medicine 2 Michael Gibbs, MD, Imaging Mastery Project Lead Editor Neuroimaging Mastery Project Presentation #6

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

3. Meet Our Neuroimaging Editorial Team Andrew Asimos, MD, FACEP Medical Director, Atrium Health Stroke Network Neurosciences Institute Clinical Professor, Department of Emergency Medicine Jonathan Clemente, MD, FACR Chief, Department of Radiology, Carolinas Medical Center Charlotte Radiology, Neuroradiology Section Adjunct Clinical Associate Professor, Department of Radiology Andrew Perron, MD, FACEP Associate Dean of Graduate Medical Education and DIO Professor of Emergency Medicine Department of Graduate Medical Education Dartmouth Hitchcock Medical Center

4. Meet Our Neuroimaging Editorial Team Christa Swisher, MD, FNCS, FACNS Neurocritical Care/Pulmonary Critical Care Consultants Department of Medicine, Atrium Health Clinical Assistant Professor, Department of Neurology Scott Wait, MD, FAANS Chief, Pediatric Neurosurgery, Levine Children’s Hospital Carolina Neurosurgery & Spine Associates Adjunct Clinical Associate Professor, Department of Neurosurgery

5. Meet Our Medical Illustrator Anne Olson Anne Olson has shared her expert Medical Illustrator skills with the CMC Department of Emergency Medicine for the past 30 years. As co-founder of Blazon Productions, LLC, Anne’s ongoing efforts to support the Imaging Mastery Project and a growing number of presentations dedicated to Neuroimaging elevate the quality and impact of this work. We are very grateful for her talents!

6. Visit Our Website www.EMGuidewire.com For A Complete Archive Of Imaging Presentations And Much More!

7. Stroke 2023;53:e314-e370. Excerpts From The 2023 AHA/ASA Subarachnoid Hemorrhage Guidelines Are Embedded Throughout This Presentation:

8. Also See The Appendix At The End Of This Presentation For A Collection Of Articles On These Six Topics: A 1 The Ottawa Subarachnoid Hemorrhage Rule A 2 Subarachnoid Hemorrhage Clinical Grading Scores A 3 Time To Aneurysm Treatment And Outcomes A 4 Aneurysm Clipping Versus Coiling A 5 Management of Middle Cerebral Artery Aneurysm A 6 Evaluation Of Third Cranial Nerve Palsy In The ED

9. Subarachnoid Hemorrhage (SAH)

10. SAH Basics Subarachnoid Hemorrhage (SAH) is located between the pia and arachnoid layers of the meninges

11. SAH Etiology The most common cause of SAH is trauma, and it is reported in up to 60% of patients with moderate to severe traumatic brain injury (TBI). The most common cause of spontaneous SAH is rupture of a cerebral aneurysm. Other causes of SAH include deep venous hemorrhage, arteriovenous malformations, vasculitis, cerebral artery dissection, and rarely hemorrhage from a malignancy.

12. SAH Etiology Aneurysmal vs. non-aneurysmal SAH can be differentiated by both the history and imaging. Traumatic Clinical history of injury SAH characteristically along the cerebral convexity (not cisterns) Other injuries seen, e.g.: skull fractures

13. SAH Etiology Aneurysmal vs. non-aneurysmal SAH can be differentiated by both the history and imaging. Aneurysmal Sudden onset of symptoms in the absence of trauma SAH characteristically located within the basal cisterns

14. SAH Etiology Perimesencephalic non-aneurysmal SAH represents is a unique subtype. Perimesencephalic Hemorrhage localized in the perimesencephalic cisterns ( ➤ ) No detectable aneurysm on CT-A Due to deep venous hemorrhage Associated with a favorable prognosis ➤

15. Aneurysmal SAH Incidence: Estimated 9.7-14.5 per 100,000 population in the United States More common in women Incidence increases with age Acute Complications: Hydrocephalus Seizures Rebleeding Cerebral ischemia Risk Factors: Tobacco use Cocaine use Hypertension Family history of aneurysm or genetic syndromes

16. Essential Anatomy

17. Aneurysms By Anatomic Location

18. Our CMC Cases Will Focus on Four Aneurysm Types

19. Hunt Hess Score The Hunt Hess Classification, that was developed in 1968, is used to grade aneurysmal SAH based on clinical presentation. Assessing the Hunt Hess Grade on ED presentation helps inform decision-making and assists with prognostication. Journal of Neurosurgery 1968;28(1):14-20.

20. Critical Care 2015;19:309. Subarachnoid Hemorrhage: Who Dies, And Why? Retrospective study of 1200 consecutive SAH patients prospectively enrolled in the Columbia University SAH Outcomes Project between 1996 and 2009. The Hunt Hess Score and mortality were correlated.

21. Modified Fisher Score The Modified Fisher Score, that is based on initial CT findings, can be used to predict the incidence of delayed cerebral ischemia (DCI) after aSAH . Neurosurgery 2006;58(7):21-27. Score CT Finding Risk Of DCI (%) No SAH or IVH 1 Minimal/thin SAH, no IVH 6 2 Minimal/thin SAH with IVH in both ventricles 15 3 Dense SAH, no IVH 35 4 Dense SAH with IVH in both ventricles 34

22. Neurosurgery 2006;58(7):21-27. Grade 1 (minimal or diffuse thin SAH without IVH); indicating low risk for symptomatic vasospasm, Grade 2 (minimal or thin SAH with IVH) and Grade 3 (thick cisternal clot without IVH), indicating intermediate risk for symptomatic vasospasm; and Grade 4 (cisternal clot with IVH), indicating high risk for symptomatic vasospasm.

23. How Can Subarachnoid Hemorrhage Be Accurately Diagnosed?

24. Stroke 2023;53:e314-e370. AHA/ASA Guidelines Evaluation For Subarachnoid Hemorrhage In patients with acute onset of severe headache without a new neurological deficit, application of the Ottawa SAH Rule may be reasonable to identify those at high risk for aneurysmal subarachnoid hemorrhage ( aSAH ). In patients who present >6 hours from symptom onset a noncontrast head CT and if negative for aSAH , lumbar puncture should be performed to diagnose/exclude aSAH . In patients who present <6 hours from symptom onset and are without neurological deficit, a noncontrast CT interpreted by a board-certified neuroradiologist is reasonable to diagnose/exclude aSAH . In patients with spontaneous SAH with a high level of concern for an aneurysmal source and a negative CT-A digital subtraction angiography is indicated to diagnose/exclude a cerebral aneurysm.

