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. […]
Category Archives: 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.
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 […]
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 […]
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 […]
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 […]
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 […]
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 […]
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 […]
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 […]
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 […]
