Subdural Hemorrhage

Subdural hemorrhage (SDH) is bleeding into the space between the dural and arachnoid meningeal layers surrounding the brain. The most common mechanism triggering the bleeding event is trauma (e.g., closed head injury) causing a tearing injury to the extracerebral “bridging” veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins, but rupture of small arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries within this space or intracranial hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension may also be causative. Acute SDH presents, immediately following head trauma Head trauma Head trauma occurs when external forces are directed to the skull and brain structures, resulting in damage to the skull, brain, and intracranial structures. Head injuries can be classified as open (penetrating) or closed (blunt), and primary (from the initial trauma) or secondary (indirect brain injury), and range from mild to severe and life-threatening. Head Trauma, with an altered level of consciousness that may span from a momentary loss of consciousness to coma Coma Coma is defined as a deep state of unarousable unresponsiveness, characterized by a score of 3 points on the GCS. A comatose state can be caused by a multitude of conditions, making the precise epidemiology and prognosis of coma difficult to determine. Coma, which makes it a potentially life-threatening condition. Chronic SDH may also occur, presenting with a more gradual neurologic deterioration. Diagnosis is based on clinical suspicion following head trauma Head trauma Head trauma occurs when external forces are directed to the skull and brain structures, resulting in damage to the skull, brain, and intracranial structures. Head injuries can be classified as open (penetrating) or closed (blunt), and primary (from the initial trauma) or secondary (indirect brain injury), and range from mild to severe and life-threatening. Head Trauma and confirmed with neuroimaging (e.g., noncontrast head CT). Management includes stabilization, stopping (possibly reversing) all anticoagulants Anticoagulants Anticoagulants are drugs that retard or interrupt the coagulation cascade. The primary classes of available anticoagulants include heparins, vitamin K-dependent antagonists (e.g., warfarin), direct thrombin inhibitors, and factor Xa inhibitors. Anticoagulants, monitoring in a neurologic ICU, and neurosurgical intervention.

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

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Overview

Definition

Subdural hematoma (SDH) is bleeding, usually caused by head trauma Head trauma Head trauma occurs when external forces are directed to the skull and brain structures, resulting in damage to the skull, brain, and intracranial structures. Head injuries can be classified as open (penetrating) or closed (blunt), and primary (from the initial trauma) or secondary (indirect brain injury), and range from mild to severe and life-threatening. Head Trauma, into the space between the dural and arachnoid meningeal layers surrounding the brain, creating a space called the subdural space.

Subarachnoid hemorrhage

Meninges Meninges The brain and the spinal cord are enveloped by 3 overlapping layers of connective tissue called the meninges. The layers are, from the most external layer to the most internal layer, the dura mater, arachnoid mater, and pia mater. Between these layers are 3 potential spaces called the epidural, subdural, and subarachnoid spaces. Meninges and meningeal spaces:
The image depicts the 3 layers (dura mater, arachnoid mater, and pia mater) surrounding the brain and spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord. The meninges serve as mechanical protection of the CNS. The meninges also support the cerebral and spinal blood vessels and allow for passage of the CSF. The subarachnoid space is filled with CSF. Only the subarachnoid space is a true space present in physiologic conditions, whereas the epidural and subdural spaces form only because of pathologic processes. The subdural space opens if the arachnoid mater separates from the dura mater, most commonly because of trauma and pathologic processes.

Image by Lecturio.

Epidemiology

  • Prevalence:
    • Found in approximately 10% of cases of head trauma Head trauma Head trauma occurs when external forces are directed to the skull and brain structures, resulting in damage to the skull, brain, and intracranial structures. Head injuries can be classified as open (penetrating) or closed (blunt), and primary (from the initial trauma) or secondary (indirect brain injury), and range from mild to severe and life-threatening. Head Trauma necessitating hospitalization
    • Found in approximately 20% of cases of severe traumatic brain injuries (TBIs)
  • More common in older individuals 
  • More common in persons on antiplatelet/anticoagulant therapies

Etiology

Head trauma: 

  • Most common cause of SDH
  • Causes injury to vascular structures that course between the dural and arachnoid meningeal layers surrounding the brain.
  • Most commonly exerts forces in the anteroposterior direction →  injury to bridging veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins to the superior sagittal sinus
  • Examples:
    • Motor vehicle accident
    • Falls
    • Assaults

Anticoagulation or coagulopathy:

