**3. Generalized seizures**

*Absence Seizures* are characterized by a sudden onset behavioral arrest, a blank stare, unresponsiveness, and sometimes a brief upward rotation of the eyes. The duration is typically a few seconds to half a minute. There is little to no post-ictal confusion, and the patient typically resumes the activity he/she was doing prior to the seizures. This seizure type is also referred to as simple absence. The ILAE's 1981 classification also recognizes five subtypes of absence seizures: absence with impairment of consciousness only, with mild clonic components, with atonic components, with tonic components, and with automatisms. In absence with mild clonic components, there are subtle clonic movements of the eyelids, corner of the mouth, or upper extremities sometimes at a frequency of 3 Hz. In absence with atonic components, there is a loss of postural tone causing the head to drop, the trunk to slump forward, the arms to drop, or the grip to relax. Falls are rare. In absence with tonic components, tonic muscle contraction of the trunk and neck extensors may cause the head to extend and the trunk to arch, thus causing retropulsion. Tonic contraction of the neck muscles may cause the head or trunk to deviate to one side. In absence with automatisms, the patient engages in purposeful or semipurposeful repetitive movements while consciousness is impaired. Examples of automatisms may include lip licking, chewing, lip smacking, swallowing, grimacing, smiling, yawning, fumbling with the hands, picking, scratching, rubbing, or aimless walking. Absence with autonomic phenomena is another subtype with signs of tachycardia, pallor, flushing, piloerection, salivation, or urinary incontinence. A mixture of clonic, atonic, tonic, automatic, and autonomic features may occur which is also referred to as complex absence. The ictal EEG pattern in absence seizures is a 3 Hz generalized monomorphic spike and wave with abrupt onset and termination. Absence seizures in the EEG laboratory can be precipitated by hyperventilation and less commonly photic stimulation.

*Atypical absence* s*eizures* are usually seen in patients with symptomatic generalized epilepsy. They are similar to absence seizures in that they have both simple and complex presentations. One distinguishing feature is that they are less abrupt in onset clinically. The seizures are usually less than 10 seconds but may be prolonged and result in absence status. They also are not usually induced by hyperventilation or photic stimulation. The ictal EEG pattern consists of a less monomorphic slow spike and wave discharge characterized by a blunt sharp wave and occurs at a frequency of < 2.5 Hz.

*Tonic-clonic seizures,* also known as grand mal seizures, are characterized by abrupt loss of consciousness followed by tonic contraction of the muscles. This leads to the ictal cry, where air is forcefully expired against a closed glottis. The mouth is forcefully closed which can result in a tongue bite. The pupils become dilated and the eyes deviate upwards. The upper extremities often symmetrically abduct and flex at the elbows while the lower extremities

Complex partial seizures are partial seizures with impairment of consciousness. They may start as simple partial seizures (auras) and progress to complex partial seizures or may begin as complex partial seizures with impairment of consciousness at the onset of the seizure. They may or may not involve automatisms. The clinical features of the complex partial seizure depend on the region affected by abnormal electrical activity. Complex partial seizures usually originate in the frontal or temporal lobes but can occur in the parietal or

*Absence Seizures* are characterized by a sudden onset behavioral arrest, a blank stare, unresponsiveness, and sometimes a brief upward rotation of the eyes. The duration is typically a few seconds to half a minute. There is little to no post-ictal confusion, and the patient typically resumes the activity he/she was doing prior to the seizures. This seizure type is also referred to as simple absence. The ILAE's 1981 classification also recognizes five subtypes of absence seizures: absence with impairment of consciousness only, with mild clonic components, with atonic components, with tonic components, and with automatisms. In absence with mild clonic components, there are subtle clonic movements of the eyelids, corner of the mouth, or upper extremities sometimes at a frequency of 3 Hz. In absence with atonic components, there is a loss of postural tone causing the head to drop, the trunk to slump forward, the arms to drop, or the grip to relax. Falls are rare. In absence with tonic components, tonic muscle contraction of the trunk and neck extensors may cause the head to extend and the trunk to arch, thus causing retropulsion. Tonic contraction of the neck muscles may cause the head or trunk to deviate to one side. In absence with automatisms, the patient engages in purposeful or semipurposeful repetitive movements while consciousness is impaired. Examples of automatisms may include lip licking, chewing, lip smacking, swallowing, grimacing, smiling, yawning, fumbling with the hands, picking, scratching, rubbing, or aimless walking. Absence with autonomic phenomena is another subtype with signs of tachycardia, pallor, flushing, piloerection, salivation, or urinary incontinence. A mixture of clonic, atonic, tonic, automatic, and autonomic features may occur which is also referred to as complex absence. The ictal EEG pattern in absence seizures is a 3 Hz generalized monomorphic spike and wave with abrupt onset and termination. Absence seizures in the EEG laboratory can be precipitated by hyperventilation and less

