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Types

One area of controversy in the field of epilepsy is how to describe the seizures experienced by patients with epilepsy and how to catagorize them in order to sensibly discuss and treat epilepsy. Several congresses have been convined to work on this problem and out of them have come the International Classification of Epilepsies and Epileptic Syndromes. This classificaton has broadly defined seizures as either generalized ("seizures in which the first clinical changes indicate initial involvement of both hemispheres..." or sides of the brain) or partial (location related or focal/local/partial) seizures.

Generalized Epilepsy

Idiopathic Generalized Epilepsies

These are forms of generalized epilepsies which have a generalized onset involving both sides of the brain. EEG (electroencephalography) recordings of the seizures show bilateral abnormal seizure patterns which are synchronized and symmetrical. Recordings done when no seizures are occurring are normal.


Benign Neonatal Familial Convulsions

These are rare seizures which occur just after birth (typically on the 3rd or 4th day of life) and manifest as rhythmic shaking of the body with or without breath holding. This condition is heritable and 14% of these babies will go on to develop epilepsy.


Benign Neonatal Convulsions

These seizures usually occur on the fifth day of life for no known reason and are not associated with either a risk for epilepsy or alteration in developmental potential. The convulsion caused shaking of the body and possible brief cessation in breathing.


Benign Myoclonic Epilepsy in Infancy

These occur in otherwise normal children during their first or second year of life. The seizures consist of brief jerks of the body or part of it similar to those experienced by most people as they are falling asleep. EEG recordings show brief burst of seizure activity, especially during the early stages of sleep. Later in life a few children who experience this will develop generalized tonic (body stiffening) - clonic (body rhythmically shaking) seizures and children with benign myoclonic epilepsy in infancy can have mild delay in development and minor personality disorders.


Childhood and Juvenile Absence Epilepsy

These seizures are associated with a momentary loss of consciousness (frequently not realized by others) with or without abnormal movements or loss of body tone and collapse. The childhood form occurs during early school years, may occur several times a day and are associated with the child later (during teens) developing generalized tonic-clonic seizures (GTCS). The juvenile form usually has an onset around puberty and the events are not uncommonly preceded by GTCSs. The EEG shows bilateral, symmetrical spike-waves which are synchronized and occur at a frequency of 3 per second.


Juvenile Myoclonic Epilepsy

Also termed Impulsive Petit Mal Epilepsy, these seizures occur around puberty and consist of single or repetitive jerking which is irregular, arrhythmic and occur bilaterally, predominately in the arms. GTCSs and, infrequently, absences may also occur. The most common time to see the seizures is shortly after awakening or when a person is sleep deprived.


Epilepsy with GTCS on Awakening

These seizures occur during the teen years and may be associated with absence or myoclonic seizures. The most common time for the seizures to occur is shortly after awakening from sleep (>90%) but they can also occur in the evening during periods of relaxation. Juveniles with this type of epilepsy will demonstrate a susceptibility to light induced seizures.



Generalized Cryptogenic or Symptomatic Epilepsies

West Syndrome

Also called Infantile Spasms, this syndrome is manifest by seizures which start in the first year of life and consist of spasms with the body flexing, extending or the head may nod. There is arrest in the baby's development and the EEG has a characteristic pattern (hypsarrhythmia) which is diagnostic. The prognosis for the baby is a function of how well the baby responds to treatment with ACTH or steroids. There are two subgroups of this syndrome

Symptomatic Group: The baby has signs of an injured brain (delay in development, signs of abnormal function of parts of the nervous system or MRI/CT scans showing areas of injury in the brain) which predate the onset of the seizures.

Cryptogenic Group: There is no known reason for the seizures and examination of the baby is normal.


Lennox-Gastaut Syndrome

Children with this syndrome have intractable seizures of multiple types (absence, tonic axial, atonic, myoclonic, GTCS or partial). The frequency of the seizures is high and episodes of status are not unusual. The children exhibit psychomotor retardation and the EEG recordings are characteristic (generalized slow (<2 ½ per second) spike and wave pattern during clinical seizures). This condition can occur in children who had West Syndrome during their infancy.

Symptomatic Group: The child has signs of an injured brain (delay in development, signs of abnormal function of parts of the nervous system or MRI/CT scans showing areas of injury in the brain) which predate the onset of the seizures.

Cryptogenic Group: There is no known reason for the seizures and examination of the child is normal.


