to car accidents, assaults, or falls. They are often caused by acceleration-deceleration trauma and transverse forces. Epidural hematoma commonly results from a blow to the side (temporal bone) of the head. The pterion region, which overlies the middle meningeal artery, is relatively weak and prone to injury. Only 20 to 30% of epidural hematomas occur outside the region of the temporal bone. The brain may be injured by prominences on the inside of the skull as it scrapes past them. Epidural hematoma is usually found on the same side of the brain which was impacted by the blow, but on very rare occasions it can be due to a contrecoup injury. A "heat hematoma" is an epidural hematoma caused by severe thermal burn, causing contraction and exfoliation of the dura mater and exfoliate from the skull, in turn causing exudation of blood from the venous sinuses. The hematoma can be seen on autopsy as brick red, or as radiolucent on CT scan, because of heat-induced coagulation of the hematoma. Pathophysiology The break of the temporal bone causes bleeding from the middle meningeal artery, hence epidural bleeding is often rapid as arteries are high-pressure flow. In 10% of cases, however, it comes from veins and can progress more slowly. A venous hematoma may be acute (occurring within a day of the injury and appearing as a swirling mass of blood without a clot), subacute (occurring in 2–4 days and appearing solid), or chronic (occurring in 7–20 days and appearing mixed or lucent). In adults, the temporal region accounts for 75% of cases. In children, however, they occur with similar frequency in the occipital, frontal, and posterior fossa regions. Epidural bleeds from arteries can grow until they reach their peak size 6–8 hours post-injury, spilling 25–75 cubic centimeters of blood into the intracranial space. As the hematoma expands, it strips the dura from the inside of the skull, causing an intense headache. It also increases intracranial pressure, causing the brain to shift, lose blood supply, be crushed against the skull, or herniate. Larger hematomas cause more damage. Epidural bleeds can quickly compress the brainstem, causing unconsciousness, abnormal posturing, and abnormal pupil responses to light. Diagnosis Diagnosis is typically by CT scan or MRI. MRIs have greater sensitivity and should be used if there is a high suspicion of epidural hematoma and a negative CT scan. Differential diagnoses include a transient ischemic attack,