Types of Epilepsy
Absence Seizure / Myoclonic Seizure / Atonic / Infantile Spasm
Tonic-clonic Seizure / Simple Partial Seizure / Complex Partial Seizure /
Epilepsy is a complex condition and is classified under different categories. We will discuss two main classifications ( generalized and partial seizures) as well as other common ones in this section.
Average incidence rates for each type of seizure:
Tonic Clonic (46.5% of all cases)
Absence (9.7% of all cases)
Complex Partial (6.0% of all cases)
Tonic Clonic & Absence (20.3% of all cases)
Tonic Clonic & Complex Partial (13.0% of all cases)
The remaining 4.5% is made up of other combinations and less common types of seizures.
1.
Generalized
Seizures – onset of abnormal electric signals
involves the
whole brain
2
varieties
a.
Convulsive
nature
·
Absence Seizures
(old
name-petit mal)
A form of epilepsy occurs primarily in children (onset 4-8 yr old) and often disappears at puberty. Episodes of brief loss of consciousness without fall of duration up to 10-30s and may occur as frequently as 100 times daily. Other manifestations include staring, transient loss of responsiveness, insignificant movements like muscle twitching and eye fluttering, no recall of events during seizure and resume their activities without any after-effects from the seizures. Its brief and subtle nature often let it go unrecognized for long periods of time or be mistakenly attributed to daydreaming especially in children.
NOTE: 1. Simple (typical) absence seizures are without motor
symptoms; complex (atypical) absence seizures are otherwise by which
differentiation from complex partial seizures is difficult and requires EEG to
distinguish them. 2. Genetic transmission probably involved. 3. Tend to become
less serve with time with appropriate treatment.
Inherited
epilepsy and often precedes generalized
tonic-clonic seizures. Absence
seizures, and muscle
contractions most frequently involving the arms are
present. Decreased sleep,
and alcohol are common precipitating factors. Treatment should be continued
indefinitely in most cases, since risk of seizure recurrent upon discontinuation is
particularly high in this condition.
·
Atonic / Astatic /
Akinetic Seizure
Typically
present during the first of life, most often between 4 and 6 months of age.
Infantile spasms represent a variety of generalized, myoclonic seizure
characterized by brief muscles contraction affecting the main body, hands and feet.
These are often not immediately recognized as seizures due to the unique and
fairly subtle motor manifestations. Treatment of infantile spasms is
problematic, since response to traditional anticonvulsant agents (medications
use for treating epilepsy) is poor.
Children with infantile spasms face considerable risks for long-term
neurological morbidity.
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b. Non-convulsive
nature
·
Clonic Seizures
·
Tonic Seizures
·
Tonic-clonic
Seizures
(old name-grand mal)
Frequently start with a sudden outcry when air is being forced through the the back of the mouth, follow by loss of consciousness and fall. It includes the alternation between the tonic part (the stiffening of the body) as in the arching of back and the clonic part (the rhythmic jerking of the body or a body part) involving all skeletal muscles. Tongue biting and uncontrolled urination are common. Confusion and tiredness remains after consciousness regained. Each episode usually last a few minutes but occasionally can last up to one hour.
2. Partial Seizures - excessive electrical abnormal signals originate from one fixed area within the brain but may subsequently progress to a partially or fully generalized seizure (involving the whole brain).
·
Simple Partial
Seizures
(w/o loss of consciousness)
Symptoms are
elementary (without loss of consciousness); a single part of the body may twitch or
experience only unusual sensory experience such as distortion in hearing or
seeing or a sudden sense of fear. Can become an “aura” if another type of
seizure follows.
·
Complex Partial
Seizures (with impaired/altered/loss of consciousness)
Constitute one of the most common seizure disorders (20-30% of
all epilepsy). An aura which varies from person to person can be an unusual smell or taste,
a change in temperature, tension, anxiety,
peculiar
odor, or hearing musical sounds, an illusion that
objects are growing smaller or larger, or an intense emotional feeling. Such auras can be
followed by seizures or can subside without further symptoms. Symptoms are complex; loss of responsiveness,
expressionless stare, lip smacking, aimless wandering, fumbling movements of
hands and a brief period of lethargy/confusion after seizures. Episodes last for
several seconds to several minutes and there is no recall of events during
seizures. Surgery as treatment is sometime necessary.
There are some unclassified
seizures, which don’t fit into the abovementioned categories or are due to
incomplete or inadequate data e.g. often seizures from sleep has no eyewitness.
Convulsions, those occur with fever (>38°C) in children between 6 months and 6 yrs of age, not secondary to an infection of brain. Between 2-5% of all children will have a febrile seizure before the age of 6. Most children with typical febrile seizures do not require specific treatment except for the need to lower the high temperature. Children with febrile seizures may be at increased risk for developing epilepsy if they have abnormal CT/EEG/MRI scan, "atypical" febrile seizures and a family history of epilepsy. Primarily occur as generalized tonic-clonic but partial seizures occur in 10-15% of the patients. Seizures last 1-2 minutes with rapid return of consciousness but in atypical febrile seizures, it is prolonged to exceed 15 minutes. Seizure occur only once during any given illness. A family history of febrile seizures is identified in about 25% of cases, which implies a possibility of inheritance.
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Links to Other types of seizures
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