Epilepsy with Myoclonic-astatic Seizures

These seizures are mixed and include myoclonic, astatic and myoclonic-astatic seizures in association with absences, GTCS, and tonic seizures as well as non convulsive status. When the status occurs it is usually on awakening and is characterized by apathy or stupor in association with infrequent myoclonus. The onset of this condition is during early childhood and is frequently preceded by a febrile seizure. The EEG has a characteristic evolution over time and the outcome of children with this condition is variable.


Epilepsy with Myoclonic Absences

Children with this type of disorder experience absences usually accompanied by severe clonic jerking of both sides of the body. There can also be tonic stiffening of the body during these episodes. These can occur several times during the day. The age of onset is about 7 years and the EEG shows characteristic changes during these episodes which is similar to that seen that seen with childhood absences.


Symptomatic Generalized Epilepsies and Syndromes

These occur most commonly in infancy and childhood and the seizures are characterized by generalized seizures and EEG recordings which differ from those described in the idiopathic generalized epilepsies. Not uncommonly the child will exhibit more than one type of seizure and the EEG is characterized by bilateral asymmetrical activity which is less rhythmic than that seen with the idiopathic generalized epilepsies. The child has clinical signs of a diffuse encephalopathy.


Symptomatic Generalized Epilepsies of Specific Etiologies

These are seizures which are a prominent feature of a disease or disorder. Malformations of portions of the brain which cause such seizures as infantile spasms. Some malformations can cause characteristic seizures such as hypothalamic hamartomas causing gelastic seizures and infants with tuberous sclerosis commonly exhibiting West Syndrome which evolves into generalized and partial seizures with aging.


Proven or Suspected Inborn Errors of Metabolism

These are seizures, generalized or partial, which result when breakdown products of chemical reactions in the body accumulate triggering the seizure or a particular substances important to the normal function of the nervous system cannot be made and the resultant deficit leads to seizures. The seizures may be stereotypic for the condition or may be mixed and the age for onset of the seizures varies with the condition, some starting at birth, some in infancy, some in childhood and some in the teens. There are even a few which do not present until adulthood. A feature of these disorders is they are heritable.


Generalized Symptomatic Epilepsies of Nonspecific Etiology

Early Myoclonic Encephalopathy

The onset of this condition is usually by 3 months of age and starts with myoclonic seizures and evolves to more severe seizures. The EEG recordings show bursts of abnormal activity interspersed with suppression of the brain's normal activity and this pattern evolves into a hysarrhythmia. Babies with this condition arrest in their development as the seizures worsen.


Early Infantile Epileptic Encephalopathy with Suppression Burst

This starts during the first few months of life and is characterized by frequent tonic spasms of the body and an EEG recording similar to that seen with Early Myoclonic Encephalopathy. This frequently is associated with developmental arrest or delay and can evolve into West Syndrome by 4-6 months of age.


Epilepsies and Syndromes Undetermined as to Whether They are Focal or Generalized
Neonatal Seizures — These can be difficult to appreciate because of the immaturity of the nervous system. Manifestations of these type of seizures may include such subtle behavior as deviation of the eyes to one side with or without jerking, repetitive movements of the mouth mimicking lip smacking, swallowing, sucking, etc., pedaling or swimming movements in the arms/legs and apneic episodes. Premature infants may exhibit tonic extension in the arms or legs. Infrequently, there can be clonic or myoclonic seizures. These last types have greater significance with regards the baby's prognosis.

Severe Myoclonic Epilepsy in Infancy
This form of epilepsy evolves out of febrile convulsions, usually in babies with a family history of febrile seizures or epilepsy. The seizures evolve during the first year of life and consist of generalized or unilateral clonic febrile seizures and evolve into myoclonic seizures and partial seizures later. There can be associated psychomotor retardation which becomes more obvious during the second year.

Epilepsy with Continuous Spike-wave During Slow-wave Sleep
This is an EEG diagnosis with the children exhibiting seizures of varying types during deep sleep (partial or generalized seizures) and also absences while awake. There can be associated neuropsycholgical disorders.

Special Syndromes
Febrile Convulsions — This is a relatively benign condition seen during early childhood. The seizures are generalized and occur in association with fevers. Usually they are brief but when prolonged there is a chance of injury to the central nervous system which then results in a permanent dysfunction. As only 4% of children having these type of seizures go on to develop epilepsy, routine use of medications to prevent these is unusual unless they become a repetitive problem.