  • Increase risk of prolonged or excessive bleeding
  • Examples (drugs):
    • Antiplatelet agents Antiplatelet agents Antiplatelet agents are medications that inhibit platelet aggregation, a critical step in the formation of the initial platelet plug. Abnormal, or inappropriate, platelet aggregation is a key step in the pathophysiology of arterial ischemic events. The primary categories of antiplatelet agents include aspirin, ADP inhibitors, phosphodiesterase/adenosine uptake inhibitors, and glycoprotein IIb/IIIa inhibitors. Antiplatelet Agents:
      • Aspirin
      • Clopidogrel
      • Prasugrel
    • Vitamin K antagonists: warfarin
    • Factor X inhibitors:
      • Rivaroxaban
      • Apixaban
      • Edoxaban
    • Heparinoids:
      • Unfractionated heparin (UFH)
      • Low-molecular-weight heparin (LMWH)
    • Thrombolytics Thrombolytics Thrombolytics, also known as fibrinolytics, include recombinant tissue plasminogen activator (TPa) (i.e., alteplase, reteplase, and tenecteplase), urokinase, and streptokinase. The agents promote the breakdown of a blood clot by converting plasminogen to plasmin, which then degrades fibrin. Thrombolytics:
      • Tissue plasminogen activator (tPA)
      • Urokinase
  • Examples (disease states):
    • Chronic liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver disease
    • Thrombocytopenia Thrombocytopenia Thrombocytopenia occurs when the platelet count is < 150,000 per microliter. The normal range for platelets is usually 150,000-450,000/µL of whole blood. Thrombocytopenia can be a result of decreased production, increased destruction, or splenic sequestration of platelets. Patients are often asymptomatic until platelet counts are < 50,000/µL. Thrombocytopenia
    • Hemophilia Hemophilia The hemophilias are a group of inherited, or sometimes acquired, disorders of secondary hemostasis due to deficiency of specific clotting factors. Hemophilia A is a deficiency of factor VIII, hemophilia B a deficiency of factor IX, and hemophilia C a deficiency of factor XI. Patients present with bleeding events that may be spontaneous or associated with minor or major trauma. Hemophilia

Cerebral atrophy:

  • Predisposes to vascular injury by allowing for excessive movement inside the cranial vault in the event of trauma.
  • Primarily causes chronic SDH
  • Examples:
    • Previous TBI
    • Previous cerebrovascular accident Cerebrovascular accident An ischemic stroke (also known as cerebrovascular accident) is an acute neurologic injury that occurs as a result of brain ischemia; this condition may be due to cerebral blood vessel occlusion by thrombosis or embolism, or rarely due to systemic hypoperfusion. Ischemic Stroke with parenchymal necrosis
    • Chronic alcoholism

Intracerebral hemorrhage Intracerebral Hemorrhage Intracerebral hemorrhage (ICH) refers to a spontaneous or traumatic bleed into the brain parenchyma and is the 2nd-most common cause of cerebrovascular accidents (CVAs), commonly known as stroke, after ischemic CVAs. Intracerebral Hemorrhage:

  • Direct extension of an intraparenchymal bleed through the cortical surface and into the subdural space
  • More likely to occur in the absence of trauma
  • Examples:
    • Intraparenchymal hypertensive bleed
    • Intraparenchymal hemorrhagic conversion of ischemic stroke Ischemic Stroke An ischemic stroke (also known as cerebrovascular accident) is an acute neurologic injury that occurs as a result of brain ischemia; this condition may be due to cerebral blood vessel occlusion by thrombosis or embolism, or rarely due to systemic hypoperfusion. Ischemic Stroke

Ruptured aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Extremity and Visceral Aneurysms of the cerebral vasculature:

  • Direct extension of an intracerebral bleed through the subarachnoid and into the subdural space 
  • More likely to occur in the absence of trauma
  • Examples:
    • Subarachnoid hemorrhage Subarachnoid Hemorrhage Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage (SAH) ( SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage (SAH); usually the result of a ruptured saccular aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Extremity and Visceral Aneurysms)
    • Carotid artery (or a branch thereof) aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Extremity and Visceral Aneurysms

Malformations of the cerebral vasculature:

  • Direct extension from the site of bleeding into the subdural space
  • More likely to occur in the absence of trauma
  • Example: Arteriovenous fistula

Brain tumor:

