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Ketogenic Diet

Description

The ketogenic diet is a high fat, adequate protein, low carbohydrate diet used to control refractory epilepsy. Although it is unclear exactly how the diet works to control seizures, the child enters a state of ketosis while on the diet, utilizing ketones as an energy source instead of glucose. The diet is quite restrictive; even small amounts of carbohydrate can stop the ketosis and lead to a breakthrough seizure. Ketogenic diets are generally used as secondary therapy after first line medications fail. Although it is not a medication and has no sedative side effects, the diet is not without side effects and risks; these include nausea/vomiting, constipation, high cholesterol (which may be reversed when the diet is stopped), hypoproteinemia, disturbances in liver function, hemolytic anemia, growth failure, kidney stones, osteoporosis, impaired immune response, abnormal heart rhythms, and even death. [Groesbeck: 2006] Adherence to and adequacy of the diet is measured by urine dipsticks for ketones. 90% seizure reduction is achieved in approximately 1/5 [Keene: 2006] to 1/3 of patients; 50-90% seizure reduction is achieved in another 1/3, and another 1/3 either have no improvement or are unable to maintain the diet. Common reasons to discontinue the diet include a less than desirable seizure reduction, side effects, and the limited diet options. [Henderson: 2006] The diet must be carefully calculated each day for the prescribed ratio of fat to protein plus carbohydrate. Free ketogenic diet software is available, for example see Ketogenic diet information (Stanford University). A modified Atkins diet has also been tried and may be helpful in the control of intractable seizures. [Kang: 2007] [Kossoff: 2008]

Selection of patients

Most physicians will use the ketogenic diet only after the patient has not achieved seizure control on antiepileptic medication. The diet is very rigorous and needs patient, family, and school cooperation. There must be some assurance that patients will not "cheat" either because they are unable to feed themselves due to youth or disability or because they understand the goals of the diet. Children who are developmentally unable to comprehend the needs of the diet but who are mobile and able to feed themselves are not good candidates as it is impossible to control their behavior over the long term. Unless medical side effects intervene, patients and families should stick to the diet for 2 months before deciding on its efficacy.

What to expect during ketogenic diet initiation

Patients are started on a fast after eating dinner the night before they enter the hospital. Upon arrival, intense education regarding the diet is begun and monitoring of the patient for blood glucose, hydration and ketosis is started. Baseline studies such as EEG, EKG, and metabolic laboratory testing may be performed. The fast is continued until ketosis is achieved (usually 1-2 days) and then a reduced-calorie ketogenic diet is started. Calories are gradually increased over the next few meals to the full caloric requirement as calculated by the nutritionist to provide a ratio of (fats):(carbohydrates) of 3-4:1. Careful monitoring and education continue until the family is comfortable with the diet. Frequent follow-ups with the pediatric neurologist are necessary over the first weeks and months after discharge. Families continue to serve the ketogenic diet meals and monitor urine ketones and seizure frequency. Over the counter and prescription medications as well as vitamins need to be included in the daily diet plan since they may contain carbohydrates. Antiepileptic medications, which will be continued at first, will be adjusted as necessary for the diet and the number of seizures. Depakote and topiramate, especially, need careful monitoring while the child is on these medications and the diet.

Discontinuing the diet

After a decision has been made to stop the diet, the child is weaned off it gradually.

Resources

Helpful Articles

Zupec-Kania B, Zupanc ML.
Long-term management of the ketogenic diet: seizure monitoring, nutrition, and supplementation.
Epilepsia. 2008;49 Suppl 8:23-6. PubMed abstract

Zupec-Kania BA, Spellman E.
An overview of the ketogenic diet for pediatric epilepsy.
Nutr Clin Pract. 2008;23(6):589-96. PubMed abstract

Kossoff EH, Dorward JL.
The modified Atkins diet.
Epilepsia. 2008;49 Suppl 8:37-41. PubMed abstract

Authors

Author: Lynne M Kerr, MD, PhD - 6/2011

Page Bibliography

Groesbeck DK, Bluml RM, Kossoff EH.
Long-term use of the ketogenic diet in the treatment of epilepsy.
Dev Med Child Neurol. 2006;48(12):978-81. PubMed abstract

Henderson CB, Filloux FM, Alder SC, Lyon JL, Caplin DA.
Efficacy of the ketogenic diet as a treatment option for epilepsy: meta-analysis.
J Child Neurol. 2006;21(3):193-8. PubMed abstract

Kang HC, Lee HS, You SJ, Kang du C, Ko TS, Kim HD.
Use of a modified Atkins diet in intractable childhood epilepsy.
Epilepsia. 2007;48(1):182-6. PubMed abstract

Keene DL.
A systematic review of the use of the ketogenic diet in childhood epilepsy.
Pediatr Neurol. 2006;35(1):1-5. PubMed abstract

Kossoff EH, Dorward JL.
The modified Atkins diet.
Epilepsia. 2008;49 Suppl 8:37-41. PubMed abstract