25. Stroke 2023;53:e314-e370. AHA/ASA Guidelines Evaluation For Subarachnoid Hemorrhage

26. AHA/ASA Guidelines

27. Annals Of Emergency Medicine 2019;74:e41–e74. 1 In the adult emergency department patient presenting with acute headache, are there risk-stratification strategies that reliably identify the need for emergent neuroimaging? 2 In the adult emergency department patient presenting with acute headache, does a normal noncontrast head computed tomography scan performed within 6 hours of headache onset preclude the need for further diagnostic workup for subarachnoid hemorrhage? 3 In the adult emergency department patient who is still considered to be at risk for subarachnoid hemorrhage after a negative noncontrast head computed tomography, is computed tomography angiography of the head as effective as lumbar puncture to safely rule out subarachnoid hemorrhage?

28. Annals Of Emergency Medicine 2019;74:e41–e74. 1 In the adult emergency department patient presenting with acute headache, are there risk-stratification strategies that reliably identify the need for emergent neuroimaging? Level A None specified Level B Use the Ottawa Subarachnoid Hemorrhage Rule as a decision rule that has high sensitivity to rule out SAH, but low specificity to rule in SAH, for patients presenting to the ED with a normal neurologic examination and peak headache severity within 1 hour of onset of pain symptoms. Although the presence of neck pain and stiffness on physical examination in ED patients with an acute headache is strongly associated with SAH, do not use a single physical sign and/or symptom to rule out SAH. Level C None specified

29. Annals Of Emergency Medicine 2019;74:e41–e74.

30. Annals Of Emergency Medicine 2019;74:e41–e74. 2 In the adult emergency department patient presenting with acute headache, does a normal noncontrast head CT performed within 6 hours of headache onset preclude the need for further diagnostic workup for subarachnoid hemorrhage? Level A None specified Level B Use a normal noncontrast head CT performed within 6 hours of symptom onset in an ED headache patient with a normal neurologic examination, to rule out nontraumatic SAH. Level C Non specified 3 In the adult emergency department patient who is still considered to be at risk for subarachnoid hemorrhage after a negative noncontrast head CT, is computed tomography angiography of the head as effective as lumbar puncture to safely rule out subarachnoid hemorrhage? Level A None specified Level B None specified Level C Perform LP or CTA to safely rule out SAH in the adult ED patient who is still considered to be at risk for SAH after a negative noncontrast head CT result.

31. Objective : To determine whether CT-A use has increased in lieu of lumbar puncture among ED patients with headache, with an increase in unruptured intracranial aneurysm detection. Methods : Retrospective analysis of 198,109 adult ED patients seen in 21 community EDs between 2015 and 2021. Results : CT cerebral angiography use increased (18.8%; 95% CI, 17.7% to 20.3%) and lumbar punctures decreased (−11.1%; 95% CI, −12.0% to −10.4%), Overall, CT-A use increased 6-fold relative to lumbar puncture, with a 33% increase in the detection of unruptured aneurysm. Subarachnoid hemorrhage (1004 cases) and bacterial meningitis (118 cases) were misdiagnosed in 5% and 18% of cases, respectively. JAMA Network Open 2024;7(4):e247373.

32. Aneurysmal SAH Cases From Carolinas Medical Center

33. Anterior Communicating Artery Aneurysm (30% Of Aneurysms)

34. Case #1 A 43-year-old female with a history of hypertension presents with sudden-onset of a severe headache accompanied by several episodes of non-bilious, non-bloody emesis . The Initial ED Examination : Vital Signs: 269/128, 84, 16, 100% She endorses severe headache Pupils are equal and reactive, there are no cranial nerve deficits No motor or sensory deficits

35. A STAT CT scan reveals diffuse subarachnoid hemorrhage with effacement of the basal cisterns ( ➤ ). Case #1 ➤ ➤ Fisher Scale 1 (6% Risk Of DCI)

36. Case #1 The Initial ED Examination : She endorses severe headache Pupils equal and reactive No cranial nerve deficits No motor or sensory deficits Hunt Hess 2 (3.2% Mortality)

37. Case #1 The CT findings of dilated temporal horns of lateral ventricles ( ➔ ) and blood in the 4 th ventricle ( ⇒ ) reflect obstructive hydrocephalus. An external ventricular drain (EVD) was placed. ⇒

38. Stroke 2023;53:e314-e370. AHA/ASA Guidelines Management Of Hydrocephalus In patients with aSAH and acute symptomatic hydrocephalus, urgent CSF drainage (using an external ventricular drain [EVD] or lumbar drain) should be provided to improve outcomes. In patients with aSAH who require EVD, implementation and adherence to EVD bundled protocols that address insertion, management, and monitoring are recommended to reduce complications and infection rates.

39. External Ventricular Drains (EVDs) are indicated in the setting of obstructive hydrocephalus secondary to ruptured intracranial aneurysms. EVDs are placed by the Neurosurgery team and these can be used to drain CSF, administer medications, and monitor intracranial pressure (ICP). AHA/ASA Guidelines

40. What Therapies Should Be Initiated During The Initial Management Of The Patient With Aneurysmal Subarachnoid Hemorrhage?

41. In patients with aSAH and an unsecured aneurysm frequent blood pressure (BP) monitoring and control with short-acting medication(s) to avoid severe hypertension, hypotension, or blood pressure variability is indicated. Background BP variability has been associated with worse outcomes, and excessive BP reduction may compromise cerebral perfusion and induce ischemia. Two previous guidelines have suggested keeping the systolic BP <160 mm Hg or <180 mm Hg. While these parameters may be reasonable to consider in practice, available evidence is insufficient to recommend any specific BP target. Other factors to appraise include brain swelling, hydrocephalus, and history of hypertension and renal impairment. Stroke 2023;53:e314-e370. AHA/ASA Guidelines Measures To Prevent Rebleeding

42. In patients with ruptured aneurysms receiving anticoagulants, rapid reversal should be performed to prevent rebleeding. Background The benefit of emergency reversal of anticoagulation has not been tested in patients presenting with aSAH . Yet, the value of immediate anticoagulation reversal has been demonstrated in other forms of intracranial hemorrhage. Consequently, immediate anticoagulation reversal in any patient presenting with aSAH is strongly recommended, using published reversal strategies. Stroke 2023;53:e314-e370. AHA/ASA Guidelines Measures To Prevent Rebleeding

43. Routine use of antifibrinolytics is not useful to improve functional outcomes. Background The largest, high-quality randomized controlled trial evaluating antifibrinolytic therapy in patients with aSAH , ULTRA (Ultra-Early Tranexamic Acid After Subarachnoid Hemorrhage), did not show a significant reduction in the rate of rebleeding nor improvement in functional outcomes among patients treated with tranexamic acid compared with standard care. Consequently, current evidence indicates that antifibrinolytic therapy is not indicated for the routine management of patients with aSAH . Stroke 2023;53:e314-e370. AHA/ASA Guidelines Measures To Prevent Rebleeding

44. Stroke 2023;53:e314-e370. AHA/ASA Guidelines Measures To Prevent And Treat Seizures In patients aSAH with either a fluctuating neurological examination, depressed mental status, ruptured MCA aneurysm, high-grade aneurysm, ICH, hydrocephalus, or cortical infarction continuous EEG monitoring is recommended. In patient with the high-risk features above prophylactic antiseizure medications are recommended. In patients without the high-risk findings above prophylactic treatment with antiseizure medications is not recommended. In patients with aSAH who present with seizures, treatment with antiseizure medications for ≤7 days is reasonable to reduce seizure-related complications in perioperative period. In patients being treated with seizure medications there is evidence that treatment with phenytoin is associated with increased mortality and this agent is not recommended.