*Atypical absence* s*eizures* are usually seen in patients with symptomatic generalized epilepsy. They are similar to absence seizures in that they have both simple and complex presentations. One distinguishing feature is that they are less abrupt in onset clinically. The seizures are usually less than 10 seconds but may be prolonged and result in absence status. They also are not usually induced by hyperventilation or photic stimulation. The ictal EEG pattern consists of a less monomorphic slow spike and wave discharge characterized by a

*Tonic-clonic seizures,* also known as grand mal seizures, are characterized by abrupt loss of consciousness followed by tonic contraction of the muscles. This leads to the ictal cry, where air is forcefully expired against a closed glottis. The mouth is forcefully closed which can result in a tongue bite. The pupils become dilated and the eyes deviate upwards. The upper extremities often symmetrically abduct and flex at the elbows while the lower extremities

**2.1.2 Complex partial seizures** 

**3. Generalized seizures** 

commonly photic stimulation.

blunt sharp wave and occurs at a frequency of < 2.5 Hz.

occipital lobes.

may briefly flex and then extend and adduct with the toes pointed. Clonic activity then ensues which is initially rapid and then slows. Gasping respirations occur as the respiratory muscles are involved in the clonic activity. The patient may become cyanotic. Urinary incontinence may occur. At the end of the seizure, the patient is unconscious for a brief period of time and then gradually recovers. Patients typically report generalized muscle soreness and sometimes a headache post-ictally.

Tonic-clonic seizures may occur independently, may arise from other generalized seizures, or may occur during secondary generalization of a partial onset seizure. The semiologic features of tonic-clonic seizures in primary generalized epilepsy may be bilaterally symmetric or may involve a forced head deviation to either side (Ochs et al., 1984). During secondarily generalized partial onset seizures, patients often assume a figure-4 posture where the contralateral arm extends, and the ipsilateral arm flexes at the elbow. This posture can occur with the legs as well. Tonic-clonic seizures may lead to injuries such as burns, head injuries, vertebral compression fractures, shoulder dislocations, and tongue and cheek lacerations.

*Myoclonic seizures* are generalized seizures characterized by brief, irregular, shock-like jerks of the head, trunk, or limbs. They can be symmetric or asymmetric and involve the whole body, regions of the body, or focal areas. They tend to occur close to sleep onset and upon awakening from sleep. Myoclonic seizures can be a feature of some idiopathic generalized epilepsies (Juvenile Myoclonic Epilepsy), symptomatic generalized epilepsies (Myoclonic-Astatic Epilepsy), the progressive myoclonic epilepsies (Lafora Disease), and infantile spasms. Myoclonus can be positive or negative. Negative myoclonus refers to the brief loss of postural tone when the body part is held against gravity. Consciousness is not impaired and there is no post-ictal confusion with single myoclonic jerks. Myoclonic seizures can occur in clusters and evolve into clonic-tonic-clonic seizures, with resultant loss of consciousness and postictal confusion. The ictal EEG pattern is characterized by brief generalized polyspike or polyspike and wave discharges which corresponds to the myoclonic jerk.

