Lennox-Gastaut Syndrome (LGS)

Lennox-Gastaut syndrome (LGS) is a rare type of early-onset epileptic encephalopathy characterized by a triad of clinical features: multiple seizure types, a characteristic brain wave pattern found on electroencephalography (EEG), and intellectual impairment. Due to the limited efficacy of available pharmacological treatments, several nonpharmacological therapies such as dietary interventions have been investigated as treatment options. These mainly include the ketogenic diet and its modified versions, which have been reported as safe and effective in the treatment of patients with LGS.1,2

Ketogenic Diet

The ketogenic diet (KD) — a high-fat, moderate-protein, and low-carbohydrate diet — is used as a nonpharmacological therapy to provide seizure control in pharmacoresistant patients with LGS. Although the exact mechanism of action of the KD in preventing seizures is not clear, the diet helps to achieve a metabolic state of ketosis, similar to fasting or starvation, which has been shown to provide seizure control in patients with epilepsy.2,3

Although the classic KD (cKD) has often been effective in reducing seizures, many patients have trouble complying with its strict regimen. Thus, with the intention of improving tolerability, palatability, and administration, the cKD was modified into 3 less restrictive forms: the medium-chain triglyceride (MCT) diet, the modified Atkins diet (MAD), and the low glycemic index treatment (LGIT).2

A literature review of 18 papers from 1989 to 2010 on the use of the KD in children with LGS showed that 47% of the children experienced at least a 50% reduction in seizures and 16% of children became seizure-free 3 to 36 months following the initiation of the diet.2,4 Further studies from 2012 to 2020 in patients with LGS also show that the KD can provide at least a 50% reduction in seizures and seizure-free status in a considerable percentage of patients.2,5,6

The most commonly reported adverse effects associated with the KD are benign, such as constipation, diarrhea, and vomiting, while severe adverse effects such as nephrolithiasis or osteopenia are rarely reported.2

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Classic Ketogenic Diet

The cKD has existed the longest, as it was first designed in 1923 to treat patients with epilepsy. In this diet, the ratio of fat to carbohydrate and protein is typically 4:1 (fat:carbohydrate and protein) so that 90% of the total calories are from fat. The fat source in cKD is mainly long-chain triglycerides (LCTs), which are obtained from standard food.2,7

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Medium-Chain Triglyceride Diet

The medium-chain triglyceride (MCT) diet was introduced in the 1970s. The main source of fats are MCT oils, which yield more ketones per kilocalorie of energy than LCTs. This means that a lower amount of fat is required to achieve a state of ketosis. Because of this, more sources of protein and carbohydrates are allowed, increasing food choices.2,8

Modified Atkins Diet

The modified Atkins diet (MAD) was created in 2003 at John Hopkins Hospital, primarily to provide an easier and more palatable dietary platform for children and adolescents having difficulties following the cKD diet. The ratio of fat to carbohydrate and protein in the MAD is lower than that in the cKD, which means that this diet is composed of less fat and thus is more palatable. It typically provides an approximate ketogenic ratio of 1:1 to 1.5:1. 

The MAD initially allows the daily consumption of 10 to 15 g of carbohydrates, which can possibly increase to 20 g after 1 to 3 months. In addition, patients may have unlimited calories, protein, and fluids, which can reduce the worry of difficult meal preparation and planning, as no detailed calculations or accurate weights are necessary.2,9

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Low Glycemic Index Treatment

The LGIT, which was first discovered effective in 2005 at Massachusetts General Hospital, is a more liberal version of the cKD that allows the inclusion of more carbohydrates, decreasing the fat content and thus making it more palatable. In addition, the diet allows the unrestricted use of fats and proteins so that the food portions do not need to be weighed out and no hospital admission is needed. Although this diet includes a higher amount of carbohydrates (40 to 60 g per day), it restricts them to low-glycemic index sources of less than 50 to avoid increases in blood glucose. Adolescents, who usually have difficulty with the cKD, often prefer this diet.2,10

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  1. Winesett SP, Bessone SK, Kossoff EHW. The ketogenic diet in pharmacoresistant childhood epilepsy. Expert Rev Neurother. 2015;15(6):621-628. doi:10.1586/14737175.2015.1044982
  2. Skrobas U, Duda P, Bryliński Ł, Drożak P, Pelczar M, Rejdak K. Ketogenic diets in the management of Lennox-Gastaut syndrome—review of literature. Nutrients. 2022;14(23):4977. doi:10.3390/nu14234977
  3. Wheless JW. History of the ketogenic diet. Epilepsia. 2008;49(s8):3-5. doi:10.1111/j.1528-1167.2008.01821.x
  4. Lemmon ME, Terao NN, Ng YT, Reisig W, Rubenstein JE, Kossoff EH. Efficacy of the ketogenic diet in Lennox-Gastaut syndrome: a retrospective review of one institution’s experience and summary of the literature. Dev Med Child Neurol. 2012;54(5):464-468. doi:10.1111/j.1469-8749.2012.04233.x
  5. Wu Q, Wang H, Fan YY, et al. Ketogenic diet effects on 52 children with pharmacoresistant epileptic encephalopathy: a clinical prospective study. Brain Behav. 2018;8(5):e00973. doi:10.1002/brb3.973
  6. Na JH, Kim HD, Lee YM. Effective and safe diet therapies for Lennox-Gastaut syndrome with mitochondrial dysfunction. Ther Adv Neurol Disord. 2020;13:1756286419897813. doi:10.1177/1756286419897813
  7. Kossoff EH, Zupec-Kania BA, Auvin S, et al; Charlie Foundation; Matthew’s Friends; Practice Committee of the Child Neurology Society. Optimal clinical management of children receiving dietary therapies for epilepsy: updated recommendations of the International Ketogenic Diet Study Group. Epilepsia Open. 2018;3(2):175-192. doi:10.1002/epi4.12225
  8. Liu YMC. Medium-chain triglyceride (MCT) ketogenic therapy. Epilepsia. 2008;49(s8):33-36. doi.org/10.1111/j.1528-1167.2008.01830.x
  9. Kossoff EH, Dorward JL. The modified Atkins diet. Epilepsia. 2008;49(s8):37-41. doi:10.1111/j.1528-1167.2008.01831.x
  10. Pfeifer HH, Thiele EA. Low-glycemic-index treatment: a liberalized ketogenic diet for treatment of intractable epilepsy. Neurology. 2005;65(11):1810-1812. doi:10.1212/01.wnl.0000187071.24292.9e

Reviewed by Harshi Dhingra, MD, on 2/28/2023.