Classification of seizure

Amarendra B. Singh090201263

Classification of seizure

• It is important to determine the type of seizure that has occurred – to find out the etiology, selecting the appropriate therapy and providing information regarding prognosis

• ILAE- International League against Epilepsy

Definitions

• Aura is the subjective sensation or phenomenon that precedes and marks the onset of the epileptic seizure - it may localize the seizure origin within the brain.

• Ictus is the attack or seizure itself.

• Postictal period is the time after the ictus during which the patient may be drowsy, confused, and disoriented.

Classification

• Partial seizure originates from a paroxysmal discharge in a focal area of cerebral cortex (temporal lobe). *

• In Primary generalized seizure the abnormal electrical discharges originate from the diencephalic activating system and spread simultaneously to all areas of brain.

Different parts have different functions, and different seizures!

Classifying SeizuresFocal (previously ‘partial’) seizure – initial activation of only part of one cerebral hemisphere occurs. (although may generalize*)

Generalized seizure – discharge from both cerebral hemispheres occurs. Loss of consciousness may occur. Seizure types:

Partial GeneralizedSimple Complex Absence Convulsive

Consciousnessis maintained

Consciousnessis lost or impaired

Altered awareness Characterized bymuscle contractionswith or without lossof consciousness

I. Generalized seizures

Tonic ClonicTonic – clonicAbsence (typical / atypical)Myoclonic Atonic

II. Focal seizures1. Simple

Motor SensoryAutonomic

2. Complex (temporal lobe or frontal lobe)3. Focal seizure with secondary generalization

III. UnknownEpileptic spasms

Generalized Seizures (Produced by the entire brain)

Symptoms

1. "Grand Mal" or Generalized tonic-clonic Unconsciousness, muscle rigidity, convulsions.

2. Absence Brief loss of consciousness

3. Myoclonic Sporadic (isolated), jerking movements

4. Clonic Repetitive jerking movements

5. Tonic Muscle stiffness, rigidity

6. Atonic Loss of muscle tone

Generalized Tonic Clonic Seizures

Generalized Tonic Clonic Seizures

Tonic seizure

Clonic seizure

Absence seizures

Thalamocortical relays are

believed to act on a

hyperexcitable cortex

A low threshold Ca2+ current Oscillatory responses in thalamic neurons

Scheme of Seizure Spread

EEG: Bilaterally synchronous, high voltage 3-per-second spike-and-wave discharge pattern.

Myoclonic seizure

Myoclonic seizure

Atonic seizure

• These are seizure involving brief loss of muscle tone, usually resulting in heavy falls with or without loss of consciousness.

Focal Seizures (Produced by a small area of the

brain)

Symptoms

1. Simple(awareness is retained)a. Simple Motorb. Simple Sensoryc. Simple Autonomic

a. Jerking, muscle rigidity, spasms, head-turningb. Unusual sensations affecting either the vision, hearing, smell, taste, or touchc. Memory or emotional disturbances

2. Complex (Impairment of awareness)

Automatisms such as lip smacking, chewing, fidgeting, walking and other repetitive, involuntary but coordinated movements

3. Focal seizure with secondary generalization

• Jacksonian March Some attacks begin in one part of the body (e.g. mouth,

thumb, great toe) and spread (march)gradually towards other parts of the body.

• Attacks vary in duration from few seconds to several hours (epilepsia partialis continua)

• Todd’s palsy is paresis of the involved limb lasting for several hours

after the seizure ceases.