Last reviewed 08/2021

Seizures are episodes during which there is disturbance of the function of the brain, which may be manifested as abnormality of motor activity, behaviour, sensation, consciousness or of autonomic function.

The term is often used synonymously with epilepsy; however it has a more diverse aetiology and the clinician should certainly refrain from diagnosing a first seizure as epilepsy.

If first seizure (1):

  • differential diagnosis of a first seizure is wide
  • necessitates individual counselling about the risk of recurrence, the pros and cons of drug treatment, and the impact on lifestyle
  • if provoked by an acute brain disturbance is unlikely to recur (3-10%), whereas a first unprovoked seizure has a recurrence risk of 30-50% over the next two years
  • in many cases a presentation for the first time with a convulsive seizure have had prior unrecognised seizures
  • a seizure can be diagnosed only by the history, but investigations should include prompt electroencephalography and usually magnetic resonance imaging
  • in most cases, after counselling, patients do not choose anti-epileptic drug treatment after a first seizure
  • driving restrictions: in the United Kingdom non-commercial driving is not permitted for 12 months after an unprovoked seizure


  1. Pohlmann-Eden B et al. The first seizure and its management in adults and children. BMJ 2006; 332:339-42.