The efficacy of the ketogenic diet in the treatment of intractable focal seizures was studied retrospectively in 34 patients (mean age, 7.5 yrs; range, 4 months to 29 yrs) and compared to 100 patients with generalized seizures at the Cleveland Clinic, OH. One fourth of focal seizure patients had more than a 50% reduction m seizure frequency after 3 months and 12 months, and 6 patients had more than 90% control. Generalized seizures responded more favorably, with 46% having a 50% reduction at 3 months and 42% at 12 months. Differences were not significant. Outcome tended to be better in Patients under 12 years of age. 
COMMENT. The ketogenic diet is a treatment option in young children with medically intractable focal seizures when surgery is not advised. Like antiepileptic drugs, however, the ketogenic diet may be accompanied by adverse events and treatment must be carefully monitored.
Adverse effects of the ketogenic diet. Wheless JW discusses the possible adverse events during initiation and maintenance of the ketogenic diet . These include the following: a) diet initiation adverse events: dehydration, hypoglycemia, and vomiting; and b) during diet maintenance: poor growth, kidney stones, hyperlipidemia, cardiomyopathy, prolonged QT interval, excessive bruising, optic neuropathy, elevated very-long-chain fatty acids, vitamin D deficiency, osteomalacia, trace mineral deficiencies, constipation, exacerbation of gastroesophageal reflux disease. Diseases that may be aggravated by the ketogenic diet include: porphyria, pyruvate carboxylase deficiency, carnitine deficiency, fatty acid oxidation defects, and mitochondrial disorders. Parents expecting that a diet treatment is “natural” and relatively innocuous should be counseled regarding risks. Deaths related to the ketogenic diet have been reported in 3 children (cardiac arrest, pneumonia, and acute hemorrhagic pancreatitis), and serious adverse events in 5 children included hypoproteinemia, hemolytic anemia, thrombocytopenia with bleeding, Fanconi’s renal tubular acidosis, and elevated liver enzymes. (Ped Neur Briefs July 2001;15:50-52).
The Hopkins method of introduction, using a period of starvation and maintenance of a 4/l;fat/nonfat ratio, appears to be more conducive to adverse events than the Mayo Clinic method that omits a starvation period and employs lower ratios.