An epileptic seizure is the body and brain's response to sudden bursts of abnormal electrical activity in the brain. A focal seizure is an epileptic seizure that begins in a small area of the brain.

There are three types of focal seizures:

• Focal aware seizures (sometimes called simple partial seizures). These seizures briefly disrupt a person's speech, movement, vision, or sense of smell or taste but do not affect a person's level of consciousness.
• Focal impaired awareness seizures (sometimes called complex partial seizures). This type of seizure alters a person's level of consciousness and makes the person stare into space. The person may notice a strange smell, taste, or feeling (aura) at the beginning of a seizure.
• Focal to bilateral tonic-clonic (sometimes called partial seizures with secondary generalization). These seizures begin like the other types of focal seizures but then spread (generalize) to the rest of the brain. This leads to epileptic seizures (tonic-clonic seizures) in which the person's muscles stiffen and jerk.

Focal seizures are the most common type of seizure in adults. They can often be controlled with medicine or surgery.