Figure 34-2. The course of fracture lines through the base of the skull. Arrows indicate point of application and direction of force. (From Courville.)
Figure 34-3. CT of postoperative tension pneumocranium (aerocele, pneumocephalus) that caused progressive drowsiness and required removal by aspiration. The air is apparent as a very-low-density collection that compresses the right frontal lobe.
Figure 34-4. Mechanisms of cerebral contusion. Arrows indicate point of application and direction of force; dark red areas indicate location of contusion. A. Frontotemporal contusion consequent to frontal injury. B. Frontotemporal contusion following occipital injury. C. Contusion of temporal lobe because of contralateral injury. D. Frontotemporal contusion as a result of injury to opposite temporooccipital region. E. Diffuse mesial temporooccipital contusion caused by a blow on the vertex. (From Courville.)
Figure 34-5. Distribution of contusions emphasizing the frontal and frontotemporal distribution in 40 consecutive autopsy cases collected by Courville. (From Courville.)
Figure 34-6. Unenhanced axial CT showing multiple hyperdense areas of hemorrhagic contusion adjacent to bony prominences of the skull base. There is also less conspicuous subarachnoid blood along the tentorium and in the insular cisterns, typical of traumatic intracranial hemorrhage.
Figure 34-7. Unenhanced coronal CT showing small hemorrhages in the corpus callosum and midbrain that are considered part of the spectrum of diffuse axonal shearing injury.
Figure 34-8. Acute epidural hematoma. Unenhanced CT scan showing a typical lens-shaped frontal epidural clot under a torn middle meningeal artery.
Figure 34-9. Acute subdural hematoma. Unenhanced axial CT showing a hyperdense concave-shaped hematoma overlying the left temporal lobe.
Figure 34-10. Subacute subdural hematoma. Unenhanced axial CT showing an isodense concave-shaped hematoma overlying the right hemisphere. Note the effacement and compression of underlying cortical sulci and ventricles.
Figure 34-11. Unenhanced axial CT showing subdural hematomas overlying both cerebral hemispheres without shift of the ventricular system. Chronicity results in the hypodense appearance of the hematomas. The presence of some hyperdense material within the left-sided hematoma indicates more recent acute blood accumulation. The bilaterally balanced masses result in an absence of horizontal displacement, but they may cause downward compression of the upper brainstem.
In the language of neurology, the term demyelinating disease has acquired a special meaning. To define these diseases precisely is difficult, for the simple reason that there is probably no disease in which myelin destruction is the exclusive pathologic change. The generally accepted pathologic criteria of a demyelinating disease are (1) destruction of the myelin sheaths of nerve fibers with relative sparing of the other elements of nervous tissue, that is, of axons, nerve cells, and supporting structures, which are less affected; (2) infiltration of inflammatory cells, particularly in a perivenous distribution; (3) lesions that are primarily in white matter, either in multiple small disseminated foci or in larger foci spreading from one or more centers. In most of the demyelinating diseases, it has been known since the early descriptions that there is some degree of neuronal and axonal degeneration, but it is the preferential effect on myelin that defines this group of disorder. The most common and important inflammatory demyelinating disease is multiple sclerosis (MS).