45. Case #1 R CT-A reveals a right 3.8 x 3.5 x 3.3 mm aneurysm of the anterior communicating artery ( → ) .

46. ACom aneurysm on reconstructed views of the cerebral vessels ( → ) . R Case #1

47. Before Coiling After Coiling ➛ ➛ Case #1 The patient underwent cerebral angiography with endovascular coiling ( → ).

48. EVD Case #1 Successfully coiled ACom aneurysm.

49. Case #1 Summary : 43-year-old female who presented as a Hunt Hess Grade 2 subarachnoid hemorrhage from a ruptured ACom aneurysm with associated obstructive hydrocephalus. She underwent placement of an EVD and then endovascular coil embolization of the aneurysm. The EVD was removed 1 0 days later. She progressed well and was discharged home with no neurologic deficits two weeks after her initial presentation.

50. Aneurysmal SAH: Definitive Management Endovascular Coiling Open Vascular Clipping Management by either method within 24 hours of presentation is desirable to reduce the risk of rebleeding. vs.

51. New England Journal of Medicine 2017;377(3):257-265.

52. Stroke 2023;53:e314-e370. AHA/ASA Guidelines Surgical And Endovascular Management Timing Surgical or endovascular treatment of the ruptured aneurysm should be performed as early as feasible after presentation, preferably within 24 hours of onset, to improve outcome. Treatment Goal Complete obliteration of the ruptured aneurysm is indicated whenever feasible to reduce the risk of rebleeding and retreatment. For patients in whom complete obliteration of the ruptured aneurysm by either clipping or primary coiling treatment is not feasible in the acute phase, partial obliteration to secure the rupture site and retreatment in a delayed fashion in those with functional recovery are reasonable to prevent rebleeding.

53. Stroke 2023;53:e314-e370. AHA/ASA Guidelines Surgical And Endovascular Management Modality Of Treatment For patients with ruptured aneurysms of the posterior circulation that are amenable to coiling, coiling is indicated in preference to clipping to improve outcome. For patients <40 years of age, clipping of the ruptured aneurysm might be considered the preferred mode of treatment to improve durability of the treatment and outcome. For patients >70 years of age the superiority of coiling or clipping to improve outcome is not well established. For patients with aSAH from ruptured aneurysms of the anterior circulation equally suitable for both primary coiling and clipping, primary coiling is recommended in preference to clipping to improve 1-year functional outcome.

54. Stroke 2023;53:e314-e370. AHA/ASA Guidelines Surgical And Endovascular Management Endovascular Adjuncts For patients with aSAH from ruptured wide-neck aneurysms not amenable to surgical clipping or primary coiling, endovascular treatment with stent-assisted coiling or flow diverters is reasonable to reduce the risk of rebleed. For patients with aSAH from ruptured fusiform/blister aneurysms, the use of flow diverters is reasonable to reduce mortality. For patients with aSAH from ruptured saccular aneurysms amenable to either primary coiling or clipping, stents or flow diverters should not be used to avoid higher risk of complications.

55. Middle Cerebral Artery Aneurysm (20% Of Aneurysms)

56. Case #2 57-year-old fe male with a history of hypertension experienced severe headache while driving leading to low-speed MVC with no sustained traumatic injuries. The Initial ED Examination : Vital Signs: 175/97, 62, 16, 100% She is drowsy but arouses to voice Pupils equal and reactive, no cranial nerve deficits No motor or sensory deficits

57. A STAT CT scan reveals diffuse subarachnoid hemorrhage that is dense in the left sylvian cistern. There is developing hydrocephalus ( ➤ ), without effaced basal cisterns Case #2 ➤ ➤ Fisher Scale 3 (35% Risk Of DCI)

58. Case #2 The Initial ED Examination : She is drowsy but awakens to voice Pupils equal and reactive No cranial nerve deficits No motor or sensory deficits Hunt Hess 3 (9.4% Mortality)

59. Case #2 CT-A reveals a ruptured 10 x 10 x 20 mm left middle cerebral artery (MCA) bifurcation aneurysm R R

60. The patient underwent EVD placement followed by a left craniotomy for clipping ( ➔ ) of a complex MCA aneurysm. Case #2 R

61. Case #2 Summary : 57-year-old female who presented as Hunt Hess 3 SAH from a ruptured MCA bifurcation aneurysm. She underwent placement of EVD and surgical clipping of the aneurysm. The patient’s hospital course was complicated by pneumonia and meningitis , but she ultimately was discharged home with no residual neurological deficit.

62. Case #3 68-year-old male who presents with sudden-onset headache and neck pain that started approximately 7 hours ago. The Initial ED Examination : Vital Signs: 185/116, 93, 19, 100% He is alert and oriented No cranial nerve deficits No motor or sensory deficits

63. Case #3 A STAT CT Scan reveals diffuse subarachnoid hemorrhage. The basal cisterns are effaced ( ➤ ) with developing hydrocephalus ➤ ➤ Fisher Scale 3 (35% Risk Of DCI)

64. Case #3 The Initial ED Examination : He is alert and endorses headache No cranial nerve deficits No motor or sensory deficits Hunt Hess 2 (3.2% Mortality)

65. Case #3 CT-A reveals a ruptured, partially thrombosed left MCA aneurysm ( ➜ ) and a smaller unruptured right MCA aneurysm ( ➤ ) R ➤ ➤ R

66. The patient underwent left c raniotomy for clipping ( ➔ ) of a complex MCA aneurysm

67. Case #3 Summary: 60-year-old male who presented as Hunt Hess 2 SAH from a ruptured MCA aneurysm. The patient underwent placement of EVD and surgical clipping of the aneurysm. The EVD was removed 1 0 days later. He was discharged home without residual neurologic deficits.

