Can you predict an immediate, complete, and sustained response to the ketogenic diet?

Purpose: Although the ketogenic diet has been in use for >80 years, little agreement exists as to which patients are most likely to have dramatic, sudden, and complete seizure control. Methods: A case-control study was performed of children with intractable epilepsy started on the ketogenic diet at our institution since June 2001. Patients with a dramatic response were defined as those becoming seizure free within 2 weeks of diet onset. These children were compared with all other patients treated with the diet over the same time period in terms of patient demographics, epilepsy characteristics, and diet parameters. Results: Eighteen early, dramatic responders over a 3-year period were identified and compared with 89 patients who were not similarly improved. The absence of complex partial seizures as the predominant seizure type (0 vs. 23%; p = 0.02) correlated with this dramatic success. The presence of infantile spasms (39% vs. 20%; p = 0.09) approached significance, but all other variables did not. Conclusions: An early, dramatic response to the ketogenic diet is more likely in patients with predominant seizure types other than complex partial. It may also be more likely to occur in children who have infantile spasms. In all other patient demographics and diet parameters, an equal likelihood of similar success was found.