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Based on the type of behavior and brain activity, seizures are divided into
two broad categories: generalized and partial (also called local or focal).
Classifying the type of seizure helps the doctor in planning the type of
treatment.
Generalized epilepsy is produced by electrical impulses that are recorded
simultaneously from throughout the entire brain, whereas partial seizures are
produced (at least initially) by electrical impulses that are generated in a
relatively small part of the brain. The part of the brain generating the
seizures is sometimes called the focus. The most common types of seizures are
listed below:
Generalized Epilepsy--
Electrical impulses generated in the entire brain
Symptoms
1. "Grand Mal" or Generalized tonic-clonic
Unconsciousness, convulsions, muscle rigidity
2. Absence
Brief loss of consciousness
3. Myoclonic
Sporadic (isolated) and brief, jerking movements
4. Clonic
Repetitive, jerking movements
5. Tonic
Muscle stiffness, rigidity
6. Atonic
Loss of muscle tone
Partial (focal) Epilepsy--
Electrical impulses generated in a small (focal) area of the brain
Symptoms
1. Auras (awareness is retained)
a. Simple Motor
b. Simple Sensory
c. Simple Psychological
a. Jerking, muscle rigidity, spasms, head-turning
b. Unusual sensations affecting either the vision, hearing, smell, taste or
touch
c. Memory or emotional disturbances
2. Complex
(Impairment of awareness)
Automatisms such as lip smacking, chewing, fidgeting, walking, and other
repetitive, involuntary but coordinated movements
3. Partial seizure with secondary generalization
Symptoms that are initially associated with a perseveration of
consciousness that then evolve into a loss of consciousness and
convulsions
Manifestations of generalized epilepsy
Generalized epilepsy can manifest itself in several ways. The most common
and dramatic, and therefore the most well known, is the generalized convulsion,
also called the grand-mal seizure. In this type of seizure, the
patient loses consciousness and usually collapses. The loss of consciousness is
followed by generalized body stiffening (called the "tonic" phase of
the seizure) for 30 to 60 seconds, then by violent jerking (the "clonic"
phase) for 30 to 60 seconds, after which the patient goes into a deep sleep (the
"postictal" or after-seizure phase). During grand-mal seizures,
injuries and accidents might occur, such as tongue biting and urinary
incontinence.
Absence seizures cause a short loss of consciousness (just a few seconds)
with few or no symptoms. The patient, most often a child, typically interrupts
an activity and stares blankly. These seizures begin and end abruptly and might
occur several times a day. Patients are usually not aware that they are having a
seizure, except that they might be aware of "losing time."
Myoclonic seizures consist of sporadic jerks, usually on both sides of the
body. Patients sometimes describe the jerks as brief electrical shocks. When
violent, these seizures might result in dropping or involuntarily throwing
objects.
Clonic seizures are repetitive, rhythmic jerks that involve both sides of the
body at the same time.
Tonic seizures are characterized by stiffening of the muscles.
Atonic seizures consist of a sudden and general loss of muscle tone,
particularly in the arms and legs, which often results in a fall.
Focal (partial) epilepsy
Focal epilepsy can also manifest itself in various ways. Most neurologists
divide the manifestations of focal epilepsy into simple, complex partial
seizures, and those that evolve into secondary generalized seizures. The
difference between simple and complex seizures is that during simple partial
seizures, the patient retains awareness; but during complex partial
seizures, the patient loses awareness.
Simple partial seizures could be further subdivided into four categories
according to the nature of their symptoms: motor, sensory, autonomic, or
psychological. Motor symptoms include movements such as jerking and stiffening.
Sensory symptoms caused by seizures involve unusual sensations affecting any of
the five senses (vision, hearing, smell, taste, or touch). When simple partial
seizures cause sensory symptoms only (and not motor symptoms), they are called
"auras."
The only common autonomic symptom (a symptom that affects a part of the body
that is beyond voluntary control; for example, heart muscle activity) is a
peculiar sensation in the stomach that is experienced by some patients with a
type of epilepsy called temporal lobe epilepsy. Finally, simple partial seizures
with psychological symptoms are characterized by various experiences involving
memory (the sensation of deja-vu), emotions (such as fear or pleasure), or other
complex psychological phenomena.
Complex partial seizures, by definition, include impairment of awareness.
Patients seem to be "out of touch," "out of it," or
"staring into space" during these seizures. There might also be some
"complex" symptoms called automatisms. Automatisms consist of
involuntary but coordinated movements that tend to be purposeless and
repetitive. Common automatisms include lip smacking, chewing, fidgeting, and
walking.
The third kind of partial seizure is one that begins as a focal seizure and
evolves into a generalized convulsive ("grand-mal") seizure.
Most patients with focal epilepsy have simple partial, complex partial, and
secondarily generalized seizures. Some patients with focal epilepsy might also
have staring spells. In about two-thirds of patients with focal epilepsy,
seizures can be controlled with medicines. Partial seizures that cannot be
treated with medicines can often be treated surgically.
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