eMedicine Specialties > Emergency Medicine > Trauma & Orthopedics
Subdural Hematoma
Updated: Oct 30, 2009
Introduction
Background
An acute subdural hematoma (SDH) is a rapidly clotting blood collection below the inner layer of the dura but external to the brain and arachnoid membrane. Two further stages, subacute and chronic, may develop with untreated acute SDH. Each type has distinctly different clinical, pathological, and imaging characteristics.
Acute subdural hematoma. Note the bright (white) image properties of the blood on this noncontrast cranial CT scan. Note also the midline shift. Image courtesy of J. Stephen Huff, MD.
Generally, the subacute phase begins 3-7 days after acute injury. (Surgical literature favors 3 days; radiological literature favors 7).
The chronic phase begins about 2-3 weeks after acute injury.
Pathophysiology
Typically, low-pressure venous bleeding of bridging veins (between the cortex and venous sinuses) dissects the arachnoid away from the dura and layers out along the cerebral convexity. Cerebral injury results from direct pressure, increased intracranial pressure (ICP), or associated intraparenchymal insults.
In the subacute phase, the clotted blood liquifies. Occasionally, in the prone patient, the cellular elements layer can appear on CT imaging as a hematocritlike effect.
In the chronic phase, cellular elements have disintegrated, and a collection of serous fluid remains in the subdural space. In rare cases, calcification develops.
Frequency
United States
Frequency is related directly to the incidence of blunt head trauma. A subdural hematoma (SDH) is the most common type of intracranial mass lesion, occurring in about a third of those with severe head injuries (Glasgow Coma Scale [GCS] score less than 9).
Mortality/Morbidity
Acute subdural hematoma (SDH) is associated with high mortality and morbidity rates.
- Simple SDH accounts for about half of all cases and implies that no parenchymal injury is present. Simple SDH is associated with a mortality rate of about 20%.
- Complicated SDH accounts for the remaining cases and implies that parenchymal injury (eg, contusion or laceration of a cerebral hemisphere) is present. Complicated SDH is associated with a mortality rate of about 50%.
Age
The majority of SDHs are associated with age factors related to the risk of blunt head trauma. Certain age factors are related to more unusual variants of this disease.
- SDH is more common in people older than 60 years. The elderly are predisposed to cerebral atrophy because they have less resilient bridging veins. Moreover, these veins can be damaged more easily in the elderly.
- Since the adhesions existing in the subdural space are absent at birth and develop with aging, bilateral SDHs are more common in infants.
- Interhemispheric SDHs are often associated with child abuse.1
Clinical
History
- Suspect acute subdural hematoma (SDH) whenever the patient has experienced a mechanism of moderately severe to severe blunt head trauma.
- Patients generally lose consciousness, but this is not an absolute.
- Chronic SDH is more difficult to anticipate, and about half of such cases offer no history of head trauma. Patients often present with progressive symptoms such as unexplained headache, personality changes, signs of increased ICP, or hemiparesis/plegia.
- Any degree or type of coagulopathy should heighten suspicion of SDH.
- Hemophiliacs can develop SDH with a seemingly trivial head trauma. An aggressive approach to diagnosis and immediate correction of the factor deficiency to 100% activity is paramount.
- Alcoholics are prone to thrombocytopenia, prolonged bleeding times, and blunt head trauma.
- Maintain a high level of suspicion in this population.
- Promptly obtain a CT scan of the head when the degree of trauma is severe, focal neurologic signs are noted, or intoxication does not resolve as anticipated.
- In alcoholics, more than any other cohort, acute or chronic SDHs can be due to the deadly combination of repetitive trauma and alcohol-associated coagulopathies.
- Patients on anticoagulants can develop SDH with minimal trauma and warrant a lowered threshold for obtaining a head CT scan.
Physical
- Physical examination of patients with head trauma should emphasize assessment of neurologic status using the GCS. Search for any focal neurologic deficits or signs of increased ICP.
