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2Brain

unless associated with significant brain swelling.

CT is the first and often only investiga-tion in the emergency setting; MRI is moresensitive for detection of small hemorrhages,which can be important for accurate progno-sis. Contusions may be subtle or impercep-tible immediately following an acute injury.Delayed hemorrhage, occurring at 12 to 48hours, is known as posttraumatic apoplexyand reflects hypocoagulability that often de-velops following head trauma and resolutionof acute swelling that serves to tamponadesmall vascular injuries (Fig. 2.11).

◆Cerebral Contusion

Cortical contusions result when the brainimpacts upon the irregular contours of theorbital roofs, petrous ridges, and sphe-noid wings in acute acceleration injury.As a result, most contusions are locatedin the cortex and immediate subcorticalwhite matter of the inferior frontal lobes,anterior or inferior temporal lobes, pos-terior cerebellum, dorsal occipital lobes,and frontal and parietal convexities. Theymay be either coup or contrecoup in loca-tion, although the latter are more com-mon. Contusions typically carry a betterprognosis than diuse axonal injury (DAI)

Fig. 2.11a–ea Hemorrhagic right temporal contusion. Right temporal hematoma with adjacent traumatic subarach-noid hemorrhage. Blood within the left sphenoid sinus indicates associated central skull base fracture.b Nonhemorrhagic right and hemorrhagic left contusions. Low-attenuation edema within the right tem-poral lobe and hematoma surrounded by vasogenic edema in the left temporal lobe. Generalized brain swelling with cisternal eacement and traumatic subarachnoid hemorrhage in the interpeduncular and quadrigeminal plate cisterns.

c,dBilateral contusions. Bilateral temporal hemorrhagic and left inferior frontal nonhemorrhagic contusions.e,fRight frontal and left parietal vertex hemorrhagic contusions. Associated right frontal subdural hema-toma, traumatic subarachnoid hemorrhage, and right sided swelling with convexity sulcal eacement.