CHAPTER 30: Epilepsy and B Vitamins

Some rare B vitamin disorders, acquired or genetic, may cause brain disorders with seizures, such as ‘pyridoxine dependent seizures’ and ‘cerebral folate deficiency’. Epilepsy is a common disease and antiepileptic drugs are often the best treatment option. Some of the many adverse effects of antiepileptic drugs due to disturbances of B vitamin status. Antiepileptic drugs, primarily those with inducer effects on liver enzyme activity, may cause a low status of folate and vitamins B₆ and B₂. Vitamin B₁₂ is usually within normal range. Data on thiamine and biotin are inconclusive. A low B vitamin status in patients on antiepileptic drugs has been related to the occurrence of megaloblastic anaemia, neuropsychiatric symptoms, foetal malformations and vascular disease. Plasma homocysteine may be employed as an indicator of B vitamin status in clinical practice. Folic acid is commonly prescribed to patients on antiepileptic drugs, primarily women of childbearing potential. Many patients with epilepsy should take prophylactic B vitamin supplements in physiologic doses (multivitamins). However, there is sparse evidence that B vitamin supplements can prevent adverse effects of antiepileptic drugs.