Bone health in people with epilepsy: is it impaired and what are the risk factors?

Diseases of the bone are becoming increasingly prevalent. Persons with epilepsy treated with antiepileptic drugs (AEDs) are at greater risk as evidenced by changes in bone turnover, osteoporosis, alterations in bone quality, and fracture. Biochemical indices of bone and mineral metabolism including calcium, vitamin D, parathyroid hormone, and bone turnover markers can be affected. AED exposure is a cause of secondary osteoporosis with decreased bone mineral density (BMD) secondary to poor bone accrual in children or accelerated bone loss in adults. Early reports described osteomalacia, a change in bone quality with increased unmineralized bone. Recent studies do not reveal osteomalacia, but there may be more subtle changes in bone quality. Multiple studies have found an increased risk of fractures in association with epilepsy and AED exposure. Cytochrome P450 enzyme inducing AEDs are most commonly associated with a negative impact on bone, but studies also suggest an effect of valproate. There is limited data regarding the newer AEDs. No single mechanism has emerged to explain all the changes in bone in association with epilepsy and AEDs. Although multiple therapies are available for the treatment of bone disease, there is limited study in persons with epilepsy. It is recommended that all persons obtain adequate amounts of calcium and vitamin D. In addition BMD screening is warranted for persons with long-term AED exposure particularly if they have other risk factors for bone disease.