Epilepsy Definition | What Is Epilepsy
Seizure is the transient occurrence of signs and/or symptoms due to abnormal, excessive,
or synchronous neuronal activity in the brain. Signs or symptoms may include alterations of
consciousness, motor, sensory, autonomic, or psychic events. Epilepsy is a condition
characterized by the occurrence of two or more seizures that are not acutely provoked by
other illnesses or conditions. Medications control rather than curing the seizure disorder. Adherence to the medication regimen is important.
Classification of Epileptic Seizures | Types of Epilepsy
Epileptic seizures are classified as either focal or generalized, based on how the abnormal brain activity begins.
[I] Focal or Partial Seizures:
When seizures appear to result from abnormal activity in just one area of brain, they are called focal (partial) seizures. These seizures fall into two categories.
- (i) Simple focal seizures: These seizures do not result in loss of consciousness. They may alter emotions or change the way things look, smell, feel, taste or sound. They may also result in involuntary jerking of a body part, such as an arm or leg, and spontaneous sensory symptoms such as tingling, dizziness and flashing lights.
- (ii) Complex partial seizures: Complex partial seizures are characterized by focal seizure activity accompanied by a transient impairment of the patient’s ability to maintain normal contact with the environment. The patient is unable to respond appropriately to visual or verbal commands during the seizure and has impaired recollection or awareness of the ictal phase. The seizures frequently begin with an aura (i.e., a simple partial seizure) that is stereotypic for the patient.
- (iii) Dyscognitive focal seizures: These seizures alter consciousness or awareness
and may cause to lose awareness for a longer period of time. Dyscognitive focal seizures often result in staring and purposeless movements such as hand rubbing, chewing, swallowing or walking in circles.
[II] Generalized Seizures (Convulsive or Non-convulsive): Seizures that appear to involve all areas of the brain are called generalized seizures. Six types of generalized seizures exist.
- (i) Absence seizures (Petit Mal): Petit Mal or Absence seizures are characterized by staring and subtle body movement. These seizures can cause a brief loss of awareness.
- (ii) Tonic seizures: Tonic seizures cause stiffening muscles. These seizures usually affect muscles in back, arms and legs and may cause to fall to the ground.
- (iii) Clonic seizures: Clonic seizures are associated with rhythmic, jerking muscle
movements. These seizures usually affect the neck, face and arms.
- (iv) Myoclonic seizures: These usually appear as sudden brief jerks or twitches of arms and legs.
- (v) Atonic seizures: Atonic seizures, also known as drop seizures, because a loss of muscle control, which may result in suddenly collapse or fall down.
- (vii) Tonic-clonic seizures (Grand Mal): Tonic-clonic seizures are characterized by a loss of consciousness, body stiffening and shaking, and sometimes loss of bladder control or biting tongue. Status epilepticus is defined as either continuous seizures lasting at least for 5 minutes, or two or more discrete seizures between which there is incomplete recovery
of consciousness. Febrile seizures occur in upto 8% of children between 6 months and 6 years of age. Long term treatment or prophylaxis for simple febrile seizures is not recommended
Unclassified epileptic seizures: Not all seizure types can be classified as partial or generalized. This appears to be especially true of seizures that occur in neonates and infants. The distinctive phenotypes of seizures at these early ages likely result, in part, from differences in neuronal function and connectivity in the immature versus mature CNS.
Epidemiology of Epilepsy Seizures
There are over 2.5 million people diagnosed with epilepsy every year. Epilepsy is one of the most common serious neurological disorders affecting about 65 million people globally. It affects 1% of the population by age 20 and 3% of the population by age 75. It is more common in males than females with the overall difference being small. Most of those with the disease (80%) are in the developing world.
Epilepsy is usually present in childhood or adolescence but may occur for the first time at any age. About 5% of the population suffers a single seizure at some time. About 0.5-1% of the population have recurrent seizure epilepsy. About 70% patients are well controlled with drugs (prolonged remissions) and 30% epilepsy patients are at least partially resistant to drug treatments
Intractable Epilepsy: It is a symptom of numerous disorders, but in the majority of sufferers the cause remains unclear despite careful history taking, examination and investigation.
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