Which patients should be provided with this option?
The ketogenic diet is a treatment option for patients of all ages with pharmacoresistant epilepsy (7, 9, 10). Although the evidence to date of its effect is far stronger for children than for adults, our experience and that of others indicates that dietary therapy should also be considered in therapy-resistant adult patients.
For a long time, many regarded the diet as a 'last resort', but 81 % of the members of an international consensus group agreed that the diet should be attempted in children in whom two drugs had been tried without satisfactory effect, and where epilepsy surgery was not an option (7). In our opinion, dietary therapy should be considered in both children and adults who have not achieved control of their seizures after trying two relevant antiepileptic drugs and who do not want epilepsy surgery or for whom this is not an option.
The diet may be effective in focal as well as generalised forms of epilepsy (7, 9, 11). It may have an anti-seizure effect for a number of paediatric epilepsy syndromes, such as West syndrome, Dravet syndrome, Rett syndrome, Lennox-Gastaut syndrome, tuberous sclerosis and syndromes associated with defects in the respiratory chain (7).
The ketogenic diet is the first-line choice in certain rare metabolic encephalopathies such as glucose transport protein type 1 deficiency and pyruvate dehydrogenase deficiency, chiefly as a metabolic treatment of the underlying disorder (7). The diet has been attempted in adults and children with super-refractory status epilepticus, but the results are uncertain (9, 12).
In children under two years, such diets are used with caution because of the risk of malnutrition. On condition that close follow-up be provided by an interdisciplinary team, we believe that it will be relevant to attempt dietary therapy for this group as well – because it will often have a good effect in children (13).
Certain rare conditions are not amenable to dietary therapy. Examples include defects in fatty acid oxidation, primary carnitine deficiency, organic aciduria and pyruvate carboxylase deficiency. The ketogenic diet is also advised against in cases of familial hyperlipidaemias, unexplained hypoglycaemia, severe gastroesophageal reflux, severe liver disease and diseases that require a high intake of carbohydrate, such as porphyria (7). In patients with insulin-dependent diabetes, certain mitochondrial diseases and when steroids are used, the diet is also less suitable.