Arteriovenous malformations of the brain are congenital anomalies of the blood vessels that are derived from maldevelopment of the capillary network, allowing direct connections between cerebral arteries and veins. The most common presenting symptoms are cerebral hemorrhage and seizures. Focal neurologic deficits and headaches may develop independent of cerebral bleeding. As a result of the widespread use of brain imaging, arteriovenous malformations are increasingly being discovered incidentally.
Brain
Advantages of Surgery and Stereotactic Radiosurgery for Brain Metastases
Stereotactic radiosurgery is an appropriate form of therapy for patients who have one to four brain metastases, no larger than 4 cm in diameter, from metastatic cancer. It appears to be effective for all types of primary tumors, even those that have been considered to be resistant to conventional radiation therapy.
Criteria for Brain Death in Adults and Children
Physicians, health care workers, members of the clergy, and laypeople throughout the world have accepted fully that a person is dead when his or her brain is dead.
Diagnostic Criteria of Infarction in MRI of the Brain in Acute Stroke
Acute: Subtle low signal (hypointense) on T1, often difficult to see at this stage, and high signal (hyperintense) on spin density and/or T2-weighted and proton density-weighted images starting 8 h after onset; should follow vascular distribution. Mass effect maximal at 24 h, sometimes starting 2 h after onset, even in the absence of parenchymal signal changes. No parenchymal enhancement with paramagnetic contrast agent. Territorial intravascular paramagnetic contrast enhancement of “slow-flow” arteries in hyperacute infarcts; at 48 h, parenchymal and meningeal enhancement can be expected.
Diagnostic Criteria of Infarction in CT Imaging of the Brain in Acute Stroke
Computed tomography (CT) is widely used for early evaluation of acute strokes. Most importantly, CT excludes acute hemorrhage or other diseases mimicking ischemia.
Diagnostic Criteria of Hemorrhage in MRI of the Brain
The imaging characteristics of blood on MRI can be variable: