The short answer is pyridoxal phosphate, but before reaching for the prescription pad it’s worth looking at the context. Intractable seizures have no set definition.¹ One practical approach is to review management when seizures continue despite the use of two appropriate anticonvulsants at maximum tolerated doses. Points to consider include whether the diagnosis is correct, as syncope and other non-epileptic events can still mislead; the cause of the seizures, for example structural, chromosomal, neurodegenerative, or metabolic conditions; whether there is an avoidable precipitant; whether the choice of drug and dose were correct, as for example carbamazepine can exacerbate some primary generalised epilepsies; and compliance.¹ Treatment options include other anticonvulsants; drugs such as vitamins, acetazolamide, or steroids; IVIG; specific diets; resective and other types of surgery, the vagal nerve stimulator, and a variety of other approaches such as yoga, epilepsy dogs, etc.

Pyridoxine dependency is a rare but well described recessive condition whose biochemical and genetic cause is unknown. It classically presents with a neonatal epileptic encephalopathy but can present with seizures later in childhood as well. For this reason it is included in the various metabolic encephalopathies with seizures which are excluded by a trial of vitamins such as pyridoxine, folinic acid, or biotin.² As early treatment may improve the …