Basics topic (see "Patient education: Subdural hematoma (The Basics)") SUMMARY AND RECOMMENDATIONS Anatomy Subdural hematoma (SDH) forms between the dural and the arachnoid membranes overlying the brain ( figure 2 and image 1). SDH often has a crescent- shaped appearance because bleeding follows the contour of the overlying dura. Most SDHs occur along the cerebral convexities but may also occur in the subdural spaces between cerebral and cerebellar hemispheres or circumferentially around the brainstem ( figure 1). (See 'Anatomy' above.) Pathophysiology Acute SDH is usually caused by tearing of the veins located between the arachnoid membranes and the dura in most cases. An arterial source may be found in approximately 20 to 30 percent of SDH cases. Etiologies SDH may be spontaneous or triggered by an inciting event. (See 'Specific etiologies' above.) Head trauma is the most common cause of SDH, with most cases related to motor vehicle accidents, falls, and assaults. Low cerebrospinal fluid pressure (intracranial hypotension) may cause SDH by a spontaneous or iatrogenic cerebrospinal fluid leak such as following lumbar puncture or ventriculostomy, lumboperitoneal shunt placement, or other neurosurgical procedures. Arterial causes of SDH include trauma, intracerebral hemorrhage, ruptured cerebral aneurysm, cerebral arteriovenous malformation, or vasculopathy. https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 13/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Neoplastic lesions may lead to SDH by mass effect or neovascular rupture. SDH associated with dural (pachymeningeal) metastasis are breast, prostate, lung, and lymphoma. Primary brain tumors are a rare source of SDH. Epidemiology Acute SDH complicates approximately 11 percent of mild to moderate head injuries that require hospitalization and approximately 20 percent of severe traumatic brain injuries. The incidence of chronic SDH ranges from 1.7 up to 20.6 per 100,000 persons/year. (See 'Epidemiology' above.) Risk factors Patients with significant cerebral atrophy, those who use antithrombotic medications, or who have other sources of coagulopathy are at an elevated risk for SDH. (See 'Risk factors' above.) Clinical manifestations The initial presentation of SDH has a wide spectrum of manifestations. Patients with severe head trauma and SDH may present with coma due to the overall insult to the brain, while those with a mild or trivial trauma and those with spontaneous SDH are likelier to present with symptoms due to the SDH alone ( table 1). (See 'Clinical manifestations' above.) Symptoms of acute SDH include weakness, numbness, visual impairment, and seizures. Patients who become symptomatic with chronic SDH are more likely to present with nonfocal symptoms than those with acute SDH. SDH may also be asymptomatic, found incidentally on imaging obtained for unrelated symptoms. Imaging features Noncontrast head computed tomography (CT) is the first-choice imaging study to rapidly diagnose SDH. Brain magnetic resonance imaging (MRI) may also be used but typically takes longer to perform than CT and is less readily available in many facilities. However, MRI may be preferred for small chronic SDH and to identifying possible underlying causes ( image 11). (See 'Imaging features' above.) Evaluation for underlying etiology Patients without antecedent trauma or obvious risk factors for SDH should be evaluated for secondary causes. This may include brain MRI or other imaging, angiography in selected cases, and laboratory evaluation for coagulopathy. (See 'Evaluation for underlying causes' above.) ACKNOWLEDGMENT https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 14/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate The UpToDate editorial staff acknowledges David Brock, MD, CIP, who contributed to an earlier version of this topic review. Use of UpToDate is subject to the Terms of Use. REFERENCES 1. Finger G, Martins OG, Basso LS, et al. Acute Spontaneous Subdural Hematoma in Posterior Fossa: Great Outcome. World Neurosurg 2018; 119:146. 2. de Beer MH, Eysink Smeets MM, Koppen H. Spontaneous Spinal Subdural Hematoma. Neurologist 2017; 22:34. 3. Benyaich Z, Laghmari M, Lmejjati M, et al. Acute Lumbar Spinal Subdural Hematoma Inducing Paraplegia After Lumbar Spinal Manipulation: Case Report and Literature Review. World Neurosurg 2019; 128:182. 4. Ropper AH, Samuels MA, Klein JP, Prasad S. Craniocerebral trauma. 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Topic 1105 Version 21.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 21/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate GRAPHICS Subdural hematoma in adults: Rapid overview of emergency management Clinical manifestations When to suspect: Trauma Unexplained acute or subacute progressive neurologic symptoms New neurologic symptoms in an older patient (especially if taking anticoagulants) Common symptoms: New and persistent headache, focal or bilateral weakness, confusion, subacute cognitive decline, seizures Signs of elevated intracranial pressure: Dilated pupil(s) Progressive drowsiness Cushing triad (bradycardia, respiratory depression, hypertension) Evaluation Assess airway, breathing, circulation, and disability to initiate supportive care Determine GCS and neurologic deficits (eg, hemiparesis, numbness, speech or vision impairment) Identify exposure to