Topic Editor: Grant E. Fraser, M.D., FRACGP, FACRRM, ASTEM

Review Date: 9/17/2012

Definition

Subdural hematoma (SDH) is the accumulation of blood in the potential space between dura mater and arachnoid mater of the brain. It is most commonly due to bridging vein disruption as they travel to the dural venous sinuses. The cause can rarely be from arterial bleeding.

Description

• Subdural hematoma is classified by the lapse of time from the initial head trauma to when symptoms first appear:
• Acute subdural hematoma (ASDH): Symptoms occur within 48-72 hours
• Subacute subdural hematoma: Symptoms occur in the range 3-20 days
• Chronic subdural hematoma (CSDH): Symptoms occur later than 20 days
• As a result of increased intracranial pressure, due to hemorrhage within the confined cranial vault, herniation may occur
• Acute subdural hematomas are symptomatic, occur more commonly in younger patients, and are hyperdense on head CT
• Subacute subdural hematomas are isodense or hypodense on head CT
• Chronic subdural hematomas are more common in older adults, and are hypodense on head CT
• Acute-on-chronic subdural hematomas are and acute hemorrhage further expanding a chronic subdural hematoma. There will be hyperdensity (new hemorrhage) adjacent to an area of hypodensity (chronic subdural) on head CT
• ASDH's are clinically the most severe, commonly being caused by acceleration-deceleration head injury, which results in tearing of bridging veins
• Subacute SDH is due to maturation of acute hematoma
• CSDH is more common in elderly or chronic alcoholic patients, and can be due to trivial head injury in older patients. Recurrence or acute bleeding within a CSDH is common

Epidemiology

Incidence/Prevalence

• SDHs occur in as many as 30% of severe head injuries
• Incidence SDH ranges from 3/100,000/year in low risk populations, to over 50/100,000 in older populations

• ASDH: Occurs more often in younger adults (31-47 years)
• CSDH : Occurs more often in older individuals, with a peak incidence in the 6th and 7th decades of life

Gender

• Subdural hematomas are more common in men (male:female ratio is 3:1)

Risk factors

• Recent trauma (both for ASDH and CSDH)
• Anticoagulant use (both for ASDH and CSDH)
• Dialysis patients at increased risk

• Advancing age
• Alcoholism
• Arachnoid cysts
• Cardiovascular disease (eg, hypertension, arteriosclerosis)
• Coagulopathy/Anticoagulant use
• Diabetes mellitus
• Epilepsy
• Male gender
• Renal dialysis patients
• Thrombocytopenia

Etiology

Etiology of ASDH

• Head trauma (overwhelming number are due to trauma)
• Non traumatic ASDH is rare, but causes include:
• Aneurysm rupture
• Anticoagulant and thrombolytic therapy
• Arteriovenous malformations
• Cerebral amyloid angiopathy
• Hematological disorders
• Hypertensive cerebral hemorrhage
• Neoplasms
• Ruptured cortical artery
• Low intracranial pressure (ICP), may be due to traumatic CSF leak or after a procedure such as lumbar puncture
• Post surgical, such as after craniotomy or CSF shunting
• In the pediatric age group: Child abuse or shaken baby syndrome
• Spontaneous or unknown

• Attributable to trauma in 75% of cases; however, injury may have been trivial in older adults or those on anticoagulants
• Spontaneous or idiopathic

History

History of ASDH

• Assess history of head trauma, anticoagulant use, falls, domestic violence or motor vehicle accidents. Suspect ASDH in cases where significant head trauma due to a blunt mechanism has occurred. Many patients will have diminished mentation on presentation, and may have further deterioration as their hematoma expands
• Approximately 85% of children with subdural hematoma from non-accidental head trauma have other signs of abuse such as bruises and fractures at various healing stages
• Other symptoms include:
• Altered level of consciousness
• Ataxia
• Confusion
• Headache
• Impaired or double vision
• Incontinence of bowel/bladder
• Nausea
• Nuchal rigidity
• Otorrhea
• Personality change
• Rhinorrhea
• Seizure
• Speech difficulties
• Vomiting
• Weakness

• Most common among elderly patients with minor trauma which is usually unidentified. Alcoholics frequently present with acute-on-chronic SDHs owing to frequent trauma and coagulopathy associated with chronic alcohol abuse
• Onset of symptoms is progressive, with patients usually presenting with some of the following:
• Altered mental status
• Aphasia
• Gait disturbance
• Headache
• Hemiparesis
• Lightheadedness
• Personality changes (apathy)
• Headache is present in up to 90% of cases, with a high likelihood of at least one of the following symptoms also being present with the headache:
• Nausea and vomiting
• Exacerbation of headache by coughing, straining, or exercise
• Sudden onset of headache
• Severe head pain
• Other common symptoms include weakness, seizures, and incontinence

Physical findings on examination

Examination of patients with head trauma should focus on assessment airway, breathing, circulatory status, oxygenation, and neurologic status using Glasgow Coma Scale (GCS).
For cases of ASDH, assessment of other injuries, and extent of head injury is critical as other trauma management and assessment may be necessary.