68. Clipping Versus Coiling Of Ruptured & Unruptured Middle Cerebral Artery Aneurysms (MCAA) #1 Comparison of the Efficacy and Safety of Endovascular Coiling Versus Clipping for Unruptured Middle Cerebral Artery Aneurysms: A Systematic Review and Meta-Analysis 2015 Word Neurosurgery #2 Clip-First Policy Versus Coil-First Policy for the Exclusion of Middle Cerebral Artery Aneurysms 2019 Journal of Neurosurgery #3 Clipping Versus Coiling for Treatment of Middle Cerebral Artery Aneurysms: A Retrospective Italian Multicenter Study 2022 Neurosurgery Review #4 Clipping Versus Coiling for Ruptured MCA Aneurysms Associated with Intracerebral Hematoma Requiring Surgical Evacuation 2023 Neurocritical Care

69. Clipping Versus Coiling Of Ruptured & Unruptured MCAA What Did These Four Studies Conclude? #1 Based on this systematic review and meta-analysis of unruptured MCAAs, after careful consideration of patient, aneurysmal, and treatment centered factors, we recommend surgical clipping for unruptured MCAA. #2 Clipping and coiling for MCAA treatment provide the same clinical outcome for ruptured and unruptured aneurysms. However, clipping provides higher short- and long-term rates of complete exclusion, which in turn decreases the risk of aneurysm retreatment. Whether this lower occlusion rate can have a clinical impact in the long- term must be further evaluated. #3 Clipping still seems superior to coiling in providing better short- and long-term occlusion rates in MCAA, and at the same time, it appears as safe as coiling in terms of clinical outcome. #4 In the specific subgroup of ruptured MCAA with intracerebral hematoma that requires surgical evacuation, clipping with concomitant hematoma evacuation could provide better functional outcomes than endovascular treatment followed by surgical evacuation.

70. Posterior Communicating Artery Aneurysm (25% Of Aneurysms)

71. Case #4 88-year-old female with history of atrial fibrillation on anticoagulation presents with sudden-onset headache accompanied with confusion. The Initial ED Examination : Vital Signs: 140/62, 73, 16, 100% Awake, mildly confused Pupils equal and reactive No cranial nerve deficits Globally weak, but no focal motor or sensory deficits

72. Case #4 A STAT CT scan Reveals Diffuse subarachnoid hemorrhage with effaced basal cisterns ( ➤ ). ➤ ➤ ➤ ➤ ➤ ➤ Fisher Scale 3 (35% Risk Of DCI)

73. Case #4 A STAT CT scan Reveals Diffuse subarachnoid hemorrhage with effaced basal cisterns ( ➤ ). ➤ ➤ What are the radiographic signs of obstructive hydrocephalus ? ➤ ➤ ➤ ➤ Fisher Scale 3 (35% Risk Of DCI)

74. Dilated lateral ventricles ➜ R ounding of the third ventricle * Blood in the fourth ventricle ➤ Case #4 ➤ Signs of acute obstructive hydrocephalus *

75. CTA reveals a ruptured bi-lobed left 17 x 9 x 10 mm posterior communicating ( PCom ) artery aneurysm ( ➔ ) Case #4

76. Case #4 Cerebral angiography with endovascular coiling ( ➔ ). Aneurysm Before Coiling Aneurysm After Coiling

77. Case #4 Summary : 88-year-old female who presented as Hunt Hess 2 SAH with obstructive hydrocephalus from a ruptured PCom aneurysm resulting in obstructive hydrocephalus . The patient underwent placement of EVD and endovascular coiling . Her hospital course was complicated by pneumonia, but she ultimately transitioned to in-patient rehab prior to discharging home

78. Case #5 75-year-old female presents with several days of right eye pain, eyelid drooping, and blurry vision. The Initial ED Examination : Vital Signs:  158/81, 85, 12, 99% Alert and oriented Disconjugate gaze No focal sensory or motor deficits These findings prompted a comprehensive eye and neurologic exam

79. Eye Exam: Right eye ptosis , no proptosis, no erythema Pupils: R 6 mm, L 3 mm Extraocular muscles: L eye intact , R eye unable to fully adduct Visual acuity 20/20, normal intraocular pressures Neurological Exam: CN V Facial sensation is intact V1, V2, V3 distributions CN VII No facial weakness raising eyebrows, closing eyes, smiling CN VIII Hearing grossly intact bilaterally to finger rub CN IX, X Palate moves symmetrically CN XI Shoulder shrug is strong and symmetric CN XII Tongue midline, no deviation No focal motor or sensory deficits

80. Which Cranial Nerve is Affected? Ptosis Mydriasis Right eye “down and out”

81. Which Cranial Nerve is Affected? A clinical diagnosis of right oculomotor nerve (CN III) palsy is made and a CT-A of the brain is ordered to assess for a compressive lesion. Ptosis Mydriasis Right eye “down and out”

82. Differential of Oculomotor Nerve (CN III) Palsy Pupil Involvement Compressive lesion (aneurysm) Pupil Sparing Microvascular diabetic ischemia Hypertension microangiopathy

83. The Occulomotor Nerve (CN III) runs in close proximity to the Posterior Communicating Artery ( PCom ) and aneurysms here can cause CN III compression.

84. Case #5 CT-A reveals an unruptured 7mm right inferiorly projecting PCom aneurysm.

85. Case #5 Angiography with endovascular coiling & placement of a Pipeline Embolization Device. Aneurysm Before Coiling Aneurysm After Coiling

86. Case #5 Summary: 75-year-old female who presented with a right CNIII palsy found to have an unruptured PCom aneurysm . She underwent endovascular coiling with placement of a flow diverter. She was discharged home on dual antiplatelet therapy. Her CN III palsy was almost completely resolved at her six month follow-up visit.

87. Internal Carotid Artery Aneurysm (7.5% Of Aneurysms)

88. Case #6 35-year-old female who presented with sudden onset headache an neck pain that woke her from sleep. The Initial ED Examination : Vital Signs: 179/111, 70, 18, 100% Photosensitivity and nuchal rigidity No cranial nerve deficits Right-sided arm/leg weakness compared with the left Reduced right arm/leg sensation to light touch

89. Case #6 The Initial ED Examination : Nuchal rigidity No cranial nerve deficits Right sided motor and sensory deficits Hunt Hess 3 (9.4% Mortality)

90. Case #6 Right CTA reveals a 4 mm inferiorly projecting ruptured left internal carotid artery (ICA) terminus aneurysm ( ➔ ) A STAT CT scan reveals diffuse subarachnoid hemorrhage. Fisher Scale 1 (6% Risk Of DCI)

91. Case #6 Cerebral Angiography with Endovascular Coiling Aneurysm Before Coiling Aneurysm After Coiling

92. Case #6 Summary : 35-year-old female who presented as Hunt Hess 3 SAH from a ruptured left internal carotid artery ( ICA) terminus aneurysm . The patient underwent endovascular coil embolization. Her hospital course was complicated by vasospasm. With intensive physical therapy, the patient was able to regain her right sided motor function.