Focal or Partial Epilepsy

These are localization-related epilepsies and syndromes which are referred to as partial, focal or local epilepsies and syndromes. Either the feature or pattern of the seizures or the clinical investigation demonstrate a focal involvement of the brain in these conditions. Patients with these conditions can have a focal area of brain which functions abnormally, has a lesion or tumor or has developed abnormally. The abnormal area is responsible for the abnormal electrical discharges which result in the seizure. Some may have several areas capable of generating abnormal seizures and some may experience a secondary generalization of the seizure activity with the seizure coming to resemble a generalized seizure in very short (within seconds) order after onset of electographic onset of the focal activity. Not uncommonly, the onset may resemble a generalized seizure to a casual observer. In certain types of focal epilepsies (idiopathic age-related focal epilepsies) mirror areas of the two half's of the brain may be capable of generating seizures.

Focal seizures are commonly described as a function of their point of onset in the brain. To do this a careful history is obtained and extensive EEG recordings coupled with video taping of the patient's behavior are done to better appreciate what the first signs and symptoms of the typical seizure are and how these symptoms and signs progress as the seizure progresses. As a result descriptions of syndromes related to anatomic localization are becoming available.

Temporal Lobe Epilepsies

These include simple partial, complex partial and secondarily generalized seizures. The simple partial seizures typically have autonomic (pupillary dilation, flushing in the face, arrest of breathing) and/or psychic symptoms (fear, panic, rage) as well as auditory and olfactory sensations including illusions. The complex partial seizures usually begin with an arrest in motor activity followed by oroailmentary automatism's such as belching, rumbling in the abdomen and then other automatism's follow which typically encompass repetitive, complex movement such as opening and closing a door. The actual seizure usually lasts less than a minute and is followed by confusion and amnesia for a variable period with recovery gradually occurring.

  • Temporal lobe seizures can arise from the medial side of the lobe (mesial temporal lobe seizures, limbic seizures, rhinencephalic seizures) or the lateral side (lateral temporal lobe seizures).
  • Mesial temporal lobe seizures start deep within the brain so EEGs done between seizures are typically normal. The chances of recording abnormal activity is greatly enhance by using sphenoidal electrodes (thin wire electrodes inserted to lay at the base of the skull below the central part of the brain using thin needles temporarily inserted through the cheek). These seizures usually start with a rising sensation in the abdomen, nausea with autonomic signs and psychic symptoms following.
  • Lateral temporal lobe seizures are characterized by auditory hallucinations/illusions, dream like state, disorders in language reception and output and visual symptoms. The seizure can then move to involve the medial temporal lobe, occipital lobe or parietal lobe with onset of corresponding symptoms referable to these areas of the brain.

Because the memory circuits originate in the temporal lobe, repeated seizure activity which involves these structures can cause difficulties with memory and intellectual function. These seizures typically start in childhood or young adulthood, tend to cluster and are frequently associated with a history of febrile convulsions and/or a family history of seizures.

Frontal Lobe Epilepsies

These are generally short, complex partial seizures with minimal or no post ictal confusion. Secondary generalization is common and rapid. Simple partial seizures can also occur. The seizures contain a prominent motor component which is either postural or tonic. At the onset of these seizures complex gestures are common and if the activity spreads to the other half of the brain falling is common. Given the complex nature of these seizures, they are not uncommonly mistaken for psychogenic seizures. The constellation of signs and symptoms which occur as the seizure starts and progresses offer clues to the site of origin of the seizure. The seizures take their name for the area of the frontal lobe from which they arise.

Seizures Types

Supplementary Motor seizures

The patient assumes a fencing position with the arms or assumes another posture or exhibits focal, tonic activity. There is speech arrest or vocalizations.

Cingulate Seizures: These are complex partial seizures with complex, automatismal gesturing occurring at the onset. Commonly, there are changes in mood and affect and autonomic signs.

Anterior Frontopolar Seizures: With these seizures one sees forced thinking, loss of contact with the environment and aversive (movement toward the side of the body opposite side of brain generating seizure) head and eye movement. As these seizures evolve the head and eyes may move back to the side of seizure onset and there may be jerking of the trunk as well as autonomic signs and the patient may fall.


Dorsolateral Seizures

Dorso refers to the upper half of the frontal lobe. So these seizures arise in the upper, lateral part of the lobe and typically cause tonic and, occasionally, clonic motor activity with associated versive head and eye movement and speech arrest.


Orbitofrontal Seizures

These are complex partial seizures where automatism's (motor and gestural) predominate with olfactory hallucinations/illusions and autonomic signs also occurring.


