26/38 7/7/23, 11:26 AM Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis - UpToDate [1] Fisher grade of cerebral vasospasm risk in subarachnoid hemorrhage Group Appearance of blood on head CT scan 1 No blood detected 2 Diffuse deposition or thin layer with all vertical layers (in interhemispheric fissure, insular cistern, ambient cistern) less than 1 mm thick 3 Localized clot and/or vertical layers 1 mm or more in thickness 4 Intracerebral or intraventricular clot with diffuse or no subarachnoid blood CT: computed tomography. Reference: 1. Fisher CM, Kistler JP, Davis JM. Relation of cerebral vasospasm to subarachnoid hemorrhage visualized by CT scanning. Neurosurgery 1980; 6:1. Graphic 81122 Version 4.0 https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-clinical-manifestations-and-diagnosis/print 27/38 7/7/23, 11:26 AM Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis - UpToDate Modified Fisher (Claassen) subarachnoid hemorrhage CT rating scale Grade Head CT criteria 0 No SAH or IVH 1 Minimal SAH and no IVH 2 Minimal SAH with bilateral IVH 3 Thick SAH (completely filling one or more cistern or fissure) without bilateral IVH 4 Thick SAH (completely filling one or more cistern or fissure) with bilateral IVH CT: computed tomography; SAH: subarachnoid hemorrhage; IVH: intraventricular hemorrhage. From: Claassen J, Bernardini GL, Kreiter K, et al. E ect of cisternal and ventricular blood on risk of delayed cerebral ischemia after subarachnoid hemorrhage: the Fisher scale revisited. Stroke 2001; 32:2012. Graphic 57558 Version 5.0 https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-clinical-manifestations-and-diagnosis/print 28/38 7/7/23, 11:26 AM Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis - UpToDate Ogilvy and Carter grading system to predict outcome for surgical management of intracranial aneurysms Criteria Points Age 50 or less 0 Age greater than 50 1 Hunt and Hess grade 0 to 3 (no coma) 0 Hunt and Hess grade 4 and 5 (in coma) 1 Fisher scale score 0 to 2 0 Fisher scale score 3 and 4 1 Aneurysm size 10 mm or less 0 Aneurysm size greater than 10 mm 1 Giant posterior circulation aneurysm size 25 mm or more 1 The total score ranges from 0 to 5, corresponding to grades 0 to 5 Adapted from: Ogilvy CS, Carter BS. A proposed comprehensive grading system to predict outcome for surgical management of intracranial aneurysms. Neurosurgery 1998; 42:959. Graphic 70705 Version 4.0 https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-clinical-manifestations-and-diagnosis/print 29/38 7/7/23, 11:26 AM Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis - UpToDate [1] Reasons for misdiagnosis of subarachnoid hemorrhage Failure to recognize spectrum of presentation of subarachnoid hemorrhage Not obtaining complete history from patients with unusual (for the patient) headaches Is the onset abrupt? Is the quality different and severity greater than prior headaches? Failure to appreciate that the headache can improve spontaneously or with non-narcotic analgesics Focusing on the secondary head injury resulting from syncope and fall or motor vehicle collision Focusing on ECG abnormalities Focusing on elevated blood pressure Overreliance on the classic presentation Misdiagnosis of other disorders (eg, viral syndrome, viral meningitis, migraine, tension-type headache, sinus-related headache, psychiatric disorder) Failure to understand the limitations of head CT scanning Sensitivity decreases as onset of headache increases False-negative results with small-volume bleeds Scan interpreted by inexperienced physician Motion artifacts or lack of thin cuts of posterior fossa False-negative results due to hematocrit of less than 30% Failure to perform lumbar puncture or interpret the CSF findings correctly Failure to perform lumbar puncture in patients with negative or inconclusive CT scans Failure to distinguish a traumatic tap from true subarachnoid hemorrhage Failure to recognize that xanthochromia may be absent very early (less than 12 hours) and very late (more than 2 weeks) ECG: electrocardiogram; CT: computed tomography; CSF: cerebrospinal fluid. Reference: 1. Suarez JI. Diagnosis and Management of Subarachnoid Hemorrhage. Continuum (Minneap Minn) 2015; 21:1263. Original gure modi ed for this publication. From: Edlow JA, Malek AM, Ogilvy CS. Aneurysmal subarachnoid hemorrhage: update for emergency physicians. J Emerg Med 2008; 34:237. Table used with the permission of Elsevier Inc. All rights https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-clinical-manifestations-and-diagnosis/print 30/38 7/7/23, 11:26 AM Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis - UpToDate reserved. Graphic 121322 Version 1.0 https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-clinical-manifestations-and-diagnosis/print 31/38 7/7/23, 11:26 AM Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis - UpToDate Etiologies of thunderclap headache Most common causes of thunderclap headache: Subarachnoid hemorrhage Reversible cerebral vasoconstriction syndromes (RCVS) Conditions that less commonly cause thunderclap headache: Cerebral infection (eg, meningitis, acute complicated sinusitis) Cerebral venous thrombosis Cervical artery dissection Spontaneous intracranial hypotension Acute hypertensive crisis Posterior reversible leukoencephalopathy syndrome (PRES) Intracerebral hemorrhage Ischemic stroke Conditions that uncommonly or rarely cause thunderclap headache: Pituitary apoplexy Colloid cyst of the third ventricle Aortic arch dissection Aqueductal stenosis Brain tumor Giant cell arteritis Pheochromocytoma Pneumocephalus Retroclival hematoma Spinal epidural hematoma Varicella zoster virus vasculopathy Vogt-Koyanagi-Harada syndrome Disputed causes of thunderclap headache: Sentinel headache (unruptured intracranial aneurysm)* Primary thunderclap headache Sentinel headache due to an unruptured intracranial aneurysm is a possible cause of thunderclap headache, but supporting data are weak. https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-clinical-manifestations-and-diagnosis/print 32/38 7/7/23, 11:26 AM Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis - UpToDate There is controversy as to whether thunderclap headache can occur as a benign and potentially recurrent headache disorder in the absence of underlying organic intracranial pathology. Graphic 81710 Version 8.0 https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-clinical-manifestations-and-diagnosis/print 33/38 7/7/23, 11:26 AM Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis - UpToDate Various radiologic patterns of subarachnoid hemorrhage on noncontrast compu tomography (CT) of the head (A) Obvious large SAH: hyperdense blood in all the basal cisterns, with some dilatation of the temporal horn the lateral ventricles, suggesting early hydrocephalus. (B) More subtle, smaller SAH: small hyperdense collection of blood in the basal cistern adjacent to the left p and suprasellar cistern (short solid arrow). (C) Perimesencephalic SAH: the long solid arrows indicate a perimesencephalic (sometimes called a pretrun SAH. These hemorrhages represent approximately 10% of nontraumatic SAHs. They are thought to be caused venous bleeding, will have a negative CTA result, and usually have an excellent outcome. However, the radiographic pattern is also observed with posterior circulation aneurysms, so all of these patients require neurosurgical consultation and vascular imaging. (D) Convexal SAH: the arrowheads indicate a high convexal SAH. This pattern is observed in two groups of patients. In younger patients, it is usually due to RCVS, but in older ones, it often indicates amyloid angiopath a patient presenting with a severe rapid-onset headache, RCVS would be the likely diagnosis. (E) Traumatic SAH: the history usually suggests a traumatic SAH (the most common cause). However, if this pattern (dashed arrows indicate small amounts of SAH abutting bone, often in the anterior frontal and temp bones) is observed in a patient without a clear history of trauma, the likely cause is a traumatic SAH. https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-clinical-manifestations-and-diagnosis/print 34/38 7/7/23, 11:26 AM Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis - UpToDate SAH: subarachnoid hemorrhage; CTA: computed tomography angiography; RCVS: reversible cerebral vasoconstriction syndrome. Reproduced from: Edlow JA. Managing Patients With Nontraumatic, Severe, Rapid-Onset Headache. Ann Emerg Med 2018; 71:400. Illus used with the permission of Elsevier