93. Vasospasm and delayed cerebral ischemia (DCI) are associated with poor outcomes. Background Narrowing of the cerebral arteries (cerebral vasospasm) occurs frequently in patients with aSAH and is associated with DCI and infarction. DCI occurs in ≈ 30% of patients, mostly between days 4 and 14 hours after aSAH . Clinical deterioration due to DCI has been defined as the occurrence of focal neurological impairment or a decrease of at least 2 points on the GCS, lasting for at least 1 hour. Several diagnostic tools have been used to identify arterial narrowing and cerebral perfusion abnormalities that may help predict DCI. Stroke 2023;53:e314-e370. Measures To Prevent And Treat Cerebral Vasospasm And DCI

94. Stroke 2023;53:e314-e370. AHA/ASA Guidelines Monitoring For Cerebral Vasospasm And DCI In patients with aSAH with suspected vasospasm or limited neurological examination, CTA or CT perfusion (CTP) can be useful to detect vasospasm and predict DCI. In patients with aSAH , transcranial Doppler (TCD) ultrasound monitoring is reasonable to detect vasospasm and predict DCI. In patients with high-grade aSAH , continuous EEG ( cEEG ) monitoring can be useful to predict DCI. In patients with high-grade aSAH , invasive monitoring of brain tissue oxygenation, lactate/pyruvate ratio, and glutamate may be considered to predict DCI. DCI = Delayed Cerebral Ischemia

95. Stroke 2023;53:e314-e370. AHA/ASA Guidelines Treatment Of Cerebral Vasospasm And DCI In patients with aSAH , early initiation of enteral nimodipine is beneficial in preventing DCI and improving functional outcomes. In patients with aSAH , maintaining euvolemia can be beneficial in preventing DCI and improving functional outcomes. In patients with aSAH and symptomatic vasospasm, elevating systolic BP values may be reasonable to reduce the progression and severity of DCI. In patients with aSAH and severe vasospasm, use of intra-arterial vasodilator therapy may be reasonable to reverse cerebral vasospasm and reduce the progression and severity of DCI. DCI = Delayed Cerebral Ischemia

96. Frontiers In Neurology 2022;doi 10.3389/fneur.2022.982498 Clinical Effectiveness of Nimodipine for the Prevention of Poor Outcome After Aneurysmal Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis Objective : In clinical practice, nimodipine is used to control cerebral vasospasm (CVS), which is one of the major causes of severe disability and mortality in patients with aneurysmal subarachnoid hemorrhage ( aSAH ). This study sought to evaluate the latest literature on nimodipine and outcomes. Methods : Systematic literature review and meta-analysis of 13 RCTs (total 1,727 patients). Results : The use of nimodipine was associated with a reduction in poor outcomes [RR, 0.69 (0.60–0.78); decreased mortality [RR, 0.50 (0.32–0.78); I2 = 62%] and the incidence of CVS [RR, 0.68 (0.46–0.99); I2 = 57%]. Conclusion : Nimodipine significantly reduces the incidence of a poor outcome, mortality, and CVS in patients with aSAH .

97. AHA/ASA Guidelines

98. Case #7 A 35-year-old female developed an abrupt headache and neck pain immediately following a job interview. Her headache was “throbbing” and worse with standing. The Initial ED Examination : Vital Signs: 137/81, 91, 24 (hyperventilating), 100% She endorses severe headache Pupils are equal and reactive, there are no cranial nerve deficits No motor or sensory deficits, gait not tested

99. Subarachnoid Hemorrhage In The Pre-Pontine Cistern ( ➤ ). CT-A (-) For Aneurysm. ➤ ➤ Fisher Scale 1 6% Risk Of DCI

100. Case #7 The Initial ED Examination : She endorses severe headache Pupils equal and reactive No cranial nerve deficits No motor or sensory deficits Hunt Hess 2 (3.2% Mortality)

101. Case #7 Summary : 35-year-old patient with a Hunt Hess 2 pre-pontine ( perimesencephalic ) non-aneurysmal subarachnoid hemorrhage. Inpatient Work-Up Repeat head CT on Hospital Day #2 unchanged MRI/MRA negative Formal cerebral arteriogram negative for vascular malformation. The patient improved with analgesics, anti-emetics, and oral dexamethasone and was discharged in stable condition without any neurological deficit on Hospital Day # 5.

102. Case #8 A 45-year-old male with a history of hypertension developed an abrupt headache and neck pain during sexual intercourse with his wife. The Initial ED Examination : Vital Signs: 155/90, 66, 16, 100% He endorses severe headache Pupils are equal and reactive, there are no cranial nerve deficits No motor or sensory deficits His gait is steady without ataxia

103. Subarachnoid Hemorrhage In The Pre-Pontine Cistern ( ➤ ). CT-A (-) For Aneurysm. ➤ ➤ Fisher Scale 1 6% Risk Of DCI

104. Case #8 The Initial ED Examination : He endorses severe headache Pupils equal and reactive No cranial nerve deficits No motor or sensory deficits Hunt Hess 2 (3.2% Mortality)

105. Case #8 Summary : 45-year-old patient with a Hunt Hess 2 pre-pontine ( perimesencephalic ) non-aneurysmal subarachnoid hemorrhage. Inpatient Work-Up Repeat head CT on Hospital Day #2 unchanged MRI/MRA negative Formal cerebral arteriogram negative for vascular malformation. The patient recovered over three days and was discharged in stable condition without any neurological deficits.

106. Current Status of Perimesencephalic Non-Aneurysmal Subarachnoid Hemorrhage Frontiers In Neurology 2022;13:960702. Perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSAH) is a distinctive disease, representing SAH centered in perimesencephalic cisterns. This diagnosis of PNSAH requires definitive exclusion of aneurysm or vascular malformation with CT-angiography and/or formal cerebral arteriography. The current hypothesis about the etiology of PNSAH is that there is deep vein rupture from aberrant venous anatomy and increased intracranial venous pressure. PNSAH is associated with mild symptoms and lower rates of hydrocephalus and symptomatic vasospasm. Conservative treatment has been the mainstream treatment. PNSAH has a benign clinical course and an excellent prognosis; in long-term follow-up, re-bleeding and death were uncommon.

