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.
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.
Treatment and medication Rarely can an underlying cause of epilepsy be found in which treatment results in a cure. Rather, antiepileptic drugs are employed to prevent the seizure from occurring. Diagnosing the type of epilepsy is crucial in determining which drug to use. For example, ethosuximide is extremely effective in absence, but useless in the partial epilepsies, some patients with medically intractable partial epilepsy can benefit from surgical removal of selected areas in the brain.
Prognosis Most patients with primary generalized epilepsy can expect to lead productive lives, whereas, one third of the patients with partial epilepsy will suffer social and economic hardships. In general the patients need to be a bit more careful about their lifestyle. Get enough sleep, not drink too much alcohol and never do drugs