Epilepsy: Types, Signs And Causes

The word epilepsy derived from Greek Word ‘Epilepsia’ which means ‘Seizure’. Epilepsy is a group of syndromes characterized by unprovoked, recurring seizure/convulsions, over time. Epilepsy is a 2 or more unprovoked seizures and convulsions in more than 24 hours apart.

The brain is the center that controls and regulates all voluntary and involuntary responses in the body. It consists of nerve cells that normally communicate with each other through electrical activity. A seizure is a sudden, uncontrolled electrical disturbance in the brain, results in changes in behaviour, movements ,feelings, and in levels of consciousness. If the person has two or more seizures or a tendency to have recurrent seizures, than it is called as epilepsy. Most seizures last from 30 seconds to 2 minutes. A seizure that lasts longer than 5 minutes is a medical emergency. A Seizure is a paroxysmal, uncontrolled electrical discharges of neurons in the brain that interrupts normal function results in episodes of abnormal motor, sensory, autonomic or psychic activity (or a combination of these). Seizure are sudden, abnormal electrical discharges from the brain that results changes in sensation, behaviour, movements, perceptions or consciousness.

TYPES

Partial/Focal seizures

Partial seizures takes place when abnormal electrical brain function occurs in one or more areas of one side of the brain. One third of the person with partial seizures may experience an aura before seizure occurs. An aura is a strange feeling either consisting of visual changes, hearing abnormalities or changes in the sense of smell.

Signs

• muscle contractions, followed by relaxation.
• one side contraction of your body.
• unusual head/eye movements.
• abdominal pain.
• rapid pulse rate
• automatisms
• sweating.
• nausea.

Partial seizure is divided into 2 categories. 1. Simple Partial Seizure 2. Complex Partial Seizure

1. Simple Partial Seizure

The seizure typically last less than 1min. These seizure do not result in loss of consciousness. Symptoms include: Sudden and unexplained feeling of joy, anger, sadness. Involuntary jerking of the part of the body such as an arm, leg. Spontaneous sensory symptoms such as tingling, vertigo, and flashing lights. Person also may hear, smell, taste, see or feel things that are not real. The person may also experience sweating, nausea, or become pale.

2. Complex Partial Seizure

In this type of seizure the person has a change in or loss of consciousness for a period of time. Commonly occur in the temporal lobe of the brain. Symptoms include: Non purposeful movements such as hand rubbing, chewing, swallowing, gagging , lip smacking, screaming, crying, laughing, running, walking in circle, . Repetitious movement such as blinking, twitching, mouth movement etc. When the person regains consciousness the person may complains of being tired or sleepy after seizure.

Generalized Seizure

Generalized seizures involve both sides of the brain and are characterized by bilateral synchronous epileptic discharges in the brain from the onset of the seizure. There is loss of consciousness. There is no warning or aura.

Types of generalized seizures include the following:

Absence or Petit mal seizure.

These seizures are characterized by an altered state of consciousness and staring episodes. Typically, the person's posture is maintained during the seizure. The mouth or face may move or the eyes may blink. The seizure usually lasts no longer than 30 seconds. When the seizure is over, the person may not recall what just occurred and acting as though nothing happened. This type of seizure is sometimes mistaken for a learning problem or behavioral problem. Absence seizures are uncommon before the age of 5 and occur more often in girls and in children. The EEG demonstrates 3 Hz spike in brain wave pattern. When untreated the seizure may occur upto 100 times a day.

Tonic clonic seizure or Grand mal seizure.

Also called as Grand Mal Seizures. This seizure is characterized by 5 distinct phases that occur. 1. The body, arms, and legs will flex (contract) for 30-40 seconds. 2. Extend (straighten out) 3. Tremor (shake) 4. Clonic period (contraction and relaxation of the muscles) . Cyanosis, excessive salivation, tongue or cheek biting, and incontinence may accompany. 5. Post ictal period. The patient usually has muscle soreness. During the post ictal period, the person may be sleepy, have problems with vision or speech, and may have a bad headache, fatigue, or body aches.