  • Primary or metastatic tumors that involve the dura may cause bleeding into the subdural space.
  • More likely to occur in the absence of trauma
  • Examples:
    • Meningioma Meningioma Meningiomas are slow-growing tumors that arise from the meninges of the brain and spinal cord. The vast majority are benign. These tumors commonly occur in individuals with a history of high doses of skull radiation, head trauma, and neurofibromatosis 2. Meningioma (primary)
    • Breast cancer Breast cancer Breast cancer is a disease characterized by malignant transformation of the epithelial cells of the breast. Breast cancer is the most common form of cancer and 2nd most common cause of cancer-related death among women. Breast Cancer (metastatic)
    • Lung cancer Lung cancer Lung cancer is the malignant transformation of lung tissue and the leading cause of cancer-related deaths. The majority of cases are associated with long-term smoking. The disease is generally classified histologically as either small cell lung cancer or non-small cell lung cancer. Symptoms include cough, dyspnea, weight loss, and chest discomfort. Lung Cancer (metastatic)
    • Prostate cancer Prostate cancer Prostate cancer is one of the most common cancers affecting men. In the United States, the lifetime risk of being diagnosed with prostate cancer is approximately 11%, and the lifetime risk of death is 2.5%. Prostate cancer is a slow-growing cancer that takes years, or even decades, to develop into advanced disease. Prostate Cancer (metastatic)

Intracranial hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension:

  • Inadequate CSF volume may create a vacuum effect within the cranial vault → transmitted to the meningeal layers → predisposes to tearing of the bridging veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins
  • May occur with or without trauma
  • Examples:
    • Dural leak after epidural procedure
      • Epidural steroid injection
      • Epidural anesthesia Anesthesia Anesthesiology is the field of medicine that focuses on interventions that bring a state of anesthesia upon an individual. General anesthesia is characterized by a reversible loss of consciousness along with analgesia, amnesia, and muscle relaxation. Anesthesiology: History and Basic Concepts prior to fetal delivery
    • CSF loss from trauma

Pathophysiology

Acute subdural hematoma

  • Trauma leading to tearing of the bridging veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins:
    • Bridging veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins drain blood from the cerebral surface into the dural sinuses.
    • Bridging veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins traverse the space between the arachnoid and dural meningeal layers.
    • Tearing allows blood to collect between these layers.
    • Bleeding is typically blocked by rising intracranial pressure ( ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP)) or direct compression by the forming thrombus.
    • Observed most commonly in the temporoparietal region.
  • Trauma leading to arterial rupture:
    • Small arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries (< 1 mm diameter) supply blood to the superficial cerebral cortex Cerebral cortex The cerebral cortex is the largest and most developed part of the human brain and CNS. Occupying the upper part of the cranial cavity, the cerebral cortex has 4 lobes and is divided into 2 hemispheres that are joined centrally by the corpus callosum. Cerebral Cortex.
    • These arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries traverse the space between the arachnoid and dural meningeal layers.
    • Rupture allows blood to collect between these layers.
    • Bleeding is typically blocked by rising ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP) or direct compression by the forming thrombus.
    • Observed most commonly in the temporoparietal region. 
  • Intracranial hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension (low CSF pressure):
    • Caused by low CSF volume, usually from a leak:
      • Spontaneous (seen in connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue disorders, such as Ehlers-Danlos or Marfan syndrome Marfan syndrome Marfan syndrome is a genetic condition with autosomal dominant inheritance. Marfan syndrome affects the elasticity of connective tissues throughout the body, most notably in the cardiovascular, ocular, and musculoskeletal systems. Marfan Syndrome)
      • Iatrogenic (e.g., lumbar puncture, epidural anesthesia Anesthesia Anesthesiology is the field of medicine that focuses on interventions that bring a state of anesthesia upon an individual. General anesthesia is characterized by a reversible loss of consciousness along with analgesia, amnesia, and muscle relaxation. Anesthesiology: History and Basic Concepts)
    • Low CSF pressure decreases buoyancy of the brain → traction on the meningeal support structures
    • Traction translated to bridging veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins/small cortical arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries → can cause tearing/rupture of these vessels
    • A vacuum effect is produced by the low ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP), causing vasodilation and further propensity to bleed. 