*Tonic seizures* are seizures which involve tonic contraction of the face, neck, axial, or appendicular musculature lasting from 10 seconds to one minute. They can involve extension or flexion of the muscles and often lead to falls and head injuries. They may be more subtle and involve only upward eye deviation. They often occur out of NREM sleep. They are usually seen in patients with symptomatic generalized epilepsy and are one of the common seizure types in patients with Lennox-Gastaut syndrome. They can also occur in epilepsy with myoclonic-astatic seizures. The ictal EEG usually shows a brief generalized attenuation of cerebral activity followed by generalized paroxysmal fast activity in the beta frequency range.

*Clonic seizures* are generalized seizures that are characterized by repetitive rhythmic clonic jerks (1-2 Hz) with impairment of consciousness and a short post-ictal phase. They can lead into a clonic-tonic-clonic seizure. It is thought that the repetitive discharges are due to rhythmic excitatory discharges from the cortex (1981; Engel, 2006). The ictal EEG demonstrates generalized polyspike and wave discharges or generalized fast activity.

*Atonic seizures* are characterized by a sudden loss of muscle tone which can lead to a head drop, a limb drop, or a drop of the whole body (a.k.a. – a drop attack). There is a brief loss of consciousness and injuries, particularly to the face, may occur (1981). Atonic seizures last less than 5 seconds, and there is minimal post-ictal confusion. Atonic seizures may be preceded by

The Classification of Seizures and Epilepsy Syndromes 75

Epilepsies with seizures precipitated by specific modes of activation

 Early infantile epileptic encephalopathy with suppression burst Other symptomatic generalized epilepsies not defined above

3. Epilepsies and syndromes undetermined whether focal or generalized

 Epilepsy with continuous spike-waves during slow wave sleep Acquired epileptic aphasia (Landau-Kleffner syndrome) Other undetermined epilepsies not defined above

Diseases in which seizures are a presenting or predominant feature

3.2 Without unequivocal generalized or focal features (i.e. – Sleep related GTCS; when the EEG shows both focal and generalized ictal or interictal discharges, and when focal

Seizures occurring only when there is an acute metabolic or toxic event

Other generalized idiopathic epilepsies not defined above

 Juvenile absence epilepsy Juvenile myoclonic epilepsy Epilepsy with GTCS on awakening

2.2 Cryptogenic or symptomatic West syndrome

2.3.1 Non-specific etiology

2.3.2 Specific syndromes

Neonatal seizures

4. Special syndromes 4.1 Situation-related seizures Febrile convulsions

adolescents and adults follows.

3.1 With both generalized and focal seizures

Severe myoclonic epilepsy in infancy

or generalized onset cannot be determined clinically)

Isolated seizures or isolated status epilepticus

(alcohol, drugs, eclampsia, nonketotic hyperglycemia)

Epilepsy*. Epilepsia,* Vol. 30, No. 4, (August 1989), pp. 389-99, ISSN 1528-1167

Table 2**.** ILAE's 1989 International Classification of Epilepsies and Epileptic Syndromes, from (1989). Proposal for revised classification of epilepsies and epileptic syndromes. Commission on Classification and Terminology of the International League Against

An epilepsy syndrome is defined as "a complex of signs and symptoms that define a unique epilepsy condition" (Engel, 2001). The groups of syndromes are: idiopathic focal epilepsies of infancy and childhood, familial (autosomal dominant) focal epilepsies, symptomatic (or probably symptomatic) focal epilepsies, idiopathic generalized epilepsies, reflex epilepsies, epileptic encephalopathies, progressive myoclonus epilepsies, and seizures not necessarily requiring a diagnosis of epilepsy (see Table 3). There are over 25 specific syndromes in the 1989 ILAE report. A discussion regarding a few of the more common syndromes affecting

2.3 Symptomatic

Lennox-Gastaut syndrome

 Epilepsy with myoclonic-astatic seizures Epilepsy with myoclonic absences

Early myoclonic encephalopathy

a brief myoclonic jerk or tonic component. Atypical absence seizures may have an atonic component. The criteria distinguishing between negative myoclonus, atonic seizures, and some atypical absences still needs to be developed (Engel 2006). Atonic seizures are usually seen in the symptomatic generalized epilepsies such as Lennox-Gastaut syndrome. The ictal EEG typically shows a high voltage spike and wave or slow wave followed by a generalized attenuation of cerebral activity or low voltage paroxysmal fast activity.