107. Frontiers In Neurology 2022;13:960702. Three Different Cases Of PNSAH Focal Pre-Pontine Hemorrhage Hemorrhage Extending Into The Left Sylvania Fissure ( ➤ ) Hemorrhage Extending Into The Interhemispheric Fissure ( ➤ ) ➤ ➤

108. Case #9 A 60-year-old male pedestrian struck as he crossed the street. He did experience brief loss of loss of consciousness. The Initial ED Examination : Vital Signs: 130/78, 81, 16, 100% He endorses severe headache The is a large frontal laceration that is repaired in the ED Pupils are equal and reactive, there are no cranial nerve deficits No motor or sensory deficits His gait is steady without ataxia

109. CT reveals diffuse traumatic subarachnoid hemorrhage ( ➔ ). Case #9

110. Case #9 Summary : 60-year-old male pedestrian struck suffers with a Hunt Hess 2 traumatic subarachnoid hemorrhage. The patient experienced transient vomiting and he was discharged home on Hospital Day #3 with no neurological deficit. At 2-week Trauma Clinic follow-up the patient had recovered completely.

111. Objective The objective of this scoping review was to understand the extent and type of evidence concerning the management of patients with traumatic subarachnoid hemorrhage (TSAH). Methods : The review included adults with SAH secondary to trauma, where “isolated TSAH” refers to the presence of SAH in the absence of any other traumatic radiographic intracranial pathology. Thirty studies were included in the analysis. Studies were grouped into 5 categories: TSAH associated with mild TBI (n = 13); severe TBI (n = 3); clinical management and diagnosis (n = 9); imaging (n = 3); and aneurysmal TSAH (n = 1). Results : Of the various finding that were demonstrated the most consistent finding was that patients with TSAH associated with minor TBI have a very low risk of clinical deterioration and surgical intervention and should be treated conservatively when considering ICU admission. Journal of Neurotrauma 2022;39:35-48. Traumatic Subarachnoid Hemorrhage: A Scoping Review

112. Key Takeaways

113. Key Takeaways Etiologies: 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 If accompanied by a CN III palsy, suspect a PCom aneurysm

114. Key Takeaways 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

115. Key Takeaways Evaluation: Calculate the Hunt Hess Score Communicating this as part of your neurological exam adds precision and helps inform prognosis

116. Key Takeaways Evaluation: The Modified Fisher Score, based on the initial head CT helps predict the incidence of delayed cerebral ischemia (DCI)

117. Key Takeaways Evaluation: Recognize CT signs of obstructive hydrocephalus. When this is present there should be an increased urgency to consult Neurosurgery

118. Key Takeaways External ventricular drain indicated for: Obstructive hydrocephalus Patients undergoing aneurysm clipping

119. Key Takeaways Blood pressure control: While AHA/ASA Guidelines do not specify a specific BP target, our institutional preference is to target a BP s <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

120. Key Takeaways 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

121. A 1 The Ottawa Subarachnoid Hemorrhage Rule A 2 Subarachnoid Hemorrhage Clinical Grading Scores A 3 Time To Aneurysm Treatment And Outcomes A 4 Aneurysm Clipping Versus Coiling A 5 Management of Middle Cerebral Artery Aneurysm A 6 Evaluation Of Third Cranial Nerve Palsy In The ED Appendix

122. Journal of the American Medical Association 2013;310:1248-1255. Objective To assess the accuracy, reliability, acceptability, and potential refinement of 3 clinical decision rules in a new cohort of patients with headache. Methods Multicenter cohort study conducted at 10 university-affiliated Canadian tertiary care emergency departments from April 2006 to July 2010. Enrolled patients were 2131 adults with a headache peaking within 1 hour and no neurologic deficits. Physicians completed data forms after assessing eligible patients prior to investigations. A 1

123. Results Of 2131 enrolled,132(6.2%) had subarachnoid hemorrhage (SAH). The decision rule including any of age 40 years or older, neck pain or stiffness, witnessed loss of consciousness, or onset during exertion had 98.5% (95% CI, 94.6%-99.6%) sensitivity and 27.5% (95% CI, 25.6%-29.5%) specificity. Adding thunderclap headache (instantly peaking pain) and limited neck flexion on examination resulted in the Ottawa SAH Rule, with 100% (95% CI, 97.2%-100.0%) sensitivity and 15.3% (95% CI, 13.8%-16.9%) specificity. Conclusion Among patients presenting to the ED with acute nontraumatic headache that reached maximal intensity within 1 hour and who had normal neurologic examination findings, the Ottawa SAH Rule was highly sensitive for identifying subarachnoid hemorrhage. These findings apply only to patients with these specific clinical characteristics and require additional evaluation in implementation studies before the rule is applied in routine clinical care. Journal of the American Medical Association 2013;310:1248-1255. A 1

124. Journal of the American Medical Association 2013;310:1248-1255. A 1

125. Journal of the American Medical Association 2013;310:1248-1255. A 1

126. Stroke2020; 2020;51(2):424-430. Objective Our objectives were to: (1) estimate the clinical impact of the Ottawa SAH rule and the 6-hour-CT rule on testing rates (CT, lumbar puncture, CT angiography); (2) validate the 6-hour-CT rule for SAH when applied prospectively in a new cohort of patients. Methods Multicenter prospective before/after implementation study from 2011 to 2016 with 6 months follow-up at 6 tertiary-care Canadian Academic Emergency Departments. Consecutive alert, neurologically intact adults with headache were included. For the intervention period, physicians were given a 1-hour lecture, pocket cards, posters were installed, and physicians indicated Ottawa SAH rule criteria when ordering CTs. A 1

127. Results 1743 patients were enrolled before and 1929 after rule implementation, including 188 with SAH. The Ottawa SAH rule was 100% (95% CI, 98.1%–100%) sensitive, and the 6-hour-CT rule was 95.5% (95% CI, 89.8–98.5) sensitive for SAH. The 6-hour-CT rule missed 5 SAHs: 1 radiology misread, 2 incidental aneurysms, 1 non-aneurysmal cause, and 1 profoundly anemic patient. Before After CT Imaging 88.0% 87.5% P=0.643 Lumbar Puncture 38.9% 25.9% P<0.0001 Additional Studies After CT 1 51.3% 42.2% P<0.0001 Hospital Admissions 9.8% 7.4% P=0.011 1 Lumbar puncture or angiography. Stroke2020; 2020;51(2):424-430. A 1

128. Conclusions The Ottawa SAH rule and the 6-hour-CT rule are highly sensitive and can be used routinely when SAH is considered in patients with headache. Implementing both rules was associated with a meaningful decrease in testing and admissions to hospital. Stroke2020; 2020;51(2):424-430. A 1

