• Epilepsy with generalized tonic-clonic seizures alone (EGTCS) starts between 5 and 40 years of age. 
  • A family history of epilepsy is common.
  • Genetics of EGTCS is complex.   
  • Generalized tonic-clonic seizures occur in everyone with this syndrome. They happen most often within 1 to 2 hours of waking up from sleep, which is why it is also known as epilepsy with tonic-clonic seizures on awakening.  
  • Common triggers for EGTCS include sleep deprivation, fatigue, alcohol, fever, menstrual cycle, and flashing lights (photosensitivity).
  • Treatment with seizure medications is usually needed long term.

What is epilepsy with generalized tonic-clonic seizures alone?

Epilepsy with generalized tonic-clonic seizures alone (EGTCS) was first described by Dr. Dieter Janz from Germany in 1962. This epilepsy syndrome used to be called grand mal seizures on awakening and are now sometimes called epilepsy with tonic-clonic seizures on awakening.

  • These tonic-clonic seizures upon awakening may start between 5 and 40 years of age. In 8 out of 10 people, it starts in teens and young adults between the ages of 11 and 23 years old. 
  • A family history of epilepsy is common in 2 out of 10 people. A family history of febrile seizures has been reported in 1 out of 10 people.  
  • The genetics of EGTCS is complex. Mutations or changes on a specific gene (CLCN2 gene) have been linked to this syndrome. There may be other mutations too.
  • People with this epilepsy syndrome have normal neurological exams. Their development and cognition (for example thinking and memory) are typically normal.

What do seizures in people with EGTCS look like?

  • People with this syndrome (EGTCS) have generalized tonic-clonic seizures most of the time on awakening or within 1 to 2 hours of waking up from sleep. This is why it is also sometimes called epilepsy with tonic-clonic seizures on awakening. Sometimes these seizures can be seen when a person is asleep or during awake hours.
  • Before seizure medicines are started, seizures may be frequent in 2 out of 10 people. 
  • This epilepsy syndrome is used to describe people who only have tonic-clonic seizures upon awakening. Yet some reports of absence and myoclonic seizures with this disorder have occurred.  
  • Seizures in people with EGTCS may be provoked by sleep deprivation, fatigue, alcohol, fever, menstrual cycle, or flashing lights (photosensitivity).

How is EGTCS diagnosed?

EGTCS is diagnosed based on the description of the seizures and when they occur. Other information is obtained from tests such as:

  • EEG (electroencephalogram): people with EGTCS have normal EEG background and generalized spike wave or polyspike wave activity. The spike wave activity is seen in sleep in 1 out of 2 people. Specific EEG changes may be seen during photic stimulation. EEG abnormalities are more likely or increased with sleep deprivation and during sleep.  
  • MRI (magnetic resonance imaging) of the brain: people with EGTCS have a normal MRI of the brain.

How is EGTCS treated?

  • These seizures are typically controlled with anti-seizure medications like valproic acid/divalproex, lamotrigine, levetiracetam, topiramate, and zonisamide. 
  • People with EGTCS should avoid sleep deprivation, alcohol, or flashing lights (due to photosensitivity). 
  • People with EGTCS who have long seizures may need emergency medical treatment or treatment with a rescue therapy, such as diazepam rectal gel (Diastat) or another form on benzodiazepine given into the nose (intranasally) or under the tongue.
    • Talk to your treating neurologist or health care provider to learn about seizure emergencies.
    • Talk to your health care team about what kind of rescue therapy could be used and when to use it.
    • When seizures last longer than usual or if a generalized seizure lasts too long (generally considered 5 minutes or longer), a child may need emergency medical care

What is the outlook?

Over 3 of 4 people with EGTCS will require seizure medication throughout their life. The outlook or prognosis is variable – some people can be controlled with medication, while others may have tonic-clonic seizures that become frequent and less dependent on sleep-wake cycle or other triggers. 

Authored by: Angel W. Hernandez MD | Pediatrics Editor on 6/2016