Partial seizures begin with an abnormal burst of electrical activity from a restricted brain area. Most partial seizures arise from the temporal or frontal lobes. Head injury, brain infections and problems in the way the brain developed are common causes of this seizure in childhood and adolescence. Often, no cause or family history of epilepsy can be identified. Partial seizures are divided into two main types, depending on whether consciousness is fully preserved.
- During simple partial seizures the person is alert, able to respond to questions or commands, and can remember what occurred during the seizure.
- During complex partial seizures, the ability to pay attention or to respond to questions or commands is impaired to some degree. Often, there is no memory of what happened during all or part of the seizure.
Simple Partial Seizures
These can cause incredibly diverse symptoms and can be difficult to diagnose unless they also affect a person’s awareness or include convulsive movements. For example:
- Iisolated abdominal (stomach) discomfort from a partial seizure is likely to be attributed to a gastrointestinal or anxiety disorder.
- Tingling in the little finger that spreads to the forearm may come from a seizure, migraine or nerve disorder.
Motor seizures that cause jerking or stiffness are most likely to be recognized. Some partial motor seizures cause weakness of one or more body parts, including the vocal apparatus, which affects the ability to speak.
Sensory Seizures
They most often cause hallucinations, or episodes that are not really happening. The hallucinations may affect only one area of the body or environment, or spread to other areas. There also may be an illusion or the distortion of a true sensation. Hallucinations and illusions can involve all types of sensations— touch, smell, taste, vision, hearing and vestibular (floating or spinning feeling).
Autonomic Seizures
These cause changes in nervous centers that automatically controls bodily functions (e.g., strange or unpleasant abdominal sensation, increased heart rate). The area of the brain that controls emotions (limbic region) strongly influences autonomic activity. This is why strong emotions are associated with changes in heart rate and breathing, feelings in the stomach or chest and why we say things such as, “I just have this feeling in my gut.” When partial seizures arise from limbic areas of the temporal or frontal lobe, autonomic changes are common.
Psychic Seizures
They cause changes in the brain that affect how we think, feel and experience things. They can affect language function, perception and memory (e.g., Deja Vu) or cause sudden emotional feelings (e.g., fear or sadness). Other symptoms may include feeling as if one is not one’s self (depersonalization) or feeling as if the world is not real, or as if one is in a dream (derealization).
Complex Partial Seizures
During these types of seizures the person typically stares and is either unable to respond or responds incompletely. Automatic movements (automatisms) occur in most complex partial seizures and can involve the mouth and face (lip smacking, chewing, tasting and swallowing movements), hands and arms (fumbling, clasping movements), vocalizations (grunts, repetition of words or phrases), or more complex acts (walking, running). These seizures usually last from 30 seconds to two minutes. Auras (simple partial seizures) often occur in the beginning and are actually the start of the seizure. After the seizure, people are usually tired and confused for 15 minutes or so and may not remember what happened during the event.
Secondarily Generalized Seizures
It begins in one area but spread to become a tonicclonic seizure. Secondarily generalized seizures occur in more than 30% of children and adults with partial epilepsy. People may or may not recall an aura, and witnesses may first observe a complex partial seizure that goes into the tonicclonic seizure. A secondarily generalized tonicclonic seizure may be difficult to distinguish from a primary generalized one, especially if it is not witnessed or occurs during sleep (most convulsive seizures in sleep begin as partial seizures). The EEG is very helpful in determining the type of seizure, while the MRI or other brain scans can help look for possible causes.