129. Stroke 2011;43:1546-1549. Three Different Aneurysmal SAH Clinical Grading Scales A 2

130. Journal of Neurosurgery 1968;28(1):14-20. The Hunt-Hess Scale , that was developed in 1968, is a graded system used to predict the rate of mortality based on the clinical features seen in patients presenting with aneurysmal subarachnoid hemorrhage. In the original study Hunt and Hess developed this scale in 275 of their patients with aneurysmal subarachnoid hemorrhage. A 2

131. Clinical Neurosurgery 1974;21(1):79-89. In 1974 Hunt and Kosnik modified the 1968 classification to include two new grades ‘0’ and ‘1a’. This revision also increased the grade by one point in the presence of serious systemic disease. A 2

132. Neurosurgery 2009;59:529-538. Preoperative Prediction Of Long-Term Outcome In Poor-Grade Aneurysmal Subarachnoid Hemorrhage Objective : To evaluate which presentation indices, demographics, and clinical information predict 12-month outcome in poor-grade aneurysmal SAH and to provide a preoperative index of prognosis. Methods : Data were obtained on all patients with poor-grade (Hunt and Hess Grades IV and V) aneurysmal SAH from a prospectively maintained SAH database and health outcomes project. Demographics, medical history, presenting clinical condition, and health outcomes were analyzed. Results : Multivariable analysis identified patient age older than 65 years ( P < 0.001), hyperglycemia ( P <0. 03), worst preoperative Hunt and Hess Grade V ( P < 0.0001), and aneurysm size of at least 13 mm ( P < 0.002) as significant predictors of poor outcome. A 2

133. Neurosurgery 2008;63(2):204-210. Grading Of SAH: Modification Of The World Federation of Neurosurgical Societies (WFNS) Scale On The Basis Of Data For A Large Series Of Patients Objective : To use a large, prospectively collected, multicenter database (n = 3567) for patients with aneurysmal SAH who were treated between 1991 and 1997 to determine the prognostic significance of clinical and radiological factors for outcomes and to use those factors to develop a grading scale to predict outcomes. Methods : 20 clinical and radiological factors were entered into univariate and multivariate analyses, to determine factors prognostic for outcomes. Grading scales based on the most powerful prognostic parameters were statistically derived and validated and were compared with the WFNS grading scale. Results : Factors predictive of outcomes included age, World Federation of Neurological Societies grade, history of hypertension, systolic blood pressure at admission, ruptured aneurysm location and size, blood clot thickness on computed tomographic scans, and angiographic vasospasm at admission. A 2

134. Neurosurgery 2008;63(2):204-210. Validation Of An Aneurysmal Subarachnoid Hemorrhage Grading Scale In 1532 Consecutive Patients Objective : To prospectively evaluate the GCS grading system and compare it to the Hunt &Hess and World Federation of Neurological Societies scales for predictive accuracy. Methods : Retrospective single-center study of 1532 patients from 1991 to 2005. The scales were evaluated using multivariable and linear regression to create receiver operator curves. The Glasgow Outcome Score was the primary outcome measure. Mortality and length of stay were secondary measures.  Results : The Glasgow Coma Score grading system was most strongly associated with all outcome measures and was the strongest predictor of mortality and persistent vegetative state. Age, vasospasm, hydrocephalus, and intracranial hematoma were found to be significant prognostic elements. A 2

135. Stroke 2011;43:1546-1549. Interobserver Variability of Grading Scales for Aneurysmal Subarachnoid Hemorrhage Objective : To assess the interobserver agreement of the commonly used World Federation of Neurological Surgeons, the Hunt & Hess, and the Prognosis on Admission of Aneurysmal Subarachnoid Hemorrhage scales. Methods : In a cohort of 50 SAH patients, 103 paired assessments were performed on the 3 admission scales by 2 independent observers per assessment with a total of 57 different raters. Patients were assessed during the first week after the hemorrhage. Kappa Prognosis On Admission Of aSAH Scale 0.64 (95% CI, 0.49 – 0.79) World Federation of Neurological Surgery Scale 0.60 (95% CI, 0.48 – 0.73) Hunt & Hess Scale 0.48 (95% CI, 0.36 – 0.59) All Scales Should Be Calculated Methodically To Ensure Accuracy A 2

136. Objective : To access the optimal onset-to-treatment time for aneurysmal subarachnoid hemorrhage (SAH). Methods : Study of 575 SAH patients at two tertiary Australian hospitals from 1/1/2010 to 12/31/2016. The association of time to treatment with three outcome measures was assessed: (1) discharge destination, (2) survival at 12 months, (3) complications. Results : The was a non-linear relationship between time to treatment and all outcome measures, with optimal outcomes occurring when treatment occurred within 12.5 hours. Conclusions : The study provides evidence that more favorable outcomes (discharge home and survival at 12 months) are seen when surgical treatment occurs with approximately 12.5 hours of presentation. JAMA Network Open 2022;5(1):e2144039. A 3

137. Objectives To compare the effects of endovascular coiling versus clipping in patients with SAH on outcomes, rebleeding, neurological deficits, and treatment complications. Methods Systematic review of randomized trials comparing coiling and clipping in patients with aneurysmal subarachnoid hemorrhage. Results & Conclusions Four randomized trials involving 2458 (ranger per trial: 20 to 2143 patients) were included. For patients in good clinical condition with ruptured SAH of either the anterior or posterior circulation, if the aneurysm is considered suitable for both neurosurgical clipping and endovascular coiling, endovascular is associated with better outcomes. Cochrane Database Of Systematic Reviews 2018;8, CD003085. A 4

138. Clipping Versus Coiling Of Ruptured & Unruptured Middle Cerebral Artery Aneurysms (MCAA) #1 Comparison of the Efficacy and Safety of Endovascular Coiling Versus Clipping for Unruptured Middle Cerebral Artery Aneurysms: A Systematic Review and Meta-Analysis 2015 Word Neurosurgery #2 Clip-First Policy Versus Coil-First Policy for the Exclusion of Middle Cerebral Artery Aneurysms 2019 Journal of Neurosurgery #3 Clipping Versus Coiling for Treatment of Middle Cerebral Artery Aneurysms: A Retrospective Italian Multicenter Study 2022 Neurosurgery Review #4 Clipping Versus Coiling for Ruptured MCA Aneurysms Associated with Intracerebral Hematoma Requiring Surgical Evacuation 2023 Neurocritical Care A 5

