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 epilepsy with tonic-clonic seizures on awakening.

  • The generalized tonic-clonic seizures begin 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. In most cases, no genetic mutations are found, however, rarely, 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. 
  • This epilepsy syndrome is used to describe people who only have tonic-clonic seizures, typically upon awakening.
  • 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, although this test may not be needed in typical cases.

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.
    • 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: 
Charuta Joshi MBBS
Authored Date: 
Reviewed By: 
Elaine Wirrell MD
Thursday, July 16, 2020