Physical findings in ASDH

• Altered level of consciousness (99%)
• Hemiparesis is contralateral to hematoma and is present in 34-47% cases
• Pupillary irregularity is ipsilateral to hematoma and is present in 47-53% cases
• Other findings include:
• Decerebrate posturing or flaccid motor exam (47%)
• Papilledema (16%)
• Sixth cranial nerve palsy (5%)
• Examination of the skull for evidence of trauma, otorrhea, rhinorrhea, signs of basilar skull fracture (raccoon's eyes, battle's sign)
• Examination for spinal injury
• Examination for other concomitant trauma

• Altered mental status is present in 50-70% of elderly patients. The presentation may include confusion, delirium, psychiatric manifestations, and/or coma
• Hemianopsia (7%)
• Hemiparesis in 45-58%, with insidious onset being common, with gradual progression, most commonly contralateral
• Papilledema (24%)
• Seizure (seen most commonly in patients with large hematomas and focal neurological deficits)
• Third or sixth cranial nerve dysfunction
• Atypical presentations may include:
• Gerstmann syndrome
• A syndrome of impairment due to injury of the left parietal lobe in the region of the angular gyrus
• Consists of writing difficulty (agraphia or dysgraphia), difficulty with the rules of calculation/arithmetic, inability to distinguish right from left, and inability to identify fingers
• Nystagmus
• Parkinsonism
• Vertigo
• Infants: Accelerated increase in head size with or without irritability, poor feeding, occasional vomiting, tension of anterior fontanelle, seizures

Blood test findings

• Coagulation profile is important for patients taking anticoagulants and alcoholics, who may have an associated coagulopathy, and at high risk for subdural hematoma. All patients with subdural hematoma should have a basic coagulation panel at minimum (PT, aPTT, and platelet count)
• Complete blood count (CBC)
• Basic metabolic profile

Radiographic findings

Diagnosis of subdural hematoma is established with imaging of the brain. CT scan (without contrast) is usually the initial diagnostic test.

• CT scan: Density of blood in a subdural hematoma varies with the age of hematoma. Subdural hematomas are hyperdense in the acute phase (1 week), isodense in the subacute phase (1-3 weeks), and hypodense in the chronic phase (3 weeks). Isodense hematomas are more difficult to detect on CT, however, they produce evidence of mass effect either by midline shift or blunting of sulci
• MRI: More sensitive than CT in detecting isodense hematomas MRI. Helpful in diagnosing lesions located in the base of skull, posterior fossa and vertex, as CT emits a large shadow effect

Differential diagnosis of ASDH

• Cerebral contusion
• Diffuse axonal injury
• Epidural hematoma
• Intracerebral bleed
• Subdural hygroma
• Shaken baby/battered child syndrome

• Alzheimer's dementia
• Encephalitis
• Meningitis
• Normal pressure hydrocephalus
• Intracranial neoplasm
• Parkinson's disease
• Stroke
• Subarachnoid hemorrhage
• Transient ischemic attacks

General treatment items

• Manage Airway, Breathing, Circulation and other traumatic/medical issues with appropriate prioritization
• Patients with GCS 8 should be intubated and given ventilator support. Such patients generally should receive ICP monitoring
• Routine hyperventilation is not recommended due to risk of reduction of cerebral perfusion pressure and subsequent cerebral ischemia. Hyperventilation is best avoided in first 24 hrs postinjury due to risk of cerebral ischemia. However, mild hyperventilation to a therapeutic goal of maintaining pCO2 at levels of 30–35 mmHg may be beneficial
• If coagulopathy or thrombocytopenia is present, this should be treated
• Guidelines for the Surgical Management of Acute Subdural Hematomas were proposed by a joint venture between the Brain Trauma Foundation and the Congress of Neurological Surgeons (2006). These guidelines state that emergent decompression is indicated if there is a midline shift 5 mm or ASDH exceeds 10 mm in thickness. Emergency decompression in a comatose patient (GCS 8) is also indicated if:
• There is a GCS decrease of 2 or more between time of injury and hospital evaluation
• Fixed and dilated pupils
• ICP >20 mmHg
• Regardless of the GCS score, ASDH patients should be surgically evacuated if the hematoma thickness is >10 mm or there is a midline shift >5 mm
• Surgical options include burr hole craniotomy, in which at least 2 burr holes are made, with clot irrigation using saline and suction; trauma craniotomy, durotomy, or hemicraniectomy
• Surgical decompression of acute subdural hematomas may have poor outcome due to underlying brain injury
• The status of basal cisterns as visualized on CT can be used as a predictor for mortality and severe disability, and as an indication for surgical evacuation. In one study, patients with GCS scores of 6–8 and cisterns absent or not visualized, there was a nearly fourfold increased risk of poor outcome, compared to patients with normal cisterns
• Medical management is advised in patients with minimal neurologic signs, ie, headache only with no other neurologic signs, no focal neurologic deficits or memory impairment. Conservative therapy consists of inpatient observation and serial CT and clinical exams
• Patients with CSDH who have no significant mass effect and no neurologic symptoms or signs except mild headache have been observed with serial CT scans
• Maintain blood pressure at normal or high levels using isotonic saline, pressors, or both
• To facilitate adequate ventilation or in cases of suspected elevated ICP, sedation and paralytics are often appropriate
• In patients presenting with signs of herniation, administer 1 g/kg mannitol rapidly by intravenous (IV) push or 3-5 mL/kg of 3% saline IV bolus
• Prophylactic anticonvulsants are indicated in the first 7 days post injury to reduce risk of seizures and prevent seizure-induced ischemia. Monitor serum drug levels and maintain therapeutic levels
• Patients with ASDH who have coagulopathy require correction all coagulopathic features. Serial prothrombin time (PT/INR), activated partial thromboplastin time (aPTT), and platelet levels imperative. Correction of coagulopathy can be achieved as follows:
• Patients on warfarin should be reversed with Prothrombin Complex Compound (PCC) 25-50 IU/kg, IV depending upon INR, with the addition of vitamin K, generally IV with dose dependent on INR. If PCC is unavailable, Fresh Frozen Plasma (FFP) may be used in dose 10-30 mL/kg depending upon the INR
• Transfusion platelets is indicated in cases with thrombocytopenia, with the goal of platelet count 100,000/m L
• Reverse heparin with protamine to achieve a normal aPTT