Chronic subdural hematoma

  • Forms from an acute SDH that has thrombosed:
    • Fibroblasts elaborate collagen over the dural layer, stabilizing the outer surface of the thrombus.
    • Thinner membrane develops over the inner surface of the clot → complete encapsulation 
    • Process takes approximately 2 weeks 
  • Liquefaction of the thrombus:
    • In > 50% of cases of acute SDH, the above-mentioned membranes calcify, while the thrombus contained therein undergoes liquefaction into a hygroma (fluid-filled sac).
    • Hygroma is protein-rich → potential osmotic draw of fluid into the cavity and expansion of the hygroma

Acute-on-chronic SDH

  • Recurrent trauma may cause bleeding into an otherwise stable (i.e., thrombosed) SDH or hygroma → enlargement and further intracranial pathologies 
  • Expansion of a hygroma due to osmotic forces → enlargement and further intracranial pathologies 

Clinical Presentation

Head trauma is the most common etiology of SDH, most often minor trauma (e.g., ground-level fall) in an elderly individual. 

Onset of symptoms

  • Acute SDH:
    • Presents immediately: up to 72 hours after the event
    • Initial presentation: coma Coma Coma is defined as a deep state of unarousable unresponsiveness, characterized by a score of 3 points on the GCS. A comatose state can be caused by a multitude of conditions, making the precise epidemiology and prognosis of coma difficult to determine. Coma in ½ of cases
    • Remainder may have a “lucid interval” between injury and onset of progressive neurologic decline.
  • Subacute SDH presents 3–14 days after the event.
  • Chronic SDH presents ≥ 15 days after the event.
  • In the absence of trauma, SDH may be difficult to categorize.

Neurologic symptoms

  • Nature of neurologic symptoms/signs depend largely on the following characteristics of the hematoma:
    • Location 
    • Size 
    • Rate of growth 
    • Acuity 
  • Common symptoms:
    • Altered level of consciousness
      • Minor trauma may cause only a momentary loss of consciousness.
      • Severe trauma victims with SDH may present in a coma Coma Coma is defined as a deep state of unarousable unresponsiveness, characterized by a score of 3 points on the GCS. A comatose state can be caused by a multitude of conditions, making the precise epidemiology and prognosis of coma difficult to determine. Coma.
      • Subacute or chronic SDH may present with gradual deterioration in level of consciousness.
    • Headache
    • Light-headedness/dizziness
    • Neck pain Neck Pain Neck pain is one of the most common complaints in the general population. Depending on symptom duration, it can be acute, subacute, or chronic. There are many causes of neck pain, including degenerative disease, trauma, rheumatologic disease, and infections. Neck Pain/stiffness
    • Visual changes
    • Nausea/vomiting
    • Balance/gait disturbance
    • Dysphagia Dysphagia Dysphagia is the subjective sensation of difficulty swallowing. Symptoms can range from a complete inability to swallow, to the sensation of solids or liquids becoming "stuck." Dysphagia is classified as either oropharyngeal or esophageal, with esophageal dysphagia having 2 sub-types: functional and mechanical. Dysphagia
  • Common signs:
    • Nuchal rigidity
    • Cranial nerve palsies
    • Ataxia
    • Seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures

Diagnosis

The diagnosis of SDH should be suspected in any elderly person presenting with head trauma Head trauma Head trauma occurs when external forces are directed to the skull and brain structures, resulting in damage to the skull, brain, and intracranial structures. Head injuries can be classified as open (penetrating) or closed (blunt), and primary (from the initial trauma) or secondary (indirect brain injury), and range from mild to severe and life-threatening. Head Trauma, altered mental status, decreased level of consciousness, or neurologic symptoms/signs. CT of the head should be performed emergently when an acute SDH is suspected.

Neuroimaging

Noncontrast head CT:

  • Imaging method of choice:
    • For acute head trauma Head trauma Head trauma occurs when external forces are directed to the skull and brain structures, resulting in damage to the skull, brain, and intracranial structures. Head injuries can be classified as open (penetrating) or closed (blunt), and primary (from the initial trauma) or secondary (indirect brain injury), and range from mild to severe and life-threatening. Head Trauma
    • For acute loss of consciousness
    • For suspected SDH (and other intracranial bleeds)
  • Acute SDH appears as a high-density crescent-shaped collection of blood along the convexity of the affected hemisphere.
    • Fresh blood appears with high intensity on CT.
    • Easily distinguishable from the surrounding anatomy 
  • Subacute and chronic SDH appear as an isodense or hypodense crescentic collection of blood with associated deformation of cerebral contours.
    • The hematoma loses its intensity as thrombosis and clot remodeling/resolution progress.
    • Subacute/chronic blood collection is more difficult to distinguish from the surrounding anatomy.
  • Unilateral SDH creates an obvious distortion of cerebral contours. 
  • Bilateral SDH may create symmetric distortion of cerebral contours and be less obvious. 

