The human ability to form sentences, speak, and understand the spoken word is controlled by a specific location within the brain. In most people who are right handed, speech and language are controlled in the left hemisphere of the brain. Those who are left-handed have their speech centers in the right hemisphere.

Any condition that damages the language centers of the brain can cause aphasia.

Causes of aphasia include:

• Stroke
• Head injury
• Brain tumor
• Brain aneurysm
• Arteriovenous malformation in the brain