Medications indicated with specific doses

Diuretics

• Furosemide [IM/IV]
• Adult Dosing
• Pediatric Dosing
• Mannitol [IV]
• Adult Dosing
• Pediatric Dosing

• Phenytoin [IM/IV]
• Adult Dosing
• Pediatric Dosing
• Fosphenytoin [IM/IV]
• Adult Dosing
• Pediatric Dosing

Dietary or Activity restrictions

In case of ASDH, most patients require enteral or total parenteral nutrition initially if mental status is decreased. Patients should be fed to full caloric replacement by day 7 post injury. For CSDH, depending on the level of consciousness, patients can usually have their diet advanced to regular food as tolerated

Disposition

Admission criteria

• ASDH patients should be admitted to the operating room or ICU by a Neurosurgeon. Subacute SDH patients should be admitted to a monitored setting

• Patients with CSDH can often be managed as outpatients in conjunction with neurosurgery, adequate home health resources, and appropriate follow-up

Monitoring

• Serial head CT's are often recommended, depending upon the nature of the SDH
• Neurosurgery will generally recommend appropriate follow-up intervals based upon the characteristics of a given patient's case
• In patients requiring anticoagulation, restarting anticoagulants after injury should be discussed with the neurosurgeon/neurologist, cardiologist and hematologist

Complications

• Postoperative complications
• Cortical injury secondary to drill procedures
• Elevated ICP and cerebral edema
• Infection (subdural empyema, meningitis)
• New or recurrent hematoma
• Seizures
• Tension pneumocephalus
• Chronic
• Delirium
• Intracranial hemorrhage (rare)
• Recurrent SDH
• Subdural hygroma
• Seizures

Prevention

• Coagulation profiles should be routinely monitored by physicians prescribing anticoagulants

Prognosis

• Mortality rate for subdural hematoma approaches 30%. Outcome is highly dependent on the presurgical neurologic status
• For ASDH, poor functional outcomes are associated with:
• Brain imaging findings where there is:
• Loss (obliteration) of the cisterns (e.g., ambient, basal, quadrigeminal)
• Midline shift
• Parenchymal lesions (generally multiple)
• Early need for surgery
• Elevated intracranial pressure
• Increased severity of injury
• Low GCS
• Older age
• CSDH has variable prognosis. Prognostic factors include:
• GCS on admission
• Radiographic findings of high risk, such as midline shift or cistern obliteration
• Nature of any surgical intervention required

Synonyms/Abbreviations

Synonyms

• Subdural hemorrhage

• SDH (Subdural hematoma)
• ASDH (Acute subdural hematoma)
• CSDH (Chronic subdural hematoma)

ICD-9-CM

• 852.20 Subdural hemorrhage following injury, without mention of open intracranial wound, with state of consciousness unspecified

ICD-10-CM

• S06.5X9 Traumatic subdural hemorrhage with loss of consciousness of unspecified duration
• I62.00 Nontraumatic subdural hemorrhage, unspecified
• I62.01 Nontraumatic acute subdural hemorrhage
• I62.02 Nontraumatic subacute subdural hemorrhage
• I62.03 Nontraumatic chronic subdural hemorrhage
• P10.3 Subdural hemorrhage due to birth injury
• 432.1 Subdural hemorrhage
• I62.0 Nontraumatic subdural hemorrhage
• S06.5 Traumatic subdural hemorrhage

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