Myoclonic Seizure.

This type of seizure refers to quick movements or sudden jerking of a group of muscles or twitches of the upper body, arms, or legs. These seizures tend to occur in clusters, meaning that they may occur several times a day, or for several days in a row.

Tonic seizure.

Tonic seizures causes stiffening of the muscles, generally those in back, arms, legs, and may cause the person to fall to the ground.

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Clonic seizure.

These type of seizures are begins with loss of consciousness and sudden loss of muscle tone followed by limb jerking that may or may not be symmetric . Symptoms include rhythmic , jerking muscle contractions usually affecting the arms, neck and face.

Atonic seizure.

Also known as ‘Drop Attack’. Seizure involves either a tonic episode or a paroxysmal loss of muscle tone and begins suddenly with the person falling to the ground. Conscious usually returns once the person hits in the ground and they have the great risk of head injury.

ETIOLOGY

The exact cause of the seizure may not be known, the more common seizures are caused by the following:

In newborns and infants:

• birth trauma
• congenital problems
• fever
• metabolic or chemical imbalances
• Genetic influence

In children, adolescents, and adults:

• alcohol or drugs
• head trauma
• infection
• Developmental disorder

Other possible causes of seizures may include the following

• brain tumor
• neurological problems
• drug withdrawal
• Overdose of antidepressants and other medications
• Stroke or Transient Ischemic Attack
• Dementia such as Alzheimers diseases
• Traumatic brain injury
• Abnormal blood vessels in brain

PATHOPHYSIOLOGY

Epilepsy differs from most neurological conditions as it has no pathogenic lesion. A variety of different electrical and chemical stimuli can give rise to seizure in any normal brain. The hallmark of epilepsy is a rather rhythmic and repetitive hyper synchronous discharge of neurons either localised in an area of cerebral cortex or generalised throughout the cortex. Neurones are interconnected in a complex network in which each individual neuron is linked through synapses with hundreds of others.

A small electrical current is discharged by neurons to release neurotransmitters at synaptic levels to communicate with each other. Neurotransmitters are divided into basic categories inhibitory or excitatory therefore neuron discharge either excite or inhibit neuron connected to it. An excited neuron will activate the next neuron whereas an inhibited neuron will not. In this manner information is conveyed, transferred and processed in CNS.A normal neuron discharges repetitively at a low baseline frequency and it is the integrated electrical activity generated by the neurons of superficial layer of cortex that is recorded in normal EEG.

If the neurons are damaged , injured or suffer a chemical or metabolic insult a change in the discharge pattern may develop. In case of epilepsy, regular low frequency discharges are replaced by bursts of high frequency discharges followed by a period of inactivity. A single neuron discharging in an abnormal manner usually has no significance. It is only when a population of neurons discharge synchronously in an abnormal way an epileptic seizure may be triggered. The abnormal discharge may remain localised or it may spread to adjacent areas recruiting more neurons as it expands. It may also generalise throughout the brain via cortical and subcortical routes including collosal and thalamocortical pathways. The area from which abnormal discharge originates is known as “epileptic focus”. An EEG recording carried out during these abnormal changes may show a variety of atypical signs depending on which area of brain is involved.

CAUSES OF EPILEPSY

Epilepsy is a general term for seizures. Hair is usually diagnosed only when a person is caught more than once.

When identified, the causes of epilepsy usually include some type of brain injury. For many, however, the cause of epilepsy is not known

Seizures occur when electric currents in the brain go beyond their normal limits. They spread to neighboring areas and create uncontrolled storms of electrical activity. Electrical insulation can infect muscles, causing cramps or dizziness.

Some of the leading causes of epilepsy include:

• Low oxygen at birth
• Head injuries from birth or accidents during adolescence or adulthood
• Components of the brain
• Genetic conditions that damage the brain, such as tubular sclerosis
• Diseases such as meningitis or encephalitis
• Stroke or other type of brain damage
• Abnormal amounts of a substance such as sodium or blood sugar