anticoagulant medications (eg, warfarin, DOACs, heparinoids) Obtain emergency imaging (eg, head CT or fast MRI) Laboratory evaluation: Complete blood count, PT, PTT, INR, basic electrolytes, pregnancy test in female of childbearing age Initial serial monitoring: Neurologic examination (hourly) for signs of deterioration Repeat head CT 6 to 8 hours after initial study and for any clinical signs of deterioration Treatment Manage trauma patients according to principles of advanced trauma life support* Perform tracheal intubation for any patient unable to protect their airway, with rapidly deteriorating mental status, or with GCS 8 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 22/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Obtain immediate neurosurgical consultation as indicated by clinical signs or imaging: Hemispheric SDH >10 mm thickness or midline shift >5 mm SDH causing brainstem compression or pupillary abnormalities SDH causing progressive neurologic deterioration (eg, GCS drop 2 points) Reverse anticoagulation (agent specific): Warfarin Reverse with 4-factor PCC and IV vitamin K Dabigatran Reverse with idarucizumab Factor Xa inhibitors (apixaban, edoxaban, rivaroxaban) Reverse with 4-factor PCC or andexanet alfa Heparin (unfractionated) Reverse with protamine sulfate Low molecular weight heparin Reverse with andexanet alfa; protamine sulfate is an alternative Medical management of intracranial pressure: Blood pressure control: Prevent HYPOtension to maintain SBP >100 mmHg: fluid resuscitation with isotonic IV fluids; phenylephrine for refractory symptoms Initial dose 0.5 to 2 mcg/kg per minute IV; maintenance dose 0.25 to 5 mcg/kg per minute Treat HYPERtension: Initial treatment to rapidly reduce SBP to <220 mmHg: nicardipine 5 mg/hour IV, titrate by 2.5 mg/hour every 5 to 15 minutes (maximum dose: 15 mg/hour); alternate: labetalol 20 mg IV bolus, may repeat every 10 minutes Subsequent treatment to reduce SBP to <160 mmHg while monitoring for stability of neurologic status Elevate head of bed >30 degrees Give antipyretics for temperature >38 degrees Celsius (eg, acetaminophen [paracetamol] 325 to 650 mg orally or PR every 4 to 6 hours or 650 mg IV every 4 hours) Repeat imaging (eg, head CT) for signs of new or progressive elevated intracranial pressure: Obtain immediate neurosurgical consultation for surgical indications (refer to above) Osmotic therapy (mannitol or hypertonic saline) or hyperventilation as temporary treatment measures https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 23/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate GCS: Glasgow coma scale; DOAC: direct oral anticoagulant; CT: computed tomography; MRI: magnetic resonance imaging; PT: prothrombin time; PTT: partial thromboplastin time; INR: international normalized ratio; SDH: subdural hematoma; PCC: prothrombin complex concentrate; IV: intravenous; SBP: systolic blood pressure; PR: per rectum. Refer to the UpToDate topics on trauma management in adults. Refer to the UpToDate topics on management of elevated intracranial pressure in adults. Graphic 132691 Version 5.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 24/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Head CT of subdural hemorrhage and cerebral edema CT image (axial view) of acute-hyperacute right subdural hemorrhage (arrows) and asymmetric cerebral edema in an eight- month-old male infant who sustained nonaccidental injury (child abuse). CT: computed tomography. Graphic 51782 Version 4.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 25/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Possible locations of subdural hematoma (SDH) Graphic 132721 Version 1.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 26/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Distinct forms of intracranial hemorrhage (ICH) Graphic 132722 Version 1.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 27/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, 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/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 28/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, 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/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 29/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Non contrast head CT demonstrates an acute traumatic epidural hematoma over the left parietal region Courtesy of Neuroradiology Department, Thomas Je erson University, Philadelphia, PA. Graphic 60726 Version 4.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 30/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate CT and MRI scans of hyperacute intracerebral hemorrhage CT and MRI studies were obtained less than six hours from symptom onset in a patient with spontaneous acute intracerebral hemorrhage. The CT scan shows a hyperdense hemorrhage predominantly in the left frontal lobe. On MRI, the central portion of the hematoma is isointense to brain parenchyma on the T1-weighted image and hyperintense on the T2-weighted and T2* gradient echo images, consistent with hemorrhage containing oxyhemoglobin. On the T2-weighted and T2* gradient echo images, the periphery of the hemorrhage is hypointense, consistent with deoxygenation that occurs more rapidly at the borders. On the T2 weighted image, tissue adjacent to and surrounding the hematoma is hyperintense, consistent with vasogenic edema. CT: computed tomography; MRI: magnetic resonance imaging; ICH: https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 31/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate intracerebral hemorrhage. Graphic 81767 Version 2.