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Three rare and severe seizure disorders and what you need to know

For people with a rare and severe form of epilepsy, it can take almost 5 years of uncontrolled seizures to get an accurate diagnosis after seizures start. Some people even reach adulthood before receiving a specific diagnosis such as Lennox-Gastaut syndrome (LGS), Dravet syndrome, or tuberous sclerosis complex (TSC). You shouldn't have to wait that long. Not knowing your specific diagnosis could mean years of searching for answers, but knowing earlier could mean all the difference—it can open a door to treatment options, access to foundations and grants or financial assistance, connect you with a supportive community of others who can share their experience, and much more.

Why do so many people remain undiagnosed?

Certain seizure disorders such as LGS, Dravet syndrome, and TSC are not easy to diagnose. Signs and symptoms may be similar to other conditions, and they’re different for everyone—even in the same person over time.

What are defining characteristics of LGS?
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Slowed development

Or delays in intellectual ability and/or physical motor skills

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Abnormal electroencephalogram (EEG)

Or brain wave pattern, also called a slow-spike wave pattern (or SSW), which may not be present anymore in adults with LGS

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Multiple seizure types

Types of seizures most common in LGS include tonic, atonic, generalized tonic-clonic, atypical absence, myoclonic, and focal aware or impaired awareness

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Seizures that can change over time

LGS is an ever-evolving condition—the types and frequency of seizures experienced during childhood may change during adolescence and adulthood. There is also a chance that seizures may go into remission, or they may recur

How is LGS treated?

There are many potential treatment options for recurring seizures.

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Medications, including antiepileptic drugs (AEDs)* or other treatments, are used to treat seizures. Certain rescue medications may be used for seizures that last longer than 5 minutes, or occur very close together without breaks

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Dietary approaches, including the ketogenic diet, a high-fat, low-carb medical diet that needs to be carefully monitored by a dietitian

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For some people, the use of implanted devices or surgical methods, including corpus callosotomy, may be recommended

It may be time to explore a treatment option and talk to your doctor for more information.

Learn more

*It may be necessary to try more than one antiepileptic medication at a time to effectively reduce the number of seizures because these drugs may work through different targets in the body. These therapies may take a while to start working, and it is not uncommon for people to be on multiple therapies at a time.

Seizures in LGS from childhood to adulthood

80% to 90% of children with LGS continue to have seizures into adulthood.

In young children, the most common initial types of seizures include: generalized tonic, atonic, atypical absence, and tonic seizures during sleep. Generalized tonic-clonic and focal seizures may also occur. Seizures happen several times per week, with most people experiencing daily seizures.

During adolescence and adulthood, the frequency of daytime seizures may decrease; however, drop seizures, which may lead to injuries, may increase. With age, tonic seizures may become the most characteristic seizure type, mainly during sleep. Generalized tonic-clonic, atonic, and atypical absence seizures may continue, and tonic seizures may occur while awake.

The importance of early diagnosis, recognition, and treatment

By catching seizures early on, your doctors can work with you to develop the right treatment plan, which may include a genetic test.

Unrecognized and/or uncontrolled seizures are linked to developmental disabilities, learning and behavioral disorders, and other negative long-term outcomes.

What are defining characteristics of Dravet syndrome?
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Seizures that can change over time

Although seizures usually start in infancy, this is an ever-evolving condition—seizure types and severity of seizures can change over time

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Seizures triggered by various events

Hyperthermia, illness, fever, certain lighting conditions, visual patterns, increased temperature such as from a hot bath, stress, excitement, or exertion may all be common seizure triggers

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Developmental delays

Most notably speech delays, following early normal development

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Recurrent and prolonged seizures

Unusually prolonged hemi-clonic and generalized tonic-clonic seizures during infancy

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Other seizure types

Eventually, other seizure types can occur (myoclonic, focal impaired awareness, shorter generalized tonic-clonic and hemi-clonic, atypical absence, and tonic seizures). Please see the seizure types section of this website to learn more

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Motor symptoms

Instability and difficulty walking, as well as intention tremors (a tremor produced with purposeful movement toward a target)

How is Dravet syndrome treated?

It may be necessary to try more than one therapy at a time to effectively reduce seizures because each therapy works on different targets in the body.

