Objectives: To evaluate the change in atonic or myoclonic seizures associated with the Lennox-Gastaut syndrome during the initiation of the ketogenic diet, and. to describe the development of a blinded crossover study of the efficacy of the ketogenic diet. Design: A before-after trial. Setting: The Johns Hopkins Hospital, Baltimore, Md. Patients: Change in clinical seizure frequency was examined in 17 consecutively treated patients with atonic or myoclonic seizures. In a few patients, a 24-hour ambulatory electroencephalogram was obtained before and after diet initiation. We demonstrated the ability to manipulate the ketosis induced by fasting with the addition of glucose (dextrose) in 1 patient. Interventions: Children fasted for 36 hours, and the diet was gradually introduced over 3 days. Parents were instructed to keep a baseline seizure frequency calendar for the month before the initiation of the diet. These calendars continued to be maintained as the diet was initiated. Main Outcome Measure: Seizure decrease from baseline. Results: The atonic or myoclonic seizures decreased in these children by more than 50% immediately. Using a 24-hour ambulatory electroencephalogram, we documented that the seizures reported by a parent represent only a fraction of the electroclinical events; the technique could be used to measure the profound decrease in electrically documented seizures. Ketosis was eliminated with glucose, 60 g/d. Conclusions: It is feasible to evaluate the ketogenic diet's efficacy in atonic or myoclonic seizures in a blinded, crossover study. The diet can be manipulated on a shortterm basis in a blinded manner, and ketosis can be achieved or eliminated.
