Generalized Tonic Clonic Seizures Alone


  • Onset usually occurs in the second decade.
  • Generalised tonic clonic seizures (GTCS) can occur at any time with majority in the early morning often precipitated by sleep deprivation and other external factors.
  • The EEG shows generalised spike and wave discharges of 3 to 4 Hz and some with photic sensitivity.
  • This is potentially a lifelong epilepsy.
  • The seizures are usually well controlled with medication.

According to the NICE Guideline: The Epilepsies:

  • The seizure type(s) and epilepsy syndrome, aetiology, and co-morbidity should be determined.
  • If there is diagnostic uncertainty, individuals should be referred to tertiary services soon (within 4 weeks) for further assessment.


Age at onset

  • ~5 to 40 years (peak ~11-23 years); ~80% have their first GTCS in the second decade of life.


  • Common genetic generalised epilepsy of complex inheritance.

Signs | Symptoms

Seizure semiology

  • All patients suffer from GTCS.


  • Occurs predominantly on awakening or related to the sleep-wake cycle.

Neurological and mental state

  • Normal

Seizure-precipitating factors

  • Sleep deprivation, fatigue, and excessive alcohol consumption.

Differential diagnosis

  • Other generalised epilepsies, such as Juvenile Myoclonic Epilepsy and Juvenile Absence Epilepsy, which share the same propensity to GTCS on awakening.
  • Genetic Epilepsies with Febrile Seizures Plus.
  • Focal epilepsy with exclusion of patients with seizure evolution to bilateral convulsive. Any focal features on history or examination should prompt neuro-imaging.



  • Usually normal background, with generalized spike and wave or generalised polyspike and wave.


Epilepsy with GTCS alone on awakening is probably lifelong with a high incidence of relapse upon withdrawal of treatment.


  • Avoidance of seizure precipitants.
  • Sodium valproate can be considered and is usually an effective drug for males, but in women of child bearing age, teratogenicity is a major concern. Other AEDs that may be useful include: levetiracetam, lamotrigine, and clobazam.
  • Sodium valproate has been associated with significant concerns of teratogenicity (i.e. malformations, cognitive impairment, and Autistic Spectrum Disorder). This is particularly true at higher dosages. The risk of teratogenicity increases with increasing dosage. It is important clinicians and women of child bearing age are aware of this risk. Ideally, pregnancies in women with epilepsy should be planned and managed by a neurologist. Medication choices should be selected and discussed keeping in mind the safety of mother and foetus.

Discussion with family


Epilepsy Action (UK) have information for Parents on Generalized Tonic Clonic Seizures



Information last reviewed: 14/01/2021.



  • Panayiotopoulos CP. The epilepsies: Seizures, syndromes and management: Based on the ILAE classifications and practice parameter guidelines. Chipping Norton, Oxfordshire: Bladen Medical Publishing; 2005.
  • Roger J, Bureau M, Dravet C, Genton P, Tassinari CA, Wolf P, editors. Epileptic syndromes in infancy, childhood and adolescence (4th ed).  Montrouge, France: John Libbey Eurotext Ltd ; 2005.