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Medications, including antiepileptic drugs (AEDs)* or other treatments specifically used to treat Dravet syndrome

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Dietary approaches, including the ketogenic diet, a high-fat, low-carb medical diet that needs to be carefully monitored by a dietitian

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Vagus nerve stimulation (VNS), which is a device that stimulates the vagus nerve to reduce seizure frequency

It may be time to explore a treatment option and talk to your doctor for more information.

Learn more

*It may be necessary to try more than one antiepileptic medication at a time to effectively reduce the number of seizures because these drugs may work through different targets in the body. These therapies may take a while to start working, and it is not uncommon for people to be on multiple therapies at a time.

Seizures in Dravet syndrome from infancy to adulthood

The most common initial seizure types include: unusually long hemi-clonic and generalized tonic-clonic seizures. Infants may also experience recurrent seizures that last more than 5 minutes or seizures that occur close together without recovery periods in between.

By approximately 2 years of age, myoclonic, focal impaired awareness, shorter generalized tonic-clonic and hemi-clonic seizures may occur. Obtundation status may occur after 2 years of age, a type of long-lasting, nonconvulsive seizure marked by less alertness.

During early childhood, myoclonic, focal impaired awareness, and atypical absence seizures may occur.

During adolescence and adulthood, people may continue to have uncontrolled seizures: focal, generalized tonic-clonic, atypical absence, myoclonic, and tonic seizures. Nighttime generalized tonic-clonic seizures may become more common, and seizures are less frequently triggered by hyperthermia.

The importance of early diagnosis, recognition, and treatment

By catching seizures early on, your doctors can work with you to develop the right treatment plan, which may include a genetic test.

Unrecognized and/or uncontrolled seizures are linked to developmental disabilities, learning and behavioral disorders, and other negative long-term outcomes.

What are defining characteristics of TSC?

The most common initial signs and symptoms of TSC include

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Cardiac tumors, which can be detected by a routine prenatal ultrasound

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White spots or patches on the skin and angiofibromas, or red spots that look like acne

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New onset or history of seizures/infantile spasms

How common are seizures in TSC?

Most people with TSC will experience seizures, and some types of seizures are more common than others. Nearly 100% of people with TSC develop recurring seizures after having their first seizure.

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About 85% of people with TSC experience seizures throughout their lifetime

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1 in 3 infants with TSC develop infantile spasms

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Before the age of 2, infantile spasms and focal seizures are the most common. Other seizure types may follow as children get older

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Up to 82% of people with TSC experience focal seizures

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12% of adults with TSC, having no history of childhood seizures, can start having seizures as an adult

How is TSC treated?

There are many potential treatments used to reduce the frequency of seizures.

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Illustration of pill bottle with two pills

Medications, including antiepileptic drugs (AEDs)* or other treatments, are used to treat seizures

Image
Illustration of an avocado

Dietary approaches, including the ketogenic diet, a high-fat, low-carb medical diet that needs to be carefully monitored by a dietitian

Image
Illustration of a person with brain highlighted

Vagus nerve stimulation (VNS), which is a device that stimulates the vagus nerve to reduce seizure frequency. Some people with TSC may not respond to these treatment approaches, and for some, surgery may be required to reduce seizure frequency

It may be time to explore a treatment option and talk to your doctor for more information.

Learn more

*It may be necessary to try more than one antiepileptic medication at a time to effectively reduce the number of seizures because these drugs may work through different targets in the body. These therapies may take a while to start working, and it is not uncommon for people to be on multiple therapies at a time.

Seizures in TSC from childhood to adulthood

People with TSC can have their first seizure at any point during their lifetime.

Seizures that happen during childhood may be subtle and may look very different from those that occur in adults. The first seizures experienced before the age of 2 are most commonly infantile spasms, focal seizures, or a combination of both. Over time, infantile spasms may change to other seizure types.

It is important to be aware of adult-onset seizures, since some people may not be diagnosed with TSC until adulthood if signs and symptoms are mild. Seizures may also stop and start again later in life or change into one of the other seizure types.

In both children and adults, seizures can change in appearance depending on where they originate in the brain and how they spread over time. Focal aware seizures can progress to focal impaired awareness or possibly generalized seizures.