- Signs of external trauma alert the physician to the expected location of coup or contrecoup injuries on CT scan.
- Any abnormality of mental status that cannot be explained completely by alcohol intoxication or the presence of another mind-altering substance should increase suspicion of SDH in the patient with blunt head trauma. Obtain an urgent CT scan.
- GCS score less than 15 after blunt head trauma, in a patient with no intoxicating substance use (or impaired mental status baseline), warrants consideration of an urgent CT scan.
- Presence of a focal neurologic sign following blunt head trauma is ominous and requires an emergent explanation.
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| Differential Diagnoses & Workup: Subdural Hematoma |
| Treatment & Medication: Subdural Hematoma |
| Follow-up: Subdural Hematoma |
| Multimedia: Subdural Hematoma |
| References |
| Further Reading |
| Next Page » |
References
Cohen M, Scheimberg I. Subdural haemorrhage and child maltreatment. Lancet. Apr 4 2009;373(9670):1173; author reply 1173-4. [Medline].
Zumofen D, Regli L, Levivier M, Krayenbühl N. Chronic subdural hematomas treated by burr hole trepanation and a subperiostal drainage system. Neurosurgery. Jun 2009;64(6):1116-21; discussion 1121-2. [Medline].
Bullock MR, Chesnut R, Ghajar J, Gordon D, Hartl R, Newell DW. Surgical management of acute subdural hematomas. Neurosurgery. Mar 2006;58(3 Suppl):S16-24; discussion Si-iv. [Medline].
Mobbs R, Khong P. Endoscopic-assisted evacuation of subdural collections. J Clin Neurosci. May 2009;16(5):701-4. [Medline].
Narita E, Maruya J, Nishimaki K, Heianna J, Miyauchi T, Nakahata J, et al. [Case of infected subdural hematoma diagnosed by diffusion-weighted imaging]. Brain Nerve. Mar 2009;61(3):319-23. [Medline].
Bell RS, Neal CJ, Lettieri CJ, Armonda RA. Severe Traumatic Brain Injury: Evolution and Current Surgical Management. Medscape. Available at http://cme.medscape.com/viewarticle/575753. Accessed June 24, 2008.
Buntain BL. Craniocerebral injuries. In: Management of Pediatric Trauma. WB Saunders; 1995:177-88.
Eijkenboom M, Gerlach I, Barker A, et al. Chronic cognitive effects of bilateral subdural haematomas in the rat. Neuroscience. 2004;124(3):523-33. [Medline].
Rockswold GL, Tintinalli JE, ed. Emergency Medicine: A Comprehensive Study Guide. 4th ed. McGraw-Hill; 1996:1142.
Saito T, Kushi H, Makino K, Hayashi N. The risk factors for the occurrence of acute brain swelling in acute subdural hematoma. Acta Neurochir Suppl. 2003;86:351-4. [Medline].
Valadka AB, Narayan RK. Injury to the cranium. In: Trauma. 3rd ed. 1996:267-78.
Wind JJ, Leiphart JW. Images in clinical medicine. Bilateral subacute subdural hematomas. N Engl J Med. Apr 23 2009;360(17):e23. [Medline].
Further Reading
Clinical guidelines
Surgical management of acute subdural hematomas.
Brain Trauma Foundation - Disease Specific Society. 2006 Mar. 9 pages. NGC:005061
ACR Appropriateness Criteria® head trauma.
American College of Radiology - Medical Specialty Society. 1996 (revised 2006). 12 pages. [NGC Update Pending] NGC:005118
Clinical trials
Teen Online Problem Solving (TOPS) - An Online Intervention Following TBI
Internet-Based Treatment for Children With Traumatic Brain Injuries & Their Families: Counselor Assisted Problem Solving (CAPS)
Keywords
subdural hematoma, head trauma, SDH, acute subdural hematoma, subacute subdural hematoma, chronic subdural hematoma, blunt head trauma, head injury, interhemispheric SDH, child abuse
