EPILEPSY

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: 

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. 

(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. 

Causes 

Epilepsy has no identifiable cause in about half of those, with the condition. In about half the people with epilepsy, the condition may be traced to various factors. 

Genetic Influence: 

Some types of epilepsy, which are categorized by the type of seizure experience, run in families. In these cases, it is likely that there is a genetic influence. 

Head trauma: Head trauma that occurs due to a car accident or other traumatic injury can cause epilepsy. 

Brain conditions: Brain conditions that result in damage to the brain, such as brain tumors or strokes, also can cause epilepsy. Stroke is a leading cause of epilepsy in adults older than age 35. 

Infectious diseases: Infectious diseases, such as meningitis, AIDS and viral encephalitis, can cause epilepsy. 

Prenatal injury: Before birth, babies are sensitive to brain damage that could be caused by several factors, such as an infection in the mother, poor nutrition or oxygen deficiencies. This brain damage can result in epilepsy or cerebral palsy. 

Developmental disorders: Epilepsy can sometimes be associated with develop- mental disorders, such as autism and neurofibromatosis. 

Stroke and other vascular diseases: 

Stroke and other blood vessel (vascular) diseases can lead to brain damage that may trigger epilepsy. 

Dementia:Dementia can increase the risk of epilepsy in older adults.

Symptoms 

Sometimes, symptoms occur before the seizure takes place. These include: 

• A sudden feeling of fear or anxiousness,

• A feeling of being sick to your stomach,

• Dizziness,

• A change in vision,

• A jerky movement of the arms and legs that may cause you to drop things,

• An out of body sensation,

• A headache.
Symptoms that indicate a seizure is in progress include:

• Losing consciousness, which is followed by confusion,

• Having uncontrollable muscle spasms,

• Drooling or frothing at the mouth,

• Falling,

• Having a strange taste in mouth,

• Clenching teeth,

• Biting of tongue,

• Having sudden, rapid eye movements,

• Making unusual noises, such as grunting,

• Losing control of bladder or bowel function,

• Having sudden mood changes.

Pathophysiology 

Mechanisms of Seizure Initiation and Propagation: 

The hypersynchronous discharges that occur during a seizure may begin in a very discrete region of cortex and then spread to neighbouring regions. Seizure initiation is characterized by two concurrent events: 1) high-frequency bursts of action potentials, and 2) hypersynchronization of a neuronal population. 

The bursting activity resulting from the relatively prolonged depolarization of the neuronal membrane is due to influx of extracellular Ca++, which leads to the opening of voltage- dependent Na+ channels, influx of Na+, and generation of repetitive action potentials. The subsequent hyperpolarizing after potential is mediated by GABA receptors and Cl− influx, or by K+ efflux, depending on the cell type. 

Seizure propagation, the process by which a partial seizure spreads within the brain, occurs when there is sufficient activation to recruit surrounding neurons. This leads to a loss of surrounding inhibition and spread of seizure activity into contiguous areas via local cortical connections, and to more distant areas via long association pathways such as the corpus callosum.