The importance of early diagnosis, recognition, and treatment

By catching seizures early on, your doctors can work with you to develop the right treatment plan, which may include a genetic test.

Unrecognized and/or uncontrolled seizures are linked to developmental disabilities, learning and behavioral disorders, and other negative long-term outcomes.

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Absence
  • Previously known as petit mal seizures
  • Causes a short period of “blanking out” or staring into space
  • Usually affect only a person’s awareness of what is going on at that time, with immediate recovery
Atonic
  • May be referred to as a “drop attack” or “drop seizure”
  • Person has a sudden loss of muscle tone and goes limp
  • Mild seizures look like a head nod or drop, while severe seizures can cause a person to fall to the ground
  • People with these types of seizures may wear helmets to protect from injuries 
Attention-deficit/hyperactivity disorder (ADHD)
  • Also known as ADHD
Atypical absence 
  • Blank staring with eye blinking, chewing movements, or lip smacking
  • Could include finger or hand rubbing, or other small hand movements
  • May begin and end gradually, usually lasting for about 5 to 30 seconds
  • May be difficult to distinguish between this seizure type and typical behavior in those with cognitive impairment 
Behavioral Issues
  • Issues with behavior or irritability 
Clonic
  • Associated with repeated jerking movements lasting a few seconds to a minute that cannot be stopped by restraining or repositioning the arms or legs
  • Most commonly occur in babies
  • Often seen as part of a tonic-clonic seizure and may be difficult to distinguish from a myoclonic seizure; however, the jerking is more regular and sustained during a clonic seizure
  • May also be associated with jerking or clonic movements that follow stiffening of muscles, as in a tonic-clonic seizure, and can last seconds to 1 to 2 minutes
Cognitive impairment
  • Or developmental delays, such as losing interest in toys
Developmental delays
  • Losing interest in toys, speech delays, or other delays identified by a doctor
Dravet syndrome
  • Dravet syndrome is a rare form of epilepsy that typically begins in the first year of life and is marked by frequent, often prolonged seizures in the early phases
Focal aware
  • Used to be called simple partial seizures
  • Person is fully alert and able to interact

Experiences can include:

  • Involuntary motor movements on one side of the body
  • Intense sensory or emotional episodes, such as déjà vu or feeling unexplained emotions
Focal impaired awareness
  • Used to be called complex partial seizures
  • Person loses consciousness, may not respond, and has no memory of the seizure

Experiences vary, but can include:

  • Starting with a blank stare, followed by chewing/lip smacking
  • Random activity like picking at the air or clothes, attempting to pick up objects, remove clothing, repeat words or phrases, etc
Generalized tonic-clonic
  • Formerly known as “grand mal” seizures and is what most people think of when they hear the word seizure
  • Person loses consciousness or awareness, muscles extend and become rigid, and then muscles jerk rhythmically on both sides of the body 
Infantile spasms
  • Occur within first year of life, usually by 4 to 8 months
  • Typically seen as a sudden bending forward of the body with stiffening of the arms and legs lasting for a few seconds
  • Some infants arch their backs as they extend their arms and legs
  • Frequently occur in clusters upon awakening or going to sleep
  • May look like a startle reflex in infants
Lennox-Gastaut syndrome (LGS)
  • Lennox-Gastaut syndrome (LGS) is a rare form of epilepsy that usually begins in childhood and is associated with multiple kinds of seizures.
Myoclonic
  • Sudden, brief shock-like muscle movements or jerks that usually don’t last more than a second or two
  • Person is alert
  • May occur in clusters and may be more pronounced upon wakening 
Personality disorders
  • Such as oppositional disorders
Renal problems
  • Problems with the kidneys
Severe aggression
  • Aggression that is extreme or unpredictable
Skin problems
  • Including bumps on skin or white spots
Sleep disturbances
  • Difficulty sleeping or staying asleep
Strange eye movements
  • Such as gazing or staring
Tonic
  • Muscles in the body, arms, or legs suddenly become stiff or tense
  • May happen during sleep or can cause a person to fall if standing
  • Typically lasts for less than 20 seconds at a time 
Tuberous sclerosis complex (TSC)
  • Tuberous sclerosis complex (TSC) is a genetic condition characterized by the development of noncancerous tumors that may cause a range of symptoms, including seizures.