What is Lennox-Gastaut Syndrome?
Lennox-Gastaut Syndrome (LGS) is a rare form of epilepsy that is characterized by multiple seizure types, cognitive deficits and spike-and-wave complexes on the EEG. Causes of LGS are varied- ‘structural’ causes include injury during birth, asphyxia, premature birth and infections of the brain. Other cases, where a definite cause cannot be found are called ‘cryptogenic’. Symptoms of LGS usually appear between the second and sixth year of life, and is associated with refractoriness to anti-epileptic drugs (meaning conventional drugs for epilepsy do not work in children with LGS). Complete recovery is unusual, but there are treatment options to decrease seizure frequency and improve quality of life.
What is the ketogenic diet?
The ketogenic diet is a high fat, adequate protein and low carbohydrate diet that has shown to be effective in refractory epilepsy. In fact, this diet was discovered when fasting was shown to produce a decrease in seizure frequency. How the ketogenic diet is effective is the subject of ongoing studies. Normally the brain uses glucose as a source of energy. On the ketogenic diet, the main energy source is fat. This fat breaks down into ketone bodies (hence the name ‘ketogenic’ diet); research has shown that ketone bodies may have an anticonvulsant effect. Some side effects of the diet include dehydration, vomiting, hypoglycemia, constipation and vitamin and mineral deficiencies. Practical things to consider are issues with palatability and the cost of being on the diet.
Is the ketogenic diet effective in LGS?
Despite the efficacy of the ketogenic diet in refractory epilepsy, a proper study of its effectiveness in LGS in not fully known. Thus, a recent study asked whether the ketogenic diet was effective in LGS.
61 children with LGS (both cryptogenic and structural) were recruited, admitted into the hospital, and the ketogenic diet comprising of a 4:1 ratio of fat: protein + carbohydrate was gradually initiated after fasting. A seizure diary was maintained, and EEG records were acquired before starting the diet, during and after the diet. Blood and lipid profiles were also collected. Children remained on the ketogenic diet for a variety of time intervals- the minimum being 18 months.
When seizure frequency and EEG profile after being on the ketogenic diet were observed, the results were quite encouraging. A complete seizure freedom in 20% of children, and substantial reduction in seizure frequency in 50% of the children was observed. Before starting the diet, EEG abnormalities were found in all children; in cases where the diet was effective, normalization in EEG characteristics was seen. So much so that, in cases where the ketogenic diet was most effective, it was possible to reduce the dose of anti-epileptic drugs.
Hence, the ketogenic diet had a good response in LGS such that children with both cryptogenic and structural causes of LGS benefitted from the diet. Benefit was seen both behaviorally (a reduction in seizure frequency), and in normalization of epileptiform activity in EEG. Hence, the authors of the study suggest that it may be worthwhile initiating the ketogenic diet much earlier in a child with LGS, rather than being a last resort.