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.
Grading of hepatic encephalopathy categorizes it in clinical stages of stepwise worsening. The description of each grade varies somewhat in the literature, but differences between adjacent grades are clear enough to be helpful in clinical practice, although neurologic descriptors are sparse. One study showed that for patients who become comatose, the Full Outline of Unresponsiveness (FOUR) score is more discriminating than the West Haven grading system because it includes brain-stem and respiration assessment, which are not further differentiated in the West Haven system.