Imaging the Brain

Brain TumorsFocal deficits, such as hemiparesis, hemianopia, or seizures, develop in many patients with primary or metastatic brain tumors. The clinical signs depend on the location of the tumor and reflect impaired regional cerebral function. Frequently, however, the initial symptoms result only from mass effect, local pressure, and distortion of adjacent structures. These symptoms consist of headache, irritability, emotional lability, forgetfulness, drowsiness, and lethargy. Most brain tumors disrupt the blood–brain barrier, allowing leakage of electrolytes, water, and protein into neuronal tissue.For initial diagnostic screening in patients with known cancers elsewhere in the body or in patients with atypical . . .