Head MRI:

  • Fluid-attenuated inversion recovery (FLAIR) sequencing 
  • Less widely used and not as readily available as CT
  • Sensitivity is superior to that of noncontrast CT in the detection of intracranial hemorrhage.
  • Acute, subacute, and chronic subdural blood appear hyperintense in CSF. 
    • May detect small SDHs that may be missed on noncontrast CT
    • May detect dural lesions (e.g., dural tears, neoplasm) missed on noncontrast CT
  • May reveal the presence and extent of associated intraparenchymal injuries

Angiography:

  • Noninvasive MRA or CTA: 
    • May be indicated for evaluation of nontraumatic or idiopathic SDH
    • May reveal small intracranial aneurysms or other vascular lesions
  • Conventional angiography may be considered if a vascular lesion is suspected but not detected by noninvasive angiography.

Contraindicated procedures

Lumbar puncture: 

  • Contraindicated when SDH is suspected
  • Increased ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP) due to expanding hematoma increases risk of herniation.
Subdural hemorrhage

Subdural hemorrhage:
Note the convexity of the hematoma and associated midline shift (with distortion of cerebral anatomy and obliteration of the lateral ventricle).

Image: “This CT scan is an example of Subdural haemorrhage caused by trauma. Single arrow marked the spread of the subdural haematoma. Double arrow marked the midline shift” by Glitzy queen00. License: Public Domain

Management

Acute SDH, especially that presenting with neurologic compromise or coma Coma Coma is defined as a deep state of unarousable unresponsiveness, characterized by a score of 3 points on the GCS. A comatose state can be caused by a multitude of conditions, making the precise epidemiology and prognosis of coma difficult to determine. Coma, is an emergent neurologic situation often requiring surgical intervention. Failure to promptly stabilize, diagnose, evaluate, and intervene could result in hemorrhagic expansion, parenchymal brain injury, elevated ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP), brain herniation, and death.

Stabilization

  • Individual should be evaluated and stabilized using advanced trauma life support/advanced cardiac life support (ATLS/ACLS) protocols.
  • Life-threatening injuries should be addressed.
  • Immediate discontinuation (and possible reversal) of antiplatelets/ anticoagulants Anticoagulants Anticoagulants are drugs that retard or interrupt the coagulation cascade. The primary classes of available anticoagulants include heparins, vitamin K-dependent antagonists (e.g., warfarin), direct thrombin inhibitors, and factor Xa inhibitors. Anticoagulants
  • Efforts to achieve/maintain hemodynamic instability
  • Noncontrast head CT as soon as possible
  • Emergent neurosurgical consultation: 
    • Surgical clinical decision making 
    • Placement of ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP) monitoring device

Stratification

Clinical decision tools used to determine operative or nonoperative management include:

  • GCS score
  • Head CT findings:
    • Clot thickness
    • Degree of midline shift
    • Presence of associated brain lesion
  • Neurologic examination
  • Presence of pupillary palsy
  • Acuity of SDH
  • Presence of comorbidities 
  • Severity of associated trauma
  • Age

Nonoperative management

  • May be appropriate for:
    • Clinically stable individuals (GCS score > 9)
    • Small hematomas (< 10 mm thickness on CT)
    • Absence of brain herniation signs by clinical and/or radiographic evaluation: 
      • Absent or minimal midline shift on CT (< 5 mm)
      • Absence of direct visualization of herniation on CT
      • Absence of physical examination findings of elevated ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP) (e.g., papilledema)
      • Absence of elevated ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP) on neuromonitoring
  • Should be monitored in a neurologic ICU
  • Should have continuous ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP) monitoring
  • Serial head CT should be performed every 6–8 hours for 36 hours.
  • Hematoma may resolve through resorption over weeks.

