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Epidural hematoma
Image:Epidural hematoma.png Epidural or extradural hematoma is a buildup of blood occurring between the dura mater(the brain'stough outer membrane) and the skull. Often due to trauma, the condition is potentially deadly because the buildup of blood may increase pressurein the intracranial spaceand compress delicate brain tissue. 15 to 20% of patients with epidural hematomas die of the injury(Sanders and McKenna, 2001).
CausesThe cause of epidural hematoma is usaully traumatic, although spontaneous hemorrhage is known to occur. Hemorrhages commonly result from acceleration-deceleration traumaand transverse forces (McCaffrey, 2001; University of Vermont). Venousepidural bleeds are usually due to shearing injuryfrom rotationalor linear forces, caused when tissues of different densities slide over one another. Epidural hematoma commonly results from a blow to the side of the head and is frequently caused by a fracture that passes through an arterial channel in the bone, most commonly a break in temporal boneinterrupting middle meningeal artery, a branch of the external carotid(Shepherd, 2004). Thus only 20 to 30% of epidural hematomas occur outside the temporal bone (Graham and Gennareli, 2000). FeaturesEpidural bleeds, like subduraland subarachnoid hemorrhages, are extra-axial bleeds, occurring outside of the brain tissue, while intra-axial hemorrhages, including intraparenchymaland intraventricular hemorrhages, occur within it (Wagner, 2004). Epidural bleeding is rapid because it is usually from arteries, which are high pressure. Epidural bleeds from arteries can grow until they reach their peak size at six to eight hours post injury, spilling from 25 to 75 cubic centimetersof blood into the intracranial space(University of Vermont; Stock and Singer, 2004). As the hematoma expands, it strips the dura from the inside of the skull, causing an intense headache. Epidural bleeds can become large and raise intracranial pressure, causing the brain to shift, lose blood supply, or be crushed against the skull. Larger hematomas cause more damage. Epidural bleeds can quickly expand and compress the brain stem, causing unconsciousness, abnormal posturing, and abnormal pupilresponses to light (Stock and Singer, 2004). 10% of epidural bleeds may be venous (Shepherd, 2004). On images produced by CT scansand MRIs, epidural hematomas usually appear convex in shape because their expansion stops at skull's sutures, where the dura mater is tightly attached to the skull. Thus they expand inward toward the brain rather than along the inside of the skull, as occurs in subdural hematoma. The lens like shape of the hematoma leads the appearance of these bleeds to be called "lentiform". Epidural hematomas may occur in combination with subdural hematomas, or either may occur alone (Shepherd, 2004). CT scans reveal subdural or epidural hematomas in 20% of unconscious patients (Downie, 2001). In the hallmark of epidural hematoma, patients may regain consciousness during what is called a lucid interval, only to descend suddenly and rapidly into unconsciousness later. The lucid interval, which depends on the extent of the injury, is a key to diagnosing epidural hemorrhage. If the patient is not treated with prompt surgical intervention, death is likely to follow (Caroline). TreatmentAs with other types of intracranial hematomas, the blood may be aspirated surgically to remove the mass and reduce the pressure it puts on the brain (McCaffrey, 2001). The hematoma is neurosurgicallyevacuated through a burr holeor craniotomy. The diagnosis of epidural hematoma requires a patient to be cared for in a facility with a neurosurgeon on call to decompress the hematoma if necessary and stop the bleed by ligating the injured vessel branches.
See also
External linksEmedicine page on epidural hematoma References
Categories: Neurotrauma| Neurology
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