Symptomatic Generalized Epilepsy

What is Symptomatic Generalized Epilepsy?

Symptomatic Generalized Epilepsy (SGE) refers to epilepsy syndromes in which the majority of seizures are generalized, but partial onset seizures can also occur. The types of generalized seizure that occur in SGE include myoclonic, tonic, atonic, atypical absence, and generalized tonic-clonic. Virtually any type of partial onset seizure can also occur, depending on the underlying brain pathology. Usually (but not always) there is a known underlying brain disorder or injury, which is often severe. These syndromes may occur in the setting of certain neurological diseases, such as Tuberous Sclerosis, or may be due to lack of oxygen at birth, trauma, infection, developmental malformations, chromosomal abnormalities or other causes. SGE syndromes typically begin in early life.

Some symptomatic generalized epilepsy syndromes are:

  • West Syndrome
  • Lennox-Gastaut Syndrome
  • Epilepsy with myoclonic-astatic seizures
  • Epilepsy with myoclonic absences
  • Early myoclonic encephalopathy
  • Early infantile epileptic encephalopathy with suppression burst
  • Progressive myoclonic epilepsies

How is SGE treated?

Antiepileptic medications are the mainstay of treatment in SGE, though certain syndromes may require additional treatments including ACTH or Immunoglobulin. The ketogenic diet may be helpful in some patients. The vagus nerve stimulator has been studied extensively in patients with SGE. In some patients it has been very helpful, while others have experienced no benefit. In patients with atonic, or drop, seizures, a surgical procedure called corpus callosotomy may help reduce the falls from seizures.

There are, however, some SGE syndromes in which other surgical options may be considered. In Tuberous Sclerosis, for example, where the epilepsy is often considered a SGE syndrome, certain tubers may be more epileptogenic than others. If such a tuber is found to be the cause of the most disabling seizures, removal of it could reduce the frequency of seizures.

What is the Prognosis of SGE?

The prognosis of SGE depends largely on the underlying cause of the seizures. For example, up to 15-30% of patients with West Syndrome without known cause become seizure free and have normal or near normal intelligence. However, patients with Lennox-Gastaut Syndrome or a progressive myoclonic epilepsy tend to have seizures throughout life, and some level of cognitive impairment.