Opercular Seizures

A primary feature of these seizures are signs and symptoms of alimentary tract involvement including chewing, swallowing, salivation, epigastric sensation, speech arrest, and sound generation. There can be speech arrest, fear and autonomic signs. If the activity spreads secondary sensory changes may occur such as numbness.


Motor Seizures

These are usually simple partial seizures and are localized based on what part of the body has movement at the onset of the seizure. If the face's motor region is involved there will commonly be speech arrest, difficulty in swallowing or vocalizations of sounds in association with the tonic or clonic movements of the face's muscles on the side opposite to the area of the brain generating the seizure. These seizures frequently spread (referred to as "marching"; i.e., seizure activity spreads up a arm or leg, marching to involve more and more adjacent muscles). After the seizure there is frequently a weakness for a variable length of time of muscles which were active in the seizure.



Other Epilepsies

 

Parietal Lobe Epilepsies

These are typically simple partial seizures which can secondarily generalize. Rarely, they can evolve into complex partial seizures. Seizures from this area of the brain typically manifest sensations such as tingling, numbness, loss of the extremity, crawling, coldness or electric sensations in regions of the body but more complex sensations such as feeling that an extremity is moving, or complex alimentary sensations may occur. Rarely, there may be a painful sensation. The involvement may march as with motor seizures of the frontal lobe. There can be complex visual symptoms such as metamorphosis with distortions, foreshortening and elongation may also occur. Severe vertigo or disorientation is a sign of involvement of the lower part of the lobe. If the dominant (usually the left) lobe is involved there can be dysfunction in processing language input and output. These seizures commonly generalize secondarily.


Occipital Lobe Epilepsies

There are two categories of Localization-Related Epilepsies or Syndromes with regards their etiology. Each have several subtypes of seizures.

These are simple partial seizures which commonly undergo secondary generalization. With spread, the seizure can evolve into a complex partial seizure. The initial visual symptoms are usually sparks, flashes or phosphenes but may be scotoma, hemianopsia or amaurosis with the symptoms occurring toward the side opposite the involved part of the brain. There can also be distortion of vision with objects appearing altered in size (too large or small), shape or tilted. Distances may also appear altered.


Idiopathic Localization-Related Epilepsies

These are age-related epilepsies in children whose clinical examinations and testing fail to demonstrate anything other than a focal area of abnormal electrical discharge as recorded by EEG. There is no known causative factor for these children's epilepsies except for a number being hereditarily acquired. These seizures are brief, not associated with neurologic or intellectual abnormalities. The pattern of seizure is generally constant for any given child.


 

Benign Childhood Epilepsy with Centrotemporal Spikes

These are focal seizures commonly occurring around sleep which involve the face, can have a sensory component and can generalize into a GTCS. They are most common in males and can start as early as age 3 and typically burn out between ages 15 and 16.

Landau-Kleffner Syndrome is a atypical form of Benign Partial Epilepsy occuring in the speech region of the left frontal lobe.


Childhood Epilepsy with Occipital Paroxysms

These seizures start with visual symptoms such as amaurosis, phosphenes, illusions or hallucinations and 25% of patients with this condition will have migraine headache prior to onset of their seizures. The seizure can then spread to involve the posterior temporal lobe and central areas of the brain with onset of behavior which can include clonic activity in one side of the body or complex patterns of body movement. Otherwise, these seizures are very similar to Benign Childhood Epilepsy with Centrotemporal Spikes.


Symptomatic Focal Epilepsies

These are epilepsies which are focal in origin and are due to known or suspected disorders of the brain as demonstrated by clinical investigations such as CAT or MRI scans, laboratory testing, etc.


Chronic Progressive Epilepsia Partialis Continua of Childhood (Kojewnikow Syndrome)

This is one of the two forms of Kojewnikow Syndrome (the other being Rasmussen's Syndrome) which is a partial motor seizure which can progress to a myoclonic seizure involving the same muscle groups as are involved by the motor seizure. These type of seizures can begin at any age and are usually associated with a demonstrable lesion such as a tumor or vascular abnormality. The seizure disorder will not progress unless the causal lesion does.


Syndromes Characterized by Seizures with Specific Modes of Precipitation

These are seizures which reliably result from an environmental or internal factor. A memory or recognition of a specific pattern triggering a complex partial seizure would be an example. Less common would be partial seizures triggered by a simple sensation (a smell, etc.) as such stimulus specific induced seizures are usually generalized. Partial seizures can also be caused by sudden, unexpected arousal, but, again, generalized seizures are more common in this setting.