What is Epilepsy?
Epilepsy is a condition of recurring seizures. A seizure is an abnormal firing of cerebral neurons, which may or may not have a clinical manifestation. We are familiar with seizures, where people fall down and shake all over.
Epilepsy is not a single disorder, but covers a wide spectrum of problems characterized by unprovoked, recurring seizures that disrupt normal neurologic functions. Epileptic seizures occur when a group of nerve cells in the brain (neurons) become activated simultaneously, emitting sudden and excessive bursts of electrical energy. This hyperactivity of neurons can occur in various locations in the brain and, depending on the location, have a wide range of effects on the sufferer from brief moments of confusion to minor spasms to loss of consciousness.
The nerves themselves may be damaged or problems might occur in neurotransmitters (die chemicals that act as messengers between nerve cells). The neurotransmitter, gamma aminobutyric acid (GABA) seems to be particularly important in suppressing seizures. Experiments also suggest that deficiencies in a receptor of the neurotransmitter serotonin may help promote epileptic seizures.
Definition of Epilepsy: Epilepsy can be defined as a group of disorders characterized by abnormal electrical activity in the brain leading to altered behavior which may manifest as a change in a person’s consciousness, movement, or actions. These physical changes are called epileptic seizures. Epilepsy is therefore sometimes called a seizure disorder. Epilepsy affects people in all nations and of all races at every age.
It must be emphasized that every seizure may not be an indication of an epileptic disorder. Many times young children with high fever go into convulsive seizures. These are called as febrile convulsions & do not occur throughout life. Similarly seizures caused due to metabolic imbalances, drug interactions or alcohol/narcotic withdrawals are also not classified as epilepsy. Moreover a single seizure does not mean that the person has epilepsy.
Classification: The two categories of seizures are generalized and partial. Generalized seizures result due to electrical impulses from the entire brain. Partial seizures are caused by activity in a portion of the brain. The part where a seizure is triggered is called the seizure focus.
Partial Seizures: Partial means that the electrical discharge starts focally at one point in the brain, eg., the left hippocampus. If the seizure spreads to other areas of the brain, but does not interfere with consciousness, then it is termed Simple. An example of a Simple Partial Seizure is clonic activity of only the right arm. If the seizure spread involves neuronal circuits affecting consciousness, then it is termed Complex. An example of a Complex Partial Seizure is when a person stops speaking, smacks his lips and is unresponsive to verbal commands for several minutes. Afterwards he will feel tired and not remember everything about the preceding seizure. Either type of partial seizure can go on to spread sufficiently so as to result in a generalized “Grand mal” seizure. Since the seizure first started focally, we say it was a Partial Seizure (simple or complex) with secondary generalization. Partial seizures are divided into simple, complex and those seizures that evolve from partial-onset into generalized tonic-clonic seizures. The difference between simple and complex seizures is that during simple partial seizures, you retain awareness. During complex partial seizures, you lose awareness.
Primary Generalized Seizures: When the abnormal electrical discharges are bilaterally synchronous at the onset. Because these seizures are without a focal onset, there can be no “Aura”, which is a warning sign and actually represents a focal or partial seizure. There are six types of generalized seizures.
Tonic-clonic (“Grand-mal” seizure): You may lose consciousness and often collapse. The body becomes stiff and shakes, and finally, one falls into a deep sleep. Injuries such as tongue-biting can occur, or you can lose bladder control.
Absence seizure (“Petit mal” seizure): You may lose awareness and gaze blankly for a few seconds. Most often there are no other symptoms except the seizures may occur a few times everyday.
Myoclonic seizure: Your body may jerk, as if being electrocuted, from a single muscular jerk to the entire body.
Clonic seizure: Both sides of your body jerk rhythmically at the same time.
Tonic seizure: Muscles suddenly become very stiff.
Atonic or akinetic seizure: Muscles relax suddenly, which can cause a sudden fall causing injuries.
Etiology: By and large, the primary generalized epilepsies, such as absence, grand mal (tonic-clonic), and myoclonic are genetically determined and present in childhood and adolescence. The partial epilepsies are more likely to be acquired (congenital, post traumatic, infection, tumor) and present in any age.
Natural history: Although certain stimuli can increase the probability of having a seizure, their occurrence is unpredictable. Many of the patients with primary generalized epilepsy will stop having seizures as they enter adulthood (independent of treatment). Medications (anticonvulsants, antiepileptics, antiseizure are valid terms to precede the word medication or drug) help prevent seizures but do not cure the patient of his epilepsy. The partial epilepsies are the most difficult to treat.