Operative management

  • May be appropriate for:
    • Clinically unstable individuals:
      • GCS score < 9
      • GCS score reduction by ≥ 2 from time of injury to time of evaluation
      • Presence of pupillary palsy
    • Large hematomas (> 10 mm thickness on CT)
    • Midline shift on CT > 5 mm, regardless of GCS score
    • ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP) > 20 mm Hg
  • Should be undertaken as soon as clinically feasible for individuals meeting these criteria (within 2–4 hours after onset of neurologic deterioration)
  • Surgical techniques:
    • Craniotomy with hematoma evacuation is the most commonly performed surgical technique.
    • Burr hole trephination
    • Decompressive craniectomy 
    • Subdural evacuation port system
  • Culprit vessel identification and tamponade may be undertaken simultaneously:
    • Traditional tamponade with ligatures
    • Endovascular embolization of the middle meningeal artery 

Prognosis

  • Mortality rate: 
    • Approximately 50% in SDH requiring surgery
    • Approximately 40% if surgical intervention is prompt (2–4 hours after injury)
    • Approximately 85% if surgical intervention is delayed
    • Approximately 60%–70% in SDH presenting with coma Coma Coma is defined as a deep state of unarousable unresponsiveness, characterized by a score of 3 points on the GCS. A comatose state can be caused by a multitude of conditions, making the precise epidemiology and prognosis of coma difficult to determine. Coma prior to evaluation
  • Age and GCS score are the most important prognostic indicators.

Differential Diagnosis

  • Ischemic stroke: ischemic infarct of the cerebral parenchyma caused by occlusion of a cerebral artery by atherosclerotic lesions or cardioembolic emboli. Ischemic stroke presents with neurologic deficits and/or altered mental status/altered level of consciousness that depends on the size and location of infarct. Diagnosis is clinical and confirmed by neuroimaging. Management includes initial stabilization, possible cerebrovascular intervention, addressing identifiable underlying etiologies (severe hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension, embolus), and management of cardiovascular risk factors. 
  • Other hemorrhagic cerebral conditions: Carotid/cerebral artery dissection, epidural hemorrhage Epidural Hemorrhage Epidural hemorrhage (EDH) is an event characterized by bleeding into the epidural space between the dural layers of the meninges and the skull. The primary mechanism triggering bleeding is trauma (i.e., closed head injury), which causes arterial injury, most commonly middle meningeal artery injury. Epidural Hemorrhage, intraparenchymal hemorrhage, and subdural hemorrhage are other hemorrhagic manifestations of the cerebral vasculature that can present with neurologic deficits and/or altered mental status/altered level of consciousness. Diagnosis is clinical and confirmed by neuroimaging. Management depends on the hemorrhagic etiology and includes initial stabilization, neurosurgical/endovascular consultation, management of ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP), and monitoring in a neurologic ICU. 
  • Hypertensive encephalopathy: neurologic deficits and/or altered mental status/altered level of consciousness that present in the setting of severe hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension. Diagnosis is based on the presence of elevated blood pressure and neurologic signs/symptoms. Neuroimaging is useful to rule out ischemic or hemorrhagic cerebrovascular accident Cerebrovascular accident An ischemic stroke (also known as cerebrovascular accident) is an acute neurologic injury that occurs as a result of brain ischemia; this condition may be due to cerebral blood vessel occlusion by thrombosis or embolism, or rarely due to systemic hypoperfusion. Ischemic Stroke

References

  1. McBride, W. (2020). Subdural hematoma in adults: etiology, clinical features, and diagnosis. Retrieved September 12, 2021, from https://www.uptodate.com/contents/subdural-hematoma-in-adults-etiology-clinical-features-and-diagnosis?search=subdural%20hemorrhage&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
  2. McBride, W. (2021). Subdural hematoma in adults: prognosis and management. Retrieved September 12, 2021, from https://www.uptodate.com/contents/subdural-hematoma-in-adults-prognosis-and-management?search=subdural%20hemorrhage&source=search_result&selectedTitle=2~150&usage_type=default&display_rank=2
  3. Iliescu I. A. (2015). Current diagnosis and treatment of chronic subdural haematomas. Journal of Medicine and Life 8:278–284. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4556906/
  4. Meagher, R. (2018). Subdural hematoma workup. Retrieved September 16, 2021, from https://emedicine.medscape.com/article/1137207-workup?ecd=ppc_google_rlsa-traf_mscp_emed_md_us
  5. Yang, A. I., Balser, D. S., Mikheev, A., et al. (2012). Cerebral atrophy is associated with development of chronic subdural haematoma. Brain Injury 26:1731–1736. https://doi.org/10.3109/02699052.2012.698364 

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