55. Extensive right-sided cerebral infarction (left side of picture) demonstrated by unenhanced CT scan, performed 4 days after the onset of stroke. There is no evidence of hemorrhage. High-quality CT scanners allow diagnosis of cerebral infarction within 6-8 hours of onset.
56. Cerebral embolism in a patient following cardiac surgery, demonstrated by unenhanced CT scan. The open arrowhead points to a high-density embolus within the distal right internal carotid artery; the filled arrowhead points to a similar embolus in the right middle cerebral artery. There is extensive hypodensity in the right middle cerebral artery distribution, reflecting an extensive area of infarction.
57. Right-sided facial palsy resulting from stroke. The patient also had right hemiplegia and complete aphasia. The signs are those of upper motor neuron lesion. The limbs are at first flaccid and areflexic, but after a variable period the reflexes recover and become exaggerated, and an extensor plantar response appears. Weakness in the face and elsewhere may recover gradually over a variable period of time.
58. Loss of postural stability is common following stroke. When the non-dominant hemisphere is involved, walking apraxia and loss of postural control are usually apparent. The patient is unable to sit upright and tends to fall sideways. Appropriate support with pillows or cushions should be provided.
59.
60.
61.
62.
63.
64.
65.
66.
67. Hemorrhagic cerebral infarction demonstrated by unenhanced CT scan one day after the onset of stroke. Note the high-density hemorrhage within the low density of the edematous, infarcted region in the right hemisphere. Hemorrhage is evident from its onset on CT scanning.
68.
69.
70. Right cavernous carotid aneurysm (arrowed), shown on coronal MRI. The signal void at the periphery of the aneurysm represents flowing blood, while the intensity in the central portion may represent either a clot or slowly flowing blood. MRI may demonstrate aneurysms clearly, but is much less successful than CT at demonstrating the presence or absence of blood in the subarachnoid space.
71. Berry aneurysm on the anterior communicating artery (a). The angiogram also shows that the anterior cerebral artery (b) is in spasm.
72.
73.
74.
75. Subarachnoid hemorrhage from an anterior communicating artery aneurysm. This uncontrasted CT scan shows areas of increased density representing blood in the interhemispheric fissure (arrows) and the septum pellucidum (arrowheads). A lesser amount of blood is present in the sylvan fissures and the perimesencephalic cistern.
76.
77.
78. Left parietal arteriovenous malformation, shown in an anteroposterior view of an internal carotid angiogram. Bleeding from AVM is usually less severe than that from aneurysms, but their size may lead to other symptoms including epilepsy.
