Some experts define a patient as having refractory seizures if treatment fails to achieve seizure freedom for 12 months or more, for whatever reason (1). The generally accepted definition of refractory seizures was proposed by Berg: failure of two or more drugs and occurrence of one or more seizures per month over 18 months (2).

  1. P. Kwan and M.J. Brodie, Early identification of refractory epilepsy, N Engl J Med 342 (2000), pp. 314–39.
  2. A.T. Berg, B.G. Vickrey and F.M. Testa et al., How long does it take for epilepsy to become intractable? A prospective investigation, Ann Neurol 60 (2006), pp. 73–9.

Adapted from Elger CE, Schmidt D. Modern management of epilepsy. Epilepsy Behav 2008;12:501-39.

Authored by: Steven C. Schachter MD on 5/2008