![]() This property allows the ASDH to outline the entire brain hemisphere. ASDH is most commonly unilateral, but some patients may harbor bilateral ASDHs.Īn ASDH, by definition, is located between the dura mater and subarachnoid mater thus, the expanding hematoma is not limited by the sutures of the calvarium, but rather by the dural sinuses. On noncontrast CT, an expanding ASDH will appear as an intensely white, crescent-shaped mass situated between the brain parenchyma and the inner table of the skull. For patients who remain conscious after an accident with an associated high propensity for ASDH formation, it is important that the physician maintains a high index of suspicion for hematoma expansion and neurologic deterioration.Īs is the case for all patients with a potential traumatic brain injury (TBI), it is imperative to obtain a head CT scan without contrast in order to adequately detect an expanding hematoma. Some patients may remain conscious after their injury, but their condition subsequently deteriorates as the hematoma enlarges with or without signs of herniation. However, the absence of these findings does not necessarily imply a good prognosis because brain parenchymal contusion and/or laceration can still lead to significant morbidity and mortality. The signs and symptoms of transtentorial or uncal herniation may be present and are dependent on the extent of the enlarging hematoma. In contrast with EDH, there is often no lucid interval for a patient with ASDH. Due to the impact of trauma, the patient is often in a comatose state with a Glasgow coma scale (GCS) score ≤8, necessitating the dispatch of emergency personnel and rapid transport of the patient to a trauma center. This chapter primarily deals with ASDHs.Īn ASDH occurs after a traumatic event involving acceleration-deceleration forces, rather than the blunt trauma and skull fracture that are typically associated with EDH. The mechanisms and rates of hematoma expansion for acute and chronic SDHs and their corresponding outcomes are different. Bleeds in patients who present after 72 hours of injury are considered either subacute or chronic, depending on their timing and the computed tomography (CT) findings. ![]() An ASDH is defined as a bleed occurring within the subdural space that occurred within 72 hours prior to the patient’s presentation. A laceration of the brain resulting in an expanding hematoma is the more ominous of the two because it implies significant parenchymal injury.Ī distinction must be made between a chronic subdural hematoma and an acute subdural hematoma. Thus, the ASDH has two potential sources of hematoma formation: the brain parenchyma and the parasagittal bridging veins. Second, with ASDH, there is an increased likelihood of injury to the underlying brain parenchyma. Diffuse axonal injury is common among patients suffering from ASDH. This phenomenon results in significant shear vectors affecting the brain parenchyma and its tethered and vulnerable venous system. The typical scenario for an ASDH involves an acceleration-deceleration shear injury (e.g., a motor vehicle accident, fall, or whiplash injury) during which the brain’s inertia continues to move the brain after the body and skull have stopped moving. First, the force of trauma or impact necessary to cause an ASDH is significantly greater than that required for an EDH. The difference in outcome between EDH and ASDH arises from two discrete but related etiologies. In contrast with a treatable epidural hematoma (EDH), an acute subdural hematoma (ASDH) carries a high risk of morbidity and mortality, even with timely decompression. ![]()
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