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 32/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Bilateral subdural hematomas from spontaneous intracranial hypotension FLAIR image on brain MRI (A) shows bilateral hyperintense subdural hematomas (arrows) that compress underlying cerebral cortex. Axial post-contrast T1-weighted image (B) shows uniform enhancement of the dura (arrowheads). Sagittal post-contrast T1-weighted image (C) shows diffuse dural enhancement (dashed arrows), pituitary hyperemia (circle), and brain sagging, suggestive of intracranial hypotension. FLAIR: fluid-attenuated inversion recovery; MRI: magnetic resonance imaging. https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 33/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Courtesy of Glenn A Tung, MD, FACR. Graphic 132680 Version 1.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 34/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Uncal herniation from subdural hematoma Noncontrast head CT shows a large right holohemispheric subdural hematoma on axial (A) and coronal (B) images. Mass effect from hematoma causes a right-to-left midline shift (line) and subfalcine herniation (arrowhead). Axial image through the temporal lobes (C) shows uncal herniation with compression of the cerebral peduncles (arrow). CT: computed tomography. https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 35/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Courtesy of Glenn A Tung, MD, FACR. Graphic 132682 Version 1.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 36/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Clinical progression of transtentorial herniation Headache Altered level of consciousness Dilation of ipsilateral pupil Cranial nerve III palsy Ptosis Loss of medial gaze Decerebrate posturing Hemiparesis Dilation of opposite pupil Alteration of respiration Bradycardia Hypertension Respiratory arrest Graphic 70683 Version 2.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 37/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Non contrast head CT demonstrates a traumatic acute subdural hematoma over the left hemisphere and a smaller subacute subdural hematoma over the right hemisphere Courtesy of Neuroradiology Department, Thomas Je erson University, Philadelphia, PA. Graphic 68424 Version 3.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 38/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Non contrast head CT demonstrates a subacute subdural hematoma over the right cerebral hemisphere CT: computed tomography. Courtesy of Neuroradiology Department, Thomas Je erson University, Philadelphia, PA. Graphic 80783 Version 4.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 39/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Pseudomembranes in chronic subdural hematomas Noncontrast head CT images (A, B, C) show chronic subdural hematoma (arrows) with pseudomembranes (arrowheads) that appear as linear or nodular densities. CT: computed tomography. Courtesy of Glenn A Tung, MD, FACR. https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 40/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Graphic 132683 Version 1.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 41/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Traumatic subdural hematoma (SDH) CT scan showing a left acute SDH (arrow). SDHs are typically crescent shaped. In this case the SDH is causing significant mass effect and shift of midline structures to the right. CT: computed tomography. Reproduced with permission from: J Claude Hemphill III, MD and Nicholas Phan, MD, FRCSC. Graphic 68102 Version 5.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 42/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Bilateral isodense subdural hematomas Noncontrast head CT shows mass effect on left lateral ventricle and subtle isodense subdural hematoma (arrow) in axial (A) and coronal (C) images. Subdural hematomas are demonstrated on transverse axial T1-weighted (B) and coronal T2-weighted (D) MRI sequences by markedly different signal intensity than compressed brain tissue. CT: computed tomography; MRI: magnetic resonance imaging. https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 43/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Courtesy of Glenn A Tung, MD, FACR. Graphic 132684 Version 1.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 44/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate MRI of the brain demonstrates a spontaneous subdural hematoma over the right cerebral hemisphere MRI: magnetic resonance imaging. Courtesy of Neuroradiology Department, Thomas Je erson University, Philadelphia, PA. Graphic 50871 Version 4.0 https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 45/46 7/5/23, 12:02 PM Subdural hematoma in adults: Etiology, clinical features, and diagnosis - UpToDate Contributor Disclosures William McBride, 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. Glenn A Tung, MD, FACR 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/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis/print 46/46