139. Clipping Versus Coiling Of Ruptured & Unruptured MCAA What Did These Four Studies Conclude? #1 Based on this systematic review and meta-analysis of unruptured MCAAs, after careful consideration of patient, aneurysmal, and treatment centered factors, we recommend surgical clipping for unruptured MCAA. #2 Clipping and coiling for MCAA treatment provide the same clinical outcome for ruptured and unruptured aneurysms. However, clipping provides higher short- and long-term rates of complete exclusion, which in turn decreases the risk of aneurysm retreatment. Whether this lower occlusion rate can have a clinical impact in the long- term must be further evaluated. #3 Clipping still seems superior to coiling in providing better short- and long-term occlusion rates in MCAA, and at the same time, it appears as safe as coiling in terms of clinical outcome. #4 In the specific subgroup of ruptured MCAA with intracerebral hematoma that requires surgical evacuation, clipping with concomitant hematoma evacuation could provide better functional outcomes than endovascular treatment followed by surgical evacuation. A 5

140. Evaluation Of Third Nerve Palsy In The Emergency Department Journal of Emergency Medicine 2008;35:239-246. A 6

141. Evaluation Of Third Nerve Palsy In The Emergency Department Journal of Emergency Medicine 2008;35:239-246. Traditional Teaching Has Been That : Compressive etiologies of CN III palsy (e.g.: aneurysm, neoplasm) cause pupillary dilatation. Non-compressive etiologies of CN III palsy (e.g.: microvascular changes) do not cause pupillary dilatation. A 6

142. Headache And Cranial Nerve III Palsy Journal of Emergency Medicine 2020;58(1):e31-e32. Imaging In Cranial Nerve III Palsy While aneurysms are a rare cause of isolated CN III palsy, these cannot be predicted or ruled out based on the physical examination alone, therefore imaging is recommended, CT-A has a high sensitivity and should be the first diagnostic step in the search for aneurysms in the patient with an isolated CN III palsy, Non-contrasted CT is not sensitive enough to detect most aneurysms, There is recent evidence that a CT-A is more sensitive than MRI for the detection of PCOM aneurysms in patients with CN III palsy. 1 1 Imaging of oculomotor (third) cranial nerve palsy. Neurology Clinics 2017;35:101–13. A 6

143. JAMA Ophthalmology 2017;135:23-28. Incidence and Etiologies of Acquired Third Nerve Palsy Using a Population-Based Method Objective : A third nerve palsy is important because a subset is caused by life-threatening aneurysms. This study sought to determine the incidence and etiologies of acquired third nerve palsy using a population-based method. A secondary aim was to evaluate the accuracy of the presence/absence of pupillary changes on etiology. Methods : All newly diagnosed cases of acquired third nerve palsy from 1/1/1978, through 12/31/2014, in Olmsted County, Minnesota, were identified using a record-linkage system of all county residents. Results : The study identified 145 newly diagnosed cases of acquired third nerve palsy over the 37-year period. The incidence was higher is patients >60 years (12.5 vs 1.7 per 100 000; 95% CI, 4.7–16.9; P < 0.001). See The Next Slide For More Results. A 6

144. JAMA Ophthalmology 2017;135:23-28. Incidence and Etiologies of Acquired Third Nerve Palsy Using a Population-Based Method Results : Ten patients (17%) with microvascular third nerve palsies had pupil involvement, while pupil involvement was seen in 16 patients (64%) with compressive third nerve palsies. While compressive lesions had a higher likelihood of pupil involvement, this finding did not exclude microvascular third nerve palsy, and a lack of pupil involvement did not rule out a compressive lesion. Distribution Of Causes In 145 Patients Microvascular 42% Trauma 12% Compression From Neoplasm 11% Post-Neurosurgery 10% Compression From Aneurysm 6% A 6

145. References 2023 Guidelines for the Management of Patients With Aneurysmal Subarachnoid Hemorrhage: A Guideline From the American Heart Association/American Stroke Association. Stroke 2023;53:e314-e370. Surgical risk as related to time of intervention in the repair of intracranial aneurysms Journal of Neurosurgery 1968;28(1):14-20. Prediction Of Symptomatic Vasospasm After Subarachnoid Hemorrhage: The Modified Fisher Scale. Neurosurgery 2006;58(7):21-27. Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting to the Emergency Department With Acute Headache. Annals Of Emergency Medicine 2019;74:e41–e74. Shifts in Diagnostic Testing for Headache in the Emergency Department, 2015 to 2021. JAMA Network Open 2024;7(4):e247373.

146. References Clinical Decision Rules to Rule Out Subarachnoid Hemorrhage for Acute Headache. Journal of the American Medical Association 2013;310:1248-1255. Prospective Implementation of the Ottawa Subarachnoid Hemorrhage Rule and 6-Hour Computed Tomography Rule. Stroke 2020;51(2):424-430. Association of Onset-to-Treatment Time With Discharge Destination Mortality and Complications Among Patents With Aneurysmal Subarachnoid Hemorrhage. JAMA Network Open 2022;5(1):e2144039. Endovascular Coiling Versus Neurosurgical Clipping for People With Aneurysmal Subarachnoid Hemorrhage. Cochrane Database Of Systematic Reviews 2018;8, CD003085. Comparison of the Efficacy and Safety of Endovascular Coiling Versus Clipping for Unruptured Middle Cerebral Artery Aneurysms: A Systematic Review and Meta-Analysis. World Neurosurgery 2015;84(4):942-953.

147. References Clip-First Policy Versus Coil-First Policy for the Exclusion of Middle Cerebral Artery Aneurysms. Journal of Neurosurgery 2019;133(4):1124-1134. Clipping Versus Coiling for Treatment of Middle Cerebral Artery Aneurysms: A Retrospective Italian Multicenter Study. Neurosurgery Review 2022;45(5):3179-3191. Clipping Versus Coiling for Ruptured MCA Aneurysms Associated with Intracerebral Hematoma Requiring Surgical Evacuation. Neurocritical Care 2023;39(1):162-171. Evaluation Of Third Nerve Palsy In The Emergency Department. Journal of Emergency Medicine 2008;35:239-246. Incidence and Etiologies of Acquired Third Nerve Palsy Using a Population-Based Method. JAMA Ophthalmology 2017;135:23-28. Headache And Cranial Nerve III Palsy. Journal of Emergency Medicine 2020;58(1):e31-e32.

148. References Im aging of oculomotor (third) cranial nerve palsy. Neurology Clinics 2017;35:101–13. Current Status of Perimesencephalic Non-Aneurysmal Subarachnoid Hemorrhage. Frontiers In Neurology 2022 ;13:960702 Traumatic SAH: A Scoping Review. Journal of Neurotrauma 2022;39:35-48. Subarachnoid Hemorrhage. New England Journal of Medicine 2017;377(3):257-265.