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Category: Brain Imaging

The following section will be dedicated to brain imaging relevant to rehabilitation. Emphasis is placed on the imaging of ischemic and hemorrhagic strokes, head trauma, and common degenerative diseases. The imaging of brain neoplasms and infections will not be covered in this section, as it is beyond the scope of this text.

Contusions and Intraparenchymal Hemorrhage

Contusions and Intraparenchymal Hemorrhage

Focal parenchymal injuries such as contusions and intraparenchymal hemorrhage usually develop as a result of contact of the brain with the osseous walls of the cranial cavity. The coup-type injuries occur at the point of contact, and the contrecoup injuries occur on the opposite side of the brain. Contusions often occur in areas where the walls of the cranial cavity are irregular, such as the anterior and middle cranial fossae. Therefore, frontal and temporal lobe contusions are common as the…

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Subdural Hematoma

Subdural Hematoma

Subdural hematoma is most commonly caused by acceleration- deceleration shearing stresses that rupture the bridging veins that extend from the movable brain to the fixed dural venous sinuses. The blood accumulates in a pre-existing but essentially volumeless subdural space. Normally, the pressure of the CSF holds the arachnoid in contact with the dura, thereby creating a real interval that is without significant volume. Because the subdural space is a real space surrounding all external surfaces of the brain, subdural hemorrhage…

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Epidural Hematoma

Epidural Hematoma

Epidural hematoma is caused by tears of the middle meningeal artery or vein, or of a dural venous sinus. The blood accumulates in the interval between the inner table of the calvarium and the dura by gradually stripping the dura from its bony attachment. CT visualizes the epidural hematoma as a well-localized biconvex radiodense mass (83) (Fig. 6-88). It is commonly, though not invariably, associated with a skull fracture. It causes mass effect upon the adjacent brain parenchyma with effacement…

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Subarachnoid and Intraventricular Hemorrhage

Subarachnoid and Intraventricular Hemorrhage

Subarachnoid and intraventricular hemorrhage can be spontaneous, as in the case of a bleeding aneurysm or arteriovenous malformation, or secondary to trauma. CT is the imaging modality of choice for evaluating these types of hemorrhages because it detects the hemorrhage from its onset as a hyperdensity. However, subarachnoid hemorrhage is not as radiodense as epidural or subdural hemorrhage because the blood will be diluted by CSF. Unless blood replaces at least 70% of the CSF, the subarachnoid hemorrhage remains isodense…

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Hemorrhagic Stroke Imaging

Hemorrhagic Stroke Imaging

A stroke is considered truly hemorrhagic if blood is found within the first 24 hours after initial symptoms. When blood is noted after this time, it is usually hemorrhagic transformation of an ischemic stroke, which is due to reperfusion injury. Hypertension is the most common cause of intraparenchymal hemorrhage, which can also be caused by ruptured aneurysm, arteriovenous malformation, and more rarely, by infarction, neoplasms, blood coagulation defects, and cerebral arteritis (81). Common hemorrhage sites include the putamen and the…

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Ischemic Stroke Imaging

Ischemic Stroke Imaging

Cerebral ischemia can be produced by thrombosis of large extracranial or small intracerebral vessels, emboli originating from atherosclerotic plaques or thrombi within more proximal vessels or the heart. In addition, decreased perfusion of systemic origin, such as shock, decreased cardiac output, or respiratory failure can also cause cerebral ischemia with or without infarction, Cerebral ischemia can be completely or partially reversible, or irreversible leading to neuronal cell death, commonly known as infarction. Once blood flow to the brain is decreased…

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Age-Related Changes and Dementing Disorders

Age-Related Changes and Dementing Disorders

The aging brain is characterized on CT or MRI as demonstrating volume increases in both cortical sulci and ventricles (Fig. 6-96). T2-weighted MR images also frequently display small areas of hyperintense signal along the anterolateral margins of the anterior horns of the lateral ventricles. These changes may or may not be associated with neurologic findings. FIGURE 6-96. A case of cortical atrophy of aging as seen by CT. Enlargement of cortical sulci and sylvian fissures (arrows) with ex vacuo ventricular…

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White Matter Diseases

White Matter Diseases

White matter diseases can be divided into demyelinating diseases, in which the white matter is normally formed and then pathologically destroyed, and dysmyelinating diseases, in which there is usually a genetically determined enzymatic disorder that interferes with the normal production or maintenance of myelin (86). The enzymatic disturbances are relatively rare; therefore, their imaging characteristics will not be described. The most common of the demyelinating disorders is multiple sclerosis (MS). The demyelinating plaques of MS are better visualized by MRI…

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Complications of Brain Injury

Complications of Brain Injury

Brain injuries may be accompanied by a number of late or long-term complications. These secondary brain injuries include cerebral herniations, which may occur under the falx cerebri or through the tentorium. Herniations can cause compression of adjacent brain substance or vessels, with the production of secondary signs and symptoms (Fig. 6-93). Penetrating injuries or fractures can injure nearby large or small vessels, producing thrombosis, embolism, traumatic aneurysm formation, or internal carotid–cavernous sinus fistula. Basal skull fractures involving the dura and…

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Diffuse Brain Injuries

Diffuse Brain Injuries

Diffuse brain injuries include diffuse axonal injury, diffuse cerebral swelling, and edema. Diffuse axonal injury is produced by high shearing stresses that occur at different parts of the brain, including at the gray matter-white matter interface. These shearing stresses cause axonal stretching commonly involving the corpus callosum, anterior commissure, and upper brain stem. Blood vessels may or may not be disrupted. When vessels are uninterrupted, the scattered small areas of edema are best demonstrated by T1-weighted MR images as slightly…

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