In an intracranial, or cerebral, aneurysm, a weakness in the wall of a cerebral artery causes localized dilation. Cerebral aneurysms usually arise at an arterial junction in the circle of Willis, the circular anastomosis connecting the major cerebral arteries at the base of the brain.

Cerebral aneurysm

Brain tumors are abnormal growths that develop after transformation of cells within the brain, cerebral vasculature, or meninges. They're usually referred to as benign or malignant.

Brain Tumor

Arteriovenous Malformation

Arteriovenous malformations (AVMs) are tangled masses of thin-walled, dilated blood vessels between arteries and veins that aren't connected by capillaries.

Amyotrophic lateral sclerosis

Commonly called Lou Gehrig's disease, amyotrophic lateral sclerosis (ALS) is the most common of the motor neuron diseases causing muscular atrophy.

Alzheimer's disease

Alzheimer's disease is a progressive degenerative disorder of the cerebral cortex, especially the frontal lobe.