Inc. All rights reserved. Graphic 121315 Version 1.0 https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-clinical-manifestations-and-diagnosis/print 35/38 7/7/23, 11:26 AM Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis - UpToDate Considerations for omitting the lumbar puncture in patients who have a negative CT within six hours of headache onset in the evaluation for subarachnoid hemorrhage Patient factors The time of onset of the headache is clearly defined. The CT is performed within six hours of headache onset. The presentation is an isolated severe rapid-onset headache (no primary neck pain, seizure, or syncope at onset, or other atypical presentations). There is no meningismus and the neurologic examination result is normal. Radiologic factors The CT scanner is a modern, third-generation or newer machine with thin cuts through the brain. The CT is technically adequate, without significant motion artifact. The hematocrit level is >30%. The physician interpreting the scan is an attending-level radiologist (or has equivalent experience in reading brain CT scans). Radiologists should specifically examine the brain CTs for subtle hydrocephalus, small amounts of blood in the dependent portions of the ventricles, and small amounts of isodense or hyperdense material in the basal cisterns. Communication factors The clinician should communicate the specific concern to the radiologist (eg, "severe acute headache; rule out SAH"). After a negative CT result, the clinician should communicate the posttest risk of SAH that persists (1 to 2 per 1000). CT: computed tomography; SAH: subarachnoid hemorrhage. Reproduced from: Edlow JA. Managing Patients With Nontraumatic, Severe, Rapid-Onset Headache. Ann Emerg Med 2018; 71:400. Table used with the permission of Elsevier Inc. All rights reserved. Graphic 121294 Version 1.0 https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-clinical-manifestations-and-diagnosis/print 36/38 7/7/23, 11:26 AM Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis - UpToDate Perimesencephalic subarachnoid hemorrhage CT scan demonstrates the typical findings of a nonaneurysmal perimesencephalic subarachnoid hemorrhage. Note the predominance of hemorrhage in the interpeduncular fossa (arrow). CT: computed tomography. Courtesy of Guy Rordorf, MD. Graphic 72476 Version 4.0 https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-clinical-manifestations-and-diagnosis/print 37/38 7/7/23, 11:26 AM Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis - UpToDate Contributor Disclosures Robert J Singer, MD No relevant financial relationship(s) with ineligible companies to disclose. Christopher S Ogilvy, MD Consultant/Advisory Boards: Cerevasc [Hydrocephalus]; Contour [Aneurysms]; Medtronic [Chronic subdural hematoma]. All of the relevant financial relationships listed have been mitigated. Guy Rordorf, MD No relevant financial relationship(s) with ineligible companies to disclose. Jos Biller, MD, FACP, FAAN, FAHA No relevant financial relationship(s) with ineligible companies to disclose. Alejandro A Rabinstein, MD Grant/Research/Clinical Trial Support: Chiesi [Small investigator- initiated project]. Consultant/Advisory Boards: AstraZeneca [Secondary stroke prevention]; Brainomix [AI for stroke diagnostics]; Novo Nordisk [Stroke risk]; Shionogi [Stroke neuroprotection]. Other Financial Interest: Boston Scientific [Adverse event adjudication committee member for stroke risk reduction device in patients with atrial fibrillation]. All of the relevant financial relationships listed have been mitigated. Jonathan A Edlow, MD, FACEP No relevant financial relationship(s) with ineligible companies to disclose. Richard P Goddeau, Jr, DO, FAHA No relevant financial relationship(s) with ineligible companies to disclose. Contributor disclosures are reviewed for conflicts of interest by the editorial group. When found, these are addressed by vetting through a multi-level review process, and through requirements for references to be provided to support the content. Appropriately referenced content is required of all authors and must conform to UpToDate standards of evidence. Conflict of interest policy https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-clinical-manifestations-and-diagnosis/print 38/38